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Shoulder pain and dysfunction in young surf lifesavers
Physical Therapy in Sport xxx (2014) 1e7
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Original research
Shoulder pain and dysfunction in young surf lifesavers Josh Carter a, Nick Marshall d, Allan Abbott a, b, c, * a
Bond Institute of Health and Sport, Faculty of Health Science and Medicine, Bond University, Australia Division of Physiotherapy, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden c Department of Physiotherapy, Karolinska University Hospital, Sweden d Surflife Physio, Miami, Australia b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 24 June 2014 Received in revised form 2 October 2014 Accepted 13 October 2014
Objectives: To determine the incidence and prevalence of significantly interrupting shoulder pain (SIP) in young surf lifesavers and to determine association with training dosage and the ‘combined elevation test’. Participants: 54 surf lifesavers aged 10e18 from the Gold Coast, Australia. Methods and outcome measures: Retrospective survey of SIP and training dosage. Cross-sectional measures of the combined elevation test. Design: Retrospective. Results: 56.5% of female surf lifesavers reported a history of SIP compared to males with 48.5%. Females had a higher combined elevation score compared to males, 28.32 ± SD 8.52 cm and 26.09 ± SD 6.64 cm, respectively. Young surf lifesavers had an incidence rate of 2.1 SIP episodes per thousand hours of training, an incidence proportion of 51.9% and prevalence of 18.5%. Combined elevation had low level positive trends with training dosages and statistically significant negative correlation with board paddling sessions per week (r ¼ 0.287, p 0.05). Those with a history of SIP had a statistically significant higher number of sessions (p ¼ 0.008), duration (p ¼ 0.015) and distance (p ¼ 0.005) swimming per week. Conclusion: Young surf lifesavers with a history of SIP have greater swimming dosage not associated with a decreased combined elevation score. More board paddling sessions per week decreased the combined elevation score of young surf lifesavers. © 2014 Elsevier Ltd. All rights reserved.
Keywords: Training dosage Swimming Injury prevention
1. Introduction Surf Lifesaving has been an integral part of Australian beach safety, recreation and culture since 1923. Surf Lifesaving Australia (SLSA) provides 70% of lifeguard services at beaches and public pools across the nation and was responsible for rescuing up to 11,000 swimmers in 2005e06 (ABS, 2006). Figures from the 201011 season show that 158,000 individuals participate in surf lifesaving with junior members, known colloquially as ‘nippers’ representing 40% of all surf lifesaving memberships. Furthermore, the participation of nippers alone within the surf lifesaving community has increased 63% over the last ten years (Surf Lifesaving Australia, 2012). Nipper programs introduce children aged 5e13 to surf lifesaving and include beach and surf safety skills, education and training.
* Corresponding author. Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD, 4229, Australia. Tel.: þ61 7 559 54449. E-mail address: [email protected] (A. Abbott).
Training may include swimming, board paddling, rescue techniques and beach sprints or relays. In the younger age groups, nipper training activities generally occur 1e2 times per week which may become more frequent for older nipper groups aged 10e13 and into youth programs aged 14e18. Participants in the nipper and youth programs can progress their training for involvement in competitive activities as they grow and improve their surf swimming, board paddling and beach running ability (Surf Lifesaving Australia, 2012). Since the early 1970's the incidence of shoulder injuries in swimming athletes has significantly increased from 3% to up to 65% in 1996 (Bak, 1996; Kennedy & Hawkins, 1974). It has been established that a large proportion of young pool swimming athletes between the ages of 13 and 25 suffer from shoulder pain and dysfunction (Sein et al., 2010). There is an additional risk of soft tissue and osseous structure injury and instability in individuals who are skeletally immature and participating in training and competition at a high intensity (Chen, Diaz, Loebenberg, & Rosen, 2005; Geier & Paletta, 2006). The repetitive extension, internal
http://dx.doi.org/10.1016/j.ptsp.2014.10.004 1466-853X/© 2014 Elsevier Ltd. All rights reserved.
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7
rotation and elevation of the arm during a swimming stroke, has been associated with proximal humeral epiphysis injuries in the skeletally immature swimmer (Schwab, 1977). The hypertrophy of structures such as the supraspinatus and biceps tendons, rotator cuff tears as well as muscle imbalances may result in shoulder laxity and impingement (Bak, 1996; Fowler, 1979; Fu, Harner, & Klein, 1991; Habermeyer, 1989; Kennedy & Hawkins, 1974; Neer, 1983; Pink & Tibone, 2000; Soslowsky, Thomopoulos, & Tun, 2000). Furthermore, decreased total glenohumeral joint range of motion can contribute to shoulder dysfunction; in particular, decreased ranges of glenohumeral internal and external rotation have been found to increase the risk of shoulder injury. (Bak, 2010; Riemann, Witt, & Davies, 2011; Tate, Turner, Knab, Jorgensen, Strittmatter, & Michener, 2012; Walker, Gabbe, Wajswelner, Blanch, & Bennell, 2012). For those surf lifesavers who partake in both competition and beach patrolling duties, the negative impacts of shoulder dysfunction may include slower swimming times and decreased performance. Additionally, shoulder dysfunction may be detrimental to effectively rescuing a swimmer in distress whilst on patrolling duties. Whilst there is a lack of evidence regarding the aetiology, incidence and prevalence of injuries in surf lifesaving training and competition, one paper from Mitchell, Brighton, and Sherker (2013) found that the most common injury types are strains, sprains, swelling and inflammation. This article did not specify what kind of strains and sprains athletes acquired or where on the body these occurred, however it should be noted that almost half of these injuries occurred in those aged less than 19 years in events that young surf lifesavers commonly participate in. Considering that activities performed by young surf life savers may render them susceptible to shoulder dysfunction, it may be worthwhile to identify an assessment tool capable of screening individuals for susceptibility to shoulder dysfunction. This study aimed to investigate the incidence and prevalence of shoulder pain and dysfunction as well as its association with training dosage and score on the ‘combined elevation test’ in young surf lifesavers. It was hypothesised that a higher training dosage and smaller measurement on the ‘combined elevation test’ would be associated with increased shoulder pain and dysfunction in this population. 2. Methods 2.1. Study design and setting A retrospective study of young surf life savers incidence and prevalence of shoulder pain and dysfunction, training history and a cross-sectional measure of the combined elevation test was undertaken from the 6th of January to the 26th of April 2014, on the Gold Coast in Queensland, Australia. Participants were recruited between the 13th of January to the 10th of February for measurement, whilst data collection was ongoing up until the 4th of March, pending the return of surveys. The study attained ethical clearance through Bond University Human Research Ethics Committee under ethics approval reference ‘RO1751’.
informed consent from the participant's parents. Exclusion criteria for the study were as follows: A) unsigned informed consent from parents of participants and B) recent history of severe acute shoulder injury defined as an injury of the shoulder within the last three days that would prevent an individual lifting their arms above the head. After applying the above criteria, a total of 54 surf lifesavers (M ¼ 31, F ¼ 23) were eligible to participate in the study. 2.3. Procedure Participants were asked to perform the ‘combined elevation test’ prior to their training sessions and were then provided with a selfreport questionnaire to complete. 2.3.1. Combined elevation test The combined elevation test measures the available active range of motion of thoracic extension, active flexion range of motion about the shoulder joints and the ability of the muscles that perform scapula retraction to perform this movement against gravity (Blanch, 2004; Harvey, 1998). Inter-observer reliability of the combined elevation test has been reported to have an ICC of 0.87 (95% ¼ 0.63e0.97) while intra-observer reliability has been reported to have an ICC of 0.97 (95% ¼ 0.88e0.99) when using centimetres as the measurement outcome (Dennisa, Fincha, Elliott, & Farhartd, 2008). The benefit of using this active test was that it replicated participant generated movements such as thoracic extension, shoulder flexion and internal rotation that are performed in surf lifesaving activities such as swimming and board paddling. The same researcher collected these measurements over a two week period at each surf lifesaving club's training events. Participants were asked to lay prone on the ground and to maintain contact of their chin, hips, knees and ankles to the ground at all times. They were then given one practice movement in which they were asked to assume the ‘streamline’ position (Fig. 1) and to lift their arms upwards together pausing at their maximum effort for three seconds. To record the measurement a simple device (Fig. 2) was made consisting of a 150 cm piece of dowel with a tape attached along its length. A small foam collar was placed over the dowel that was able to slide up and down the dowel with minimal resistance. The foam collar was then placed at the participants fingertips whilst resting in prone. They were then asked to slide the foam collar up the piece of dowel with their fingers and to hold the collar at their maximum effort for three seconds. The examiner then stabilised the foam collar and read off the measurement from the bottom of the collar (Fig. 3).
