Temporal parameters and patterns of the foot roll over during walking: normative data for healthy adults

Gait and Posture 10 (1999) 97 – 108 www.elsevier.com/locate/gaitpost

Temporal parameters and patterns of the foot roll over during walking: normative data for healthy adults Yves Blanc a,c,*, Claude Balmer b, Theodor Landis c, Franc¸ois Vingerhoets c Laboratoire de Cine´siologie, Hoˆpitaux Uni6ersitaires, 24 Rue Micheli du Crest, 1211 Gene`6e 14, Switzerland b Balmer Informatique Industrielle S.A., Le Mont sur Lausanne, Switzerland c Clinique de Neurologie Hoˆpital Cantonal, Hopitaux Uni6ersitaires, 24 Rue Micheli du Crest, 1211 Gene`6e 14, Switzerland a

Received 3 March 1998; received in revised form 22 February 1999; accepted 19 March 1999

Abstract Temporal parameters of the gait cycle and foot roll over in 105 healthy adults (75 women and 30 men aged 16 to 63 years) were collected using foot switches. The subjects walked unobserved at their preferred pace and velocity in a hallway 19 m long and 2.8 m wide. After correction for height, a significant gender influence remained on stance parameters and stride duration. For these adults, age had an effect on the forward tilt of the foot and the double support time only. Differences due to side related only to foot patterning and not stride, stance and swing times. Asymmetry coefficient for temporal parameters of gait cycle and foot roll over revealed the greatest asymmetry in metatarsal head and great toe latency and support. These reference data are considered valid in a laboratory using sensors and signal processing comparable to ours. © 1999 Elsevier Science B.V. All rights reserved. Keywords: Gait analysis; Foot switches; Foot roll over; Temporal parameters; Adults’ normal data

1. Introduction Foot switches are one method of measuring temporal parameters gait. Individual sensors can be attached to the sole of the foot [1 – 5] or included in modified insoles [6 – 9] or shoes [10– 12]. Arrays of sensors have been embedded in walkways to study spatial rather than temporal parameters of the stepping cycles [13–15]. Foot pressure distribution is a useful investigation in foot pathologies such as diabetic neuropathy or rheumatoid arthritis [16 – 25]. Their reliability to measure temporal parameters of stance vary with the capture rate of data (from 25 [26 – 28] to 250 Hz [29]), which in turn depends on the number of load cells. Unless insoles are used and multi-strides recorded, swing phase information and single support times cannot be obtained. Foot switches should provide information on the support pattern and timing of the foot roll over, duration of the stride periods and phases. Accurate mea* Corresponding author. Fax: +41-22-3727799. E-mail address: [email protected] (Y. Blanc)

surement of initial and final foot contact times are usually used as a reference clock for all gait data. Foot roll-over timing enables measurements of the mediolateral and longitudinal behaviour of the foot. These elements are crucial to distinguish between normal and pathological gait and for a comprehensive analysis of leg and foot muscular activities. [3]. The purpose of this study was to provide norms for the nature and timing of the foot floor contact and to quantify right and left asymmetry of temporal parameters from a normal population walking in a long corridor. Foot switches were used because they; 1. quantify the foot roll-over pattern, 2. reflect differences between right and left foot, 3. allow measurement of many consecutive gait cycles.

2. Method The subjects (105 in total, consisting of 75 women and 30 men) were recruited from the local area (Table 1). They had no known orthopaedic, metabolic or neurological impairment or painful condition that

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might alter their walking pattern and none were taking any sedative medication. All gave oral informed consent. After attachment of the foot switches, subjects were allowed to walk until they were comfortable. The floor was covered by linoleum and its temperature, which ranged from 22 to 25°C was not perceived as a cold surface. Subjects wore casual loose fitting clothing that did not impede hip and knee motion. They walked bare foot, at their own speed and self selected pace along a corridor 19 m long and 2.8 m wide. All data were collected during level walking at their preferred speed while they were alone and unobserved in the corridor. The on/off foot switches were constructed in our laboratory as described previously [3] except for the rear foot. Here the original arrangement of two sensors placed under the heel were replaced by one sensor with five switches in parallel. Sensors were placed beneath the heel, the 1st, 5th metatarsal heads and the great toe of each foot (Fig. 1) Each sensor was attached to the skin with double side adhesive tape and secured by a band of skin tape. The mean delay of the sensors to detect floor contact is 0.3 ms and −0.5 ms at contact off. Each switch was connected to a specific resistor placed on the dorsum of the foot, then the encoded signal was carried via a cable to a radio transmitter (Biomes 88, Glonner GMBH, Germany) worn around the subject’s waist. The coded signal was sampled at 700 Hz before transmission to the receiver. A warning circuit controlled the on/off occurrence of each switch during each stance phase. A dedicated circuit recognized the periods of each gait cycle and incremented a stride counter at the beginning of the stance phase. The combined signals of the switches (Fig. 2) and the stride counter were displayed on line on a strip chart recorder (U8008, Fritz Schwartzer GMBH, Germany) for visual quality control. At the same time, the signals were sampled at a frequency of 2 kHz per channel and stored for subsequent computation. In this study, foot roll over was defined as the sequential order of closure and opening of switches. The latency between initial contact (IC) and each switch (Fig. 3), determines the foot contact sequence. For each foot all the gait cycles were sorted according to the sequence of switches closing and opening during forward tilt and push off. Frequency tables of the combinations were established. Table 1 Subjects’ characteristics Gender

Age (years) mean (range)

Mass (kg) mean (range)

Height (cm) mean (range)

Women Men

32.3 (16–63) 31.7 (20–52)

57.3 (42–70) 69.2 (52–83)

164.4 (150–176) 176.7 (165–196)

Fig. 1. Overall view of foot switches placement.

Each switch latency plus its closure duration indicates the time of foot flat and push off. Perry [30] has defined this pattern as three ‘rockers’. All the strides of the steady state of walking were selected for analysis. The first and last three strides, the three preceding and following a turn were discarded from the computation. Each remaining stride was expressed by the following measures: “ Stride duration (stride)= time elapsed between two consecutive contacts of the same foot with the floor. “ Cadence (unit: stridesmin − 1). “ Stance phase (stance)= time of support on one foot. “ Swing phase (swing)=time when one foot is off the ground. “ Support time on each switch= time during which the corresponding part of the foot is on the ground: heel support duration (supHeel), 5th metatarsal head (supM5), 1st metatarsal head (supM1), great toe (supGT). “ Initial (IDS) and Terminal (TDS) double supports, respectively at the beginning and at the end of the stance phase when the two feet are on the ground. Their sum represents the double support phase (Dsup).

