- Email: [email protected]
The effect of saddle nose width and cutout on saddle pressure distribution and perceived discomfort in women during ergometer cycling
Applied Ergonomics 70 (2018) 175–181
Contents lists available at ScienceDirect
Applied Ergonomics journal homepage: www.elsevier.com/locate/apergo
The effect of saddle nose width and cutout on saddle pressure distribution and perceived discomfort in women during ergometer cycling
T
Anna Sofie Larsen, Frederik G. Larsen, Frederik F. Sørensen, Mathias Hedegaard, Nicolai Støttrup, Ernst A. Hansen, Pascal Madeleine∗ Sport Sciences, Department of Health Science and Technology, Aalborg University, Denmark
A R T I C LE I N FO
A B S T R A C T
Keywords: Bicycling Discomfort Gender Saddle design Variability
The objectives were 1) to design and produce two novel unpadded bicycle saddles with a wide/medium width and partial nose cutout; 2) to investigate the responses on pressure distribution and perceived discomfort in female cyclists. For comparison, a standard saddle was also tested. Nineteen female cyclists pedaled on an ergometer cycle for 20 min with each saddle in a counterbalanced order. A pressure mat measured saddle interface pressure. Discomfort ratings were collected using a visual analogue scale. Total mean saddle pressure remained similar across saddles. The wide saddle increased anterior and decreased posterior mean saddle pressure as compared with the standard (p < .002) and the medium saddle (p < .001). Significantly increased ischial tuberosity discomfort was found for the novel saddles (p < .001), while crotch discomfort was not significantly different between saddles. The medium width saddle appeared to be the best compromise since increased crotch discomfort was avoided and saddle pressures were redistributed. Such design may be suggested as an alternative to traditional saddles for women reporting discomfort in the perineal region.
1. Introduction Cycling is a popular recreational activity with a number of associated health benefits including reduced all-cause mortality, risk of cardiovascular diseases and cancer (Hallal et al., 2012). For competitive cycling, cyclists adopt a more sportive position and spend more time on the saddle. This can lead to discomfort and injuries in the perineal region (Hermans et al., 2016). Frequently reported saddle-related complaints and injuries among women (Table 1) include urinary complaints, sexual dysfunction, vulvar hypertrophy, pain, tenderness and numbness in the perineal region (Hermans et al., 2016; Trofaier et al., 2016). Perineal pain, tenderness, numbness and sexual dysfunction are believed to be caused by compression of the pudendal neurovascular bundle (Dettori and Norvell, 2006; Partin et al., 2014; Trofaier et al., 2016). Particularly, pressure below the pubic symphysis (Gemery et al., 2007) has been suspected to cause compression of the pudendal nerves and arteries in females during cycling (Leibovitch and Mor, 2005). Urological dysfunction, skin lesions, vulvar hypertrophy, and genital and perineal discomfort are likely to be caused by increased pressure on the genitals from sitting on a saddle (Leibovitch and Mor, 2005). However, the existing knowledge regarding the cause of complaints and injuries is still limited (Trofaier et al., 2016). Saddle manufacturers have presented various innovative saddle
∗
designs as alternatives to the traditional standard saddle. The aims have been to decrease discomfort and the risk of non-traumatic saddle-related injuries by reducing pressure on the perineal area. Saddles with partial (fully removing middle section of the saddle nose) or complete (saddle without protruding nose) cutout design have been produced (Asplund et al., 2007). Several studies have compared innovative and standard saddle designs (Bressel and Larson, 2003; Chen and Liu, 2014; Keytel and Noakes, 2002; Bressel et al., 2009b). Complete nose removal obviously entails a reduced saddle area to compress the perineal area, thereby reducing the perineal pressure and reduced discomfort compared with other saddle designs (Bressel et al., 2009b; Chen and Liu, 2014). On the other hand, removing the saddle nose impairs the perceived riding stability (Bressel et al., 2009a; Chen and Liu, 2014). This is perhaps the reason why a complete cutout saddle is often unpopular among competitive cyclists (Schwarzer et al., 2002). Cycling with saddles using a grooved or partial cutout saddle design (partially removing middle section of the saddle nose, leaving a hollow section or fully removing middle section of the saddle nose), has led to equivocal results. Studies have shown that with a partial cutout design it is possible to decrease numbness (Taylor et al., 2002) and increase comfort (Keytel and Noakes, 2002). Additionally, Gemery et al. (2007) found that a grooved saddle design similar to a partial cutout design entailed better preservation of the symphysis space and reduced
Corresponding author. Sport Sciences, Dept. of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers vej 7, 9220 Aalborg Ø, Denmark. E-mail address: [email protected] (P. Madeleine).
https://doi.org/10.1016/j.apergo.2018.03.002 Received 15 November 2017; Received in revised form 26 January 2018; Accepted 5 March 2018 0003-6870/ © 2018 Elsevier Ltd. All rights reserved.
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
Table 1 Articles reporting types and prevalence of non-traumatic saddle related discomfort and injuries in female cyclists. Author(s)
N
Participants
Average training
Saddle related discomfort and injuries
Baeyens et al. (2002)
6
Competitive female cyclists
463 km/week
Battaglia et al. (2009)
6
6.6 h/week
Buller (2001)
52
Horseback and mountain bike female riders Female cyclists
Unilateral chronic swelling of the labium majus, typical unilateral lymphoedema and regularly inflammatory skin prevalence. Clitoral micro-calcifications (83%) and perineal tenderness or discomfort.
Christiaans and Bremner (1998) Guess et al. (2006) Hermans et al. (2016)
56
Not reported
48 114
Cycling conference female attendants Female cyclists Female recreational cyclists
Humphries (2002) LaSalle et al. (1999) Wilber et al. (1995)
4 333 224
Female competitive cyclists Female cyclists Female recreational cyclists
Not reported
Burning sensation or pain in the perineum (81%) and perineal numbness (70%). Discomfort when riding (74%) and saddle soreness (29%).
Minimum 16.1 km/week Per season: < 1000 km: 6/114 (5.3%) 1000-3000 km: 63/114 (55.3%) 3000-5000 km: 23/114 (20.2%) > 5000 km: 22/114 (19.3%) Not reported Not reported 103.2 km/week
Genital pain, tingling or numbness during the last month (60%). Vulvar discomfort (40%), numbness of external genitals (35%), numbness of perineum (6%) and perineal pain (4%).
Unilateral vulvar hypertrophy. Perineal numbness (34%). Perineal pain, numbness, soreness, swelling of soft tissue, skin irritation and “pain in the butt”.
Fig. 1. Geometry top part specifications of the three saddle designs; a standard saddle without a partial cutout (standard), a saddle with a narrow partial cutout (medium), and a saddle with a wide partial cutout (wide). The top part of the saddles was made of obomodulan® 500 (OBO-Werke, Stadthagen, Germany) mounted on a custom aluminum alloy base.
in female cyclists. The purpose of the present study was to fill that gap. Therefore, we designed, produced and investigated the acute effects of two novel saddle nose cutout designs (medium and wide) on pressure distribution and perceived discomfort compared with a standard saddle design (standard). It was hypothesized that 1) changing the saddle nose design from a standard design to a cutout design would change pressure distribution and size of center of pressure (COP) variability in anteriorposterior direction, 2) a cutout saddle design would decrease crotch discomfort without changing the ischial tuberosity discomfort compared with a standard saddle.
compression of the pudendal arteries and nerves. Further, Sommer et al. (2010) argued that a wider partial cutout is more protective of perineal compression. In contrast, others have reported that partial cutout saddles increase pressure around the cutout, resulting in increased perineal pressure (Partin et al., 2012; Froböse et al., 2003). In a review by Partin et al. (2014), it was concluded that partial cutout saddles do not offer a protective effect of the female perineum. However, the partial cutout saddles might have been too narrow to show a protective effect. Thus, increasing the width of the saddle nose and cutout could decrease the pressure applied to the perineal area and thereby reduce discomfort and risk of injury (Sommer et al., 2010). The equivocal results found may be explained by geometric differences among the tested saddles. To our knowledge, no study has (i) designed and produced saddles of similar surface areas with different saddle nose and partial cutout width and; (ii) subsequently investigated the influence on pressure and discomfort
176
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
2. Methods 2.1. Participants Nineteen recreational female cyclists (23.4 ± 1.9 years, 66.7 ± 8.4 kg, 1.68 ± 0.04 m) volunteered to participate after receiving information about the study. Participants were included if they cycled between 1 and 6 h per week, were free from injuries in the lower extremities and pain in the perineal area within the preceding 6 months. The participants cycled on average 4.1 ± 1.6 h per week. All participants signed an informed consent prior to participation. The study was carried out in accordance with the Helsinki declaration and approved by the local ethics committee (N-20160023). 2.2. Saddle design Three unpadded saddles (standard, medium and wide) with different nose geometries were designed based on commercially available saddles and modeled (Fig. 1) in SOLIDWORKS (Dassault Systémes, Vélizy, France) and manufactured in-house (Aalborg University, Denmark). The saddles consisted of a top part made of obomodulan® 500 (OBO-Werke, Stadthagen, Germany), which was mounted on a custom aluminum alloy base. A custom-made aluminum alloy seat post piece, designed to fit the standard SRM seat tube was attached to the base and enabled fixation to the ergometer bike. All three saddles were designed with different nose geometries, but with identical posterior geometry based on recommendations by (Sequenzia et al., 2016; Spears et al., 2003) and in line with the rules of the Union du Cyclisme International1 (Fig. 1). We decided not to add cushioning considering the relationship between seat dimensions, seat shape, seat material and interface pressure is unclear (Hiemstra-van Mastrigt et al., 2016). With respect to the anterior part, the standard saddle was designed with a 4 cm outer nose width and an overall surface area of 160 cm2. The medium saddle was designed as a partial cutout saddle with a 2 cm cutout, an outer nose width of 6 cm and an overall surface area of 152 cm2. The wide saddle was designed as a partial cutout saddle with a 4 cm cutout, an outer nose width of 8 cm and an overall surface area of 157 cm2.
Fig. 2. Experimental setup showing a female cyclist pedaling on an ergometer cycle. A pressure mat measured saddle interface pressure. A visual analogue scale was used to collect discomfort ratings.