2.2. Participants Young surf lifesavers from Nobby's Beach, Burliegh and Northcliffe Lifesaving clubs on the Gold Coast in Queensland, Australia, were invited to participate in the study. Potential participants were educated about the research protocol through written and verbal delivery of an explanatory statement. Participant's parents were required to sign a consent form prior to testing. Inclusion criteria for the study were as follows: A) surf lifesavers aged 10e18, B) currently competing in surf lifesaving events and C) signed
Fig. 1. Streamline position.
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7
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(McMaster & Troup, 1993; Walker et al., 2012). Participants responded to the questions with the assistance of their parents. The questionnaire is available for use on request from the authors. 3. Results 3.1. Data analysis
Fig. 2. Combined elevation measuring device.
2.3.2. Shoulder questionnaire The self-report questionnaire contained 27 questions aiming to investigate participant demographic characteristics (age and gender), training history (type, frequency, and duration), competition history (type, duration) and shoulder pain and dysfunction history since the beginning of their lifesaving career (type, cause, duration and management). The authors independently developed the questionnaire and consequently it has not been validated. Short answer and nominal response alternatives were provided on the questionnaire. The a priori definition for shoulder pain and dysfunction used was a significant interfering shoulder pain (SIP) that interfered with training or competition, or progression in training and caused cessation or modification of training or racing
Fig. 3. Demonstration of recording of combined elevation.
Descriptive statistics were used to analyse continuous and nominal data which are presented as means and standard deviations or number of participants and percentages in Table 1. Continuous data was normally distributed. Bivariate associations between the combined elevation test, SIP episodes, average number of swimming sessions, swimming hours and swimming distance covered per session as well as average board paddling sessions per week were investigated with Pearson's correlation coefficient r (Table 2). The strength of the correlation coefficient was valued according to Domholdt (2000) who suggested the following scale: .00e.25 ¼ little, if any correlation; .26e.49 ¼ low correlation; .50e.69 ¼ moderate correlation; .70e.89 ¼ high correlation; and .90e1.00 ¼ very high correlation. Considering a potential effect size of r ¼ 0.35, a one tail a ¼ 0.05 and a power of 80%, a sample size of 46 was needed for the Pearson's bivariate correlation testing. An Independent samples t-test was used to analyse potential differences in the combined elevation test and training dosage between participants with a history of SIP compared to those without a history of SIP (Table 4). Considering an effect size of Cohen's d ¼ 0.80, a one tail a ¼ 0.05 and a power of 80%, a sample size of 42 participants were needed for the independent sample ttest. Incidence and prevalence of SIP was calculated using algorithms published by Knowles, Marshall, and Guskiewicz (2006) and can be seen in Table 3. G*Power 3.1.7 was used for sample size calculations and IBM SPSS Statistics 20 software was used for all other data analyses. 3.1.1. Physiological demographics Participants were separated by gender (M ¼ 31, F ¼ 23) and their physiological demographic information is reported in Table 1. The average age of males was 12.03 (±1.45) years whilst the average age of females was 12.78 (±1.70) years. Average combined elevation scores for males were 26.09 cm (±6.64) and 28.32 cm (±8.52) for females. 3.1.2. Surf lifesaving demographics On average females completed more swimming sessions per week (3.61 ± 2.24) and more distance per session (3.54 km ± 1.79) compared to males who completed 2.34 (±1.61) sessions per week and 3.03 km (±1.7) per session. A total of 56.5% (n ¼ 13) of females reported SIP compared to 48.4% (n ¼ 15) of males. Similarly, 21.7% (n ¼ 5) of females reported currently suffering SIP compared to 16.7% (n ¼ 5) of males. With regards to participant's history of surf lifesaving training, females had participated on average for 1.99 years (±1.25) and males 1.87 years (±1.08). Over this time, females demonstrated more episodes of SIP with 2.14 (±0.95) episodes compared to males with 1.87 (±0.92) episodes. The surf lifesaving activity most effected by SIP for both males and females was board paddling, with 56.5% (n ¼ 13) of females and 29% (n ¼ 9) of males having to miss or change their board paddling training. Furthermore 34.8% (n ¼ 8) of females and 22.6% (n ¼ 7) of males missed or adapted their swimming training sessions due to shoulder pain and dysfunction. The most consistently approached medical practitioner for diagnosis and treatment of SIP was a physiotherapist as 71.4% (n ¼ 10) of females and 19.4% (n ¼ 6) of males with an injury attending a practice.
Please cite this article in press as: Carter, J., et al., Shoulder pain and dysfunction in young surf lifesavers, Physical Therapy in Sport (2014), http:// dx.doi.org/10.1016/j.ptsp.2014.10.004
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7
Table 1 Demographic and descriptive data analysis of participants. Total (n ¼ 54)
Male (n ¼ 31)
Total (%)
Physiological demographics Gender Age (yrs) Weight (kg) Height (cm) BMI (kg/m2) Combined elevation score (cm) SLS demographics Number of swimming sessions per week Distance per session (km) Time swimming per week (h) Number of Board paddling sessions per week Duration participating in SLS training (yrs) History of shoulder pain Currently suffering from shoulder pain Number of episodes of shoulder pain Onset of Shoulder pain - Sudden - Gradual Activities affected by shoulder pain - Swimming - Board paddling - Strength training - SLS competition - Sleep Received treatment for shoulder pain - Physiotherapist - Doctor - Hospital accident and emergency - Other
e e e e e e e e e e e 51.9 18.5 e
Female (n ¼ 23)
Mean
S.D.
N (%)
Mean
S.D.
N (%)
e 12.03 43.77 153.26 18.39 26.09
e 1.45 11.29 11.99 2.74 6.64
57.4 e e e e e
e 12.78 47.37 157.48 19.1 28.32
e 1.70 8.08 10.26 2.9 8.52
42.6 e e e e e
2.34 3.03 4.27 2.89 1.87
1.61 1.7 3.05 1.88 1.08 e e 0.92 e
e e e e e 15 (48.4) 5 (16.7) e
3.61 3.54 6.15 1.80 1.99
2.24 1.79 4.74 1.18 1.25 e e 0.95 e
e e e e e 13 (56.5) 5 (21.7) e
e e 1.87 e
33.3 20.4
e e 2.14 e
10 (32.3) 5 (16.1) e
e
27.8 40.7 14.8 14.8 9.3
e 7 9 6 3 2
e
e
(22.6) (29) (19.4) (9.7) (6.5)
e
29.6 3.7 0 0
8 (34.8) 6 (26.1) 8 (34.8) 13 (56.5) 2 (8.7) 5 (21.7) 3 (13) e
e
6 (19.4) 2 (6.5) 0 0
10 (71.4) 0 0 0
Table 2 Pearson's r bivariate correlations. Combined elevation Combined elevation Average Swimming sessions per week Average hours swimming per week Average distance swimming per week Average board paddling sessions per week Number of SIP episodes
Average swimming sessions per week
Average hours swimming per week
Average distance swimming per week
Average board paddling sessions per week
0.070 0.130
e 0.210
Number of SIP episodes
e 0.158 0.229 0.206 ¡0.287* 0.160
e 0.937* 0.930* 0.212 0.110
e 0.944* 0.143 0.170
*P 0.05 (Bolded values).
