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The objective of this study is to examine the three-dimensional foot shape data and determine foot type’s distribution among Chinese children and adolescents. A total of sixteen three-dimensional foot shape variables of 5069 Chinese children were measured through filming, including 3 girth-related variables, 3 length-related variables, 2 width-related variables, and 8 height-related variables. Cluster analysis was performed to classify these three-dimensional feet data of Chinese children and adolescents into three identified foot types, namely Robust Feet, Slender Feet, and Flat Feet, which differ in terms of length, volume, and arch height. Three foot types’ distribution varies across the different foot length groups. The foot types classification may be used in the design of shoe lasts and in the manufacture of comfortable footwear to minimize error fitting.Keywords: foot shape; cluster analysis; shoes making

Diffusion tensor imaging (DTI) measures the displacement of water molecules across tissue components and thus provides information on the microstructure of brain white matter. This study examined the effect of Tai Chi and the relation of Tai Chi experiences and skills with brain white matter. Fractional anisotropy (FA) was obtained from the DTI magnetic resonance images of two group participants, namely, the long-term Tai Chi practitioners and sedentary counterparts. Whole-brain voxel-based analysis showed that the Tai Chi group had higher FA in the splenium of corpus callosum (p = 0.015) than the control group. Rank correlation analysis revealed that in the Tai Chi group, the FA value of the splenium of corpus callosum was moderately related with exercise duration (r = 0.45, p = 0.045) but highly related with skill level (r = 0.699, p = 0.001). Long-term Tai Chi practice could benefit to the brain white matter, and these impacts were correlated with exercise duration and skill level.

BACKGROUND Knowledge of children's foot shape is essential for podiatric healthcare and footwear design. Differences in foot shapes relative to sex and age were demonstrated among white children; however, no study has examined the foot characteristics of Asian children according to sex and age. This study aimed to analyze the age- and sex-associated differences in foot measurements in Chinese children. MATERIAL AND METHODS We recruited 1240 boys and 1303 girls from China as participants for the present study. Foot dimensions were recorded by a video filming system, and 12 foot-shape measurements were acquired. One-way ANOVA was used to calculated the changes in measurements with age for boys and girls. Scores were analyzed as raw and normalized to foot length using the independent-samples t test. RESULTS Most measurements increased significantly at 7-8 and 8-9 years for girls and 8-9 and 10-11 years for boys. Arch height, instep length, and heel width showed greatest increases for both sexes ages 7-12 years (P

This study aims to compare the insole load of three maximum-effort cutting tasks in basketball. Sixteen male basketball players were recruited to participate in the study. The Pedar Mobile system was used to record the insole plantar load distribution during three cutting tasks (45° cutting, 90° cutting, and sideward cutting). The peak pressures (PP) and maximum force (MF) at the total foot and at each foot mask were used in data analysis. ANOVA with repeated measures was employed to investigate the differences in the measures among these cutting tasks. At the total foot, the highest MF value was showed when performing sideward cutting. At the heel, the highest PP and MF were found when performing 90° cutting. The PP and MF were lower when performing 90° cutting than when conducting 45° and sideward cuttings at the medial midfoot and the central forefoot. Furthermore, the MF value was lower when performing 45° cutting than when conducting sideward cutting at the medial midfoot and the central forefoot. These findings corroborate the fact that plantar loads differed during the three maximum-effort cutting maneuvers. Differences in the plantar loads for different cutting may be potential risks for overuse-related injuries to the lower extremities of basketball players.

Background We recently reported age and gender differences in foot shape and size in Chinese school children aged between 7–12 years. This study aimed to analyze age and gender differences in foot shape and size in Chinese adolescents aged between 13–18 years. Material/Methods The study included 1,252 adolescent boys and 1274 adolescent girls from seven regions in China. Twelve measurements of foot shape were recorded using a video filming system. One-way analysis of variance (ANOVA) compared the changes in the measurements with age. An independent t-test was used to analyze gender-associated differences in foot size and shape. Results In adolescent boys, foot length and width increased significantly at 13–14 years and heel width, arch height, and fifth metatarsal head height increased until 18 years (P0.8). Adolescent boys showed a significant increase in ball width and girth, and instep length and height compared with adolescent girls, who had a longer medial foot length and higher fifth metatarsal head height compared with adolescent boys (P0.5). Conclusions Age and gender associated differences were found in foot measurements in Chinese adolescents, aged between 13–18 years. These differences should be considered by shoe manufacturers and when making clinical decisions about normal foot development.