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Fig. 2. Example of foot switches patterns from a 51-year-old healthy man. The variation of pattern around mid stance represents the inter strides variability of the great toe contact. A, left foot; B, right foot; C, stride counter incrementing on the right side; D, decoded signal of each switch. IC = initial contact. FO =foot off the ground. IDS= initial double support. SSUP = single support corresponds to the swing phase of the contralateral side. TDS =terminal double support. “

Single support (Ssup) corresponds to the swing phase of the contralateral foot. All the latencies are referred to the delay between the foot IC and the onset of each switches when the corresponding part of the foot contacts the ground. They are named: “ Latencies of heel (latHeel), 5th metatarsal head (latM5), 1st metatarsal head (latM1), great toe (latGT). Relationships between stance phase and foot roll over are also expressed by the following quantities: “ Heel to Ball (HeelBall)is equal to the time from heel contact to 5th or 1st metatarsal heads on. It represents the shortest latency between latM1 and latM5 and corresponds to the heel rocker [30]. “ Heel to GT (HeelGT)=time from heel to great toe contact. “ Heel-and-ball=period of time when the heel and the metatarsal heads are on the floor but the great toe is still off the ground. “ FootFlat: time when all the switches are on. This definition induces a large range of values corresponding to the variation of latGT. This sequence does not represent the ankle rocker [30] which is equal to heel off minus HeelBall. “ PushOff corresponds to the forefoot rocker [30]. It is equal to the difference between stance minus LatHeel plus supHeel.

Asymmetry is a good indicator of most gait abnormalities [31] and we used the asymmetry coefficient proposed by Robinson et al. [32] Asymmetry coefficient= 100[(Varright − Varleft) /((Varright + Varleft)/2)]

Fig. 3. Latency from initial contact. Close up of the combined (A) and decoded (B) signals during a stance phase.

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where Varright is a temporal variable recorded for the right side and Varleft is the corresponding variable for the left side. A negative value of the asymmetry coefficient indicates a greater value on the left side. Hotelling’s T2 test were used to test differences of means for repeated measures between left and right foot for all the variables. The potential influence of gender, height and side were investigated by ANOVA before and after normalization of the temporal variables to the stride duration. A 0.05 a level of significance was selected for all statistical tests. Bonferoni correction for multiple correlation was applied.

Heel M5 GT M1 Heel GT M5 M1

5.

0.6 0.3

The remaining 0.5% of the strides are scattered into 12 combinations represented by one or two cycles. Overall roll over from initial contact to foot off. The strides were scattered into 37 categories. The expected sequence or so called normal roll over represents 83.9% of the strides. The seven more frequent patterns include 96.5% of the strides:

Forward tilt/push off 3. Results Bilateral evaluation was found in 76 subjects and 29 displayed a unilateral evaluation. This represents a total of 181 feet tested and 3252 walking cycles.Based on the latencies and duration of each switch, the 3252 strides were sorted in the following foot roll-over patterns: 1. The heel was always the foot-ground initial contact. 2. Forward tilt of the foot: the expected order of switch closure from initial contact to foot flat is heel, M5, M1 then GT. (‘=’ denotes that two switches were detected ON during the same ms). Combinations Heel M5 M1 GT Heel M1 M5 GT Heel M5 M1= GT Heel M5 GT M1 Heel M5= M1 GT Heel M1 GT M5 Heel M1 M5=GT 3.

First contact to be off the ground:

Heel M1 M5 GT 4.

Frequency (%) 92.9 2 1.9 1.8 1.2 0.1 0.1

99.6% 0.2% 0.1% 0.1% Push off: the expected sequence is heel, M5, M1 then GT off the ground. This represents the order of switch opening (‘=’ denotes that two switches were detected OFF during the same ms).A total of 18 combinations were present but only six were made up of more than four strides.

Combinations Heel M5 M1 GT Heel M1 M5 GT Heel M5= M1 GT Heel M5 M1=GT

Frequency (%) 89.5 7.1 1.1 0.9

Heel Heel Heel Heel Heel Heel Heel

M5 M5 M5 M1 M5 M5 M5

Frequency (%) M1 GT/Heel M5 M1 GT 83.9 M1 GT/Heel M1 M5 GT 6.1 M1= GT/Heel M5 M1 GT 1.7 M5 GT/Heel M5 M1 GT 1.7 GT M1/Heel M5 M1 GT 1.4 M1 GT/Heel M5= M1 GT 0.9 M1 GT/Heel M5 M1= GT 0.8

Descriptive data and statistics of the gait cycle and foot roll over were expressed, for each foot, by mean, standard deviation and range of the corresponding measured and computed variables for men and women by age decade (Tables 2–5). Women tended to have a higher cadence than men when walking at their preferred pace and velocity. Differences between all right and left variables were significant (T2 P= 0.0007) when considering the complete set of variables. However, differences were not significant if only stride, stance and swing duration were considered (T2 P= 0.33). The wide range of latency was responsible for this apparent discrepancy. The correlation coefficient, the intercept and the slope for the relation to the stride time are presented in Table 6 while Table 7 shows the relation to the stance time. When comparing men and women, without normalization, ANOVA revealed a gender effect alone on stride, stance, swing duration, cadence and on all the variables linked to support events (PB 0.05) except for the SupGT (P =0.91). The differences of LatM5, LatM1, LatGT were not significant (P\ 0.05). After normalization to stride duration, %latM5, %supHeel, %supM1, %supGT were different (PB 0.02) When considering the effect of side, differences of the mean stride, stance, swing times and cadence were not statically significant (P\0.05). Nevertheless, differences of latency and support periods of the great toes were statically significant (PB 0.05). This can be explained by the wide variation of the great toe latency. Intercept and slope for the relation of subject’s height and the temporal parameters are not presented because the coefficients of correlation range between − 0.10

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Table 2 Mean, standard deviation, range and number of feet tested to measure temporal parameters of the gait cycle and foot roll over Age 530 Quantity