3.1.3. Incidence and prevalence of shoulder injuries in young surf lifesavers As can be seen in Table 3, the overall SIP incidence rate for young surf lifesavers that participated in this study is 2.1 episodes (SE ¼ 0.003, CI ¼ 3.78, 7.98) per thousand hours of surf lifesaving training. The incidence proportion, assuming all young surf lifesaver in this study were at risk of SIP, was 51.9% (SE ¼ 0.068,
Table 3 Incidence and prevalence of shoulder injuries in young surf lifesavers. Training variable a
Incidence rate/1000 h of training Incidence proportionb Point prevalencec
Value
Standard error
CI
2.1 51.9% 18.5%
0.003 0.068 0.053
3.78, 7.98 0.39, 0.65 0.08, 0.29
a Incidence rate e based on calculation of the total number of injuries reported in those above the age of 10 per sum of the total training hours per career. b Incidence proportion e the amount of shoulder injuries occurring in those who are at risk of a shoulder injury. c Point prevalence e those currently injured of those who were at risk of a shoulder injury.
CI ¼ 0.39, 0.65) while the point prevalence or those currently suffering from SIP was 18.5% (SE ¼ 0.053, CI ¼ 0.08, 0.29). There is a significant negative correlation (r ¼ 0.287, p 0.05) between average number of board paddling sessions per week and the combined elevation score (Table 3). No significant correlations were observed between the occurrence of SIP, swim training dosage and the combined elevation test score. Participant's with a history of SIP completed more swimming sessions per week (p ¼ 0.008), hours of swimming per week (p ¼ 0.015), and distance swimming per week (p ¼ 0.005). 4. Discussion Aiming to investigate the incidence of SIP within young surf lifesavers, this study reported that 2.1 episodes of SIP occurred per thousand hours of training. The study also found SIP to be quite prevalent in young surf life savers with more than half experiencing SIP at some time and 1 in 5 currently experiencing SIP. This is not unlike previous literature which has reported incidence of SIP within the young pool swimming population to range from 0.3 e 4
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Table 4 Independent t-test for participants with a shoulder injury history versus no history of injury. Training dosage
Mean diff
95% CI
Effect size Cohen's d
df
t-value
Sig.
Combined elevation test Swimming sessions completed per week Hours of swimming completed per week Distance swimming per week Board paddling session per week
3.283 1.400 2.563 9.295 0.069
7.321 to 0.756 2.425 to 0.374 4.613 to 0.513 15.663 to 2.926 0.851 to 0.989
0.444 0.751 0.687 0.805 0.041
52 52 52 51 44
1.631 2.739 2.509 2.947 0.150
0.109 0.008 0.015 0.005 0.881
episodes per 1000 swim hours and a prevalence increasing with level of competitiveness (Bak, Bue, & Olsson, 1989; McMaster & Troup, 1993; Richardson, Jobe, & Collins, 1980; Walker et al., 2012; Wolf, Ebinger, Lawler, & Britton, 2009). Compared to pool swimming, surf lifesaving involves both swimming and board paddling in undulating and unpredictable water which one would assume requires greater physical demand. This difference was however not mirrored in the incidence rates of SIP between pool swimmers and surf lifesavers. On the contrary, one could postulate that the variable nature of swimming and board paddling in surf lifesaving may aid in a lower prevalence of SIP compared to the repetitive nature of a pool swimming stroke. This study also sort to investigate the associations between SIP, the combined elevation test and training dosage. Interestingly, very minimal correlation between combined elevation and swimming dosage is seen, which was contrary to the hypothesised results. This discrepancy seen between training dosage and combined elevation may be underpinned by the age group of the participants who are €m, 2004) skeletally immature (Jansson, Saartok, Werner, & Renstro and more prone to hypermobility due to increased amounts of type three collagen compared to adult counterparts (Izzo & Fabbriciani, 2014). These factors may explain why combined elevation scores were not negatively correlated with swimming dosage. Whilst investigating the effect of glenohumeral laxity on injury in swimmers, Wanivenhaus, Fox, and Chaudhury (2012) suggested that up to a point, some laxity may be of benefit to allow swimmers to achieve greater amplitudes of movement within their strokes e such is that an increased range of shoulder movement may be associated with lesser risk of injury due the ability to generate more force from a single stroke therefore negating the need for an increased stroke rate. Furthermore, increased swimming training in this population may improve motor control and muscle power around the shoulder joint (Mariscalco, 2005) which could lead to the minimally positive correlation with combined elevation score. This study did however confirm that surf lifesavers with histories of SIP participate in statistically significantly more training than those without a history of SIP. It is possible that inherent hypermobility in this population could create issues for young surf lifesavers with increased training load and explain the correlation given that, if anything, their combined elevation scores are trending towards increased range of motion. Prolonged high training loads can have a detrimental effect on glenohumeral stability due to repetitive loading of ligamentous structures (Rupp, Berninger, & Hopf, 1995). This lack of stability requires increased dynamic stabilisation through the rotator cuff complex which could cause muscular fatigue resulting in shoulder injury or dysfunction (Rodeo, 2004). The idea of shoulder laxity resulting in shoulder dysfunction or injury further supports the findings of this study and is in line with previous research (Bak & Fauno, 1997; Beach, Whitney, & Dickoff-Hoffman, 1992). It can be seen that the amount of board paddling sessions per week has a statistical significant negative correlation with the combined elevation score (Table 2). The board paddling positions (Fig. 4) is one in which the individual begins in a forward flexed position with scapula protraction, glenohumeral abduction and
flexion to ‘catch’ the water and then the arm is progressed into glenohumeral internal rotation and extension while the thorax extends. By consistently cycling through these positions the sub acromial space is decreased which may predispose board paddlers to impingement symptoms and consequently, a poor combined elevation score (Kibler, Sciascia, & Dome, 2006; Smith, Kotajarvi, Padgett, & Eischen, 2002). As previously mentioned, board paddlers are required to repetitively extend at the thoracic spine and sustain that extended position many times in a board race. Poorly sustained thoracic extension may limit the full amount of movement available at the glenohumeral joint. Crawford and Jull (1993) suggested that there was a strong negative relationship between range of glenohumeral flexion and thoracic extension in young swimmers which supports this notion and would suggest a decreased ability to flex the arm at the glenohumeral joint in poor combined elevation test. Internal rotation at the glenohumeral joint is a dominant movement in the sport of board paddling as this movement is responsible for generating the force to propel an individual forwards through the water. The muscles most associated with this movement are the pectoralis major, latissisimus dorsi and subscapularis
Fig. 4. Surf lifesaving board paddling positions.
