Xiaole Sun, Yang Yang, Lin Wang, Xini Zhang and Weijie Fu
This study aimed to explore the effects of strike patterns and shoe conditions on foot loading during running. Twelve male runners were required to run under shoe (SR) and barefoot conditions (BR) with forefoot (FFS) and rearfoot strike patterns (RFS). Kistler force plates and the Medilogic insole plantar pressure system were used to collect kinetic data. SR with RFS significantly reduced the maximum loading rate, whereas SR with FFS significantly increased the maximum push-off force compared to BR. Plantar pressure variables were more influenced by the strike patterns (15 out of 18 variables) than shoe conditions (7 out of 18 variables). The peak pressure of midfoot and heel regions was significantly increased in RFS, but appeared in a later time compared to FFS. The influence of strike patterns on running, particularly on plantar pressure characteristics, was more significant than that of shoe conditions. Heel-toe running caused a significant impact force on the heel, whereas wearing cushioned shoes significantly reduced the maximum loading rate. FFS running can prevent the impact caused by RFS. However, peak plantar pressure was centered at the forefoot for a long period, thereby inducing a potential risk of injury in the metatarsus/phalanx.
Jing-guang Qian, Yang Su, Ya-wei Song, Ye Qiang and Songning Zhang
A Comparison of a Multi-body Model and 3D Kinematics and EMG of Double-leg Circle on Pommel Horse
The purpose of this study was to establish a multi-segment dynamic model in the LifeMOD to examine kinematics of the center of mass and foot, and muscle forces of selected upper extremity muslces during a double-leg circle (DLC) movement on pommel horse in gymnastics and compared with three-dimensional kinematics of the movement and surface electromyographic (sEMG) activity of the muscles. The DLC movement of one elite male gymnast was collected. The three-dimensional (3D) data was imported in the Lifemod to create a full-body human model. A 16-Channel surface electromyography system was used to collect sEMG signals of middle deltoid, biceps brachii, triceps brachii, latissimusdorsi, and pectoralis major. The 3D center of mass and foot displacement showed a good match with the computer simulated results. The muscle force estimations from the model during the four DLC phases were also generally supported by the integrated sEMG results, suggesting that the model was valid. A potential application of this model is to help identify shortcomings of athletes and help establish appropriate training plans errors in the DLC technique during training.
This study examined the effects of one single bout daily versus triple bouts of resistance exercise for 12 weeks on muscular strength and anaerobic performance of the upper body. Twenty young male adults (age: 22.0 ± 1.0 years, bench press: 44.0 ± 10.3 kg) were randomly assigned to a single bout (SB) or triple bouts (TB) of resistance exercise group. Maximal strength and anaerobic performance of the upper body using the bench press (one-repetition maximum) and the modified 30 s Wingate test were determined before and after the intervention. Additionally, changes in lactate levels before and after the Wingate test were measured. Although the SB and TB groups showed a significant increase in maximal strength (post-intervention, SB: 67.2 ± 9.2 and TB: 67.6 ± 7.6 kg, respectively) compared with the values at pre-intervention (SB: 44.6 ± 11.4 and TB: 43.9 ± 8.7 kg, respectively), there was no significant difference for this variable between the two groups post-intervention (p > 0.05). The anaerobic performance of the upper body in the SB and TB groups also displayed improvements without significant difference between the two groups after the completion of different training regimes. On the basis of the same training volume, multiple bouts of resistance training showed similar improvements in maximal strength and anaerobic performance to one bout of resistance training in young adult men without prior experience in resistance training