Arm length (right side) was measured from the superior part of acromion to the heads of the first metacarpalia. Torso length was measured from seat to incisura jugularis of the manubrium sterni. The mean ± SD (cm) of the torso length, arm length, inseam length, hip width and thigh circumference were respectively 57.1 ± 1.8, 64.3 ± 3.0, 79.5 ± 3.3, 35.0 ± 2.4 and 60.4 ± 5.7 cm. Saddle height, setback and reach were set according to previous existing recommendations; the saddle height, the distance between the middle of the saddle and the top of the pedal spindle at the bottom dead center pedal position, was set as recommended at 107% of inside leg length (De Vey Mestdagh, 1998). The saddle setback was set, so that it was possible to follow a straight line from the fifth-metatarsal to the inferior pole of patella when the crank arm was positioned at the 90° horizontal forward parallel position (Silberman et al., 2005). Reach distance was determined from table values based on torso and arm length (De Vey Mestdagh, 1998). Handlebar height was 6 cm below saddle height (Bressel and Larson, 2003; Silberman et al., 2005). Participants wore their own sports shoes and tights without padding to avoid influence on perceived discomfort (Marcolin et al., 2015). When seated, participants were asked to keep their hands steadily positioned on the top of the handlebars and refrain from changing position or standing up after initial seating to eliminate potential sliding of the pressure mat and pressure relief. Saddle pressure distribution was collected by the pressure mat at a sample frequency of 25 Hz. Static measurements of saddle pressure distribution at right leg crank angle 0-90-180-270° were collected for 1 s, prior to each bout. For dynamic measurements, participants rode for 20 min with a constant power output of 150 W throughout all bouts and were told to maintain a cadence as close to 80 rpm as possible (78.9 ± 2.1 rpm, cadence was monitored and displayed). A 10 min rest period was given between each 20 min ride. Saddle pressure data was collected during cycling over a 55 s interval between min 19-20. The local body discomfort were obtained from all participants using a VAS (Bressel et al., 2009b; Chen and Liu, 2014). The experimenters
2.3. Study design and experimental setup The subjects participated in a single laboratory session lasting 2 h in which each participant tested all three saddles in a counterbalanced cross-over design to account for eventual trial order effect. Participants rode an SRM ergometer (Schoberer Rad Messtechnik, Jülich, Germany) in a controlled environment (21 ± 2 °C). A pressure mat (S2119, Novel, München, Germany) made of flexible Lycra® material and containing 512 sensors, each with a sensing area of 1 cm2, arranged in 16 rows × 32 columns, was used for measuring pressure between body and saddle. The S2119 was calibrated for pressure range 0–360 kPa. Accuracy was tested by applying a 10 kg weight on 4 different positions on the sensor mat area (mean force deviation was 3.6 ± 1.7%). Further, static (standing and sitting) and dynamic (cycling) tests were performed prior to the series of recordings. A 10 cm digital visual analog scale (VAS) (Aalborg University, Denmark) was used to assess perceived discomfort (Fig. 2). 2.4. Procedure Anthropometric measurements (inside leg length, arm length, height, torso length) were measured using a BIO SIZE anthropometric measurement tool (Bicisupport Srl, Casatenovo, Italy) and used for bike fitting. Inside leg length was measured barefooted from floor to pubis. 1 http://www.uci.ch/mm/Document/News/Rulesandregulation/16/51/61/ ClarificationGuideoftheUCITechnicalRegulation-2017.01.01-ENG_English.pdf.
177
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
Table 2 Mean ± SD of the dependent variables for standard, medium, and wide saddle design as well as differences between saddles (N = 19). Saddle Design Variables
Standard (No cutout)
Medium (Narrow Cutout)
Wide (Wide Cutout)
Ischial tuberosity discomfort (cm) Crotch discomfort (cm) Static total mean pressure (kPa/kg) Static anterior mean pressure (kPa/kg) Static posterior mean pressure (kPa/kg) Dynamic total mean pressure (kPa/kg) Dynamic anterior mean pressure (kPa/kg) Dynamic posterior mean pressure (kPa/kg) SD COP anterior-posterior direction (cm)
4.5 ± 2.8 2.7 ± 2.9 0.29 ± 0.04 0.18 ± 0.12 0.34 ± 0.08 0.31 ± 0.05 0.24 ± 0.14 0.35 ± 0.05 0.28 ± 0.11
5.8 ± 2.8a 1.3 ± 1.5 0.30 ± 0.06 0.23 ± 0.15a 0.34 ± 0.11 0.32 ± 0.07 0.24 ± 0.14 0.36 ± 0.07 0.21 ± 0.08a,c
6.5 ± 2.3a 1.7 ± 2.2 0.27 ± 0.05 0.31 ± 0.16a,b 0.25 ± 0.12a,b 0.31 ± 0.05 0.36 ± 0.16a,b 0.29 ± 0.08a,b 0.29 ± 0.16b
a b c
Significantly different from the standard saddle. Significantly different from the medium saddle. Significantly different from the wide saddle.
presented an illustration of the buttock area with crotch and ischial tuberosity clearly represented and asked participants to rate their ischial tuberosity and crotch discomfort separately. Participants first rated crotch discomfort, followed by ischial tuberosity discomfort. Ratings were conducted immediately after pressure measurements. Zero represented “no discomfort”, and 10 represented “maximal discomfort”. The area of ischial tuberosity and crotch were considered to correspond to the posterior and anterior part of the saddle (Fig. 1), respectively.
two-way RM-ANOVA with saddle design (standard × medium × wide) and crank arm position (0-90-180-270°) as within subject factors was used. For dynamic tests, a one-way RM-ANOVA with saddle design (standard × medium × wide) as factor was applied. A least significant difference (LSD) test was used as post-hoc analysis if the RM-ANOVA reached significance. Mauchly's test of sphericity was applied during all ANOVA testing. If the data violated the sphericity assumption, Greenhouse-Geisser corrections were applied. Results were considered significant if p < .05.
2.5. Data analysis
3. Results
A custom written MATLAB script (MathWorks Inc., Natick, MA, USA) processed saddle pressure and VAS data. Pressure data was lowpass filtered using a 2nd order zero-lag Butterworth filter (5 Hz cut-off frequency) and normalized to body mass before sensors were segmented to represent each saddle surface area (Potter et al., 2008). Saddles were divided into an anterior and posterior part (Fig. 1) and pressure mat cells covering the cut-out were discarded to minimize hammocking effects (Ferguson-Pell and Cardi, 1993). Mean pressure was calculated as the average of all samples for each sensor for each trial (Bressel and Cronin, 2005). If sensors were saturated (> 360 kPa) for more than 10% of the sample duration, the data was discarded and replaced by interpolated values using adjacent sensors. Interpolation was conducted with the MATLAB built-in function ‘griddata.m’. Saturation issues were observed in 6.6 ± 2.8 cells across all mean dynamic measurements. Pressure values from the cells were used to calculate a total, anterior, and posterior mean saddle pressure. The center of pressure (COP) was calculated for each entire saddle using the segmented sensors (Chumanov et al., 2010) and subsequently used to calculate the size of variability, i.e., standard deviation COP trajectory in anterior-posterior direction. To control for trial order effect concerning discomfort between trials, the changes in discomfort over trials were assessed for both discomfort in crotch area and ischial tuberosity area.
No sign of trial order effect was found neither for ischial tuberosity discomfort (F(2, 36) = 0.421, p = .66) nor for crotch discomfort (χ2(N = 19, df = 2) = 0.58, p = .75). The mean ± SD of the ischial tuberosity discomfort were 5.8 ± 2.8, 5.6 ± 2.9 and 5.3 ± 2.5 after the first, second and third dynamic trial, while the mean ± SD crotch discomfort were respectively 2.3 ± 2.5, 1.6 ± 1.7 and 1.8 ± 2.3. The mean ± SD of the dependent variables are presented in Table 2.
There was no effect of saddle design on total mean saddle pressure in the four crank arm conditions (0-90-180-270°) for the static measurements (F(6, 108) = 1.528, p = .176). A significant effect of saddle design was found for anterior (F(2,36) = 18.71, p < .001) and posterior (F(2,36) = 9.68, p < .001) mean saddle pressure. Least significant difference post-hoc test revealed higher static anterior mean pressure for the wide saddle compared with the standard (p < .001) and the medium saddle (p < .001) and higher static anterior mean pressure in the medium saddle compared with the standard saddle (p = .03). Lower static posterior mean saddle pressure was found in the wide saddle compared with the standard saddle (p = .002) and the medium saddle (p = .005).
2.6. Statistical analysis
3.2. Saddle pressure – dynamic condition
Statistical analysis was conducted in SPSS 24.0 (IBM, Armok, NY, USA). All results are presented as mean ± standard deviation unless otherwise stated. Dependent variables that were not normally distributed, as determined by the Shapiro-Wilks test, were log-transformed. However, dependent variables that were not log-transformable (discomfort) due to zero values were kept as non-parametric data and analyzed using a Friedman test with saddle (standard × medium × wide) as factor. For static pressure recordings, a
Fig. 3 shows the mean dynamic pressure distribution for the three saddles for a representative participant. There was no significant effect of saddle design on total mean saddle pressure for the dynamic measurements (F(2,36) = 0.18, p = .84). A significant main effect of saddle design was found for dynamic anterior (F(2,36) = 11.505, p < .001) and posterior (F(2,36) = 11.498, p < .001) mean saddle pressure. Post hoc analyses showed a higher dynamic anterior mean saddle pressure for the wide saddle compared with the standard (p = .002) and the
3.1. Saddle pressure – static condition
178
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
Fig. 3. Pressure distribution for the standard, the medium, and the wide saddle for one representative participant over 55 s for min 19-20 during ergometer cycling. The x and y axes represent the coordinate system used when computing the center of pressure in the medio-lateral and anterior-posterior direction, respectively.
medium saddle (p < .001). The wide saddle also displayed a lower posterior mean saddle pressure compared with the standard (p = .003) and the medium saddle (p < .001).