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7
(Wanivenhaus et al., 2012). Decreased range of glenohumeral external rotation as a result of tightness of these muscles has been shown to negatively change scapulohumeral rhythm, by limiting the amount of posterior tilt occurring at the scapula (Lin, Kim, & Yang, 2006). It is possible that the decreased score on the combined elevation test could be explained by the need for board paddlers to maintain the arm in a position of glenohumeral internal rotation in order to have an effective ‘catch’ phase of their stroke and consequently limiting the scapula's contribution to glenohumeral rhythm (Richardson et al., 1980). Poor scapulohumeral rhythm could similarly contribute to a poor score on the combined elevation by precipitating imbalances in muscle power (Cools, Witvrouw, Mahieu, & Danneels, 2005; Madsen, Bak, Jensen, & Welter, 2011) or through poor neuromuscular control (Cools, Witvrouw, DeClercq, Vanderstraeten, & Cambier, 2004; Ebaugh, McClure, & Karduna, 2006). Further contributing to decreased combined elevation scores may be a limitation of glenohumeral internal rotation due to posterior cuff muscle tightness leading to unwanted translation of the head of the humerus in a superior and anterior direction (Harryman, Sidles, Clark, McQuade, Gibb, & Matsen, 1990). Individuals demonstrating shortening of the pectoralis minor muscle exhibit altered scapular kinematics, as a result of decreased posterior tilt of the scapula and greater internal rotation during humeral elevation (Borstad & Ludewig, 2005). The combination of these factors resulting from excessive training may explain the association with poor combined elevation scores. In addition, narrowing of the sub acromial space may cause rotator cuff tendon impingement throughout 60e120 degrees of humeral flexion and abduction with internal rotation (Brossman, Preidler, Pedowitz, White, Trudell, & Resnick, 1996). This position is one in which board paddlers repeat many times throughout their training and competition and may result in shoulder dysfunction and poor combined elevation scores. When interpreting these findings, methodological limitations need to be considered. For example, the shoulder survey provided to participants required information from greater than two years previous to be discussed and consequently, recall bias is a limitation in this study. Measurement of the combined elevation score was taken at the participants fingertips which may bias results in favour of those with larger hand size or finger length. In future this could be improved by measuring from the metocarpalphalangeal joints of the hand to standardise this measure. Future studies should also collect SIP occurrences and training dosage data prospectively to minimise participant recall bias. Considering that hypermobility may have played a role in decreasing the association of the combined elevation test with increased training dosage, in the future it may prove worthwhile to control for participant's mobility with a well-known measure such as the Beighton score (Keer & Grahame, 2003, pp. 2e4). The Beighton score may potential be useful in developing cut-off scores for hyper and hypomobility on the combined elevation test. It may also be worthwhile to investigate whether such a simple measure as the combined elevation test is associated with shoulder injury in a population that is skeletally mature such as elite Ironmen and women over the age of 18. 5. Conclusion This research adds valuable information to the unique sport and community of surf lifesaving by revealing swimming training dosage and board paddling training as aetiological factors associated with SIP in young life savers. It highlights the incidence rate of SIP in this population and is suggestive that preventative measures would be of large benefit to young surf lifesavers. Furthermore, it
shows that in this age group of 10e18 year olds, the combined elevation measure may not predict SIP due to skeletal immaturity, hypermobility and significant improvements in scapulohumeral strength and control from the significant amount of training they undertake. However, it may be able to be used to predict SIP in those who are partaking in substantial amounts of board paddling sessions. Conflict of interest None declared. Ethical approval The ethical clearance and informed consent document were approved through Bond University Human Research Ethics Committee under ethics approval reference ‘RO1751’. Funding None declared. References Australian Bureau of Statistics. (2006). Surf lifesaving e An Australian icon in transition, cat. no. 1301.0. Viewed 14 Jan 2014 http://www.abs.gov.au/AUSSTATS/ [email protected]/2f762f95845417aeca25706c00834efa/ 845def90bfdc637aca257235007e7501!OpenDocument#Douglas%20Booth% 20argues%20that%20SLSA%20%E2%80%98. Bak, K. (1996). Nontraumatic glenohumeral instability and coracoacromial impingement in swimmers. Scandinavian Journal of Medicine & Science in Sports, 6, 132e144. Bak, K. (2010). The practical management of swimmer's painful shoulder: etiology, diagnosis, and treatment. Clinical Journal of Sport Medicine, 20(5), 386e390. Bak, K., Bue, P., & Olsson, G. (1989). Injury patterns in Danish competitive swimming. Ugeskrift for Laeger, 151, 2982e2984. Bak, K., & Fauno, P. (1997). Clinical findings in competitive swimmers with shoulder pain. American Journal of Sports Medicine, 25(2), 254e260. Beach, M., Whitney, S., & Dickoff-Hoffman, S. (1992). Relationship of shoulder flexibility, strength, and endurance to shoulder pain in competitive swimmers. Journal of Orthopaedic and Sports Physical Therapy, 16(6), 262e268. Blanch, P. (2004). Conservative management of shoulder pain in swimming. Physical Therapy in Sport, 5, 109e124. Borstad, J., & Ludewig, P. (2005). The effect of long versus short pectoralis minor resting length on scapular kinematics in healthy individuals. Journal of Orthopaedic and Sports Physical Therapy, 35(4), 227e238. Brossmann, J., Preidler, K. W., Pedowitz, R. A., White, L. M., Trudell, D., & Resnick, D. (1996). Shoulder impingement syndrome: influence of shoulder position on rotator cuff impingement: an anatomic study. AJR American Journal of Roentgenology, 167(6), 1511e1515. Chen, F. S., Diaz, V. A., Loebenberg, M., & Rosen, J. E. (2005). Shoulder and elbow injuries in the skeletally immature athlete. Journal of the American Academy of Orthopaedic Surgeons, 13(3), 172e185. Cools, A., Witvrouw, E., DeClercq, G., Vanderstraeten, G., & Cambier, D. (2004). Evaluation of isokinetic force production and associated muscle activity in the scapular rotators during a protraction-retraction movement in overhead athletes with impingement symptoms. British Journal of Sports Medicine, 38, 64e68. Cools, A., Witvrouw, E., Mahieu, N., & Danneels, L. A. (2005). Isokinetic scapular muscle performance in overhead athletes with and without impingement symptoms. Journal of Athletic Training, 40, 104e110. Crawford, H., & Jull, G. (1993). The influence of thoracic posture and movement on range of arm elevation. Physiotherapy Theory and Practice, 9(3), 143e148. Dennisa, R., Fincha, C., Elliott, B., & Farhartd, P. (2008). The reliability of musculoskeletal screening tests used in cricket. Physical Therapy in Sport, 9, 25e33. Domholdt, E. (2000). Physical therapy research: Principles and applications (2nd ed.). Philadelphia: Saunders-Elsevier. Ebaugh, D., McClure, P., & Karduna, A. (2006). Effects of shoulder muscle fatigue caused by repetitive overhead activities on scapulothoracic and glenohumeral kinematics. Journal of Electromyography & Kinesiology, 16, 224e235. Fowler, P. (1979). Symposium: shoulder problems in overhead-overuse sports. American Journal of Sports Medicine, 79(7), 141e142. Fu, F. H., Harner, C., & Klein, A. (1991). Shoulder impingement syndrome. A critical review. Clinical Orthopaedics and Related Research, 269, 162e173. Geier, C., & Paletta, G. (2006). Shoulder instability in the skeletally immature athlete. Operative Techniques in Sports Medicine, 14, 159e164. Habermeyer, P. (1989). Tendon ruptures of the shoulder. Orthopade, 18, 257e266. Harryman, D., Sidles, J., Clark, J., McQuade, K., Gibb, T., & Matsen, F. (1990). Translation of the humeral head on the glenoid with passive glenohumeral motion. Journal of Bone and Joint Surgery, 72(9), 1334e1343.
