Effects of different footwear on landing forces from a grand jeté in trained dancers

The Grand Jete movement is a popular leap elevation movement used in ballet, modern, contemporary and jazz dance. The move involves taking off from one foot and landing on the other foot reaching the highest point possible in the air and lifting legs to a split position. Dancers may perform many grand jetes in a single routine. The aim of this study was to investigate whether footwear used by dancers can reduce the vertical impact forces caused by landing from high leaps. The study was approved by the university’s ethics committee and informed consent was given by ten highly-trained dancers (age mean 23.1, s=1.6 years; height 1.64, s=.08 m; mass 57.7, s=5.2 kg). The participants all performed a grand jete in three different footwear conditions: bare feet, jazz shoes and dance trainers with shock absorbing properties. Landing forces were recorded using a Kistler force plate sampling at 1000 Hz. Peak impact force was determined as the maximum vertical force occurring during the first 0.07 s of contact. Statistical analysis consisted of repeated measures ANOVA. Maximumforce during the landing phase decreased from 4.00 BW (s=0.72) in the barefoot condition to 3.95 BW (s=0.69) in the jazz shoes condition and 3.58 BW (s=0.68) in the trainers condition (F2,9=2.5, P=0.108, Z2=0.22, power=0.44).Higher impact peak and loading rate values were found in the barefoot condition compared to the shodconditions, with the trainers showing the lowest values. However, there were no significant differences between the footwear conditions for impact peak force(F2,9=0.50, P¼0.616, Z2=0.05, power=0.12),time-to-peak impact force (F2,9=0.44 , P=0.653, Z2=0.05, power=0.11), or loading rate to the poin of maximum vertical force (F2,9=0.53, P=0.597, Z2=0.06, power=0.12). The results showed lower maximum landing forces, impact peak force and loading rates in the dance trainers compared to the barefoot and jazz shoes conditions. Although the values were not significantly different, the small difference between footwear conditions may prove important with the onset of fatigue during a routine. Dancers should train to develop safe landing techniques when performing barefooted

Comparisons between swing phase characteristics of race walkers and distance runners

The aim of this study was to analyze swing characteristics during race walking and to compare these with distance running. The rules of race walking demand that no visible flight time should occur and the stance leg must be straightened from initial contact to midstance. Previous research has not examined whether these rules also have an effect on swing and what consequences might arise. Ten male race walkers and ten male distance runners walked or ran respectively on an instrumented treadmill for 10 km with two in-dwelling force plates. Trials lasted 30 seconds and simultaneous 2D video data were recorded and digitized at 125 Hz. The moment of inertia of the thigh, shank, foot and whole lower limb was calculated using the parallel axis theorem. The distance runners were faster with longer strides, although cadence was not different. The race walkers had shorter swing times, longer contact times, and smaller maximum knee flexion angles (100° ± 6) than the distance runners (56° ± 6). The smaller knee flexion angles in race walkers meant they experienced greater swing leg moment of inertia than the distance runners but there were few associations in either group between knee flexion angle or moment of inertia with key performance parameters. Swing phase kinematics in race walking are restricted by the rules of the event and result in knee angular motions different from those in distance running, preventing race walkers from reaching the speeds attainable by distance runners

Gait parameter changes during 10000 metre treadmill running

The purpose of this study was to measure the effects of fatigue on gait parameters during running. Research has shown that changes due to fatigue include those of step length, cadence, flight time, and joint angles. Thirteen male distance runners ran 10000 m at a pace equivalent to 103% of their personal best time. Kinetic data was collected using a Gaitway treadmill (1000 Hz), and kinematic data using two RedLake MotionPro high-speed cameras (250 Hz). Data was collected at five points. Repeated measures ANOVA showed that there were significant differences in maximum force, impulse, and contact time (p < .01). Dependent t-tests showed a significant difference for the knee angle at take-off (p < .01). The kinetic and temporal changes occurred as early as 3000 m. Athletes are recommended to race at a constant pace to reduce the effects of fatigue