This study assessed the effect of 1-year regular Tai Chi (TC) on neuromuscular reaction in elderly women. A total of 41 elderly women (55 years-68 years) completed the study. The TC group (n = 21) performed the 24-form TC, while the control group (C, n = 20) was instructed to read newspapers or watch television when the TC group practised. Electromyogram measurements were conducted before and after intervention. After a year-long intervention, the post-test results of between-group neuromuscular reaction time showed significant differences in the rectus femoris (t = 3.607, p = 0.001), semitendinosus (t = 2.678, p = 0.011), anterior tibialis (t = 3.455, p = 0.001), and gastrocnemius muscles (t = 4.061, p = 0.000). Within-group results showed that the TC group had significantly shorter neuromuscular reaction time compared to its baseline value in the rectus femoris (t = 3.066, p = 0.006), semitendinosus (t = 2.485, p = 0.022), anterior tibialis (t = 2.311, p = 0.032), and gastrocnemius muscles (t = 2.462, p = 0.023). Results suggested that year-long regular TC can improve neuromuscular reaction function in elderly women.

This study examined the effects of regular Tai Chi (TC) exercise on the kinaesthesia of the knee and ankle joints of older women. A total of 43 women aged 55-68 years participated in this study. In a 24-week study period, the TC group (n = 22) underwent an organized TC exercise, whereas the control group (n = 21) maintained a sedentary lifestyle. Customized instruments were used to measure the threshold for the detection of the passive motion of the knee and ankle joints. After 24 weeks, the TC group showed a significantly smaller threshold for the detection of passive motion of knee extension (31.4%, p = 0.009), knee flexion (27.0%, p = 0.044), and ankle dorsal flexion (28.9%, p = 0.014) than the control group. Other comparisons showed no significant differences. The 24-week TC exercise benefited the lower-limb kinaesthesia of the knee joint flexion and extension and ankle dorsal flexion.

This study examined whether the shoe usage time influences the comfort perception and direction change performance of badminton shoes. Fifteen university badminton players performed direction change trials with maximum-effort at new and extensively worn shoe conditions. Two professional badminton shoe models (Shoe Y and Shoe L) were selected to examine if both tested shoes would have similar usage time effect on comfort perception and direction change performance. Comfort perception of in-shoe climate, overall fit, medial-lateral stability, overall cushioning, shoe-ground traction, and overall comfort were measured using a 150 mm Visual Analogue Scales, immediately after the direction change trials. After finishing data collection of new shoe condition (day 1), the tested shoes were assigned to the university badminton team players to simulate the extensively worn condition that normally used during badminton training for eight weeks (i.e., 96 hours in total). The identical testing procedure was performed...

This study examined the effects of 24 weeks of Tai Chi Quan on the postural control of elderly women. A total of 43 women aged 55-68 years participated in the study. A Tai Chi group (n = 22) underwent an organized Tai Chi exercise, whereas the control group (n = 21) maintained a habitual, no-regular-exercise lifestyle. A Good Balance tester (Metitur, Finland) was used to measure the time, paths and velocity of the center of pressure (COP) of subjects during stance while shifting COP to targeted positions shown on a monitor. After 24 weeks, the Tai Chi group showed significantly shorter total (18.6%, p = 0.005), mediolateral (21.9%, p = 0.002) and anteroposterior (18.3%, p = 0.002) COP sway paths than the control group. The results indicate that 24 weeks of the Tai Chi exercise improved the efficiency of postural control for elderly women.

This study investigated the effects of different periods of Tai Chi exercise on knee and ankle joint kinesthesia. A total of 20 Tai Chi practitioners and 19 controls completed the final test. Customized devices were used to measure the kinesthesia of the knee and ankle joints at the start, after 24 weeks and after 48 weeks of the intervention. Results showed that the 24-week Tai Chi intervention considerably improved the kinesthesia of the knee flexion and extension and ankle dorsiflexion. The 48-week Tai Chi intervention improved the kinesthesia towards knee flexion and extension, ankle dorsiflexion and plantar flexion. Moreover, the 48-week Tai Chi intervention had better kinesthesia towards knee extension and ankle dorsiflexion compared with the 24-week Tai Chi intervention. Our results suggest that long-term (48 weeks versus 24 weeks) Tai Chi exercise benefits the knee and ankle kinesthesia of elderly women.