Mean

Men SD

Range

Feet n =

Mean

Women SD

Range

Feet n=

Times in ms Stride Stance Swing latHeel latM5 latM1 latGT SinSup SupHeel SupM5 SupM1 SupGT IDS TDS Dsup Cadence HeelBall HeelGT Heel-and-ball FootFlat PushOff

1098.00 669.37 428.96 0 58.67 122.26 274.93 431.50 427.63 520.67 487.67 392.04 119.05 120.10 239.15 54.84 58.67 274.93 305.37 169.36 241.74

67.98 46.28 26.14 0 12.70 59.44 93.58 27.25 58.24 44.69 58.23 101.88 18.04 17.45 31.24 3.29 12.70 93.58 68.53 98.90 54.46

972–1268 590–785 372–484 0 30–82 65–314 116–420 377–483 296–508 440–606 369–580 233–586 96–166 98–166 203–302 47.32–61.73 30–82 116–420 158–411 38–385 139–356

27 27 27 27 27 27 27 20 27 27 27 27 20 20 20 27 27 27 27 27 27

1031.67 623.78 407.87 0 60.32 109.08 261.21 407.15 371.54 456.71 452.97 361.16 108.79 109.15 217.94 58.41 59.89 261.21 262.03 128.43 252.24

69.98 52.73 23.07 0 14.25 38.37 90.42 23.47 52.94 55.45 52.69 99.41 19.11 19.38 36.50 3.71 14.03 90.42 53.07 77.40 33.66

929–1272 519–795 362–477 0 35–98 49–265 90–476 374–468 249–530 361–602 312–560 135–648 58–154 58–156 141–291 47.17–64.59 35–98 90–476 12–4369 5–315 177–388

63 63 63 63 63 63 63 34 63 63 63 63 34 34 34 63 63 63 63 63 63

Data normalised to stride duration (unit= percentage of stride duration %Stance 60.94 1.13 58.51–63.88 27 %Swing 39.08 1.14 36.12–41.58 27 %latM5 5.33 1.08 2.92–7.02 27 %latM1 11.01 4.61 5.82–24.92 27 %latGT 25.07 8.48 10.13–37.63 27 %Sinsup 39.21 1.25 36.53–41.83 20 %supHeel 38.96 4.89 27.77–47.28 27 %supM5 47.38 2.16 42.93–52.06 27 %supM1 44.53 5.34 29.29–50.78 27 %supGT 35.65 8.89 20.88–51.18 27 %IDS 10.79 1.28 8.8–14.05 20 %TDS 10.89 1.26 8.78–14.37 20 %Dsup 21.68 2.05 19.04–25.92 20

60.41 39.59 5.85 10.56 25.36 39.45 35.92 44.19 43.90 34.92 10.48 10.52 21.00

1.52 1.53 1.32 3.63 8.64 1.38 3.62 3.48 4.24 8.88 1.39 1.40 2.52

55.57–65.01 34.99–44.43 3.55–9.28 4.19–26.74 8.63–48.03 37.6–44.19 25.38–43.08 36.8–51.52 33.3–51.18 13.62–53.25 6.24–12.67 6.21–12.82 15.1–24.26

63 63 63 63 63 34 63 63 63 63 34 34 34

Data normalised to stance duration (unit= percentage of stance duration) St – latM5 8.75 1.73 4.8–11.67 27 St – latM1 18.02 7.37 9.76–40 27 St – latGT 41.24 14.28 16.52–64.32 27 St – Dsup 64.39 2.81 58.72–68.38 20 St – SupHeel 63.90 7.78 46.11–77.76 27 St – SupM5 77.75 3.37 71.18–86.87 27 St – SupM1 73.13 9.12 47.01–86.06 27 St – SupGT 58.39 14.17 35.68–83.48 27 St – IDS 17.70 1.94 14.31–22.59 20 St – TDS 17.85 1.74 15.01–22.49 20 St – Dsup 35.54 2.75 31.62–41.28 20

9.67 17.48 42.03 65.34 59.42 73.13 72.69 57.75 17.31 17.36 34.67

2.13 5.96 14.33 3.54 5.41 5.20 7.03 14.38 2.04 1.99 3.50

6.06–15.06 6.72–43.37 13.83–77.91 61.1–74.73 44.07–68.46 62.64–82.8 55.32–86.24 22.09–85.38 10.55–20.62 11.18–20.55 25.6–438.99

63 63 63 34 63 63 63 63 34 34 34

and 0.33. The coefficients of correlation of the subject’s height with the stride and the stance duration were 0.052 (P=0.352) for the men and 0.242 (P= 0.003) for the women. When considering the influence of height and sex, ANOVA revealed an influence of height on stride and swing (P =0.009) and supM5 (P= 0.01). After correction for height, an effect of

sex remained on stride (P = 0.21), stance (P =0.018), supHeel (P=0.004), supM5 and supM1 (P =0.001) and cadence (P = 0.013). When age was used as a covariate, the time from heel to great toe contact (HeelGT) (P = 0.039) and double support (Dsup) (P = 0.008) were related to age.

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An asymmetry coefficient of 0% would have indicated symmetry between right and left variables. A negative mean coefficient indicates a left side variable greater than the right (Table 8). The greatest variation was obtained for the variables related to the medial side of the foot.

4. Discussion When only stride, stance and swing timing are required, sensors under the heel and great toe are sufficient [9–11]; but sensors under the metatarsal heads are important for a more complete picture of foot be-

Table 3 Mean, standard deviation, range and number of feet tested to measure temporal parameters of the gait cycle and foot roll over Age between 31 and 40 Quantity Mean

