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We aimed to determine whether there were any differences in how surfers used their lead and trail limbs when landing two variations of a simulated aerial manoeuvre, and whether technique affected the forces generated at landing. Fifteen competitive surfers (age 20.3 ± 5.6 years, height 178.2 ± 9.16 cm, mass 71.0 ± 10.5 kg) performed a Frontside Air (FA) and Frontside Air Reverse (FAR), while we collected the impact forces, ankle and knee muscle activity, and kinematic data. A principal component analysis (PCA) was used to reduce 41 dependent variables into 10 components. A two-way MANOVA revealed that although there were no limb x aerial variation interactions, surfers generated significantly higher relative loading rates at landing for the trail limb compared to the lead limb (+28.8 BW/s

Elliptical trainers that increase the inter-pedal distance may have potential benefits for knee osteoarthritis by decreasing the amount of knee varus. Modifying elliptical trainers with a converging footpath and reduced inter-pedal distance may be beneficial for reducing anterior knee pathology risk by decreasing knee valgus angles. Twenty-one college students participated in a single testing session. Participants exercised on two different elliptical trainers, one modified with a converging footpath and reduced inter-pedal width, and a standard elliptical trainer. Participants exercised for 2 min at three ramps incline at 120 strides per minute and constant work rate. Three-dimensional kinematics and electromyography of the dominant lower limb were recorded. Multiple 2 × 3 (Elliptical x Incline) ANOVAs with Bonferroni corrections were used to compare the two elliptical trainers at each incline for kinematics and muscle activity. The modified elliptical trainer displayed significantly decreased peak knee valgus (

This study aimed to explore how asymptomatic athletes with a patellar tendon abnormality (PTA), who are at high risk of developing patellar tendinopathy, alter their landing technique and net patellar tendon loads generated in response to fatigue. Seven asymptomatic players with a PTA performed five successful vertical stop-jump trials before and after a fatigue protocol. Fatigue protocol involved participants repeatedly performing sets of 30 submaximal jump exercises on a sledge apparatus followed by 30 s rest until the task failure criteria were reached. Three-dimensional ground reaction forces, lower limb kinematics and net peak patellar tendon force were recorded during the stop-jump task. No significant between-fatigue condition differences in net patellar tendon loading, or most secondary outcome variables were observed. Only some fatigue changes were seen during the vertical landing phase. Asymptomatic PTA participants did not modify their landing technique or net patellar tendon loading during a stop-jump task in response to fatigue. The lack of between-fatigue condition differences displayed by the asymptomatic PTA participants during both landing phases suggest that these individuals may not be capable of sufficient movement variability in their landing strategies to adapt to fatigue.

Analysing player kinematics during a match using "gold-standard" 3D video-based motion analysis techniques is a difficult prospect indeed. The development of small, wireless, wearable sensors offers the potential to reduce the challenges of measuring kinematics during match-play without hindering performance. The present study examined the viability of using wireless tri-axial accelerometers to examine whether key performance measures of drag flicks executed by expert specialist drag-flickers are predicted by the kinematics of the striking phase. Linear mixed models were used to examine whether the speed and accuracy of players' drag flicks were predicted by the duration of stick-ball contact, and the kinematics of the lead lower limb at stick-ball contact and ball release. Results revealed that stick and lead lower limb kinematics significantly predicted shot accuracy but not shot speed. Shorter drag-time predicted more accurate flicks (p = 0.03) as did a more vertical leg at stick-ball contact (p = 0.016) and a more horizontal thigh at ball release (p = 0.001). This may indicate that there are more ways to produce fast drag flicks than accurate ones. This study illustrates that wireless tri-axial accelerometers can be used on-field to measure the effects of kinematics on key performance measures.

This study investigated the immediate and short-term effects of minimalist shoes (MS) and traditional running shoes (TRS) on vertical loading rates, foot strike pattern and lower limb kinematics in a group of habitual barefoot runners. Twelve habitual barefoot runners were randomly given a pair of MS or TRS and were asked to run with the prescribed shoes for 1 month. Outcome variables were obtained before, immediate after and 1 month after shoe prescription. Average and instantaneous vertical loading rates at the 1-month follow-up were significantly higher than that at the pre-shod session (P 0.474). Foot strike angle in the TRS group was significantly lower than that in the MS group (P = 0.045, η2p = 0.585). However, there was no significant time nor shoe effect on overstride, knee and ankle excursion (P > 0.061). Habitual barefoot runners appeared to land with a greater impact during shod running and they tended to have a more rearfoot strike pattern while wearing TRS. Lower limb ...

The effect of seat tube angle at selected seat heights (96, 100 and 104% trochanteric height) on heart rate, VO2 and lower limb kinematics was evaluated in 14 competitive male road racing cyclists during discontinuous submaximal exercise (200 W) on an air-resistance ergometer at seat tube angles of 68, 74 and 80 degrees. The tests were randomized to complete the nine combinations (three seat heights, three tube angles) in opposite directions from a starting tube angle of 74 degrees and 100% trochanteric height to avoid any time or sequence bias. Power efficiency was calculated for each combination from work done and VO2. All results were analysed using ANOVA for repeated measures. At a seat tube angle of 80 degrees, mean VO2 was significantly lower and power efficiency significantly higher compared with an angle of 74 degrees at all three seat heights, while heart rate was significantly lower only at a seat height equal to trochanteric height. At a seat tube angle of 74 degrees, mean VO2 and heart rate were significantly lower and power efficiency significantly higher compared with an angle of 68 degrees at all three seat heights. Hip range of movement and maximum and minimum hip angle were significantly less at an angle of 80 degrees compared with 68 degrees. Further biomechanical analysis suggested that the improvement in cycling efficiency observed at steeper seat tube angles was produced in part by the resultant altered ankling pattern of the cyclist.

Little is known of the performance characteristics of the shotokan karate mae-geri kick. The aim of this study was to compare the execution time, the lower limb kinetics and kinematics, and their respective repeatability in the mae-geri kick of karate athletes of two different standards. Seventeen adult black belt karate competitors (9 national and 8 international athletes) performed six kicks with their dominant lower limb on a striking surface, combining maximum force impact and velocity. Execution time of movement and lower limb kinematics were recorded with a high-speed camera. Maximum force at impact and the forces exerted on the ground were measured using three force plates. The duration of the kick was significantly shorter for international than for national standard athletes. However, no significant difference in the maximum impact force of the kick was observed between the two groups. In addition, significant kinematic differences were observed between the groups, with two angles of motion and one velocity peak occurring sooner in the kick movement for the international athletes, specifically for the knee joint. International athletes also performed the kick with a significantly higher repeatability for duration and kinematics, specifically during the pre-loading phase that precedes the attack phase. We conclude that the duration of the kick and repeatability of lower limb kinematics could be useful in selecting top-level karate athletes and monitoring their training status.