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7 Harvey, D. (1998). Screening test protocols. Pre-participation screening of athletes: A program developed by the Australian Institute of Sport, Olympic Athlete program and the Australian Sports Injury Prevention Taskforce. Canberra, Australia: Australian Sports Commission. Izzo, V., & Fabbriciani, C. (2014). The shoulder: skeletal injuries and ligamentous instability. Pediatric and Adolescent Sports Traumatology, 83e96. Jansson, A., Saartok, T., Werner, S., & Renstrom, P. (2004). General joint laxity in 1845 Swedish school children of different ages: age- and gender-specific distributions. Paediatrica, 93, 1202e1206. Keer, R., & Grahame, R. (2003). Hypermobility syndrome: Recognition and management for physiotherapists. Elsevier. Kennedy, J., & Hawkins, R. (1974). Swimmers shoulder. Physician and Sportsmedicine, 2, 34e38. Kibler, W., Sciascia, A., & Dome, D. (2006). Evaluation of apparent and absolute supraspinatus strength in patients with shoulder injury using the scapular retraction test. American Journal of Sports Medicine, 34, 1643e1647. Knowles, S., Marshall, S., & Guskiewicz, K. (2006). Issues in estimating risks and rates in sports injury research. Journal of Athletic Training, 42(2), 207e215. Lin, J., Lim, H., & Yang, J. (2006). Effect of shoulder tightness on glenohumeral translation, scapular kinematics, and scapulohumeral rhythm in subjects with stiff shoulders. Journal of Orthopaedic Research, 24(5), 1044e1051. Madsen, P., Bak, K., Jensen, S., & Welter, U. (2011). Training induces scapular dyskinesis in pain-free competitive swimmers: a reliability and observational study. Clinical Journal of Sport Medicine, 21, 109e113. Mariscalco, M. (2005). Upper extremity injuries in the adolescent athlete. Sports Medicine and Arthroscopy Review, 19(1), 17e26. McMaster, W. C., & Troup, J. (1993). A survey of interfering shoulder pain in United States competitive swimmers. American Journal of Sports Medicine, 21, 67e70. Mitchell, R., Brighton, B., & Sherker, S. (2013). The epidemiology of competition and training-based surf sport-related injury in Australia, 2003e2011. Journal of Science and Medicine in Sport, 16(1), 18e21. Neer, C. (1983). Impingement lesions. Clinical Orthopaedics and Related Research, 70e77. Pink, M., & Tibone, J. (2000). The painful shoulder in the swimming athlete. Orthopedic Clinics of North America, 31, 247e261.
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Richardson, A., Jobe, F., & Collins, H. (1980). The shoulder in competitive swimming. American Journal of Sports Medicine, 8, 159e163. Riemann, B., Witt, J., & Davies, G. (2011). Glenohumeral joint rotation range of motion in competitive swimmers. Journal of Sports Sciences, 29(11), 1191e1199. Rodeo, S. (2004). Swimming. In S. Krishnan, R. Hawkins, & R. Warren (Eds.), The shoulder and the overhead athlete. Philadelphia, PA: Lippincott, Williams & WiIlkins. Rupp, S., Berninger, K., & Hopf, T. (1995). Shoulder problems in high level swimmers: impingement, anterior instability, muscular imbalance? International Journal of Sports Medicine, 16(8), 557e562. Schwab, S. (1977). Epiphyseal injuries in the growing athlete. Canadian Medical Association Journal, 117, 626e630. Sein, M., Walton, J., Linklater, J., Appleyard, R., Kirkbride, B., Kuah, D., et al. (2010). Shoulder pain in elite swimmers: primarily due to swim-volumeeinduced supraspinatus tendinopathy. British Journal of Sports Medicine, 44(2), 105e113. Smith, J., Kotajarvi, B., Padgett, D., & Eischen, J. (2002). Effect of scapular protraction and retraction on isometric shoulder elevation strength. Archives of Physical Medicine and Rehabilitation, 83, 367e370. Soslowsky, L., Thomopoulos, S., & Tun, S. (2000). Overuse activity injures the supraspinatus tendon in an animal model: a histologic and biomechanical study. Journal of Shoulder and Elbow Surgery, 9, 79e84. Surf Lifesaving Australia. (2012). Nipper numbers exceed 60,000. Retrieved March 1, 2014, from http://sls.com.au/content/nipper-numbers-exceed-60000. Tate, A., Turner, G., Knab, S., Jorgensen, C., Strittmatter, A., & Michener, A. (2012). Risk factors associated with shoulder pain and disability across the lifespan of competitive swimmers. Journal of Athletic Training, 47(2), 149e158. Walker, H., Gabbe, B., Wajswelner, H., Blanch, P., & Bennell, K. (2012). Shoulder pain in swimmers: a 12-month prospective cohort study of incidence and risk factors. Physical Therapy in Sport, 13, 243e249. Wanivenhaus, F., Fox, A., & Chaudhury, S. (2012). Epidemiology of injuries and prevention strategies in competitive swimmers. Orthopedic Surgery, 4, 246e251. Wolf, B., Ebinger, A., Lawler, M., & Britton, C. (2009). Injury patterns in division I collegiate swimming. American Journal of Sports Medicine, 37(10), 2037e2042.
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Physical Therapy in Sport journal homepage: www.elsevier.com/ptsp
Original research
Shoulder pain and dysfunction in young surf lifesavers Josh Carter a, Nick Marshall d, Allan Abbott a, b, c, * a
Bond Institute of Health and Sport, Faculty of Health Science and Medicine, Bond University, Australia Division of Physiotherapy, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden c Department of Physiotherapy, Karolinska University Hospital, Sweden d Surflife Physio, Miami, Australia b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 24 June 2014 Received in revised form 2 October 2014 Accepted 13 October 2014
Objectives: To determine the incidence and prevalence of significantly interrupting shoulder pain (SIP) in young surf lifesavers and to determine association with training dosage and the ‘combined elevation test’. Participants: 54 surf lifesavers aged 10e18 from the Gold Coast, Australia. Methods and outcome measures: Retrospective survey of SIP and training dosage. Cross-sectional measures of the combined elevation test. Design: Retrospective. Results: 56.5% of female surf lifesavers reported a history of SIP compared to males with 48.5%. Females had a higher combined elevation score compared to males, 28.32 ± SD 8.52 cm and 26.09 ± SD 6.64 cm, respectively. Young surf lifesavers had an incidence rate of 2.1 SIP episodes per thousand hours of training, an incidence proportion of 51.9% and prevalence of 18.5%. Combined elevation had low level positive trends with training dosages and statistically significant negative correlation with board paddling sessions per week (r ¼ 0.287, p 0.05). Those with a history of SIP had a statistically significant higher number of sessions (p ¼ 0.008), duration (p ¼ 0.015) and distance (p ¼ 0.005) swimming per week. Conclusion: Young surf lifesavers with a history of SIP have greater swimming dosage not associated with a decreased combined elevation score. More board paddling sessions per week decreased the combined elevation score of young surf lifesavers. © 2014 Elsevier Ltd. All rights reserved.
Keywords: Training dosage Swimming Injury prevention
1. Introduction Surf Lifesaving has been an integral part of Australian beach safety, recreation and culture since 1923. Surf Lifesaving Australia (SLSA) provides 70% of lifeguard services at beaches and public pools across the nation and was responsible for rescuing up to 11,000 swimmers in 2005e06 (ABS, 2006). Figures from the 201011 season show that 158,000 individuals participate in surf lifesaving with junior members, known colloquially as ‘nippers’ representing 40% of all surf lifesaving memberships. Furthermore, the participation of nippers alone within the surf lifesaving community has increased 63% over the last ten years (Surf Lifesaving Australia, 2012). Nipper programs introduce children aged 5e13 to surf lifesaving and include beach and surf safety skills, education and training.