Table 3 Overview table of significant differences between saddle designs. Variables
3.3. Center of pressure A significant main effect of saddle design was found for the SD of COP in anterior-posterior direction (F(2,36) = 5.46, P = .008). The post-hoc analysis showed lower SD of COP in the medium saddle compared with the standard (p < .001) and the wide saddle (p = .01).
Ischial tuberosity discomfort Crotch discomfort Static total mean pressure Static anterior mean pressure Static posterior mean pressure Dynamic total mean pressure Dynamic anterior mean pressure Dynamic posterior mean pressure SD COP anterior-posterior direction
3.4. Discomfort A significant main effect of saddle design was found on ischial tuberosity discomfort (F(2,36) = 9.97, p < .001). The post-hoc analysis showed higher ischial tuberosity discomfort for the medium (p = .01) and the wide saddle (p < .001) compared with the standard saddle. No significant effect of saddle design was found on crotch discomfort (χ2(N = 19, df = 2) = 3.303, p = .19).
Saddle Design Standard (No Cutout)
Medium (Narrow Cutout)
Wide (Wide Cutout)
– 0 0 – + 0 –
+ 0 0 + + 0 –
+ 0 0 ++ – 0 +
+
+
–
+
–
+
0: no significant difference between saddle designs; -: significantly smaller than the compared saddle design; +: significantly larger than the compared saddle design. ++: significantly greater than both the standard and medium saddle.
4. Discussion the standard and medium saddle (Table 3). These findings were consistent with the results of the static measurements. Further, the static measurements also revealed higher anterior pressure in the medium saddle compared with the standard saddle. Previous studies have reported an increase in anterior pressure when a partial cutout saddle is used (Froböse et al., 2003; Rodano et al., 2002). On the contrary, Bressel et al. (2009a) found no difference in anterior mean pressure between a standard and partial cutout saddle, while posterior mean saddle pressure was higher for the partial cutout saddle. These discrepancies can mostly be explained by different methodological approaches such as bike type, testing setup, body position, and specifications of the partial cutout. For example, Bressel et al. (2009a) measured saddle pressure using non-stationary cycling on road. The difference in pressure distribution with the medium saddle, i.e., greater anterior pressure in static compared with dynamic measurements, may be explained by the pedaling motion. However, the analysis of pressure distribution in seated static cycling positions revealed that the total mean seat pressure distribution remained similar in the four different arm crank positions. Higher anterior and lower posterior mean pressure with the wide saddle can mostly be explained by a greater geometrical difference between the wide saddle and the standard and medium saddle, causing a different pelvic position on the saddle. Bressel and Larson (2003)
The objective of the present study was to design, produce and investigate the acute effects of saddle designs. The wide cutout saddle resulted in increased anterior, decreased posterior and similar total dynamic mean saddle pressure as compared with the standard and medium saddle. The medium saddle led to a lower SD of COP in the anterior-posterior direction as compared with the standard and the wide saddle. Furthermore, higher ischial tuberosity discomfort was perceived with the medium and wide saddle compared with the standard saddle while the crotch discomfort did not change. 4.1. Changes in anterior and posterior saddle pressure between saddles In line with our hypothesis, we found a change in pressure distribution during cycling underlining the importance of the nose and cutout width of unpadded saddles. Consistent with the existing literature (Bressel et al., 2009a; Guess et al., 2006), no difference in total mean saddle pressure was found between the three different saddles, in either the static or dynamic cycling conditions, indicating that the participants did not redistribute weight to the handlebars between the three saddles, which previously have been reported in cutout designs (Bressel et al., 2009a; Bressel and Larson, 2003). The analysis of pressure distribution revealed that the anterior and posterior pressure increased and decreased respectively with the wide saddle compared with 179
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
speculated that a cutout design will increase discomfort in the crotch area, as a cutout saddle increases anterior pressure (Froböse et al., 2003). To oppose the findings of Froböse et al. (2003), the present study found decreased posterior pressure and increased ischial tuberosity discomfort in the wide saddle (Table 3). Per contra to our findings, De Looze et al. (2003) in review and Zenk et al. (2012) in an experimental study, reported discomfort to be associated with pressure during static sitting. However, two recent reviews have concluded that the positive relationship between discomfort and pressure remains a matter of debate (Hiemstra-van Mastrigt et al., 2016; Zemp et al., 2015). As such, there exist interdependencies between discomfort, pressure, posture and, movement (Hiemstra-van Mastrigt et al., 2016). Arguably, less pressure in sensitive areas of the saddle interface would cause higher discomfort than higher pressures in less sensitive areas. The present findings suggest that pressure may not necessarily be a direct mediator of perceived discomfort during ergometer cycling. Although the present study did not find a difference in crotch discomfort between saddle designs, the results showed that the partial cutout saddles did not increase crotch discomfort, indicating that saddle nose redesign is possible without increasing discomfort while redistributing pressure (Fig. 3). The present results indicate that the partial cutout saddles without padding may alleviate discomfort in the crotch area by redistributing anterior pressure from areas susceptible to pressure to less sensitive areas.
indicated that the greater the cutout (partial vs. complete) the greater the pelvic tilt. Even though neither the medium or wide saddle had a complete cutout, it may be speculated that the wide partial cutout design allows for a greater anterior tilt compared with the medium cutout saddle, causing an increased pressure in the anterior region as reported earlier (Bressel and Larson, 2003). Likewise, results from the existing literature (Bressel et al., 2009b) on increased pressure in partial cutout saddles may be explained by the inverse relationship between pressure and area of loading. As suggested by Sommer et al. (2010), one can speculate that the wide saddle may have resulted in pressure release around the perineal area (area of the external genitalia) and redistribution of pressure to surrounding less sensitive anatomical anterior regions (Fig. 3). All in all, the present results highlighted the possibility of redistributing pressure anteriorly and posteriorly, using a cutout design, while maintaining total mean pressure consistent in between designs. The possibility of redistribution of pressure may be essential in the attempt to reduce pressure in sensitive perineal regions. 4.2. Differences in the size of variability of the center of pressure displacement between saddles Furthermore, we hypothesized that a change in saddle nose design would entail a change in COP size variability. The present results revealed a significantly lower SD of COP in anterior-posterior direction in the medium saddle compared with the standard and the wide saddle and a significantly higher SD of COP in the wide saddle compared with medium saddle (Table 3). It has previously been suggested that an increase in the size of COP variability reflects a larger need for pressure relief related to discomfort (Søndergaard et al., 2010). Hence the medium saddle most likely offered a more effective pressure relief compared with the standard and wide saddle. For the wide saddle, the higher SD of COP compared with the medium saddle could imply greater need for relief, indicating a diminution of the potential protective effects with the wide saddle. However, the width of the wide saddle may also have had an influence on the pelvic movement, causing a greater SD of COP due to altered knee motion. Some participants subjectively indicated the wide saddle altered the knee motion during pedaling. The present findings in terms of SD of COP indicate that the medium saddle can have beneficial effects, i.e. lower size of variability in the anterior-posterior direction, and therefore diminish the need for pressure relief during cycling, while the wide saddle was too wide to accommodate some participants.
4.4. Methodological considerations The current study showcased the potential to design, manufacture, and evaluate female-specific saddles of different specifications, while also displaying the possibility of testing three saddles without eliciting any trial order effect (no increases in discomfort over time). The predetermined fixed power output and cadence ensured standardization of pressure on the perineal floor (Bressel and Cronin, 2005) and redistribution of pressure to the handlebars (Bressel et al., 2009a). Twenty minutes of exposure to each saddle was determined acceptable, as actual cycling would allow for pressure relief by shifting of seating position when needed. However, observations of longer periods of subjective and biomechanical effects may be desired to clarify long term effects. These studies should also assess technical limitations (reliability, hysteresis and creep) related to the use of pressure mat (Ferguson-Pell and Cardi, 1993). In the present study, the participants were seated in a sportive bike-fitted position to mimic competitive riding known to result in increased anterior pressure (Partin et al., 2012). However, torso angles were not controlled, and it is likely that not all participants assumed the same riding position, and that some participants were seated in a position that elicited more crotch discomfort or that some subjects were more susceptible to crotch discomfort, causing large deviations of crotch discomfort (Table 2). Finally, the fact that we designed unpadded saddles, except for the minor padding provided by the pressure mat, could partly explain the increased ischial tuberosity discomfort compared with previous studies using padded saddles (Chen and Liu, 2014; Keytel and Noakes, 2002; Verma et al., 2016). However, we decided to design, manufacture and test saddles without padding to enable a thorough evaluation of the effects of saddle geometry on pressure distribution and discomfort in women during ergometer cycling. Further studies are needed to investigate the effects of long-term use of saddle geometry and padding on discomfort and non-traumatic saddles related injuries.
4.3. Influences of saddle design on perceived discomfort in women It was hypothesized that cutout unpadded saddles would decrease discomfort in the crotch area with no changes in the ischial tuberosity area compared with a standard saddle. For comparison, the present study found no difference in crotch discomfort between saddles (Table 2), suggesting individual differences in the perineal floor and/or how discomfort is perceived. The observed variations in discomfort could be due the complex interactions between of anthropometrics and unpadded saddles on pressure and discomfort during cycling. In addition, our results displayed increased ischial tuberosity discomfort with the medium and the wide saddle compared with the standard saddle. A previous study investigating standard, partial and complete cutout saddle designs, recommended female cyclists to use partial cutout saddles based on discomfort ratings (Bressel et al., 2009b) while another study reported lower discomfort when using a grooved saddle design comparable to a partial cutout design (Keytel and Noakes, 2002). Chen and Liu (2014) investigated the effect of nose length on perceived discomfort and found decreased perineal discomfort and increased ischial tuberosity discomfort with shorter nose length. These findings indicate that removing material from the center of the saddle nose is likely to decrease crotch discomfort (Bressel et al., 2009b; Chen and Liu, 2014; Keytel and Noakes, 2002). Contradictory, others
5. Conclusion This is the first study to systematically investigate subjective and biomechanical responses during cycling with three unpadded saddles of different nose widths and cutouts in female cyclists. Discomfort ratings varied greatly between participants and increased ischial tuberosity discomfort was reported for the unpadded medium and wide saddle 180
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
while crotch discomfort was similar between saddles. We also found increased anterior pressure and decreased posterior pressure in the wide saddle compared with the standard and medium saddle and greater COP size variability compared with the medium saddle. These findings suggest that the size of the cutout has an influence on both pressure distribution and COP size variability. The medium saddle demonstrated a higher posterior pressure, redistributing mass away from the crotch area, and lower COP size variability compared with the standard and wide saddle. The medium saddle may thus be suggested as an alternative to traditional saddles when aiming at decreasing pressure in the perineal region during seated cycling among females. In the future, saddle manufacturers may consider the idea of designing and producing individualized saddles based on individual anatomy and perceived discomfort.