Men SD

Range

Feet n =

Times in ms Stride 1115.58 74.68 989–1249 19 Stance 684.74 57.15 589–784 19 Swing 430.90 18.34 400–465 19 latHeel 0 0 0 19 latM5 56.90 7.95 47–76 19 latM1 106.42 23.95 72–156 19 latGT 284.05 72.18 141–393 19 SinSup 434.65 17.86 405–468 17 SupHeel 432.37 55.26 330–538 19 SupM5 527.21 50.81 453–589 19 SupM1 521.63 58.07 383–599 19 SupGT 399.74 109.44 201–573 19 IDS 131.35 18.00 96–158 17 TDS 129.88 16.05 102–160 17 Dsup 261.24 32.20 198–316 17 Cadence 54.02 3.66 48.04–60.67 19 HeelBall 56.90 7.95 47–76 19 HeelGT 284.05 72.18 141–393 19 Heel-and-ball 325.95 55.86 204–409 19 FootFlat 148.32 97.97 1–296 19 PushOff 252.37 39.08 194–336 19 Data normalised to stride duration (unit= percentage of stride duration) %Stance 61.31 1.11 59.26–62.97 19 %Swing 38.69 1.12 37.03–40.84 19 %latM5 5.11 0.65 4.11–6.28 19 %latM1 9.56 2.23 6.3–15.77 19 %latGT 25.75 7.57 12.97–39.14 19 %SinSup 38.52 0.78 37.45–40.14 17 %SupHeel 38.68 3.32 30.3–43.6 19 %supM5 47.21 2.48 44.08–51.41 19 %supM1 46.67 3.17 38.73–50.98 19 %supGT 35.48 8.34 20.02–47.75 19 %IDS 11.58 1.03 9.51–13.36 17 %TDS 11.46 0.84 9.97–12.81 17 %Dsup 23.05 1.61 19.62–25.3 17 Data normalised to stance duration (unit= percentage of stance duration) St – latM5 8.33 1.08 6.61–10.25 19 St – latM1 15.62 3.76 10.2–26.49 19 St – latGT 42.15 13.00 21.27–66.05 19 St – Dsup 62.62 2.14 59.69–67.28 17 St – SupHeel 63.09 5.27 49.55–69.24 19 St – SupM5 77.00 3.97 71.03–84.12 19 St – SupM1 76.10 4.87 65.03–83.88 19 St – SupGT 57.71 12.98 33.78–78.28 19 St – IDS 18.81 1.47 15.95–21.39 17 St – TDS 18.61 1.14 16.69–20.41 17 St – Dsup 37.42 2.09 32.89–40.31 17

Mean

Women SD

Range

Feet n=

1013.63 618.67 394.93 0 58.47 97.13 258.57 395.04 379.20 454.67 458.17 358.93 112.62 112.89 225.50 59.56 58.40 258.57 282.00 131.39 239.47

79.62 58.53 26.19 0 13.92 22.19 78.53 28.37 63.08 51.14 53.35 85.24 22.26 22.28 43.81 4.82 13.81 78.53 61.95 75.40 30.44

866–1143 509–729 347–435 0 35–84 61–155 90–401 346–435 246–499 372–549 342–568 222–538 76–150 76–149 155–296 52.49–69.28 35–84 90–401 139–404 21–304 179–303

30 30 30 30 30 30 30 26 30 30 30 30 26 26 26 30 30 30 30 30 30

60.97 39.03 5.75 9.61 25.48 38.95 37.22 44.86 45.14 35.38 11.02 11.04 22.06

1.54 1.56 1.20 2.25 7.33 1.58 3.90 3.58 3.12 7.80 1.56 1.56 3.01

58.51–64.33 35.58–41.49 3.4–7.7 6.37–16.16 9.86–36.78 35.8–41.34 27.42–44.32 35.37–49.65 35.66–50.53 22.68–52.14 8.74–13.81 8.67–13.94 17.9–27.68

30 30 30 30 30 26 30 30 30 30 26 26 26

9.42 15.79 41.89 63.94 61.01 73.63 74.03 57.93 18.02 18.05 36.07

1.87 3.81 12.23 4.00 5.89 6.20 4.71 12.12 2.13 2.11 4.00

5.37–12.63 10.66–26.86 15.87–61.39 56.44–69.79 45.39–70.38 58.09–83.82 59.27–80.94 38.61–83.95 14.76–21.78 14.72–21.78 30.21–43.56

30 30 30 26 30 30 30 30 26 26 26

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Table 4 Mean, standard deviation, range and number of feet tested to measure temporal parameters of the gait cycle and foot roll over Age between 41 and 50 Quantity Mean

Men SD

Range

Feet n =

Mean

Women SD

Range

Feet n=

Times in ms Stride Stance Swing latHeel latM5 latM1 latGT SinSup SupHeel SupM5 SupM1 SupGT IDS TDS Dsup Cadence HeelBall HeelGT Heel-and-ball FootFlat PushOff

25.32 16.28 27.77 0 15.22 16.79 48.14 28.87 58.86 53.04 34.10 58.77 12.03 12.19 21.95 1.37 15.22 48.14 73.26 38.89 62.05

1029–1078 617–655 391–456 0 34–66 85–124 396–487 389–456 388–502 445–558 450–529 134–258 94–121 94–122 199–238 55.66–58.31 34–66 396–487 264–405 23–78 115–250

4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4

1036.38 632.96 403.50 0 52.13 119.13 287.54 404.00 380.17 474.92 439.21 344.13 113.78 114.78 228.57 58.24 52.13 287.54 261.04 97.44 252.79

85.71 58.26 30.73 0 14.44 59.30 95.58 30.89 55.16 49.63 51.83 84.29 18.19 18.96 34.58 4.37 14.44 95.58 41.07 65.95 42.17

942–1267 565–788 363–487 0 27–91 66–334 96–436 363–481 300–512 396–588 324–506 230–526 73–152 73–154 182–306 47.36–63.69 27–91 96–436 178–333 12–248 173–338

24 24 24 24 24 24 24 23 24 24 24 24 23 23 23 24 24 24 24 24 24

1053.75 634.25 419.25 0 50.75 104.00 441.50 416.50 438.00 502.75 490.50 191.50 109.00 109.00 218.00 56.96 50.75 441.50 334.00 50.50 196.25

Data normalised to stride duration (unit= percentage of stride duration) %stance 60.21 1.91 57.5–62.0 4 %swing 39.77 1.92 38–42.5 4 %latM5 4.84 1.55 3.15–6.38 4 %latM1 9.90 1.80 7.88–11.98 4 %latGT 41.93 4.89 36.73–47.33 4 %SinSup 39.50 1.99 37.58–42.3 4 %supHeel 41.49 4.64 37.49–46.78 4 %supM5 47.65 3.96 43–51.76 4 %supM1 46.52 2.31 43.48–49.07 4 %supGT 18.16 5.45 12.49–23.93 4 %IDS 10.37 1.38 8.72–11.76 4 %TDS 10.37 1.37 8.76–11.79 4 %Dsup 20.73 2.58 18.46–23 4