The objective of this study is to compare the muscular activity of lower extremity muscles while running on treadmill and on overground surfaces. A total of 13 experienced heel-to-toe runners participated in the study. Electromyographic (EMG) data of four lower extremity muscles, including rectus femoris, tibialis anterior, biceps femoris, and gastrocnemius, were collected using the Noraxon EMG system while running on a treadmill and on overground surfaces at a running speed of 3.8 m/s. The obtained data were then analyzed. In this study, throughout the stance phase, the EMG values in the rectus femoris (P

The global literature suggests that female sex workers (FSWs) experience high rates of sexual violence perpetrated by their clients, especially when FSWs are under the influence of alcohol. However, such data are limited in China. The current study is aimed to fill in the literature gap by examining the association between alcohol use by FSWs and client-perpetrated sexual violence against FSWs in China. A total of 1022 FSWs were recruited through community outreach in Guangxi, China. Female sex workers completed a self-administered survey on their demographic information, alcohol use, and sexual violence perpetrated by clients. Multivariable regression was employed to assess the relationship between alcohol use and client-perpetrated sexual violence among FSWs while controlling for possible confounders. Results indicated that alcohol use was positively associated with the experience of sexual violence in both bivariate and multivariable analyses. Women who were at a higher risk level of alcohol use were more likely to experience sexual violence perpetrated by clients even after controlling confounders (e.g., demographics and alcohol-serving practice). Given the association between alcohol use and client-perpetrated sexual violence, preventing or reducing alcohol use among FSWs could be an effective strategy to protect these women from sexual violence perpetrated by their clients. Alternatively, psychological counseling and other support should be available to these women so they can reduce their alcohol use as a maladaptive coping strategy. We call for culturally appropriate alcohol use reduction components, incorporated with sexual violence reduction strategies including adaptive coping skills training as well as empowerment, and targeting both FSWs and their clients.

In this study we investigated the association between mental health problems and negative experiences among female sex workers (FSWs) in China. A total of 1,022 FSWs completed a self-administered survey on their demographic characteristics, mental health status, substance use behaviors, and experiences of partner violence. We found that alcohol use was independently predictive of mental health problems when both partner violence and illicit drug use were accounted for in the multivariate logistic regression models. The findings underscore the urgent need for effective alcohol reduction interventions and mental health promotion programs among FSWs in China and other developing countries.

Ethylene vinyl acetate and polyurethane are widely used materials for shoe midsoles. The present study investigated the durability of running shoes made from ethylene vinyl acetate and one type of polyurethane (polyurethane-1), which have similar hardness and density, and another type of polyurethane (polyurethane-2), which has high hardness/density. All shoes differed from one another only in terms of the midsole material used. Eight male runners participated in the present study and used the shoes to run 500 km (10 × 50 km). The cushioning and energy return characteristics of each shoe were measured using an impact tester before and after each 50-km run. The results showed that as the running distance increased, the peak force of midsole materials changed with different patterns. Ethylene vinyl acetate and polyurethane-1 showed greater cushioning than polyurethane-2 over 500 km (ethylene vinyl acetate, 918.2-968.0 N; polyurethane-1, 909.6-972.9 N; polyurethane-2, 983.0-1105.6 N). Polyurethane-1 showed greater cushioning from 200 km to 300 km compared with 0 km (0 km, 972.9 ± 66.3 N; 200 km, 909.6 ± 61.2 N; 250 km, 921.9 ± 51.2 N; 300 km, 924.6 ± 51.9 N). The cushioning of ethylene vinyl acetate shoes was diminished after 500 km compared with that at 0 km (968.0 ± 25.9 N vs. 921.1 ± 20.1 N). Ethylene vinyl acetate resulted in greater energy returns than polyurethane. Both foam category and hardness/density affected the critical biomechanical properties of running shoes.