* Corresponding author. Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD, 4229, Australia. Tel.: þ61 7 559 54449. E-mail address: [email protected] (A. Abbott).
Training may include swimming, board paddling, rescue techniques and beach sprints or relays. In the younger age groups, nipper training activities generally occur 1e2 times per week which may become more frequent for older nipper groups aged 10e13 and into youth programs aged 14e18. Participants in the nipper and youth programs can progress their training for involvement in competitive activities as they grow and improve their surf swimming, board paddling and beach running ability (Surf Lifesaving Australia, 2012). Since the early 1970's the incidence of shoulder injuries in swimming athletes has significantly increased from 3% to up to 65% in 1996 (Bak, 1996; Kennedy & Hawkins, 1974). It has been established that a large proportion of young pool swimming athletes between the ages of 13 and 25 suffer from shoulder pain and dysfunction (Sein et al., 2010). There is an additional risk of soft tissue and osseous structure injury and instability in individuals who are skeletally immature and participating in training and competition at a high intensity (Chen, Diaz, Loebenberg, & Rosen, 2005; Geier & Paletta, 2006). The repetitive extension, internal
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7
rotation and elevation of the arm during a swimming stroke, has been associated with proximal humeral epiphysis injuries in the skeletally immature swimmer (Schwab, 1977). The hypertrophy of structures such as the supraspinatus and biceps tendons, rotator cuff tears as well as muscle imbalances may result in shoulder laxity and impingement (Bak, 1996; Fowler, 1979; Fu, Harner, & Klein, 1991; Habermeyer, 1989; Kennedy & Hawkins, 1974; Neer, 1983; Pink & Tibone, 2000; Soslowsky, Thomopoulos, & Tun, 2000). Furthermore, decreased total glenohumeral joint range of motion can contribute to shoulder dysfunction; in particular, decreased ranges of glenohumeral internal and external rotation have been found to increase the risk of shoulder injury. (Bak, 2010; Riemann, Witt, & Davies, 2011; Tate, Turner, Knab, Jorgensen, Strittmatter, & Michener, 2012; Walker, Gabbe, Wajswelner, Blanch, & Bennell, 2012). For those surf lifesavers who partake in both competition and beach patrolling duties, the negative impacts of shoulder dysfunction may include slower swimming times and decreased performance. Additionally, shoulder dysfunction may be detrimental to effectively rescuing a swimmer in distress whilst on patrolling duties. Whilst there is a lack of evidence regarding the aetiology, incidence and prevalence of injuries in surf lifesaving training and competition, one paper from Mitchell, Brighton, and Sherker (2013) found that the most common injury types are strains, sprains, swelling and inflammation. This article did not specify what kind of strains and sprains athletes acquired or where on the body these occurred, however it should be noted that almost half of these injuries occurred in those aged less than 19 years in events that young surf lifesavers commonly participate in. Considering that activities performed by young surf life savers may render them susceptible to shoulder dysfunction, it may be worthwhile to identify an assessment tool capable of screening individuals for susceptibility to shoulder dysfunction. This study aimed to investigate the incidence and prevalence of shoulder pain and dysfunction as well as its association with training dosage and score on the ‘combined elevation test’ in young surf lifesavers. It was hypothesised that a higher training dosage and smaller measurement on the ‘combined elevation test’ would be associated with increased shoulder pain and dysfunction in this population. 2. Methods 2.1. Study design and setting A retrospective study of young surf life savers incidence and prevalence of shoulder pain and dysfunction, training history and a cross-sectional measure of the combined elevation test was undertaken from the 6th of January to the 26th of April 2014, on the Gold Coast in Queensland, Australia. Participants were recruited between the 13th of January to the 10th of February for measurement, whilst data collection was ongoing up until the 4th of March, pending the return of surveys. The study attained ethical clearance through Bond University Human Research Ethics Committee under ethics approval reference ‘RO1751’.
informed consent from the participant's parents. Exclusion criteria for the study were as follows: A) unsigned informed consent from parents of participants and B) recent history of severe acute shoulder injury defined as an injury of the shoulder within the last three days that would prevent an individual lifting their arms above the head. After applying the above criteria, a total of 54 surf lifesavers (M ¼ 31, F ¼ 23) were eligible to participate in the study. 2.3. Procedure Participants were asked to perform the ‘combined elevation test’ prior to their training sessions and were then provided with a selfreport questionnaire to complete. 2.3.1. Combined elevation test The combined elevation test measures the available active range of motion of thoracic extension, active flexion range of motion about the shoulder joints and the ability of the muscles that perform scapula retraction to perform this movement against gravity (Blanch, 2004; Harvey, 1998). Inter-observer reliability of the combined elevation test has been reported to have an ICC of 0.87 (95% ¼ 0.63e0.97) while intra-observer reliability has been reported to have an ICC of 0.97 (95% ¼ 0.88e0.99) when using centimetres as the measurement outcome (Dennisa, Fincha, Elliott, & Farhartd, 2008). The benefit of using this active test was that it replicated participant generated movements such as thoracic extension, shoulder flexion and internal rotation that are performed in surf lifesaving activities such as swimming and board paddling. The same researcher collected these measurements over a two week period at each surf lifesaving club's training events. Participants were asked to lay prone on the ground and to maintain contact of their chin, hips, knees and ankles to the ground at all times. They were then given one practice movement in which they were asked to assume the ‘streamline’ position (Fig. 1) and to lift their arms upwards together pausing at their maximum effort for three seconds. To record the measurement a simple device (Fig. 2) was made consisting of a 150 cm piece of dowel with a tape attached along its length. A small foam collar was placed over the dowel that was able to slide up and down the dowel with minimal resistance. The foam collar was then placed at the participants fingertips whilst resting in prone. They were then asked to slide the foam collar up the piece of dowel with their fingers and to hold the collar at their maximum effort for three seconds. The examiner then stabilised the foam collar and read off the measurement from the bottom of the collar (Fig. 3).
2.2. Participants Young surf lifesavers from Nobby's Beach, Burliegh and Northcliffe Lifesaving clubs on the Gold Coast in Queensland, Australia, were invited to participate in the study. Potential participants were educated about the research protocol through written and verbal delivery of an explanatory statement. Participant's parents were required to sign a consent form prior to testing. Inclusion criteria for the study were as follows: A) surf lifesavers aged 10e18, B) currently competing in surf lifesaving events and C) signed
Fig. 1. Streamline position.
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7
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(McMaster & Troup, 1993; Walker et al., 2012). Participants responded to the questions with the assistance of their parents. The questionnaire is available for use on request from the authors. 3. Results 3.1. Data analysis
Fig. 2. Combined elevation measuring device.
2.3.2. Shoulder questionnaire The self-report questionnaire contained 27 questions aiming to investigate participant demographic characteristics (age and gender), training history (type, frequency, and duration), competition history (type, duration) and shoulder pain and dysfunction history since the beginning of their lifesaving career (type, cause, duration and management). The authors independently developed the questionnaire and consequently it has not been validated. Short answer and nominal response alternatives were provided on the questionnaire. The a priori definition for shoulder pain and dysfunction used was a significant interfering shoulder pain (SIP) that interfered with training or competition, or progression in training and caused cessation or modification of training or racing
Fig. 3. Demonstration of recording of combined elevation.