Angular kinematics in elite race walking performance

The purpose of this study was to measure and analyse the important angular kinematic variables in elite race walking. Research has shown that these variables include knee angle at contact and midstance, rotation of the hips and shoulders, and hip extension velocity. Eighty elite race walkers were videoed during competition and analysed using 3D-DLT with SIMI Motion. The knee angle was found to be almost straight at contact in most athletes and hyperextended by the vertical upright position. Athletes varied in the amount of rotation at the hips and shoulders, with 50 km men having greater hip rotation and 20 km women having greater shoulder rotation. There was much more variation in the values found for elbow and shoulder angles. Very few angular measurements correlated with key race walking variables such as speed, step length and cadence

The measurement of kinetic variables in race walking

The purpose of this study was to measure kinetic variables during race walking. Forty national and international race walkers walked either 5 km or 10 km at a pace equivalent to 105% of their season’s best time. Junior athletes walked 5 km, while senior athletes (mostly 20 km walkers) walked 10 km. Kinetic data were collected using a Gaitway treadmill (1000 Hz). Data were collected at the 2.5 km point. Men had longer step lengths than women and walked faster as a result. There was little difference in cadence. Average flight times for each group of athlete were approximately 0.04 s. Senior athletes showed more ‘typical’ race walking vertical force patterns than the juniors; this may be linked to quantity of training experience and gait efficiency. Athletes are advised to develop muscular strength endurance to cope with loading rates upon initial contact

Gait parameter differences between the legs during race walking

Prior research on the effects of fatigue during race walking has shown changes in step length and frequency (Knicker & Loch, 1990: New Studies in Athletics, 5, 25–38). It is unclear whether these changes are consistent for both legs. The purpose of the study was to investigate the differences between the legs for kinetic variables during race walking, and to measure changes occurring because of fatigue. The study was approved by the university’s ethics committee and informed consent was given by fourteen international race walkers, of whom four were females (age mean 28.2, s=7.4 years; stature 1.77, s=0.10 m; mass 66.0, s=11.7 kg). Each participant walked for 10 km on a treadmill (Gaitway, Traunstein). The average treadmill speed was 12.4 km h-1 (s=0.7) and each athlete walked at a constant pace. Data were recorded using the Gaitway treadmill, which has two in-dwelling force plates (Kistler, Winterthur). The sampling rate was 1000 Hz. Data were collected for 30 s at four times during the walk, at 2500 m, 4500 m, 6500 m and 8500 m. Statistical analysis consisted of repeated measures ANOVA. There was a significant difference between the legs for first peak force (F1,13=32.6, P¼0.001, Z2=0.71, power=0.99), weight acceptance rate (F1,13=14.5, P=.002, Z2=0.53, power=0.94), and push-off rate (F1,13=36.2, P=0.001, Z2=0.74, power=1), although these differences did not change significantly with distance walked. There was also a significant difference between the legs’ step lengths (F1,13=30.1, P=0.001, Z2=0.70, power=0.99), midsupport forces (F1,13=9.6, P=0.009, Z2=0.42, power=0.82), and propulsive force peaks (F1,13=20.6, P=0.001, Z2=0.61, power=0.99); the overall values for these variables also increased significantly with distance walked (P<0.001, P=0.009, and P<0.001 respectively). However, there was no effect of distance on the differences between the legs for any variable. The results show significant leg dominance during race walking. Athletes should be aware that these imbalances need rectification to prevent injury and maintain efficient walking technique. The imbalances did not appear to worsen with the onset of fatigue although this may occur over the longer championship distances of 20 and 50 km