The objective of this study is to compare plantar loads during running on different overground surfaces. Fifteen heel-to-toe runners participated in the study. Plantar load data were collected and analyzed using an insole sensor system during running on concrete, synthetic rubber, and grass surfaces at a running speed of 3.8 m/s. Compared with running on concrete surface, running on natural grass showed a lower magnitude of maximum plantar pressure at the total foot (451.8 kPa vs. 401.7 kPa, p = 0.016), lateral midfoot (175.3 kPa vs. 148.0 kPa, p = 0.004), central forefoot (366.3 kPa vs. 336.8 kPa, p = 0.003), and lateral forefoot (290.2 kPa vs. 257.9 kPa, p = 0.004). Moreover, running on natural grass showed a longer relative contact time compared with running on a concrete surface at the central forefoot (81.9% vs. 78.8%, p = 0.017) and lateral forefoot (75.2% vs. 73.1%, p = 0.007). No significant difference was observed in other multiple comparisons. Different surfaces affected the plantar loads while running. The differences may help us to understand potential injury mechanisms.

Thirteen male children ascending and descending stairs with loads that equalled 0%, 10%, 15% and 20% of their body weight were the subject of our research: the boys were wearing an asymmetrical single-strap athletic bag or a symmetrical double-strap backpack during our experiments with them. The maximum spinal tilt to the loading side and to the support side, and the range of spinal motions, were obtained by using a motion analysis system. Our results showed that symmetry of spinal posture was observed both when they ascended staircase with all loads and descended in a backpack. When carrying an athletic bag with 15% and 20% of their body weight while ascending the staircase, the lateral spinal tilt to the supporting side was significantly increased. We concluded that a symmetrical backpack with a load not exceeding 20% or an asymmetrical single-strap athletic bag with a load not exceeding 10% should be recommended for school children in order to promote safer staircase use. STATEMENT OF RELEVANCE: Children carrying heavy school bags may develop spinal problems. This study suggested that when they are using stairs, a symmetrical backpack with a load within 20% body weight is acceptable for them. When they are carrying an asymmetrical single-strap athletic bag, the bag's weight should not exceed 10% of the body weight in order to avoid excessive spinal tilt.

Global literature suggests that partner violence contributes to HIV-related vulnerability and risk among women. Female sex workers (FSWs) play a significant role in China's skyrocketing increase of heterosexual transmission of HIV. The aim of this article is to examine the association between partner violence and HIV risk among FSWs in China. This study, based on a cross-sectional survey of 1,022 FSWs recruited from communities in China, attempted to address the relationship between partner violence and HIV risk among this vulnerable population. About 58% of the FSWs had experienced violence from their stable partners (including 55.5% reporting emotional violence, 20.1% physical violence, and 16.2% sexual violence) and 45% from their clients (including 39.7% reporting emotional violence, 17.1% physical violence, and 16.8% sexual violence). Partner violence perpetuated by either stable partners or clients was strongly associated with most of the HIV risk measures we assessed. This study confirmed the association of partner violence and HIV risk among FSWs. We call for culturally appropriate interventions for both partner violence and HIV risk reduction among FSWs in China.

The purpose of this study was to determine whether there are differences in the perceived comfort, plantar pressure, and rearfoot motion between laced running shoes and elastic-covered running shoes. Fifteen male amateur runners participated in the study. Each participant was assigned laced running shoes and elastic-covered running shoes for use during the study. The perceived comfort, plantar loading, and rearfoot motion control of each type of shoes during running were recorded. When the laced running shoes and elastic-covered running shoes were compared, the elastic-covered running shoes were given a lower perceived comfort rating in terms of shoe length, width, heel cup fitting, and forefoot cushioning. The elastic-covered running shoes also recorded higher peak plantar pressure in the lateral side of the forefoot, as well as larger maximum rearfoot pronation. Overall, shoelaces can help runners obtain better foot-shoe fit. They increase the perceived comfort, and decrease the maximum pronation and plantar pressure. Moreover, shoelaces may help prevent injury in running by allowing better control of the aforementioned factors.

To quantify subjective perception of fit using objective measurements, 15 healthy male subjects were invited to participate in this study. Subjective fit ratings of shoes during standing and walking were measured using fit questionnaire with VAS scale. Pressure sensors and foot scanner were used to determine the shod-foot interface pressure and the dimensional differences. Regression was run and the capability of objective measurement to predict fit rating was determined. The R square increased from 30.7% (dimensional difference) and 25.5% (pressure sensors) to 62.6% by (dimensional difference and pressure sensors). Each of the objective measurements above has its own limitation in quantifying fit. However, when using both dimensional difference and pressure sensors, they were able to compensate the limitations and restrictions of each other, thereby increasing the power to predict subjective fit rating.