design on potential penile hypoxia and erectile dysfunction. BJU Int. 99, 135–140. Guess, M.K., Connell, K., Schrader, S., Reutman, S., Wang, A., LaCombe, J., Toennis, C., Lowe, B., Melman, A., Mikhail, M., 2006. Genital sensation and sexual function in women bicyclists and runners: are your feet safer than your seat? J. Sex. Med. 3, 1018–1027. Hallal, P.C., Andersen, L.B., Bull, F.C., Guthold, R., Haskell, W., Ekelund, U., Alkandari, J.R., Bauman, A.E., Blair, S.N., Brownson, R.C., Craig, C.L., Goenka, S., Heath, G.W., Inoue, S., Kahlmeier, S., Katzmarzyk, P.T., Kohl, H.W., Lambert, E.V., Lee, I.M., Leetongin, G., Lobelo, F., Loos, R.J.F., Marcus, B., Martin, B.W., Owen, N., Parra, D.C., Pratt, M., Puska, P., Ogilvie, D., Reis, R.S., Sallis, J.F., Sarmiento, O.L., Wells, J.C., 2012. Global physical activity levels: surveillance progress, pitfalls, and prospects. Lancet 380, 247–257. Hermans, T.J.N., Wijn, R.P.W.F., Winkens, B., Van Kerrebroeck, P.E.V.A., 2016. Urogenital and sexual complaints in female club cyclists—a cross-sectional study. J. Sex. Med. 13, 40–45. Hiemstra-van Mastrigt, S., Groenesteijn, L., Vink, P., Kuijt-Evers, L.F., 2016. Predicting passenger seat comfort and discomfort on the basis of human, context and seat characteristics: a literature review. Ergonomics 60, 889–911. Humphries, D., 2002. Unilateral vulval hypertrophy in competitive female cyclists. Br. J. Sports Med. 36, 463–464. Keytel, L.R., Noakes, T.D., 2002. Effects of a novel bicycle saddle on symptoms and comfort in cyclists. S. Afr. Med. J. 92, 295–298. LaSalle, M., Salimpour, P., Adelstein, M., Mourtzinos, A., Wen, C., Renzulli, J., Goldstein, B., Goldstein, L., Cantey-Kiser, J., Krane, R.J., Goldstein, I., 1999. Sexual & urinary tract dysfunction in female bicycles. J. Urol. Off. Organ Am. Urol. Assoc. 161, 269. Leibovitch, I., Mor, Y., 2005. The vicious cycling: bicycling related urogenital disorders. Eur. Urol. 47, 277–286. Marcolin, G., Petrone, N., Reggiani, C., Panizzolo, F.A., Paoli, A., 2015. Biomechanical comparison of shorts with different pads: an insight into the perineum protection issue. Medicine (Baltim.) 94, e1186. Partin, S.N., Connell, K.A., Schrader, S., Lacombe, J., Lowe, B., Sweeney, A., Reutman, S., Wang, A., Toennis, C., Melman, A., Mikhail, M., Guess, M.K., 2012. The bar sinister: does handlebar level damage the pelvic floor in female cyclists? J. Sex. Med. 9, 1367–1373. Partin, S.N., Connell, K.A., Schrader, S.M., Guess, M.K., 2014. Les lanternes rouges: the race for information about cycling-related female sexual dysfunction. J. Sex. Med. 11, 2039–2047. Potter, J.J., Sauer, J.L., Weisshaar, C.L., Thelen, D.G., Ploeg, H.L., 2008. Gender differences in bicycle saddle pressure distribution during seated cycling. Med. Sci. Sports Exerc. 40, 1126–1134. Rodano, R., Squadrone, R., Sacchi, M., Marzegan, A., 2002. Saddle pressure distribution in cycling: comparison among saddles of different design and materials. ISBS - Conf. Proc. Arch. 1, 606–609. Schwarzer, U., Sommer, F., Klotz, T., Cremer, C., Engelmann, U., 2002. Cycling and penile oxygen pressure: the type of saddle matters. Eur. Urol. 41, 139–143. Sequenzia, G., Fatuzzo, G., Oliveri, S.M., Barbagallo, R., 2016. Interactive re-design of a novel variable geometry bicycle saddle to prevent neurological pathologies. Int. J. Interact. Des. Manuf. 10, 165–172. Silberman, M.R., Webner, D., Collina, S., Shiple, B.J., 2005. Road bicycle fit. Clin. J. Sport Med. 15, 271–276. Sommer, F., Goldstein, I., Korda, J.B., 2010. Bicycle riding and erectile dysfunction: a review. J. Sex. Med. 7, 2346–2358. Søndergaard, K.H.E., Olesen, C.G., Søndergaard, E.K., de Zee, M., Madeleine, P., 2010. The variability and complexity of sitting postural control are associated with discomfort. J. Biomech. 43, 1997–2001. Spears, I.R., Cummins, N.K., Brenchley, Z., Donohue, C., Turnbull, C., Burton, S., Macho, G.A., 2003. The effect of saddle design on stresses in the perineum during cycling. Med. Sci. Sports Exerc. 35, 1620–1625. Taylor, K.S., Richburg, A., Wallis, D., Bracker, M., 2002. Using an experimental bicycle seat to reduce perineal numbness. Phys. Sportsmed. 30, 27–44. Trofaier, M.L., Schneidinger, C., Marschalek, J., Hanzal, E., Umek, W., 2016. Pelvic floor symptoms in female cyclists and possible remedies: a narrative review. Int. UrogynEcol. J. Pelvic Floor Dysfunct. 27, 513–519. Verma, R., Hansen, E.A., de Zee, M., Madeleine, P., 2016. Effect of seat positions on discomfort, muscle activation, pressure distribution and pedal force during cycling. J. Electromyogr. Kinesiol. 27, 78–86. Wilber, C.A., Holland, G.J., Madison, R.E., Loy, S.F., 1995. An epidemiological analysis of overuse injuries among recreational cyclists. Int. J. Sports Med. 16, 201–206. Zemp, R., Taylor, W.R., Lorenzetti, S., 2015. Are pressure measurements effective in the assessment of office chair comfort/discomfort? a review. Appl. Ergon. 48, 273–282. Zenk, R., Franz, M., Bubb, H., Vink, P., 2012. Technical note: spine loading in automotive seating. Appl. Ergon. 43, 290–295.
Conflicts of interest The authors declare no conflicts of interests. Acknowledgement The authors would like to thank the Department of Manufacturing Engineering (M-Tech) at Aalborg University for assistance with producing the saddles. References Asplund, C., Barkdull, T., Weiss, B.D., 2007. Genitourinary problems in bicyclists. Curr. Sports Med. Rep. 6, 333–339. Baeyens, L., Vermeersch, E., Bourgeois, P., Baeyens, L., Vermeersch, E., Bourgeois, P., 2002. Bicyclist's vulva: observational study. BMJ Br. Med. J. (Clin. Res. Ed.) 325, 138. Battaglia, C., Nappi, R.E., Mancini, F., Cianciosi, A., Persico, N., Busacchi, P., 2009. Ultrasonographic and Doppler findings of subclinical clitoral microtraumatisms in mountain bikers and horseback riders. J. Sex. Med. 6, 464–468. Bressel, E., Bliss, S., Cronin, J., 2009a. A field-based approach for examining bicycle seat design effects on seat pressure and perceived stability. Appl. Ergon. 40, 472–476. Bressel, E., Bliss, S., Cronin, J., 2009b. Influence of bicycle seat design on perceived comfort and stability during non-stationary bicycling. Med. Sci. Sports Exerc. 41, 247. Bressel, E., Cronin, J., 2005. Bicycle seat interface pressure: reliability, validity, and influence of hand position and workload. J. Biomech. 38, 1325–1331. Bressel, E., Larson, B.J., 2003. Bicycle seat designs and their effect on pelvic angle, trunk angle, and comfort. Med. Sci. Sports Exerc. 35, 327–332. Buller, J.C., 2001. Female cyclists and perineal symptoms: an experimental bicycle seat. Clin. J. Sport Med. 11, 289–290. Chen, Y.L., Liu, Y.N., 2014. Optimal protruding node length of bicycle seats determined using cycling postures and subjective ratings. Appl. Ergon. 45, 1181–1186. Christiaans, H.H.C.M., Bremner, A., 1998. Comfort on bicycles and the validity of a commercial bicycle fitting system. Appl. Ergon. 29, 201–211. Chumanov, E.S., Remy, C.D., Thelen, D.G., 2010. Computational techniques for using insole pressure sensors to analyse three-dimensional joint kinetics. Comput. Methods Biomech. Biomed. Engin. 13, 505–514. De Vey Mestdagh, K., 1998. Personal perspective: in search of an optimum cycling posture. Appl. Ergon. 29, 325–334. De Looze, M.P., Kuijt-Evers, L.F.M., Van Dieën, J., 2003. Sitting comfort and discomfort and the relationship with objective measures. Ergonomics 46, 985–997. Dettori, N.J., Norvell, D.C., 2006. Non-traumatic bicycle injuries. Sport. Med. 36, 7–18. Ferguson-Pell, M., Cardi, M.D., 1993. Prototype development and comparative evaluation of wheelchair pressure mapping systems. Assis. Technol. 5, 78–91. Froböse, I., Baeyens, L., Tofaute, K., 2003. Ergonomics of 2 bicycle saddles: pressure at the pudendal area in women of a normal saddle with gel and of a saddle with a hole. Proj. Wellcom - Dtsch. Sport. Köln, pp. 1–15. Gemery, J.M., Nangia, A.K., Mamourian, A.C., Reid, S.K., 2007. Digital three-dimensional modelling of the male pelvis and bicycle seats: impact of rider position and seat
181
Contents lists available at ScienceDirect
Applied Ergonomics journal homepage: www.elsevier.com/locate/apergo
The effect of saddle nose width and cutout on saddle pressure distribution and perceived discomfort in women during ergometer cycling
T
Anna Sofie Larsen, Frederik G. Larsen, Frederik F. Sørensen, Mathias Hedegaard, Nicolai Støttrup, Ernst A. Hansen, Pascal Madeleine∗ Sport Sciences, Department of Health Science and Technology, Aalborg University, Denmark
A R T I C LE I N FO
A B S T R A C T
Keywords: Bicycling Discomfort Gender Saddle design Variability
The objectives were 1) to design and produce two novel unpadded bicycle saddles with a wide/medium width and partial nose cutout; 2) to investigate the responses on pressure distribution and perceived discomfort in female cyclists. For comparison, a standard saddle was also tested. Nineteen female cyclists pedaled on an ergometer cycle for 20 min with each saddle in a counterbalanced order. A pressure mat measured saddle interface pressure. Discomfort ratings were collected using a visual analogue scale. Total mean saddle pressure remained similar across saddles. The wide saddle increased anterior and decreased posterior mean saddle pressure as compared with the standard (p < .002) and the medium saddle (p < .001). Significantly increased ischial tuberosity discomfort was found for the novel saddles (p < .001), while crotch discomfort was not significantly different between saddles. The medium width saddle appeared to be the best compromise since increased crotch discomfort was avoided and saddle pressures were redistributed. Such design may be suggested as an alternative to traditional saddles for women reporting discomfort in the perineal region.