Descriptive statistics were used to analyse continuous and nominal data which are presented as means and standard deviations or number of participants and percentages in Table 1. Continuous data was normally distributed. Bivariate associations between the combined elevation test, SIP episodes, average number of swimming sessions, swimming hours and swimming distance covered per session as well as average board paddling sessions per week were investigated with Pearson's correlation coefficient r (Table 2). The strength of the correlation coefficient was valued according to Domholdt (2000) who suggested the following scale: .00e.25 ¼ little, if any correlation; .26e.49 ¼ low correlation; .50e.69 ¼ moderate correlation; .70e.89 ¼ high correlation; and .90e1.00 ¼ very high correlation. Considering a potential effect size of r ¼ 0.35, a one tail a ¼ 0.05 and a power of 80%, a sample size of 46 was needed for the Pearson's bivariate correlation testing. An Independent samples t-test was used to analyse potential differences in the combined elevation test and training dosage between participants with a history of SIP compared to those without a history of SIP (Table 4). Considering an effect size of Cohen's d ¼ 0.80, a one tail a ¼ 0.05 and a power of 80%, a sample size of 42 participants were needed for the independent sample ttest. Incidence and prevalence of SIP was calculated using algorithms published by Knowles, Marshall, and Guskiewicz (2006) and can be seen in Table 3. G*Power 3.1.7 was used for sample size calculations and IBM SPSS Statistics 20 software was used for all other data analyses. 3.1.1. Physiological demographics Participants were separated by gender (M ¼ 31, F ¼ 23) and their physiological demographic information is reported in Table 1. The average age of males was 12.03 (±1.45) years whilst the average age of females was 12.78 (±1.70) years. Average combined elevation scores for males were 26.09 cm (±6.64) and 28.32 cm (±8.52) for females. 3.1.2. Surf lifesaving demographics On average females completed more swimming sessions per week (3.61 ± 2.24) and more distance per session (3.54 km ± 1.79) compared to males who completed 2.34 (±1.61) sessions per week and 3.03 km (±1.7) per session. A total of 56.5% (n ¼ 13) of females reported SIP compared to 48.4% (n ¼ 15) of males. Similarly, 21.7% (n ¼ 5) of females reported currently suffering SIP compared to 16.7% (n ¼ 5) of males. With regards to participant's history of surf lifesaving training, females had participated on average for 1.99 years (±1.25) and males 1.87 years (±1.08). Over this time, females demonstrated more episodes of SIP with 2.14 (±0.95) episodes compared to males with 1.87 (±0.92) episodes. The surf lifesaving activity most effected by SIP for both males and females was board paddling, with 56.5% (n ¼ 13) of females and 29% (n ¼ 9) of males having to miss or change their board paddling training. Furthermore 34.8% (n ¼ 8) of females and 22.6% (n ¼ 7) of males missed or adapted their swimming training sessions due to shoulder pain and dysfunction. The most consistently approached medical practitioner for diagnosis and treatment of SIP was a physiotherapist as 71.4% (n ¼ 10) of females and 19.4% (n ¼ 6) of males with an injury attending a practice.
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7
Table 1 Demographic and descriptive data analysis of participants. Total (n ¼ 54)
Male (n ¼ 31)
Total (%)
Physiological demographics Gender Age (yrs) Weight (kg) Height (cm) BMI (kg/m2) Combined elevation score (cm) SLS demographics Number of swimming sessions per week Distance per session (km) Time swimming per week (h) Number of Board paddling sessions per week Duration participating in SLS training (yrs) History of shoulder pain Currently suffering from shoulder pain Number of episodes of shoulder pain Onset of Shoulder pain - Sudden - Gradual Activities affected by shoulder pain - Swimming - Board paddling - Strength training - SLS competition - Sleep Received treatment for shoulder pain - Physiotherapist - Doctor - Hospital accident and emergency - Other
e e e e e e e e e e e 51.9 18.5 e
Female (n ¼ 23)
Mean
S.D.
N (%)
Mean
S.D.
N (%)
e 12.03 43.77 153.26 18.39 26.09
e 1.45 11.29 11.99 2.74 6.64
57.4 e e e e e
e 12.78 47.37 157.48 19.1 28.32
e 1.70 8.08 10.26 2.9 8.52
42.6 e e e e e
2.34 3.03 4.27 2.89 1.87
1.61 1.7 3.05 1.88 1.08 e e 0.92 e
e e e e e 15 (48.4) 5 (16.7) e
3.61 3.54 6.15 1.80 1.99
2.24 1.79 4.74 1.18 1.25 e e 0.95 e
e e e e e 13 (56.5) 5 (21.7) e
e e 1.87 e
33.3 20.4
e e 2.14 e
10 (32.3) 5 (16.1) e
e
27.8 40.7 14.8 14.8 9.3
e 7 9 6 3 2
e
e
(22.6) (29) (19.4) (9.7) (6.5)
e
29.6 3.7 0 0
8 (34.8) 6 (26.1) 8 (34.8) 13 (56.5) 2 (8.7) 5 (21.7) 3 (13) e
e
6 (19.4) 2 (6.5) 0 0
10 (71.4) 0 0 0
Table 2 Pearson's r bivariate correlations. Combined elevation Combined elevation Average Swimming sessions per week Average hours swimming per week Average distance swimming per week Average board paddling sessions per week Number of SIP episodes
Average swimming sessions per week
Average hours swimming per week
Average distance swimming per week
Average board paddling sessions per week
0.070 0.130
e 0.210
Number of SIP episodes
e 0.158 0.229 0.206 ¡0.287* 0.160
e 0.937* 0.930* 0.212 0.110
e 0.944* 0.143 0.170
*P 0.05 (Bolded values).
3.1.3. Incidence and prevalence of shoulder injuries in young surf lifesavers As can be seen in Table 3, the overall SIP incidence rate for young surf lifesavers that participated in this study is 2.1 episodes (SE ¼ 0.003, CI ¼ 3.78, 7.98) per thousand hours of surf lifesaving training. The incidence proportion, assuming all young surf lifesaver in this study were at risk of SIP, was 51.9% (SE ¼ 0.068,
Table 3 Incidence and prevalence of shoulder injuries in young surf lifesavers. Training variable a
Incidence rate/1000 h of training Incidence proportionb Point prevalencec
Value
Standard error
CI
2.1 51.9% 18.5%
0.003 0.068 0.053
3.78, 7.98 0.39, 0.65 0.08, 0.29
a Incidence rate e based on calculation of the total number of injuries reported in those above the age of 10 per sum of the total training hours per career. b Incidence proportion e the amount of shoulder injuries occurring in those who are at risk of a shoulder injury. c Point prevalence e those currently injured of those who were at risk of a shoulder injury.
CI ¼ 0.39, 0.65) while the point prevalence or those currently suffering from SIP was 18.5% (SE ¼ 0.053, CI ¼ 0.08, 0.29). There is a significant negative correlation (r ¼ 0.287, p 0.05) between average number of board paddling sessions per week and the combined elevation score (Table 3). No significant correlations were observed between the occurrence of SIP, swim training dosage and the combined elevation test score. Participant's with a history of SIP completed more swimming sessions per week (p ¼ 0.008), hours of swimming per week (p ¼ 0.015), and distance swimming per week (p ¼ 0.005). 4. Discussion Aiming to investigate the incidence of SIP within young surf lifesavers, this study reported that 2.1 episodes of SIP occurred per thousand hours of training. The study also found SIP to be quite prevalent in young surf life savers with more than half experiencing SIP at some time and 1 in 5 currently experiencing SIP. This is not unlike previous literature which has reported incidence of SIP within the young pool swimming population to range from 0.3 e 4
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7
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Table 4 Independent t-test for participants with a shoulder injury history versus no history of injury. Training dosage
Mean diff
95% CI
Effect size Cohen's d
df
t-value
Sig.