This study investigated the available and utilized friction during non-slip gait in level walking, and determined the limit which human starts to walk carefully to adapt to slippery surface. Sixteen floor–footwear-contaminant conditions with different slipperiness (dynamic coefficient of friction, DCOF, from 0.11 to 1.06) were employed. Fifteen harnessed Chinese male performed ten self-paced walking trials in each condition without slips. The utilized friction (COFu) was obtained from the maximum value of shear to normal ground reaction force ratio during the first 25% stance. ANOVA and Tukey tests showed three subsets with similar COFu, and confirmed the hypothesis that the utilized friction drops gradually when the available friction drops below a certain critical limit. Non-linear regression models were applied to the data to determine the COFu to be 0.20 and the limit of available ground friction which human starts to walk carefully to adapt to slippery surface (DCOFlimit) to be 0.41.

Data regarding female sex workers’ (FSWs) self-perceived stigma and their mental health are limited, particularly in developing countries. This study, using a cross-sectional survey among 310 FSWs in China, addresses this issue. Data indicate that most of these FSWs had medium to high levels of self-perceived stigma, 30% had elevated depressive symptoms, 18% had suicidal ideation, and 9% had suicidal attempt in the past 6 months. After controlling for potential confounders, FSWs’ high-level self-perceived stigma was significantly associated with their poor mental health. The authors call for culturally appropriate approaches to reduce stigma and promote psychological well-being among this marginalized and vulnerable population.

This study examines the effects of a 16-week Tai Chi (TC) training program on the muscle strength, endurance, and reaction time of the lower extremities of elderly people. A total of 40 elderly individuals (aged 60 years) completed the study. They were divided into two groups: the TC group (11 men and 11 women) underwent a supervised TC exercise program for 16 weeks, while the control group (9 men and 9 women) received general education for a comparable time period. Pre- and post-intervention measurements were conducted. An isokinetic dynamometer was used to measure the maximum concentric strength and dynamic endurance of the knee flexors and the extensors, and the maximum concentric strength of the ankle plantarflexors and dorsiflexors. The neuromuscular response of the rectus femoris, semitendinosus, gastrocnemius, and anterior tibialis muscles was measured by the onset latency to sudden perturbations using an electromyography system. After 16 weeks, the TC group showed a 19.9% increase in muscle strength of the knee flexors (p

Ankle sprain is the most common injury in sports, but the mechanism of injury is not clear. Injury mechanisms can be studied through many different approaches. Over the years, ankle kinematics has been studied during simulated subinjury or close-to-injury situations, that is, sudden simulated ankle spraining motion on inversion platforms. Because these tests did not induce real injury, they could only somewhat suggest the ankle kinematics during an ankle sprain injury. The most direct way is to investigate real injuries using biomechanical measuring techniques. However, it is obviously unethical to do experiments where test subjects are purposefully injured. Nevertheless, in rare cases, accidents may occur during biomechanical testing. It has been shown that video sequences from sports competitions can provide limited but valuable information for qualitative ankle injury analysis. However, quantitative biomechanics analysis of sport injury is not easy as it requires calibrated multiview video sequences. This study presented an accidental supination ankle sprain injury that occurred in a laboratory under a high-speed video and plantar pressure capturing setting.

This study presented a method to estimate the complete ground reaction forces from pressure insoles in walking. Five male subjects performed 10 walking trials in a laboratory. The complete ground reaction forces were collected during a right foot stride by a force plate at 1000 Hz. Simultaneous plantar pressure data were collected at 100 Hz by a pressure insole system with 99 sensors covering the whole plantar area. Stepwise linear regressions were performed to individually reconstruct the complete ground reaction forces in three directions from the 99 individual pressure data until redundancy among the predictors occurred. An additional linear regression was performed to reconstruct the vertical ground reaction force by the sum of the value of the 99 pressure sensors. Five other subjects performed the same walking test for validation. Estimated ground reaction forces in three directions were calculated with the developed regression models, and were compared with the real data recorded from force plate. Accuracy was represented by the correlation coefficient and the root mean square error. Results showed very good correlation in anterior-posterior (0.928) and vertical (0.989) directions, and reasonable correlation in medial-lateral direction (0.719). The root mean square error was about 12%, 5% and 28% of the peak recorded value. Future studies should aim to generalize the methods or to establish specific methods to other subjects, patients, motions, footwear and floor conditions. The method gives an extra option to study an estimation of the complete ground reaction forces in any environment without the constraints from the number and location of force plates.