1. Introduction Cycling is a popular recreational activity with a number of associated health benefits including reduced all-cause mortality, risk of cardiovascular diseases and cancer (Hallal et al., 2012). For competitive cycling, cyclists adopt a more sportive position and spend more time on the saddle. This can lead to discomfort and injuries in the perineal region (Hermans et al., 2016). Frequently reported saddle-related complaints and injuries among women (Table 1) include urinary complaints, sexual dysfunction, vulvar hypertrophy, pain, tenderness and numbness in the perineal region (Hermans et al., 2016; Trofaier et al., 2016). Perineal pain, tenderness, numbness and sexual dysfunction are believed to be caused by compression of the pudendal neurovascular bundle (Dettori and Norvell, 2006; Partin et al., 2014; Trofaier et al., 2016). Particularly, pressure below the pubic symphysis (Gemery et al., 2007) has been suspected to cause compression of the pudendal nerves and arteries in females during cycling (Leibovitch and Mor, 2005). Urological dysfunction, skin lesions, vulvar hypertrophy, and genital and perineal discomfort are likely to be caused by increased pressure on the genitals from sitting on a saddle (Leibovitch and Mor, 2005). However, the existing knowledge regarding the cause of complaints and injuries is still limited (Trofaier et al., 2016). Saddle manufacturers have presented various innovative saddle
∗
designs as alternatives to the traditional standard saddle. The aims have been to decrease discomfort and the risk of non-traumatic saddle-related injuries by reducing pressure on the perineal area. Saddles with partial (fully removing middle section of the saddle nose) or complete (saddle without protruding nose) cutout design have been produced (Asplund et al., 2007). Several studies have compared innovative and standard saddle designs (Bressel and Larson, 2003; Chen and Liu, 2014; Keytel and Noakes, 2002; Bressel et al., 2009b). Complete nose removal obviously entails a reduced saddle area to compress the perineal area, thereby reducing the perineal pressure and reduced discomfort compared with other saddle designs (Bressel et al., 2009b; Chen and Liu, 2014). On the other hand, removing the saddle nose impairs the perceived riding stability (Bressel et al., 2009a; Chen and Liu, 2014). This is perhaps the reason why a complete cutout saddle is often unpopular among competitive cyclists (Schwarzer et al., 2002). Cycling with saddles using a grooved or partial cutout saddle design (partially removing middle section of the saddle nose, leaving a hollow section or fully removing middle section of the saddle nose), has led to equivocal results. Studies have shown that with a partial cutout design it is possible to decrease numbness (Taylor et al., 2002) and increase comfort (Keytel and Noakes, 2002). Additionally, Gemery et al. (2007) found that a grooved saddle design similar to a partial cutout design entailed better preservation of the symphysis space and reduced
Corresponding author. Sport Sciences, Dept. of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers vej 7, 9220 Aalborg Ø, Denmark. E-mail address: [email protected] (P. Madeleine).
https://doi.org/10.1016/j.apergo.2018.03.002 Received 15 November 2017; Received in revised form 26 January 2018; Accepted 5 March 2018 0003-6870/ © 2018 Elsevier Ltd. All rights reserved.
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
Table 1 Articles reporting types and prevalence of non-traumatic saddle related discomfort and injuries in female cyclists. Author(s)
N
Participants
Average training
Saddle related discomfort and injuries
Baeyens et al. (2002)
6
Competitive female cyclists
463 km/week
Battaglia et al. (2009)
6
6.6 h/week
Buller (2001)
52
Horseback and mountain bike female riders Female cyclists
Unilateral chronic swelling of the labium majus, typical unilateral lymphoedema and regularly inflammatory skin prevalence. Clitoral micro-calcifications (83%) and perineal tenderness or discomfort.
Christiaans and Bremner (1998) Guess et al. (2006) Hermans et al. (2016)
56
Not reported
48 114
Cycling conference female attendants Female cyclists Female recreational cyclists
Humphries (2002) LaSalle et al. (1999) Wilber et al. (1995)
4 333 224
Female competitive cyclists Female cyclists Female recreational cyclists
Not reported
Burning sensation or pain in the perineum (81%) and perineal numbness (70%). Discomfort when riding (74%) and saddle soreness (29%).
Minimum 16.1 km/week Per season: < 1000 km: 6/114 (5.3%) 1000-3000 km: 63/114 (55.3%) 3000-5000 km: 23/114 (20.2%) > 5000 km: 22/114 (19.3%) Not reported Not reported 103.2 km/week
Genital pain, tingling or numbness during the last month (60%). Vulvar discomfort (40%), numbness of external genitals (35%), numbness of perineum (6%) and perineal pain (4%).
Unilateral vulvar hypertrophy. Perineal numbness (34%). Perineal pain, numbness, soreness, swelling of soft tissue, skin irritation and “pain in the butt”.
Fig. 1. Geometry top part specifications of the three saddle designs; a standard saddle without a partial cutout (standard), a saddle with a narrow partial cutout (medium), and a saddle with a wide partial cutout (wide). The top part of the saddles was made of obomodulan® 500 (OBO-Werke, Stadthagen, Germany) mounted on a custom aluminum alloy base.
in female cyclists. The purpose of the present study was to fill that gap. Therefore, we designed, produced and investigated the acute effects of two novel saddle nose cutout designs (medium and wide) on pressure distribution and perceived discomfort compared with a standard saddle design (standard). It was hypothesized that 1) changing the saddle nose design from a standard design to a cutout design would change pressure distribution and size of center of pressure (COP) variability in anteriorposterior direction, 2) a cutout saddle design would decrease crotch discomfort without changing the ischial tuberosity discomfort compared with a standard saddle.
compression of the pudendal arteries and nerves. Further, Sommer et al. (2010) argued that a wider partial cutout is more protective of perineal compression. In contrast, others have reported that partial cutout saddles increase pressure around the cutout, resulting in increased perineal pressure (Partin et al., 2012; Froböse et al., 2003). In a review by Partin et al. (2014), it was concluded that partial cutout saddles do not offer a protective effect of the female perineum. However, the partial cutout saddles might have been too narrow to show a protective effect. Thus, increasing the width of the saddle nose and cutout could decrease the pressure applied to the perineal area and thereby reduce discomfort and risk of injury (Sommer et al., 2010). The equivocal results found may be explained by geometric differences among the tested saddles. To our knowledge, no study has (i) designed and produced saddles of similar surface areas with different saddle nose and partial cutout width and; (ii) subsequently investigated the influence on pressure and discomfort
176
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
2. Methods 2.1. Participants Nineteen recreational female cyclists (23.4 ± 1.9 years, 66.7 ± 8.4 kg, 1.68 ± 0.04 m) volunteered to participate after receiving information about the study. Participants were included if they cycled between 1 and 6 h per week, were free from injuries in the lower extremities and pain in the perineal area within the preceding 6 months. The participants cycled on average 4.1 ± 1.6 h per week. All participants signed an informed consent prior to participation. The study was carried out in accordance with the Helsinki declaration and approved by the local ethics committee (N-20160023). 2.2. Saddle design Three unpadded saddles (standard, medium and wide) with different nose geometries were designed based on commercially available saddles and modeled (Fig. 1) in SOLIDWORKS (Dassault Systémes, Vélizy, France) and manufactured in-house (Aalborg University, Denmark). The saddles consisted of a top part made of obomodulan® 500 (OBO-Werke, Stadthagen, Germany), which was mounted on a custom aluminum alloy base. A custom-made aluminum alloy seat post piece, designed to fit the standard SRM seat tube was attached to the base and enabled fixation to the ergometer bike. All three saddles were designed with different nose geometries, but with identical posterior geometry based on recommendations by (Sequenzia et al., 2016; Spears et al., 2003) and in line with the rules of the Union du Cyclisme International1 (Fig. 1). We decided not to add cushioning considering the relationship between seat dimensions, seat shape, seat material and interface pressure is unclear (Hiemstra-van Mastrigt et al., 2016). With respect to the anterior part, the standard saddle was designed with a 4 cm outer nose width and an overall surface area of 160 cm2. The medium saddle was designed as a partial cutout saddle with a 2 cm cutout, an outer nose width of 6 cm and an overall surface area of 152 cm2. The wide saddle was designed as a partial cutout saddle with a 4 cm cutout, an outer nose width of 8 cm and an overall surface area of 157 cm2.
Fig. 2. Experimental setup showing a female cyclist pedaling on an ergometer cycle. A pressure mat measured saddle interface pressure. A visual analogue scale was used to collect discomfort ratings.