61.04 38.97 5.04 11.26 27.61 39.00 36.64 45.79 42.64 33.31 10.94 11.03 21.97

1.18 1.18 1.35 4.53 8.50 1.15 3.85 2.38 5.80 8.28 1.15 1.23 1.98

57.16–2.78 37.22–42.75 2.77–8.88 6.93–26.49 9.34–40.37 37.22–42.7 29.56–43.98 39.17–50.21 25.69–50.21 22.31–51.17 7.1–12.78 7.11–12.78 17.72–24.63

24 24 24 24 24 23 24 24 24 24 23 23 23

Data normalised to stance duration (unit= percentage of stance duration) St – latM5 8.02 2.46 5.19–10.53 4 St – latM1 16.43 2.85 12.98–19.78 4 St – latGT 69.71 8.57 60.46–77.63 4 St – Dsup 65.64 3.62 62.04–69.62 4 St – SupHeel 69.11 9.69 60.82–81.36 4 St – SupM5 79.25 7.95 70.97–86.87 4 St – SupM1 77.33 4.79 71.77–81.85 4 St – SupGT 30.09 8.71 21.72–39.39 4 St – IDS 17.21 2.08 14.35–18.97 4 St – TDS 17.19 1.92 15.24–19.46 4 St – Dsup 34.40 3.66 30.38–37.96 4

8.23 18.38 45.21 64.00 60.00 75.06 69.90 54.58 17.93 18.07 36.00

2.12 7.15 13.86 2.69 6.06 4.38 9.65 13.59 1.77 1.75 2.70

4.66–4.2 11.22–42.39 15.41–64.31 60.18–70.47 48.7–70.17 64.08–84.31 41.12–81.29 35.55–84.43 11.72–20.66 12.44–20.54 29.37–39.82

24 24 24 23 24 24 24 24 23 23 23

haviour. Our results demonstrate clearly that the heel was always the initial foot-ground contact. Contrary to common belief, the sequential foot roll over during forward tilt and push off was not always from rear foot to lateral then medial forefoot sides followed by the great toe. This sequence was present in only 83.9% of the strides and deviations were more frequent during

the push off period (third rocker). This feature was found independently among subjects, side and strides and can be influenced by foot morphology and foot progression angle. For example, a decreased outward foot rotation is likely to favour M1 losing contact before M5 and vice versa. Synchronisation of switches’ opening and closing can be increased by the limited

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bandwith of our telemetry equipment and combined signals for each foot was sampled every 1.42 ms. Therefore it is possible that two switches were detected more than usual as being ‘on’ or ‘off’ during the same interval. The number of false synchronisations would be decreased by a reduction of the transition time at switch opening and closure combined with a higher sampling rate. Contact times, chronology of contact

and swing events in the study using plantar pressure measuring devices have limited accuracy due to the low capture frequency, i.e. at 25 Hz the time interval between two measures is 40 ms [27]. Usually a threshold is set on sensors sensitivity to avoid inadvertent foot contact by e.g. shoe pressure. This introduces a delay in the registered beginning of stance and premature detection of swing shortening the

Table 5 Mean, standard deviation, range and number of feet tested to measure temporal parameters of the gait cycle and foot roll over Age ]51 Quantity

Mean

Men SD

Range

Feet n =

Mean

Women SD

Range

Feet n=

Times in ms Stride Stance Swing latHeel latM5 latM1 latGT SinSup SupHeel SupM5 SupM1 SupGT IDS TDS Dsup Cadence HeelBall HeelGT Heel-and-ball FootFlat PushOff

1101.50 667.00 434.50 0 50.00 103.00 250.25 435.00 406.50 513.50 520.25 416.00 115.75 115.50 231.25 54.89 50.00 250.25 303.50 156.25 260.50

110.86 80.55 31.67 0 10.10 18.20 103.39 32.07 49.55 80.22 59.20 182.07 25.32 24.37 49.37 5.52 10.10 103.39 34.74 150.47 42.67

1005–1199 592–743 402–469 0 36–60 84–125 127–343 402–469 353–470 435–595 465–584 260–615 91–140 92–138 188–275 50.04–59.7 36–60 127–343 260–345 25–343 216–314

4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4

1119.88 704.25 415.13 0 78.13 139.00 338.25 414.50 425.50 521.13 491.63 364.25 144.63 145.25 289.88 54.25 77.38 338.25 285.75 103.57 278.75

140.54 105.09 35.93 0 24.97 90.85 148.61 36.30 81.59 72.32 39.63 80.41 34.72 34.95 69.41 6.09 24.54 148.61 36.77 80.91 33.92

1007–1348 613–873 384–477 0 54–127 66–308 152–608 381–475 351–581 452–648 433–531 262–508 114–204 114–203 232–402 44.51–59.58 54–127 152–608 214–332 22–218 246–351

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

Data normalised to stride duration (unit= percentage of stride duration) %stance 60.46 1.38 58.85–62.12 4 %swing 39.54 1.39 37.88–41.15 4 %latM5 4.62 1.24 3.01–5.96 4 %latM1 9.31 0.86 8.36–10.45 4 %latGT 23.57 11.62 10.62–34.13 4 %SinSup 39.58 1.36 37.95–41.19 4 %supHeel 36.90 2.34 34.7–39.3 4 %supM5 46.43 2.80 43.24–49.75 4 %supM1 47.19 1.10 46.22–48.71 4 %supGT 36.83 12.87 25.87–51.42 4 %IDS 10.42 1.27 9.05–11.68 4 %TDS 10.40 1.18 9.15–11.54 4 %Dsup 20.81 2.39 18.71–22.94 4 Data normalised to stance duration St – latM5 7.68 St – latM1 15.38 St – latGT 39.30 St – Dsup 65.50 St – SupHeel 61.01 St – SupM5 76.74 St – SupM1 78.07 St – SupGT 60.59 St – IDS 17.21 St – TDS 17.17 St – Dsup 34.38