This study investigated the plantar pressure distribution during gait on wooden surface with different slipperiness in the presence of contaminants. Fifteen Chinese males performed 10 walking trials on a 5-m wooden walkway wearing cloth shoe in four contaminated conditions (dry, sand, water, oil). A pressure insole system was employed to record the plantar pressure data at 50Hz. Peak pressure and time-normalized pressure-time integral were evaluated in nine regions. In comparing walking on slippery to non-slippery surfaces, results showed a 30% increase of peak pressure beneath the hallux (from 195.6 to 254.1kPa), with a dramatic 79% increase in the pressure time integral beneath the hallux (from 63.8 to 114.3kPa) and a 34% increase beneath the lateral toes (from 35.1 to 47.2kPa). In addition, the peak pressure beneath the medial and lateral heel showed significant 20-24% reductions, respectively (from 233.6-253.5 to 204.0-219.0kPa). These findings suggested that greater toe grip and gentler heel strike are the strategies to adapt to slippery surface. Such strategies plantarflexed the ankle and the metatarsals to achieve a flat foot contact with the ground, especially at heel strike, in order to shift the ground reaction force to a more vertical direction. As the vertical ground reaction force component increased, the available ground friction increased and the floor became less slippery. Therefore, human could walk without slip on slippery surfaces with greater toe grip and gentler heel strike as adaptation strategies.

Tai Chi Chuan is a favourite form of exercise throughout the world and has drawn increasing research interest from international scientists. Biomechanical research into Tai Chi has grown substantially and has provided evidence of the beneficial effects of Tai Chi exercise on health, fitness, and prevention of falls. This paper reviews studies that have explored the biomechanical aspects of Tai Chi, such as balance, kinematics, kinetics, strength, and neuromuscular activities.

The purpose of this study was to explore the factors associated with suicidal ideation and attempt among female sex workers (FSWs) in China. A cross-sectional survey was administered among 454 FSWs in a rural county of Guangxi, China. About 14% of FSWs had thought of suicide and 8% had attempted suicide in the past 6 months. Multiple logistic regression analyses indicated that those FSWs who were dissatisfied with life, abused alcohol, were deceived or forced into commercial sex, and had stable sexual partners were more likely to report suicidal ideation. Female sex workers who had multiple stable partners, experienced sexual coercion, and worried about an inability to make enough money were more likely to report a suicide attempt. These FSWs who entered commercial sex because of financial needs or who were influenced by the peers were less likely to report a suicide attempt. Our data suggested that the rates of suicidal ideation and attempts were high among FSWs in China, and there were multiple factors associated with their suicidality. Future health education and promotion efforts among FSWs need to take into consideration substance abuse, interpartner conflict, and psychological stress.

Objective and participants: The present study measured the difference in plantar pressure between the preferred and non-preferred foot in four soccer-related movements in 15 male university soccer players (mean (SD) age 20.9 (1.3) years, mean (SD) height 173 (4) cm and mean (SD) weight 61.7 (3.6) kg). Design: To record plantar pressure distribution, players randomly wore three types of soccer shoes (classical 6-stud and 12-stud, and specially designed 12-stud) embedded with an insole pressure recorder device with 99 sensors, divided into 10 areas for analysis. Plantar pressure was recorded in five successful trials in each of the four soccer-related movements: running (at 3.3 m/s), sideward cutting, 45° cutting and landing from a vertical jump. Results: Plantar pressures of the preferred and non-preferred foot were different in 115 of 120 comparisons. The overall plantar pressure of the preferred foot was higher than that of the non-preferred foot. Specifically, in each of the four movements, higher pressure was found in the preferred foot during the take-off phase, whereas this was found in the non-preferred foot during the landing phase. This would suggest a tendency of the preferred foot for higher motion force and of the non-preferred foot for a greater role in body stabilisation. Conclusions: The data indicate that the preferred and non-preferred foot should be treated independently with regard to strength/power training to avoid unnecessary injuries. Different shoes/insoles and different muscular strengthening programmes are thus suggested for each of the soccer player’s feet.