Arm length (right side) was measured from the superior part of acromion to the heads of the first metacarpalia. Torso length was measured from seat to incisura jugularis of the manubrium sterni. The mean ± SD (cm) of the torso length, arm length, inseam length, hip width and thigh circumference were respectively 57.1 ± 1.8, 64.3 ± 3.0, 79.5 ± 3.3, 35.0 ± 2.4 and 60.4 ± 5.7 cm. Saddle height, setback and reach were set according to previous existing recommendations; the saddle height, the distance between the middle of the saddle and the top of the pedal spindle at the bottom dead center pedal position, was set as recommended at 107% of inside leg length (De Vey Mestdagh, 1998). The saddle setback was set, so that it was possible to follow a straight line from the fifth-metatarsal to the inferior pole of patella when the crank arm was positioned at the 90° horizontal forward parallel position (Silberman et al., 2005). Reach distance was determined from table values based on torso and arm length (De Vey Mestdagh, 1998). Handlebar height was 6 cm below saddle height (Bressel and Larson, 2003; Silberman et al., 2005). Participants wore their own sports shoes and tights without padding to avoid influence on perceived discomfort (Marcolin et al., 2015). When seated, participants were asked to keep their hands steadily positioned on the top of the handlebars and refrain from changing position or standing up after initial seating to eliminate potential sliding of the pressure mat and pressure relief. Saddle pressure distribution was collected by the pressure mat at a sample frequency of 25 Hz. Static measurements of saddle pressure distribution at right leg crank angle 0-90-180-270° were collected for 1 s, prior to each bout. For dynamic measurements, participants rode for 20 min with a constant power output of 150 W throughout all bouts and were told to maintain a cadence as close to 80 rpm as possible (78.9 ± 2.1 rpm, cadence was monitored and displayed). A 10 min rest period was given between each 20 min ride. Saddle pressure data was collected during cycling over a 55 s interval between min 19-20. The local body discomfort were obtained from all participants using a VAS (Bressel et al., 2009b; Chen and Liu, 2014). The experimenters
2.3. Study design and experimental setup The subjects participated in a single laboratory session lasting 2 h in which each participant tested all three saddles in a counterbalanced cross-over design to account for eventual trial order effect. Participants rode an SRM ergometer (Schoberer Rad Messtechnik, Jülich, Germany) in a controlled environment (21 ± 2 °C). A pressure mat (S2119, Novel, München, Germany) made of flexible Lycra® material and containing 512 sensors, each with a sensing area of 1 cm2, arranged in 16 rows × 32 columns, was used for measuring pressure between body and saddle. The S2119 was calibrated for pressure range 0–360 kPa. Accuracy was tested by applying a 10 kg weight on 4 different positions on the sensor mat area (mean force deviation was 3.6 ± 1.7%). Further, static (standing and sitting) and dynamic (cycling) tests were performed prior to the series of recordings. A 10 cm digital visual analog scale (VAS) (Aalborg University, Denmark) was used to assess perceived discomfort (Fig. 2). 2.4. Procedure Anthropometric measurements (inside leg length, arm length, height, torso length) were measured using a BIO SIZE anthropometric measurement tool (Bicisupport Srl, Casatenovo, Italy) and used for bike fitting. Inside leg length was measured barefooted from floor to pubis. 1 http://www.uci.ch/mm/Document/News/Rulesandregulation/16/51/61/ ClarificationGuideoftheUCITechnicalRegulation-2017.01.01-ENG_English.pdf.
177
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
Table 2 Mean ± SD of the dependent variables for standard, medium, and wide saddle design as well as differences between saddles (N = 19). Saddle Design Variables
Standard (No cutout)
Medium (Narrow Cutout)
Wide (Wide Cutout)
Ischial tuberosity discomfort (cm) Crotch discomfort (cm) Static total mean pressure (kPa/kg) Static anterior mean pressure (kPa/kg) Static posterior mean pressure (kPa/kg) Dynamic total mean pressure (kPa/kg) Dynamic anterior mean pressure (kPa/kg) Dynamic posterior mean pressure (kPa/kg) SD COP anterior-posterior direction (cm)
4.5 ± 2.8 2.7 ± 2.9 0.29 ± 0.04 0.18 ± 0.12 0.34 ± 0.08 0.31 ± 0.05 0.24 ± 0.14 0.35 ± 0.05 0.28 ± 0.11
5.8 ± 2.8a 1.3 ± 1.5 0.30 ± 0.06 0.23 ± 0.15a 0.34 ± 0.11 0.32 ± 0.07 0.24 ± 0.14 0.36 ± 0.07 0.21 ± 0.08a,c
6.5 ± 2.3a 1.7 ± 2.2 0.27 ± 0.05 0.31 ± 0.16a,b 0.25 ± 0.12a,b 0.31 ± 0.05 0.36 ± 0.16a,b 0.29 ± 0.08a,b 0.29 ± 0.16b
a b c
Significantly different from the standard saddle. Significantly different from the medium saddle. Significantly different from the wide saddle.
presented an illustration of the buttock area with crotch and ischial tuberosity clearly represented and asked participants to rate their ischial tuberosity and crotch discomfort separately. Participants first rated crotch discomfort, followed by ischial tuberosity discomfort. Ratings were conducted immediately after pressure measurements. Zero represented “no discomfort”, and 10 represented “maximal discomfort”. The area of ischial tuberosity and crotch were considered to correspond to the posterior and anterior part of the saddle (Fig. 1), respectively.
two-way RM-ANOVA with saddle design (standard × medium × wide) and crank arm position (0-90-180-270°) as within subject factors was used. For dynamic tests, a one-way RM-ANOVA with saddle design (standard × medium × wide) as factor was applied. A least significant difference (LSD) test was used as post-hoc analysis if the RM-ANOVA reached significance. Mauchly's test of sphericity was applied during all ANOVA testing. If the data violated the sphericity assumption, Greenhouse-Geisser corrections were applied. Results were considered significant if p < .05.
2.5. Data analysis
3. Results
A custom written MATLAB script (MathWorks Inc., Natick, MA, USA) processed saddle pressure and VAS data. Pressure data was lowpass filtered using a 2nd order zero-lag Butterworth filter (5 Hz cut-off frequency) and normalized to body mass before sensors were segmented to represent each saddle surface area (Potter et al., 2008). Saddles were divided into an anterior and posterior part (Fig. 1) and pressure mat cells covering the cut-out were discarded to minimize hammocking effects (Ferguson-Pell and Cardi, 1993). Mean pressure was calculated as the average of all samples for each sensor for each trial (Bressel and Cronin, 2005). If sensors were saturated (> 360 kPa) for more than 10% of the sample duration, the data was discarded and replaced by interpolated values using adjacent sensors. Interpolation was conducted with the MATLAB built-in function ‘griddata.m’. Saturation issues were observed in 6.6 ± 2.8 cells across all mean dynamic measurements. Pressure values from the cells were used to calculate a total, anterior, and posterior mean saddle pressure. The center of pressure (COP) was calculated for each entire saddle using the segmented sensors (Chumanov et al., 2010) and subsequently used to calculate the size of variability, i.e., standard deviation COP trajectory in anterior-posterior direction. To control for trial order effect concerning discomfort between trials, the changes in discomfort over trials were assessed for both discomfort in crotch area and ischial tuberosity area.
No sign of trial order effect was found neither for ischial tuberosity discomfort (F(2, 36) = 0.421, p = .66) nor for crotch discomfort (χ2(N = 19, df = 2) = 0.58, p = .75). The mean ± SD of the ischial tuberosity discomfort were 5.8 ± 2.8, 5.6 ± 2.9 and 5.3 ± 2.5 after the first, second and third dynamic trial, while the mean ± SD crotch discomfort were respectively 2.3 ± 2.5, 1.6 ± 1.7 and 1.8 ± 2.3. The mean ± SD of the dependent variables are presented in Table 2.
There was no effect of saddle design on total mean saddle pressure in the four crank arm conditions (0-90-180-270°) for the static measurements (F(6, 108) = 1.528, p = .176). A significant effect of saddle design was found for anterior (F(2,36) = 18.71, p < .001) and posterior (F(2,36) = 9.68, p < .001) mean saddle pressure. Least significant difference post-hoc test revealed higher static anterior mean pressure for the wide saddle compared with the standard (p < .001) and the medium saddle (p < .001) and higher static anterior mean pressure in the medium saddle compared with the standard saddle (p = .03). Lower static posterior mean saddle pressure was found in the wide saddle compared with the standard saddle (p = .002) and the medium saddle (p = .005).
2.6. Statistical analysis
3.2. Saddle pressure – dynamic condition
Statistical analysis was conducted in SPSS 24.0 (IBM, Armok, NY, USA). All results are presented as mean ± standard deviation unless otherwise stated. Dependent variables that were not normally distributed, as determined by the Shapiro-Wilks test, were log-transformed. However, dependent variables that were not log-transformable (discomfort) due to zero values were kept as non-parametric data and analyzed using a Friedman test with saddle (standard × medium × wide) as factor. For static pressure recordings, a
Fig. 3 shows the mean dynamic pressure distribution for the three saddles for a representative participant. There was no significant effect of saddle design on total mean saddle pressure for the dynamic measurements (F(2,36) = 0.18, p = .84). A significant main effect of saddle design was found for dynamic anterior (F(2,36) = 11.505, p < .001) and posterior (F(2,36) = 11.498, p < .001) mean saddle pressure. Post hoc analyses showed a higher dynamic anterior mean saddle pressure for the wide saddle compared with the standard (p = .002) and the
3.1. Saddle pressure – static condition
178
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
Fig. 3. Pressure distribution for the standard, the medium, and the wide saddle for one representative participant over 55 s for min 19-20 during ergometer cycling. The x and y axes represent the coordinate system used when computing the center of pressure in the medio-lateral and anterior-posterior direction, respectively.
medium saddle (p < .001). The wide saddle also displayed a lower posterior mean saddle pressure compared with the standard (p = .003) and the medium saddle (p < .001).
Table 3 Overview table of significant differences between saddle designs. Variables
3.3. Center of pressure A significant main effect of saddle design was found for the SD of COP in anterior-posterior direction (F(2,36) = 5.46, P = .008). The post-hoc analysis showed lower SD of COP in the medium saddle compared with the standard (p < .001) and the wide saddle (p = .01).
