Yaodong Gu

Biomechanical analysis of the plantar and upper pressure with different sports shoes

The purpose of the study is to probe into the difference in plantar pressure and dorsal pressure of three types of sports shoes: Basketball Shoes (BS); Running Shoes (RS); Tennis Shoes (TS). The novel insole measurement system and pressure sensor chips are utilised to obtain plantar and dorsal pressure. As to dorsal pressure, maximal Lateral Metatarsophalangeal (LM) joint of TS is distinctively different from BS and RS, mean LM of RS is apparently distinct from BS and TS. These distinctions might be of importance while designing shoes; factors like athletic performance, perceived comfort and injury prevention should be taken into consideration.

A comparative biomechanical analysis of habitually unshod and shod runners based on a foot morphological difference.

Running is one of the most accessible physical activities and running with and without footwear has attracted extensive attention in the past several years. In this study 18 habitually male unshod runners and 20 habitually male shod runners (all with dominant right feet) participated in a running test. A Vicon motion analysis system was used to capture the kinematics of each participants lower limb. The in-shoe plantar pressure measurement system was employed to measure the pressure and force exerted on the pressure sensors of the insole. The function of a separate hallux in unshod runners is analyzed through the comparison of plantar pressure parameters. Owing to the different strike patterns in shod and unshod runners, peak dorsiflexion and plantarflexion angle were significantly different. Habitually shod runners exhibited a decreased foot strike angle (FSA) under unshod conditions; and the vertical average loading rate (VALR) of shod runners under unshod conditions was larger than that under shod conditions. This suggests that the foot strike pattern is more important than the shod or unshod running style and runners need to acquire the technique. It can be concluded that for habitually unshod runners the separate hallux takes part of the foot loading and reduces loading to the forefoot under shod conditions. The remaining toes of rearfoot strike (RFS) runners function similarly under unshod conditions. These morphological features of shod and unshod runners should be considered in footwear design to improve sport performance and reduce injury.

Effects of different unstable sole construction on kinematics and muscle activity of lower limb

Unstable sole construction can change biomechanics of lower extremity as highlighted by some previous studies, which could potentially help developing special training or rehabilitation schemes. In this study, unstable elements are fixed in heel and forefoot zone to exert unstable perturbations, and the position changes (medial, neutral and lateral) of unstable elements in forefoot coronal plane are adjusted to analyze changes of lower extremity kinematics and muscle activities. Twenty-two healthy male subjects participated in the test, walking with control shoes and experimental shoes randomly under self-selected speed. Kinematics and surface electromyography measurements were carried out simultaneously. It is found that experimental shoes can lead to the reduction of knee abduction and internal rotation and hip internal rotation, with p<.05. Ankle inversion and internal rotation amplitude were also reduced, which are associated with significantly increased activation levels of muscles (TA-tibialis anterior, PL-peroneus longus, LG-lateral gastrocnemius) in order to compensate perturbations. It is suggested that a training equipment incorporating unstable elements would enhance postural control by adjusting lower extremity kinematics and reorganizing muscle activity. More research can be conducted to testify the feasibility of unstable shoes construction on human postural control and gait, even guide training regime design, injury prevention and rehabilitation.

Foot Morphological Difference between Habitually Shod and Unshod Runners

Foot morphology and function has received increasing attention from both biomechanics researchers and footwear manufacturers. In this study, 168 habitually unshod runners (90 males whose age, weight & height were 23±2.4years, 66±7.1kg & 1.68±0.13m and 78 females whose age, weight & height were 22±1.8years, 55±4.7kg & 1.6±0.11m) (Indians) and 196 shod runners (130 males whose age, weight & height were 24±2.6years, 66±8.2kg & 1.72±0.18m and 66 females whose age, weight & height were 23±1.5years, 54±5.6kg & 1.62±0.15m)(Chinese) participated in a foot scanning test using the easy-foot-scan (a three-dimensional foot scanning system) to obtain 3D foot surface data and 2D footprint imaging. Foot length, foot width, hallux angle and minimal distance from hallux to second toe were calculated to analyze foot morphological differences. This study found that significant differences exist between groups (shod Chinese and unshod Indians) for foot length (female p = 0.001), width (female p = 0.001), hallux angle (male and female p = 0.001) and the minimal distance (male and female p = 0.001) from hallux to second toe. This study suggests that significant differences in morphology between different ethnicities could be considered for future investigation of locomotion biomechanics characteristics between ethnicities and inform last shape and design so as to reduce injury risks and poor performance from mal-fit shoes.

Lower extremities kinematics variety of young women jogging with different heel height

The purpose of this study is to evaluate the kinematics changes in hip, knee and ankle during jogging while wearing shoes with heel height of flat (1.5 cm), low (4.5 cm) and high (7 cm) three conditions. We observed an increased motion of range of knee abduction-adduction and hip flexionextension in high heel jogging, which may induce high loading force in knee joints. In addition, we observed decrease in ankle inversion during heel height jogging gait. Collectively, these findings suggest that permanent wearing of shoes with heel height may contribute to knee osteoarthritis and higher risk of ankle sprain.