(unit= percentage of stance duration) 2.22 4.85–10.14 4 1.21 13.93–16.82 4 19.95 17.09–56.88 4 3.24 62.33–68.66 4 3.33 56.99–64.18 4 2.88 73.48–80.08 4 2.17 74.97–80.0 4 19.92 43.12–82.77 4 1.82 15.09–19.18 4 1.59 15.54–18.57 4 3.30 31.18–37.67 4

62.73 37.22 6.88 11.79 29.46 37.16 37.77 46.50 44.46 33.11 12.77 12.82 25.59

1.42 1.41 1.53 6.04 9.62 1.37 2.70 1.87 6.31 8.80 1.37 1.39 2.71

60.87–65.15 34.85–39.03 5.1–9.48 6.55–22.99 14.37–45.1 34.79–38.91 34.86–43.1 43.07–48.32 34.4–50.45 19.44–48.02 11.29–15.13 11.32–15.15 22.97–29.82

8 8 8 8 8 8 8 8 8 8 8 8 8

10.95 18.63 46.84 59.29 60.17 74.14 71.05 52.89 20.32 20.41 40.73

2.25 9.09 14.69 3.36 3.41 3.30 11.18 14.37 1.75 1.74 3.38

8.17–14.55 10.77–35.28 23–69.89 53.91–62.88 55.98–66.78 68.68–78.08 52.81–2.87 30.11–76.85 18.24–23.45 18.6–23.25 37.12–46.21

8 8 8 8 8 8 8 8 8 8 8

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Table 6 Principal gait parameters regression analysis with stride time as the independent variablea Men

Feet n =

Correlation coefficient and P value with Bonferoni correction

Intercept (SE)

slope (SE) 0.71 0.28 0.04 0.24 −0.30 0.21 0.29 0.41 0.59 0.40 1.01 0.19 0.40

(0.02) (0.02) (0.02) (0.07) (0.17) (0.02) (.023) (.089) (.047) (0.98) (0.18) (0.02) (0.03)

0.71 0.28 0.81 0.27 0.04 0.20 0.29 0.55 0.55 0.29 0.30 0.20 0.41

(0.01) (0.01) (0.01) (0.04) (0.09) (0.01) (0.01) (0.36) (0.03) (0.05) (0.09) (0.01) (0.02)

Stance Swing latM5 latM1 latGT IDS SinSup SupHeel SupM5 SupM1 SupGT TDS Dsup

55 55 55 55 55 46 46 55 55 55 55 46 46

0.97 0.87 0.26 0.39 −0.22 0.79 0.88 0.53 0.86 0.49 0.61 0.78 0.84

PB0.02 PB0.02 P=0.32 P= 0.01 P=0.58 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02

−112.83 (23.79) 112.74 (23.87) 10.57 (22.93) −158.43 (87.18) 623.86 (192.40) −111.19 (26.88) 105.64 (26.37) −29.79 (98.97) −137.05 (52.23) 59.37 (108.51) −736.87 (199.02) −92.3 (26.64) −203.53 (43.854).

Women Stance Swing latM5 latM1 latGT IDS SinSup SupHeel SupM5 SupM1 SupGT TDS Dsup

126 126 126 126 126 92 92 126 126 126 126 92 92

0.97 0.87 0.44 0.53 0.37 0.82 0.90 0.81 0.82 0.46 0.28 0.82 0.84

PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 P= 0.01 PB0.02 PB0.02

−109.11 110.03 −23.97 −172.54 −145.02 −98.48 99.19 −195.30 −107.96 142.44 42.12 −101.64 −199.98

a

(14.86) (14.88) (15.39) (44.04) (92.86) (15.39) (15.40) (37.59) (35.51) (56.39) (94.39) (15.46) (28.33)

Coefficient of correlation, intercepts and standard errors (SE) were calculated from the equation y = intercept = slope * stride time.

contact time [33]. Kalpen et al. [34] reported a delay up to 40 ms to detect heel contact and 20 ms at forefoot landing when comparing foot switch data with a Kistler force plate data but did not discuss errors at foot off. Although insoles with few sensors [29] can be captured at 250 Hz (gap 4 ms), mismatches between sensors and the area of great toe, 1st and 5th metatarsal heads jeopardises accuracy. Stresses in the bent sole transfers shear force components through the load cells and may cause prolonged stance or false forefoot contacts especially when metatarsal joints are close to maximal dorsi flexion between 55 and 70% of the gait cycle [35]. Therefore the summation of these approximations leads us to consider that multi sensor insoles are inappropriate when accurate and reliable temporal parameters are required. They should be reserved to evaluate feet that have the potential risk of ulceration, or pain in the plantar tissue and to test efficacy of therapeutic footwear. In all of these studies, men were taller than women but nevertheless, gender influenced stride time and consequently cadence. The results agreed with those reported elsewhere [36,37]. When corrected for height, the gender effect alone remains, indicating that for the same height women have a greater cadence than men. This may result in inaccurate measurements when only

the subject’s height is known and used to calculate temporal parameters. The association of age with forward tilt of the foot (HeelGT) and double support time shows that these variables may be predominantly linked to foot pre-positioning in swing and balance control mechanisms [38]. The oldest subject (63 years) was still too young to have experienced the dramatic changes in velocity, stance, single support and double support that start during the seventh decade [39]. When considering the side, the absence of significant difference of the mean stride time is not surprising as the subjects walked back and forth in a corridor. Low coefficients of asymmetry of gross parameters such as stride, stance and swing are not surprising either, because the subjects walked along a straight path. However, large asymmetry coefficient of latencies and supports of the medial part of the foot was not induced by an adaptation to the floor surface but indicated a predominance of the lateral side of the foot during the forward tilt of the foot. This predominance may be influenced by the degree of forefoot pronation along with the dorsi-flexion of the first metatarsal joint and foot progression angle. Swing time is influenced by a variety of factors such as the velocity of walking and the capability of the

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106

opposite leg to support the entire body weight. The faster we walk the shorter is the swing time [30,38]. However, theoretically, many combinations of stride length and cadence can give the same speed. This is unlikely to have influenced our results if we consider the small inter strides variation of subjects while walking at their comfortable speed. A difference between left and right swing duration indicates an asymmetry in single support and a perturbed gait pattern. Limping, whatever the reason, is more likely to modify the symmetry of gait [30]. When the left and right sides are not recorded simultaneously, normalisation to stride or stance duration suppresses absolute time differences between trials. Deviations from the normal foot roll-over pattern are more likely to be comparable with quantities normalised to stance duration. The type of floor surface influences temporal parameters of gait, especially in an older population [40]. However, this is unlikely to have biased our results when considering the age range of our subjects. We can hypothesize that a potentially slippery floor might trigger a more cautious and slow gait of elderly or disabled persons. Consequently stride duration, stance –swing ratio, latency values and initial contact might be af-

fected first but asymmetry coefficient might be unaffected. Thus normalisation by stride or stance time could be a practical solution because normalised parameters are less dependent on speed [41].