Ischial tuberosity discomfort Crotch discomfort Static total mean pressure Static anterior mean pressure Static posterior mean pressure Dynamic total mean pressure Dynamic anterior mean pressure Dynamic posterior mean pressure SD COP anterior-posterior direction
3.4. Discomfort A significant main effect of saddle design was found on ischial tuberosity discomfort (F(2,36) = 9.97, p < .001). The post-hoc analysis showed higher ischial tuberosity discomfort for the medium (p = .01) and the wide saddle (p < .001) compared with the standard saddle. No significant effect of saddle design was found on crotch discomfort (χ2(N = 19, df = 2) = 3.303, p = .19).
Saddle Design Standard (No Cutout)
Medium (Narrow Cutout)
Wide (Wide Cutout)
– 0 0 – + 0 –
+ 0 0 + + 0 –
+ 0 0 ++ – 0 +
+
+
–
+
–
+
0: no significant difference between saddle designs; -: significantly smaller than the compared saddle design; +: significantly larger than the compared saddle design. ++: significantly greater than both the standard and medium saddle.
4. Discussion the standard and medium saddle (Table 3). These findings were consistent with the results of the static measurements. Further, the static measurements also revealed higher anterior pressure in the medium saddle compared with the standard saddle. Previous studies have reported an increase in anterior pressure when a partial cutout saddle is used (Froböse et al., 2003; Rodano et al., 2002). On the contrary, Bressel et al. (2009a) found no difference in anterior mean pressure between a standard and partial cutout saddle, while posterior mean saddle pressure was higher for the partial cutout saddle. These discrepancies can mostly be explained by different methodological approaches such as bike type, testing setup, body position, and specifications of the partial cutout. For example, Bressel et al. (2009a) measured saddle pressure using non-stationary cycling on road. The difference in pressure distribution with the medium saddle, i.e., greater anterior pressure in static compared with dynamic measurements, may be explained by the pedaling motion. However, the analysis of pressure distribution in seated static cycling positions revealed that the total mean seat pressure distribution remained similar in the four different arm crank positions. Higher anterior and lower posterior mean pressure with the wide saddle can mostly be explained by a greater geometrical difference between the wide saddle and the standard and medium saddle, causing a different pelvic position on the saddle. Bressel and Larson (2003)
The objective of the present study was to design, produce and investigate the acute effects of saddle designs. The wide cutout saddle resulted in increased anterior, decreased posterior and similar total dynamic mean saddle pressure as compared with the standard and medium saddle. The medium saddle led to a lower SD of COP in the anterior-posterior direction as compared with the standard and the wide saddle. Furthermore, higher ischial tuberosity discomfort was perceived with the medium and wide saddle compared with the standard saddle while the crotch discomfort did not change. 4.1. Changes in anterior and posterior saddle pressure between saddles In line with our hypothesis, we found a change in pressure distribution during cycling underlining the importance of the nose and cutout width of unpadded saddles. Consistent with the existing literature (Bressel et al., 2009a; Guess et al., 2006), no difference in total mean saddle pressure was found between the three different saddles, in either the static or dynamic cycling conditions, indicating that the participants did not redistribute weight to the handlebars between the three saddles, which previously have been reported in cutout designs (Bressel et al., 2009a; Bressel and Larson, 2003). The analysis of pressure distribution revealed that the anterior and posterior pressure increased and decreased respectively with the wide saddle compared with 179
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
speculated that a cutout design will increase discomfort in the crotch area, as a cutout saddle increases anterior pressure (Froböse et al., 2003). To oppose the findings of Froböse et al. (2003), the present study found decreased posterior pressure and increased ischial tuberosity discomfort in the wide saddle (Table 3). Per contra to our findings, De Looze et al. (2003) in review and Zenk et al. (2012) in an experimental study, reported discomfort to be associated with pressure during static sitting. However, two recent reviews have concluded that the positive relationship between discomfort and pressure remains a matter of debate (Hiemstra-van Mastrigt et al., 2016; Zemp et al., 2015). As such, there exist interdependencies between discomfort, pressure, posture and, movement (Hiemstra-van Mastrigt et al., 2016). Arguably, less pressure in sensitive areas of the saddle interface would cause higher discomfort than higher pressures in less sensitive areas. The present findings suggest that pressure may not necessarily be a direct mediator of perceived discomfort during ergometer cycling. Although the present study did not find a difference in crotch discomfort between saddle designs, the results showed that the partial cutout saddles did not increase crotch discomfort, indicating that saddle nose redesign is possible without increasing discomfort while redistributing pressure (Fig. 3). The present results indicate that the partial cutout saddles without padding may alleviate discomfort in the crotch area by redistributing anterior pressure from areas susceptible to pressure to less sensitive areas.
indicated that the greater the cutout (partial vs. complete) the greater the pelvic tilt. Even though neither the medium or wide saddle had a complete cutout, it may be speculated that the wide partial cutout design allows for a greater anterior tilt compared with the medium cutout saddle, causing an increased pressure in the anterior region as reported earlier (Bressel and Larson, 2003). Likewise, results from the existing literature (Bressel et al., 2009b) on increased pressure in partial cutout saddles may be explained by the inverse relationship between pressure and area of loading. As suggested by Sommer et al. (2010), one can speculate that the wide saddle may have resulted in pressure release around the perineal area (area of the external genitalia) and redistribution of pressure to surrounding less sensitive anatomical anterior regions (Fig. 3). All in all, the present results highlighted the possibility of redistributing pressure anteriorly and posteriorly, using a cutout design, while maintaining total mean pressure consistent in between designs. The possibility of redistribution of pressure may be essential in the attempt to reduce pressure in sensitive perineal regions. 4.2. Differences in the size of variability of the center of pressure displacement between saddles Furthermore, we hypothesized that a change in saddle nose design would entail a change in COP size variability. The present results revealed a significantly lower SD of COP in anterior-posterior direction in the medium saddle compared with the standard and the wide saddle and a significantly higher SD of COP in the wide saddle compared with medium saddle (Table 3). It has previously been suggested that an increase in the size of COP variability reflects a larger need for pressure relief related to discomfort (Søndergaard et al., 2010). Hence the medium saddle most likely offered a more effective pressure relief compared with the standard and wide saddle. For the wide saddle, the higher SD of COP compared with the medium saddle could imply greater need for relief, indicating a diminution of the potential protective effects with the wide saddle. However, the width of the wide saddle may also have had an influence on the pelvic movement, causing a greater SD of COP due to altered knee motion. Some participants subjectively indicated the wide saddle altered the knee motion during pedaling. The present findings in terms of SD of COP indicate that the medium saddle can have beneficial effects, i.e. lower size of variability in the anterior-posterior direction, and therefore diminish the need for pressure relief during cycling, while the wide saddle was too wide to accommodate some participants.
4.4. Methodological considerations The current study showcased the potential to design, manufacture, and evaluate female-specific saddles of different specifications, while also displaying the possibility of testing three saddles without eliciting any trial order effect (no increases in discomfort over time). The predetermined fixed power output and cadence ensured standardization of pressure on the perineal floor (Bressel and Cronin, 2005) and redistribution of pressure to the handlebars (Bressel et al., 2009a). Twenty minutes of exposure to each saddle was determined acceptable, as actual cycling would allow for pressure relief by shifting of seating position when needed. However, observations of longer periods of subjective and biomechanical effects may be desired to clarify long term effects. These studies should also assess technical limitations (reliability, hysteresis and creep) related to the use of pressure mat (Ferguson-Pell and Cardi, 1993). In the present study, the participants were seated in a sportive bike-fitted position to mimic competitive riding known to result in increased anterior pressure (Partin et al., 2012). However, torso angles were not controlled, and it is likely that not all participants assumed the same riding position, and that some participants were seated in a position that elicited more crotch discomfort or that some subjects were more susceptible to crotch discomfort, causing large deviations of crotch discomfort (Table 2). Finally, the fact that we designed unpadded saddles, except for the minor padding provided by the pressure mat, could partly explain the increased ischial tuberosity discomfort compared with previous studies using padded saddles (Chen and Liu, 2014; Keytel and Noakes, 2002; Verma et al., 2016). However, we decided to design, manufacture and test saddles without padding to enable a thorough evaluation of the effects of saddle geometry on pressure distribution and discomfort in women during ergometer cycling. Further studies are needed to investigate the effects of long-term use of saddle geometry and padding on discomfort and non-traumatic saddles related injuries.
4.3. Influences of saddle design on perceived discomfort in women It was hypothesized that cutout unpadded saddles would decrease discomfort in the crotch area with no changes in the ischial tuberosity area compared with a standard saddle. For comparison, the present study found no difference in crotch discomfort between saddles (Table 2), suggesting individual differences in the perineal floor and/or how discomfort is perceived. The observed variations in discomfort could be due the complex interactions between of anthropometrics and unpadded saddles on pressure and discomfort during cycling. In addition, our results displayed increased ischial tuberosity discomfort with the medium and the wide saddle compared with the standard saddle. A previous study investigating standard, partial and complete cutout saddle designs, recommended female cyclists to use partial cutout saddles based on discomfort ratings (Bressel et al., 2009b) while another study reported lower discomfort when using a grooved saddle design comparable to a partial cutout design (Keytel and Noakes, 2002). Chen and Liu (2014) investigated the effect of nose length on perceived discomfort and found decreased perineal discomfort and increased ischial tuberosity discomfort with shorter nose length. These findings indicate that removing material from the center of the saddle nose is likely to decrease crotch discomfort (Bressel et al., 2009b; Chen and Liu, 2014; Keytel and Noakes, 2002). Contradictory, others
5. Conclusion This is the first study to systematically investigate subjective and biomechanical responses during cycling with three unpadded saddles of different nose widths and cutouts in female cyclists. Discomfort ratings varied greatly between participants and increased ischial tuberosity discomfort was reported for the unpadded medium and wide saddle 180
Applied Ergonomics 70 (2018) 175–181
A.S. Larsen et al.