A biomechanical investigation of right-forward lunging step among badminton players

ABSTRACT This study presents the kinematics and plantar pressure characteristics of eight elite national-level badminton athletes and eight recreational college-level badminton players while performing a right-forward lunge movement in a laboratory-simulated badminton court. The hypothesis was that recreational players would be significantly different from elite players in kinematics and plantar pressure measures. Vicon® motion capture and Novel® insole plantar pressure measurement were simultaneously taken to record the lower extremity kinematics and foot loading during stance. Recreational players showed significantly higher peak pressure in the lateral forefoot (P = 0.002) and force time integral in the lateral forefoot (P = 0.013) and other toes (P = 0.005). Elite athletes showed higher peak pressure in the medial forefoot (P = 0.003), hallux (P = 0.037) and force time integral in the medial forefoot (P = 0.009). The difference in landing techniques for the lunge step between elite athletes and recreational players was observed with peak ankle eversion (−38.2°±2.4° for athletes and −11.1°±3.9° for players, P = 0.015); smaller knee range of motion in the coronal and transverse planes, with differences in peak knee adduction (28.9°±6.8° for athletes and 15.7°±6.2° for players, P = 0.031); peak knee internal rotation (20.3°±1.3° for athletes and 11.8°±3.2° for players, P = 0.029) and peak hip flexion (77.3°±4.1° for athletes and 91.3°±9.3° for players, P = 0.037).

FOOT LOADING PATTERNS WITH DIFFERENT UNSTABLE SOLES STRUCTURE

Foot loading patterns can be changed by using different unstable sole structures, detailed quantification of which is of great significance for research and technological development in falling prevention and lower limb disorders rehabilitation. In this study, unstable soles constructions are adjusted through unstable elements in heel and medial, neutral and lateral forefoot and the foot loading patterns are comparatively studied. A total of 22 healthy male subjects participated in this test. Subjects are asked to walk over a 12 m walkway with control shoes and experimental shoes in self-adapted speed. Significant peak pressure, contact area and pressure-time integral differences in middle foot are found between control shoes and experimental shoes. In addition, peak pressure and pressure-time integral are found to increase significantly with unstable elements adding to center forefoot. The results showed that adjusting the unstable elements in coronal plane of forefoot could effectively alter the distribution of plantar pressure, this could potentially offer a mechanism for preventing falling of elderly and rehabilitation of lower extremity malfunctions. This study also demonstrates a novel concept that unstable element could be effectively adjusted in terms of position to meet different functional requirement.

PLANTAR PRESSURE DISTRIBUTION CHARACTER IN YOUNG FEMALE WITH MILD HALLUX VALGUS WEARING HIGH-HEELED SHOES

Young females with mild hallux valgus (HV) have been identified as having an increased risk of first ray deformation. Little is known, however, about the biomechanical changes that might contribute to this increased risk. The purpose of this study was to compare kinetics changes during walking for mild HV subjects with high-heel-height shoes. Twelve female subjects (six with mild HV and six controls) participated in this study with heel height varying from 0 cm (barefoot) to 4.5 cm. Compared to healthy controls, patients had significantly higher peak pressure on the big toe area during barefoot walking. When the heel height increased, loading was transferred to medial side of the forefoot, and the big toe area suffered more impact compared to barefoot in mild HV. This study also demonstrated that the center of pressure (COP) inclines to medial side alteration after high-heeled shoes wearing. These findings indicate that mild HV people should be discouraged from wearing high-heeled shoes.

Plantar pressure distribution during high-heeled Latin dancing

The impact of high-heeled shoes on the human gait kinetic is an important research field. Most published studies have been focused on the effects of high-heeled shoes on normal walking, while works on more intensive locomotion such as dancing is very limited. The purpose of this work was to investigate the foot pressure distribution, impact force and impulse during Latin dancing with different heel heights. Biomechanical measurements were performed for typical dance steps on six professional dance athletes. The load of each sole zone was calculated and the significance of the heel height effect was determined with statistical analysis. The results indicate that increasing heel height could cause an increase of impact forces in the forefoot and a reduction in the heel region. The effect of the heel height in dancing is different from normal gait and the lateral metatarsal region was identified as the most intensely affected zone in dancing.

An electromyographic study of the effect of hand grip sizes on forearm muscle activity and golf performance

ABSTRACT The study describes the differences in surface electromyography (EMG) activity of two forearm muscles in the lead and trail arm at specific phases of the golf swing using a 7-iron with three different grip sizes among amateur and professional golfers. Fifteen right-handed male golfers performed five golf swings using golf clubs with three different grip sizes. Surface EMG was used to measure muscle activity of the extensor carpi radialis brevis (ECRB) and flexor digitorum superficialis (FDS) on both forearms. There were no significant differences in forearm muscle activity when using the three golf grips within the group of 15 golfers (p > 0.05). When using the undersize grip, club head speed significantly increased (p = 0.044). During the backswing and downswing phases, amateurs produced significantly greater forearm muscle activity with all three grip sizes (p < 0.05). In conclusion, forearm muscle activity is not affected by grip sizes. However, club head speed increases when using undersize grips.