5. Conclusion Temporal parameters of the foot roll over in stance along with stride, swing, double and single supports times are reported for healthy adults walking bare foot in a hallway at their preferred pace and velocity. Both height and gender influenced stride time and cadence. Age had an effect on the forward tilt of the foot and the double support time only. Stride, stance and swing phases were not different on the right or left side. Conversely, sequential variations of the foot roll over were more frequent on the medial than on the lateral side of either the right or left foot. These data may be used for the interpretation of kinematics and EMG activity of indoor gait analysis on long walkways. Variations of roll over the forefoot during push off is more frequent than expected; therefore, gait asymmetry should be interpreted with caution.

Table 7 Principal gait parameters regression analysis with stance time as the independent variablea Men

Feet n =

Correlation coefficient and P value with Bonferoni correction

Intercept (SE)

Slope (SE)

Swing latM5 latM1 latGT IDS SinSup SupHeel SupM5 SupM1 SupGT TDS Dsup

55 55 55 55 46 46 55 55 55 55 46 46

0.75 0.28 0.39 −0.29 0.84 0.82 0.54 0.85 0.47 0.67 0.87 0.92

PB0.02 P= 0.2 P= 0.01 P= 0.18 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02

201.87 15.07 −114.95 639.59 −84.26 174.95 38.62 −19.42 141.92 −644.59 −80.56 −164.82

(27.35) (19.07) (72.92) (158.40) (20.07) (26.12) (82.28) (45.99) (91.59) (156.11) (17.12) (26.95)

0.33 0.06 0.33 −0.52 0.30 0.37 0.57 0.80 0.53 10.52 0.30 0.60

(0.04) (0.02) (0.10) (0.23) (0.02) (0.03) (0.12) (0.06) (0.13) (0.23) (0.02) (0.03)

Women Swing latM5 latM1 latGT IDS SinSup SupHeel SupM5 SupM1 SupGT TDS Dsup

126 126 126 126 92 92 126 126 126 126 92 92

0.74 0.50 0.54 0.36 0.88 0.82 0.83 0.82 0.49 0.30 0.91 0.92

PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02 PB0.02

195.69 −19.96 −130.82 −67.63 −79.55 167.05 −113.12 −15.18 188.44 72.38 −87.56 −167.23

(16.89) (12.32) (36.33) (78.38) (10.51) (16.811) (29.42) (29.12) (46.67) (77.92) (9.35) (16.92)

0.33 0.12 0.38 0.53 0.30 0.37 0.78 0.75 0.41 0.45 0.32 0.62

(0.02) (0.01) (0.05) (0.12) (0.01) (0.02) (0.04) (0.04) (0.07) (0.12) (0.01) (0.02)

a

Coefficient of correlation, intercepts and standard errors (SE) were calculated from the equation y = intercept = slope *stance time.

Y. Blanc et al. / Gait and Posture 10 (1999) 97–108 Table 8 Mean asymmetry coefficient and 95 percent confidence interval with respect to age groups Variables Age 530 Stride

Age 31–40

−0.09% −0.10% −0.24; 0.06 −0.3; 0.09 Stance −0.34% −0.22% −1.09; 0.4 −0.85; 0.4 Swing 0.34% 0.12% −0.9; 1.6 −1; 1.25 latM5 0.38% −2.05% −8.1; 8.8 −12.02; 7.9 latM1 1.26% 7.02% −12.5; 15 −3.7; 17.7 latGT 5.1% 14.5% −11.4; 21.6 0.5; 28.5 SupHeel −2.48% 0.5% −5.6; 0.7 −3.4; 4.4 SupM5 −2.66% 2.75% −4.5; −0.7 −0.13; 5.6 SupM1 3.25% 0.23% −0.2; 6.7 −2.5; 3.05 SupGT −5.44% −9.88% −16.7; 5.8 −19.2; −0.5 Dsup −0.54% −0.12% −1.15; 0.07 −0.53; 0.28

Age 41–50

Age ]51

0.06% −0.21% −0.15; 0.28 −0.47; 0.05 0.09% −0.27% −1.5; 1.7 −1.5; 0.9 0.01% −0.12% −2.2; 2.3 −2.3; 2.09 −2.41% 12.07% −10.2; 15.04 −13.1; 37.3 −2.07% −2.14% −15.9; 11.8 −16.4; 12.1 −11.74% 16.98% −31.6; 8.1 −2.64; 36.4 −3.17% −4.01% −7.14; 0.8 −13; 5 −2.4% −2.76% −4.1; −0.6 −6.95; 1.4 6.94% −1.72% −0.19; 14.07 −7.1; 3.7 3.11% −7.19% −14.5; 20.7 −26.1; 11.7 −0.30% −0.20% −1.08; 0.4 −0.74; 0.33

Acknowledgements The equipment for this study was provided by the foundation ‘Centre de Recherches Me´dicales Carlos et Elsie de Reuter’. This research was partially supported by the grant No. 3200-051090.97/1 of the Swiss National Science Foundation. The authors gratefully acknowledge Bernadette Mermillod for her help and guidance with statistics, Albert Rieben from the medical computer department, Hoˆpital Cantonal, for writing the software that sorts the gait cycles and Eric Viel D.Sc. for checking the manuscript.

References [1] Schwartz RP, Heath AL, Wright JN. Electrobasographic method of recording gait. Arch Surg 1923;27:926–34. [2] Schwartz RP, Heath AL. Gait and muscle function recorded by the electrobasograph. J Bone Joint Surg 1926;18:445–54. [3] Blanc Y, Vadi P. An inexpensive but durable foot-switch for telemetered locomotion studies. Biotelem Patient Monit 1981;8:240 – 5. [4] Tybursky DJ, Davis RB, DeLuca P. Initial contact and toe off: a comparison of measurement technologies. In: Proceedings 8th annual East coast clinical gait laboratory conference, 1993;129 – 30. [5] Ross JD, Ashman JD. A thin foot switch. J Biomechanics 1987;20:733 – 4. [6] Patterson FR, Gorman LK, Wetzel MC. Advantages of a simple contact switch for human locomotion. Am J Phys Med 1984;63:11 – 7. [7] Perry J. Clinical gait analyzer. Bull Prostet Res. Fall 1974;188 – 92.