To measure the plantar pressure in four soccer-related movements in 15 male soccer players (mean (SD) age 20.9 (1.3) years, height 173 (4) cm, weight 61.7 (3.6) kg).To record plantar pressure distribution, the players wore soccer boots with 12 circular studs and with an insole pressure recorder device equipped with 99 sensors. Plantar pressure was recorded in five successful trials in each of the four soccer-related movements: running, sideward cutting, 45 degrees cutting and landing from a vertical jump. Each footprint was divided into 10 recorded areas for analysis.Compared with running at 3.3 m/s, maximal speed sideward cutting and 45 degrees cutting induced higher peak pressure (p0.05) under the second toe, medial forefoot, medial arch and medial heel. The peak pressure of the maximal jump landing was lower under the medial forefoot and lateral forefoot as compared with running (p0.05). The pressure-time integral showed that sideward cutting and 45 degrees cutting induced higher pressures (p0.05) than running for all recorded areas, except for the lateral forefoot and the lateral arch. In all the four soccer-related movements, a higher pressure was found on the medial side of the plantar surface as compared with the lateral side.These data suggest that the medial side of the plantar surface may be more prone to injuries, and that foot orthosis adoption, improved soccer boot design and specific muscle training could be considered to reduce pressure and the subsequent risk of injury.

Background Badminton players often perform powerful and long-distance lunges during such competitive matches. The objective of this study is to compare the plantar loads of three one-step maximum forward lunges in badminton. Methods Fifteen right-handed male badminton players participated in the study. Each participant performed five successful maximum lunges at three directions. For each direction, the participant wore three different shoe brands. Plantar loading, including peak pressure, maximum force, and contact area, was measured by using an insole pressure measurement system. Two-way ANOVA with repeated measures was employed to determine the effects of the different lunge directions and different shoes, as well as the interaction of these two variables, on the measurements. Results The maximum force (MF) on the lateral midfoot was lower when performing left-forward lunges than when performing front-forward lunges (p = 0.006, 95% CI = −2.88 to −0.04%BW). The MF and peak pressures (PP) on the great toe region were lower for the front-forward lunge than for the right-forward lunge (MF, p = 0.047, 95% CI = −3.62 to −0.02%BW; PP, p = 0.048, 95% CI = −37.63 to −0.16 KPa) and left-forward lunge (MF, p = 0.015, 95% CI = −4.39 to −0.38%BW; PP, p = 0.008, 95% CI = −47.76 to −5.91 KPa). Conclusions These findings indicate that compared with the front-forward lunge, left and right maximum forward lunges induce greater plantar loads on the great toe region of the dominant leg of badminton players. The differences in the plantar loads of the different lunge directions may be potential risks for injuries to the lower extremities of badminton players.

Heavy backpacks have raised extensive discussion among children, parents and health-care professionals about their potential to cause shoulder and back pain and even spine deformity (Mackenzie et al., 2003). The weight of school bags in terms of the percentage of body weight of children has been reported as 17.7 per cent in the United States (Pascoe et al., 1997), 20 per cent in Italy (Negrini and Carabalona, 2002) and 20 per cent in Hong Kong (Hong Kong Society for Child Health and Development, 1988). The heavy loads caused spinal symptoms (Johnson et al., 1995), back pain (Sheir-Neiss et al., 2003), fatigue (Negrini and Carabalona, 2002), breathing restriction (Lai and Jones, 2001) and even acute injuries (Wiersema et al., 2003).

Background. Tai Chi exercise improved the balance control and muscle strength of the lower extremities. The aim of this study is to quantify the one-leg stance duration and plantar pressure distribution during the one-leg stance in Tai Chi and to try to elaborate on its probable effects on the ability to balance on one leg. Methods. Sixteen experienced Tai Chi practitioners participated in this study. The Novel Pedar-X insole system was used to record the plantar forces during the execution of a set of 42-form Tai Chi movements and during normal walking. The one-leg stance duration and plantar pressure distribution during the one-leg stance were analyzed. Findings. In Tai Chi exercise, the total duration spent in the one-leg stance was less (p < 0.05), the duration of each one-leg stance was longer (p < 0.01) and the medial–lateral displacement of the centre of pressure was greater (p < 0.05) than during normal walking. The peak pressure and pressure–time integral of the second and third metatarsal heads and the fourth and fifth metatarsal heads were significantly greater (p < 0.05) than those of other plantar regions during the one-leg stance in normal walking, whereas the peak pressure and pressure–time integral of the first metatarsal head and the great toe were significantly greater (p < 0.05) than those of other plantar regions during the one-leg stance in Tai Chi exercise. Interpretation. The longer duration of each one-leg stance and the plantar pressure distribution characteristics during the one-leg stance in Tai Chi exercise may be associated with an improved ability to balance on one leg. The findings may provide useful information toward the development of strengthening programs, strategies for the prevention of falls, and the promotion of a physically active lifestyle.