while crotch discomfort was similar between saddles. We also found increased anterior pressure and decreased posterior pressure in the wide saddle compared with the standard and medium saddle and greater COP size variability compared with the medium saddle. These findings suggest that the size of the cutout has an influence on both pressure distribution and COP size variability. The medium saddle demonstrated a higher posterior pressure, redistributing mass away from the crotch area, and lower COP size variability compared with the standard and wide saddle. The medium saddle may thus be suggested as an alternative to traditional saddles when aiming at decreasing pressure in the perineal region during seated cycling among females. In the future, saddle manufacturers may consider the idea of designing and producing individualized saddles based on individual anatomy and perceived discomfort.
design on potential penile hypoxia and erectile dysfunction. BJU Int. 99, 135–140. Guess, M.K., Connell, K., Schrader, S., Reutman, S., Wang, A., LaCombe, J., Toennis, C., Lowe, B., Melman, A., Mikhail, M., 2006. Genital sensation and sexual function in women bicyclists and runners: are your feet safer than your seat? J. Sex. Med. 3, 1018–1027. Hallal, P.C., Andersen, L.B., Bull, F.C., Guthold, R., Haskell, W., Ekelund, U., Alkandari, J.R., Bauman, A.E., Blair, S.N., Brownson, R.C., Craig, C.L., Goenka, S., Heath, G.W., Inoue, S., Kahlmeier, S., Katzmarzyk, P.T., Kohl, H.W., Lambert, E.V., Lee, I.M., Leetongin, G., Lobelo, F., Loos, R.J.F., Marcus, B., Martin, B.W., Owen, N., Parra, D.C., Pratt, M., Puska, P., Ogilvie, D., Reis, R.S., Sallis, J.F., Sarmiento, O.L., Wells, J.C., 2012. Global physical activity levels: surveillance progress, pitfalls, and prospects. Lancet 380, 247–257. Hermans, T.J.N., Wijn, R.P.W.F., Winkens, B., Van Kerrebroeck, P.E.V.A., 2016. Urogenital and sexual complaints in female club cyclists—a cross-sectional study. J. Sex. Med. 13, 40–45. Hiemstra-van Mastrigt, S., Groenesteijn, L., Vink, P., Kuijt-Evers, L.F., 2016. Predicting passenger seat comfort and discomfort on the basis of human, context and seat characteristics: a literature review. Ergonomics 60, 889–911. Humphries, D., 2002. Unilateral vulval hypertrophy in competitive female cyclists. Br. J. Sports Med. 36, 463–464. Keytel, L.R., Noakes, T.D., 2002. Effects of a novel bicycle saddle on symptoms and comfort in cyclists. S. Afr. Med. J. 92, 295–298. LaSalle, M., Salimpour, P., Adelstein, M., Mourtzinos, A., Wen, C., Renzulli, J., Goldstein, B., Goldstein, L., Cantey-Kiser, J., Krane, R.J., Goldstein, I., 1999. Sexual & urinary tract dysfunction in female bicycles. J. Urol. Off. Organ Am. Urol. Assoc. 161, 269. Leibovitch, I., Mor, Y., 2005. The vicious cycling: bicycling related urogenital disorders. Eur. Urol. 47, 277–286. Marcolin, G., Petrone, N., Reggiani, C., Panizzolo, F.A., Paoli, A., 2015. Biomechanical comparison of shorts with different pads: an insight into the perineum protection issue. Medicine (Baltim.) 94, e1186. Partin, S.N., Connell, K.A., Schrader, S., Lacombe, J., Lowe, B., Sweeney, A., Reutman, S., Wang, A., Toennis, C., Melman, A., Mikhail, M., Guess, M.K., 2012. The bar sinister: does handlebar level damage the pelvic floor in female cyclists? J. Sex. Med. 9, 1367–1373. Partin, S.N., Connell, K.A., Schrader, S.M., Guess, M.K., 2014. Les lanternes rouges: the race for information about cycling-related female sexual dysfunction. J. Sex. Med. 11, 2039–2047. Potter, J.J., Sauer, J.L., Weisshaar, C.L., Thelen, D.G., Ploeg, H.L., 2008. Gender differences in bicycle saddle pressure distribution during seated cycling. Med. Sci. Sports Exerc. 40, 1126–1134. Rodano, R., Squadrone, R., Sacchi, M., Marzegan, A., 2002. Saddle pressure distribution in cycling: comparison among saddles of different design and materials. ISBS - Conf. Proc. Arch. 1, 606–609. Schwarzer, U., Sommer, F., Klotz, T., Cremer, C., Engelmann, U., 2002. Cycling and penile oxygen pressure: the type of saddle matters. Eur. Urol. 41, 139–143. Sequenzia, G., Fatuzzo, G., Oliveri, S.M., Barbagallo, R., 2016. Interactive re-design of a novel variable geometry bicycle saddle to prevent neurological pathologies. Int. J. Interact. Des. Manuf. 10, 165–172. Silberman, M.R., Webner, D., Collina, S., Shiple, B.J., 2005. Road bicycle fit. Clin. J. Sport Med. 15, 271–276. Sommer, F., Goldstein, I., Korda, J.B., 2010. Bicycle riding and erectile dysfunction: a review. J. Sex. Med. 7, 2346–2358. Søndergaard, K.H.E., Olesen, C.G., Søndergaard, E.K., de Zee, M., Madeleine, P., 2010. The variability and complexity of sitting postural control are associated with discomfort. J. Biomech. 43, 1997–2001. Spears, I.R., Cummins, N.K., Brenchley, Z., Donohue, C., Turnbull, C., Burton, S., Macho, G.A., 2003. The effect of saddle design on stresses in the perineum during cycling. Med. Sci. Sports Exerc. 35, 1620–1625. Taylor, K.S., Richburg, A., Wallis, D., Bracker, M., 2002. Using an experimental bicycle seat to reduce perineal numbness. Phys. Sportsmed. 30, 27–44. Trofaier, M.L., Schneidinger, C., Marschalek, J., Hanzal, E., Umek, W., 2016. Pelvic floor symptoms in female cyclists and possible remedies: a narrative review. Int. UrogynEcol. J. Pelvic Floor Dysfunct. 27, 513–519. Verma, R., Hansen, E.A., de Zee, M., Madeleine, P., 2016. Effect of seat positions on discomfort, muscle activation, pressure distribution and pedal force during cycling. J. Electromyogr. Kinesiol. 27, 78–86. Wilber, C.A., Holland, G.J., Madison, R.E., Loy, S.F., 1995. An epidemiological analysis of overuse injuries among recreational cyclists. Int. J. Sports Med. 16, 201–206. Zemp, R., Taylor, W.R., Lorenzetti, S., 2015. Are pressure measurements effective in the assessment of office chair comfort/discomfort? a review. Appl. Ergon. 48, 273–282. Zenk, R., Franz, M., Bubb, H., Vink, P., 2012. Technical note: spine loading in automotive seating. Appl. Ergon. 43, 290–295.
Conflicts of interest The authors declare no conflicts of interests. Acknowledgement The authors would like to thank the Department of Manufacturing Engineering (M-Tech) at Aalborg University for assistance with producing the saddles. References Asplund, C., Barkdull, T., Weiss, B.D., 2007. Genitourinary problems in bicyclists. Curr. Sports Med. Rep. 6, 333–339. Baeyens, L., Vermeersch, E., Bourgeois, P., Baeyens, L., Vermeersch, E., Bourgeois, P., 2002. Bicyclist's vulva: observational study. BMJ Br. Med. J. (Clin. Res. Ed.) 325, 138. Battaglia, C., Nappi, R.E., Mancini, F., Cianciosi, A., Persico, N., Busacchi, P., 2009. Ultrasonographic and Doppler findings of subclinical clitoral microtraumatisms in mountain bikers and horseback riders. J. Sex. Med. 6, 464–468. Bressel, E., Bliss, S., Cronin, J., 2009a. A field-based approach for examining bicycle seat design effects on seat pressure and perceived stability. Appl. Ergon. 40, 472–476. Bressel, E., Bliss, S., Cronin, J., 2009b. Influence of bicycle seat design on perceived comfort and stability during non-stationary bicycling. Med. Sci. Sports Exerc. 41, 247. Bressel, E., Cronin, J., 2005. Bicycle seat interface pressure: reliability, validity, and influence of hand position and workload. J. Biomech. 38, 1325–1331. Bressel, E., Larson, B.J., 2003. Bicycle seat designs and their effect on pelvic angle, trunk angle, and comfort. Med. Sci. Sports Exerc. 35, 327–332. Buller, J.C., 2001. Female cyclists and perineal symptoms: an experimental bicycle seat. Clin. J. Sport Med. 11, 289–290. Chen, Y.L., Liu, Y.N., 2014. Optimal protruding node length of bicycle seats determined using cycling postures and subjective ratings. Appl. Ergon. 45, 1181–1186. Christiaans, H.H.C.M., Bremner, A., 1998. Comfort on bicycles and the validity of a commercial bicycle fitting system. Appl. Ergon. 29, 201–211. Chumanov, E.S., Remy, C.D., Thelen, D.G., 2010. Computational techniques for using insole pressure sensors to analyse three-dimensional joint kinetics. Comput. Methods Biomech. Biomed. Engin. 13, 505–514. De Vey Mestdagh, K., 1998. Personal perspective: in search of an optimum cycling posture. Appl. Ergon. 29, 325–334. De Looze, M.P., Kuijt-Evers, L.F.M., Van Dieën, J., 2003. Sitting comfort and discomfort and the relationship with objective measures. Ergonomics 46, 985–997. Dettori, N.J., Norvell, D.C., 2006. Non-traumatic bicycle injuries. Sport. Med. 36, 7–18. Ferguson-Pell, M., Cardi, M.D., 1993. Prototype development and comparative evaluation of wheelchair pressure mapping systems. Assis. Technol. 5, 78–91. Froböse, I., Baeyens, L., Tofaute, K., 2003. Ergonomics of 2 bicycle saddles: pressure at the pudendal area in women of a normal saddle with gel and of a saddle with a hole. Proj. Wellcom - Dtsch. Sport. Köln, pp. 1–15. Gemery, J.M., Nangia, A.K., Mamourian, A.C., Reid, S.K., 2007. Digital three-dimensional modelling of the male pelvis and bicycle seats: impact of rider position and seat
181