Combined elevation test Swimming sessions completed per week Hours of swimming completed per week Distance swimming per week Board paddling session per week
3.283 1.400 2.563 9.295 0.069
7.321 to 0.756 2.425 to 0.374 4.613 to 0.513 15.663 to 2.926 0.851 to 0.989
0.444 0.751 0.687 0.805 0.041
52 52 52 51 44
1.631 2.739 2.509 2.947 0.150
0.109 0.008 0.015 0.005 0.881
episodes per 1000 swim hours and a prevalence increasing with level of competitiveness (Bak, Bue, & Olsson, 1989; McMaster & Troup, 1993; Richardson, Jobe, & Collins, 1980; Walker et al., 2012; Wolf, Ebinger, Lawler, & Britton, 2009). Compared to pool swimming, surf lifesaving involves both swimming and board paddling in undulating and unpredictable water which one would assume requires greater physical demand. This difference was however not mirrored in the incidence rates of SIP between pool swimmers and surf lifesavers. On the contrary, one could postulate that the variable nature of swimming and board paddling in surf lifesaving may aid in a lower prevalence of SIP compared to the repetitive nature of a pool swimming stroke. This study also sort to investigate the associations between SIP, the combined elevation test and training dosage. Interestingly, very minimal correlation between combined elevation and swimming dosage is seen, which was contrary to the hypothesised results. This discrepancy seen between training dosage and combined elevation may be underpinned by the age group of the participants who are €m, 2004) skeletally immature (Jansson, Saartok, Werner, & Renstro and more prone to hypermobility due to increased amounts of type three collagen compared to adult counterparts (Izzo & Fabbriciani, 2014). These factors may explain why combined elevation scores were not negatively correlated with swimming dosage. Whilst investigating the effect of glenohumeral laxity on injury in swimmers, Wanivenhaus, Fox, and Chaudhury (2012) suggested that up to a point, some laxity may be of benefit to allow swimmers to achieve greater amplitudes of movement within their strokes e such is that an increased range of shoulder movement may be associated with lesser risk of injury due the ability to generate more force from a single stroke therefore negating the need for an increased stroke rate. Furthermore, increased swimming training in this population may improve motor control and muscle power around the shoulder joint (Mariscalco, 2005) which could lead to the minimally positive correlation with combined elevation score. This study did however confirm that surf lifesavers with histories of SIP participate in statistically significantly more training than those without a history of SIP. It is possible that inherent hypermobility in this population could create issues for young surf lifesavers with increased training load and explain the correlation given that, if anything, their combined elevation scores are trending towards increased range of motion. Prolonged high training loads can have a detrimental effect on glenohumeral stability due to repetitive loading of ligamentous structures (Rupp, Berninger, & Hopf, 1995). This lack of stability requires increased dynamic stabilisation through the rotator cuff complex which could cause muscular fatigue resulting in shoulder injury or dysfunction (Rodeo, 2004). The idea of shoulder laxity resulting in shoulder dysfunction or injury further supports the findings of this study and is in line with previous research (Bak & Fauno, 1997; Beach, Whitney, & Dickoff-Hoffman, 1992). It can be seen that the amount of board paddling sessions per week has a statistical significant negative correlation with the combined elevation score (Table 2). The board paddling positions (Fig. 4) is one in which the individual begins in a forward flexed position with scapula protraction, glenohumeral abduction and
flexion to ‘catch’ the water and then the arm is progressed into glenohumeral internal rotation and extension while the thorax extends. By consistently cycling through these positions the sub acromial space is decreased which may predispose board paddlers to impingement symptoms and consequently, a poor combined elevation score (Kibler, Sciascia, & Dome, 2006; Smith, Kotajarvi, Padgett, & Eischen, 2002). As previously mentioned, board paddlers are required to repetitively extend at the thoracic spine and sustain that extended position many times in a board race. Poorly sustained thoracic extension may limit the full amount of movement available at the glenohumeral joint. Crawford and Jull (1993) suggested that there was a strong negative relationship between range of glenohumeral flexion and thoracic extension in young swimmers which supports this notion and would suggest a decreased ability to flex the arm at the glenohumeral joint in poor combined elevation test. Internal rotation at the glenohumeral joint is a dominant movement in the sport of board paddling as this movement is responsible for generating the force to propel an individual forwards through the water. The muscles most associated with this movement are the pectoralis major, latissisimus dorsi and subscapularis
Fig. 4. Surf lifesaving board paddling positions.
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J. Carter et al. / Physical Therapy in Sport xxx (2014) 1e7
(Wanivenhaus et al., 2012). Decreased range of glenohumeral external rotation as a result of tightness of these muscles has been shown to negatively change scapulohumeral rhythm, by limiting the amount of posterior tilt occurring at the scapula (Lin, Kim, & Yang, 2006). It is possible that the decreased score on the combined elevation test could be explained by the need for board paddlers to maintain the arm in a position of glenohumeral internal rotation in order to have an effective ‘catch’ phase of their stroke and consequently limiting the scapula's contribution to glenohumeral rhythm (Richardson et al., 1980). Poor scapulohumeral rhythm could similarly contribute to a poor score on the combined elevation by precipitating imbalances in muscle power (Cools, Witvrouw, Mahieu, & Danneels, 2005; Madsen, Bak, Jensen, & Welter, 2011) or through poor neuromuscular control (Cools, Witvrouw, DeClercq, Vanderstraeten, & Cambier, 2004; Ebaugh, McClure, & Karduna, 2006). Further contributing to decreased combined elevation scores may be a limitation of glenohumeral internal rotation due to posterior cuff muscle tightness leading to unwanted translation of the head of the humerus in a superior and anterior direction (Harryman, Sidles, Clark, McQuade, Gibb, & Matsen, 1990). Individuals demonstrating shortening of the pectoralis minor muscle exhibit altered scapular kinematics, as a result of decreased posterior tilt of the scapula and greater internal rotation during humeral elevation (Borstad & Ludewig, 2005). The combination of these factors resulting from excessive training may explain the association with poor combined elevation scores. In addition, narrowing of the sub acromial space may cause rotator cuff tendon impingement throughout 60e120 degrees of humeral flexion and abduction with internal rotation (Brossman, Preidler, Pedowitz, White, Trudell, & Resnick, 1996). This position is one in which board paddlers repeat many times throughout their training and competition and may result in shoulder dysfunction and poor combined elevation scores. When interpreting these findings, methodological limitations need to be considered. For example, the shoulder survey provided to participants required information from greater than two years previous to be discussed and consequently, recall bias is a limitation in this study. Measurement of the combined elevation score was taken at the participants fingertips which may bias results in favour of those with larger hand size or finger length. In future this could be improved by measuring from the metocarpalphalangeal joints of the hand to standardise this measure. Future studies should also collect SIP occurrences and training dosage data prospectively to minimise participant recall bias. Considering that hypermobility may have played a role in decreasing the association of the combined elevation test with increased training dosage, in the future it may prove worthwhile to control for participant's mobility with a well-known measure such as the Beighton score (Keer & Grahame, 2003, pp. 2e4). The Beighton score may potential be useful in developing cut-off scores for hyper and hypomobility on the combined elevation test. It may also be worthwhile to investigate whether such a simple measure as the combined elevation test is associated with shoulder injury in a population that is skeletally mature such as elite Ironmen and women over the age of 18. 5. Conclusion This research adds valuable information to the unique sport and community of surf lifesaving by revealing swimming training dosage and board paddling training as aetiological factors associated with SIP in young life savers. It highlights the incidence rate of SIP in this population and is suggestive that preventative measures would be of large benefit to young surf lifesavers. Furthermore, it
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Please cite this article in press as: Carter, J., et al., Shoulder pain and dysfunction in young surf lifesavers, Physical Therapy in Sport (2014), http:// dx.doi.org/10.1016/j.ptsp.2014.10.004