Background and Purpose. The concept of proper foot movement is always emphasized in practicing Tai Chi (TC). The purposes of this study were to describe the foot movement characteristics of TC and to compare duration of single- and double-limb support time during TC and during walking. Subjects. Sixteen experienced TC practitioners participated in the study. Methods. The participants’ performance of a whole set of 42-form TC movements was recorded with 2 cameras. A motion analysis system was used to identify the supporting and stepping characteristics of the foot during the practice. Results. Seven foot support patterns and 6 step directions were identified. The results revealed that, compared with normal walking, TC movement had more double-limb support and less single-limb support in terms of total duration. The duration of each support pattern was longer, and movement from one pattern to the next was slow. The duration of each step direction was short, and changes of direction were frequent. Discussion and Conclusion. Support patterns changed slowly, and, combined with various step directions, they were found to be better than those of walking in simulating the gait challenges that may be encountered in daily activities.

Information about soccer injuries is required to develop prevention and rehabilitation programmes. Most soccer injuries occur in the lower extremities. This type of injury is reviewed here. Definitions of injury, injury rate, injury percentage, mechanism of injury, anatomical region of injury, type of injury, and severity of injury are summarised. In each section, a description and summary of the data are provided. Finally, the limitations of the studies and suggestions to improve the investigation of soccer injuries are provided.

The study investigated the effects of carrying methods and loads on gait phase and ground reaction force during stair ascent and descent in children. The carrying methods that were examined included the backpack and one-strap athletic bag. The load weights included 0%, 10%, 15%, and 20% of body weight. Thirteen school children aged 12.21 +/- 0.98 years were recruited as subjects. A Novel Pedar System was used to record and analyze the insole pressure during stair walking with different loads. The load that caused a significant increase in the peak force in each bag and stair mode was 15% of body weight, except for stair ascent carrying the athletic bag, where the load was 10% of body weight. The maximum peak force that was induced by this load in stair descent was 1.25 times that in descent with no load, 1.89 times that in ascent with the same load, and 2.19 times that in ascent with no load. The force-to-time ratio in descent was about three times that in ascent.

Objectives: to investigate the effects of regular Tai Chi (TC) or jogging exercise on neuromuscular reaction in older people. Design: cross-sectional study. Setting: university biomechanics laboratory. Subjects: 21 long-term elderly TC practitioners were compared with 18 regular elderly joggers and 22 sedentary counterparts. Measurements: electromyography (EMG) was used to detect the neuromuscular reaction of the leg muscles to an unexpected ankle inversion perturbation. The latency of the muscles, which was defined as the time that the moment of perturbation began to the onset of the EMG response, was evaluated. Results: a one-way ANOVA revealed that there were significant differences in the latency of the rectus femoris (R) and anterior tibialis (T) muscles between the three groups, but that there were no differences in the latency of the semitendinosus (S) and gastrocnemius (G) muscles. Further tests indicated that the R and T muscles in the TC and jogging groups were activated significantly faster than those in the control group. No significant difference was found for the muscle onset latencies between the TC and jogging groups. Conclusion: maintaining information processing speed during ageing is important, because of the role that it plays in many everyday events. The R and T muscles in the regular TC and jogging groups showed faster responses to unexpected ankle inversion perturbations, which is helpful for the timely correction of postural disturbances, than those in the sedentary control group.

The study reported herein investigated age difference in trunk kinematics during walking with different backpack weights. Two groups of boys, aged 6 and 12 years old, participated in the study. A multiple trial test was conducted with backpacks loaded with 0%, 10%, 15%, and 20% of each subject's body weight. The subjects walked on a treadmill at a self-selected comfortable speed for 20min. The movements of the subjects in sagital plan were filmed and analyzed. The results indicate that trunk inclination angle progressively increased with the increase backpack weight in both age groups. Carrying a load heavier than 15% of body weight resulted in a significantly increased trunk inclination angle when compared to no load. The 12-year-old children showed a significantly lager amplitude in the trunk inclination angle than the 6-year-old children when carrying the same backpack weight.