Muscle activity of the stance knee in elite race walkers

The purpose of this study was to compare knee muscle activity in race walkers with different knee extension patterns. Three international athletes walked over two force plates recording at 1000 Hz. Video data were simultaneously recorded at 100 Hz; the digitised data were combined with the force data to calculate net muscle moments and joint powers. EMG testing was carried out on three muscles which cross the knee. The two walkers with legal techniques had similar moment and power patterns, whereas the non-legal walker experienced a longer period of eccentric flexor moment at the beginning of stance, which may have affected his ability to extend his knee correctly. After this, all three athletes experienced a period of isometric contraction at the knee. Achieving correct technique requires both strength endurance exercises and mobility development

The effects of fatigue on race walking technique

The purpose of this study was to measure the effects of fatigue on gait parameters during race walking. Research has shown that fatigued athletes require gait alterations in order to maintain speed. Eighteen competitive race walkers walked either 5 km or 10 km at a pace equivalent to 105% of their season’s best time. Junior athletes walked 5 km, while senior athletes (mostly 20 km walkers) walked 10 km. Kinetic data were collected using a Gaitway treadmill (1000 Hz). Data were collected at three points during the 5 km walks and at four points during the 10 km walks. Repeated measures ANOVA showed that there were significant differences in impulse and contact time parameters (p < .01). The kinetic and temporal changes occurred as early as 1 km. Athletes are recommended to race at a constant pace to reduce the effects of fatigue

Effects of fatigue on technique during 5 km road running

The purpose of this study was to investigate the effects of fatigue on kinematic parameters during a 5 km road race, and to establish how men and women fatigue differently. 17 highly competitive distance runners (9 male, 8 female) were videoed (50 Hz) as they completed the English National 5 km championships. Three-dimensional kinematic data were analysed using motion analysis software (SIMI, Munich). Data were recorded at 950 m, 2,400 m, and 3,850 m. Repeated measures ANOVA showed a significant decrease in speed (p < 0.01) which occurred due to both decreased step length and cadence (p < 0.05). Differences in speed, step length and contact time between men and women were found (p < 0.05). Athletes can reduce the risk of fatigue by using appropriate racing tactics

Kinematic differences between defended and undefended shots in netball

Successful shooting in netball depends not only on achieving the correct angle, velocity and height of release, but also on how well the shooter can adjust these factors when faced with a defender. However, few studies, if any, have analysed the difference between shots taken with a defender present and those without (usually due to a penalty against the defender). The aim of the study was to examine the difference in kinematic variables between defended and undefended shots during netball games. The study was approved by the university’s ethics committee and informed consent was given by eight elite netballers (age mean 22.1, s=2.3 years; stature 1.81, s=.08 m; mass 69.0, s=8.7 kg). Each participant was filmed playing in a Netball Superleague game during the 2007/2008 season. Two stationary Canon DM-XL1 digital cameras were placed on a balcony overlooking the playing area, so as not to interfere with the players or spectators. The sampling rate was 50 Hz, and the shutter speed 1/500 s. Two successful shots per player were digitised and analysed using SIMI Motion (Munich) and filtered using a Butterworth low-pass 2nd order filter. The two shots consisted of one successful defended shot, and one successful undefended shot (due to a penalty awarded against the opposing team’s defender). Statistical analysis consisted of dependent t-tests. The height of release was higher for defended shots (2.16 m, s=0.28) than in undefended shots (1.93 m, s=0.04). This was caused partially due to greater elbow extension during the shooting action. The maximum elbow angle for defended shots was 138° (s=25) and for undefended shots 108° (s=23). The significant difference found between these values (P=0.049) was the only one found between the two shooting conditions. The angle of release at the shoulder was higher for defended shots (141°, s= 22) compared to undefended (133°, s=7), as was the vertical velocity of the wrist at release (0.54 m s -1, s=0.31 and 0.43 m s -1, s=0.12 respectively). Several differences were found between shooting with and without a defender, although only one was found to be significant. Nonetheless, it was clear that shooting with a defender present required a greater height of release, and larger shooting arm joint angles. It is important for netball players and coaches to shoot with defenders present during training in order to practice the style of shooting required during a game