107

[8] Perry J, Bontgrager E, Antonelli D. Footswitch definition of basic gait characteristics. In: Kenedi RM, editor. Disability. London: MacMillan, 1979;131 – 5. [9] Hausdorff JM, Ladin Z, Wei JY. Footswitch system for measurement of the temporal parameters of gait. J Biomechanics 1995;28:347 – 51. [10] Marey E-J. Le mouvement. Paris: Masson, 1894:6 – 8. [11] Winter DA, Greenlaw RK, Hobson DA. A microswitch shoe for use in locomotion studies. J Biomechanics 1972;5:553 –4. [12] Zuniga EN, Leavitt LA. Analysis of gait: a method of measurement. In: Nelson RC, Morehouse CA, editors. Biomechanics, IV. London: Mac Millan, 1974:85 – 90. [13] Gabel RH, Johnston RC, Crowninshield RD. A gait analyzer/ trainer instrumentation system. J Biomechanics 1979;12:543–9. [14] Law HT, Minns RA. Measurement of the spatial and temporal parameters of gait. Physiotherapy 1989;75:81 – 4. [15] Law HT. Microcomputer-based low-cost method for measurement of spatial and temporal parameters of gait. J Biomed Eng 1987;9:115 – 20. [16] Cavanagh PR, Michiyoshi A. A technique for the display of pressure distribution beneath the foot. J Biomechanics 1980;13:69 – 75. [17] Lord M. Foot pressure measurement: a review of methodology. J Biomed Eng 1981;3:91 – 9. [18] Lord M, Reynolds DP, Hughes JR. Foot pressure measurement: a review of clinical findings. J Biomed Eng 1986;8:283 –94. [19] Boulton AJM. The importance of abnormal foot pressures and gait in the causation of foot ulcers. In: Connor H, Boulton AJM, Ward JD, editors. The Foot in Diabetes. New York: Wiley, 1987:11 – 21. [20] Boulton AJM, Betts RP, Franks CI, Ward JD, Duckworth T. The natural history of foot pressure abnormalities in neuropathic diabetic subjects. Diabetes Res 1987;5:73 – 7. [21] Boulton AJM, Betts RP, Franks CI, Newrick PG, Ward JD, Duckworth T. Abnormalities of foot pressure in early diabetic neuropathy. Diabetic Med 1987;4:225 – 8. [22] Cavanagh PR, Sanders LJ, Sims DS. The role of pressure distribution measurement in diabetic foot care. J Rehabil Res Dev 1987;25:53 – 4. [23] Crouse J, Wall JC, Marble AE. Measurement of the temporal and spatial parameters of gait using a microcomputer based system. J Biomed Eng 1987;9:64 – 8. [24] Hughes J, Kriss S, Klenerman L. A clinician’s view of foot pressure: a comparison of three different methods of measurement. Foot Ankle 1987;7:277 – 84. [25] Hughes J. The clinical use of pedobarography. Acta Orthop Belg 1993;59:10 – 6. [26] Cavanagh PR, Morag E, Boulton AJM, Young MJ, Deffner KT, Pammer SE. The relationship of static foot structure to dynamic foot function. J Biomechanics 1997;30:243 – 50. [27] Harrison AJ, Folland JP. Investigation of gait protocols for plantar pressure measurement of non-pathological subjects using a dynamic pedobarograph. Gait and Posture 1997;6:50–5. [28] Quaney B, Meyer K, Cornwall MW, McPoil TG. A comparison of the dynamic pedobarograph and EMED systems for measuring dynamic foot pressures. Foot Ankle 1995;16:562 – 6. [29] Fiolkowski P, Bauer J. The effects of viscoelastic insoles on gait kinetics. In: Proceedings Third Symposium on Footwear Biomechanics. International Society of Biomechanics August 21–27, 1997, Tokyo. [30] Perry J. Gait analysis. Normal and pathological function. In: Slack Incorporated, editor. Thorofare, 1992:33 – 7. [31] Dewar ME, Judge G. Temporal asymmetry as a gait quality indicator. Med Biol Eng Comput 1980;18:689 – 93. [32] Robinson RO, Herzog W, Nigg BM. Use of force platform variables to quantify the effects of chiropractic manipulation on gait symmetry. J Manipulative Physiol Ther 1987;10:172–6.

108

Y. Blanc et al. / Gait and Posture 10 (1999) 97–108

[33] Perry J. Gait analysis. Normal and pathological function. Slack Incorporated, editor, Thorofare 1992:436–7. [34] Kalpen A, Seitz P. Comparison between the force values measured with the Pedar system and Kistler platform: proceedings fourth EMED user meeting, Ulm, Germany 1994. Gait and Posture 1994;4:236 –7. [35] Meyer JM. Cine´siologie de l’avant pied. The`se de privat docent. Universite´ de Gene`ve. Gene`ve, 1985:87. [36] Murray MP, Kory RC, Sepic SB. Walking patterns of normal women. Arch Phys Med Rehabil 1970;51:637–50. [37] O8 berg T, Karsznia A, O8 berg K. Basic gait parameters: reference data for normal subjects, 10–79 years of age. J Rehab Research

.

Develop 1992;30:210 – 23. [38] Gabell A, Nayak USL. The effect of age on variability in gait. J Gerontol 1984;39:662 – 6. [39] Judge JO, O0 unpuu S, Davis RB. Effects of age on the biomechanics and physiology of gait. Clin Geriatr Med 1996;12:659– 78. [40] Willmott M. The effect of a vinyl floor surface and a carpeted floor surface upon walking in elderly hospital in-patients. Age Ageing 1986;15:119 – 20. [41] Shiavi R, Hunt MA, Waggoner M. Foot contact timing and the effect of walking speed in normal childhood and adult gait. Med Biol Eng Comput 1988;26:342 – 8.