Expert Perceptual Behavior under the Spatiotemporal Visual Constraints in Table Tennis

OBJECTIVES The perceptual ability to detect movement is essential for expert table tennis players. A spatiotemporal occlusion paradigm was employed to examine the critical information that facilitates athletes’ perception.METHODS Thirty-one expert table tennis players, 29 participants and 2 demonstrators, volunteered to participate in the study. Four types of temporal conditions and five types of spatial occlusions were displayed in experimental videos of two opponents playing a table tennis forehand stroke. Period t1–4 represented the four temporal conditions, with 250, 500, 750, and 1000 ms of action being occluded, respectively. The five types of spatial occlusion involved showing the kinematics of only the ball, paddle, arm, trunk, or head. The participants were instructed to judge the landing direction of the ball on the basis of the information in the footage.RESULTS The footage depicted the longest period of play. Furthermore, in separate trials, the spatial information (for the ball, torso, or head) was missing because of occlusion. The absence of such critical spatiotemporal information impaired the ability of players to make an accurate prediction.CONCLUSION Players obtained crucial spatiotemporal information if the timeframe of the video was relatively complete and spatial information on the opponent’s torso and head was available. For peak performance, expert table tennis players perceive and detect the optical flow of the ball’s flight and consider invariant information concerning their opponent’s torso and head.

A Biomechanical Analysis of the Effect of Pilates Exercise on Female College Students with Knee Joint Deformity

BACKGROUND Current research on genu varum shows the favorable influence of exercise on the biomechanics of the knee joint by reducing the static malalignment and mechanical imbalances, however the transference to a more optimum gait has not been investigated.OBJECTIVES To investigate the effects of Pilates exercise on the changes of gait and lower limb malalignment in female students with genu varum.METHODS A total of 23 female college students with verified genu varum participated in this study. The participants were randomly assigned to two groups a Pilates exercise group (n=15) and a control group (n=8). The Pilates exercise group participated in 1 hour Pilates exercise 3 times per week for a total of 10 weeks. Each of the participants had an X-ray and performed gait 5 times before and after the exercise treatment. The participants kinetic and kinematic data were gathered using an eight Vicon Motion camera system and two force platforms.RESULTS For the Pilates group gait their maximum extension and internal rotation knee moment, and maximum adduction and internal rotation hip moment significantly increased, while the maximum knee moment flexion decreased. For the control group gait their maximum hip extension and hip adduction moment significantly decreased. For the Pilates group there was a significant reduction in the distance from the anatomical axis to the weight bearing line in the left leg, but there was no significant change for the control group.CONCLUSIONS The results suggest that Pilates exercise may be beneficial for females with genu varum by helping to improve both their static alignment and helping their gait to become more balanced.

Physiological Response of Imagery Running with or without an Avatar in 3D Virtual Reality: A Preliminary Study

OBJECTIVES The present study is aimed at observing the physiological response imagery running with an avatar in 3D virtual reality (VR) and to explore the differences in physiological responses between imagery running with and without an avatar in 3D VR.METHODS We randomly assigned 32 healthy adults to either a group with Avatar (n = 19) or a group without (n = 13). The group with avatar performed imagery exercise with an avatar in 3D VR and the group without Avatar performed it without an avatar in 3D VR. Both groups were instructed to mentally imagine performing running in VR without executing actual physical movements. We recorded electro-physiological data before, during, and after the 20-min intervention. We also measured the participants’ level of presence and intensity of experienced cybersickness.RESULTS In the group with Avatar, all physiological responses increased from the resting to the intervention period. The group with Avatar also showed a higher level of presence and fewer cybersickness symptoms than the group without Avatar.CONCLUSIONS The results suggest imagery running with an avatar in 3D VR might be effective as an alternative exercise.

Longitudinal Association of Handgrip Strength with Medical Use and the Risk of Hospitalization in Korean Adults

OBJECTIVES Age-related loss of muscular strength may contribute to medical health condition. Decreased handgrip strength is associated with an increased risk of chronic diseases, disability, and mortality. However, it is not known whether handgrip strength is also linked with hospitalization and medical use from the long-term cohort study in middle-aged adults. Thus, we aimed to investigate the association of handgrip strength levels, medical use, and hospitalization in Korean adults.METHODS This large prospective study was based on data from Korean Longitudinal Study of Ageing 2006 to 2018. In total, 9,228 participants aged ≥45 years were included for this study. Handgrip strength was measured using dynamometer, and classified into quartiles by sex-specific cutoff point.RESULTS Significantly higher hazard ratio (HR) for hospitalization was observed in lower handgrip strength (HR: 1.22, 95% CI:1.11-1.34) compared to higher handgrip strength (reference) in the fully adjusted model. We also found longitudinal association of handgrip strength levels and the use of hospitalization and outpatient medical care during 12 years following period using mixed effect modes with time-dependent interaction.CONCLUSIONS Our results suggests that lower handgrip strength was associated with increased the risk of hospitalization and use of medical care in Korean population. This study highlights the maintaining of muscular strength may play an important role in the reduction of risk for hospitalization and medical use by preventing chronic diseases.

The Effects of a Medial Heel Wedge on the Weight-Bearing Response of Hindfoot Valgus and the Total Weight-Bearing Responses of the Navicular and Talus Bones

OBJECTIVES Medial heel wedges are commonly prescribed to manage the weight-bearing response of hindfoot valgus and the total weight-bearing responses of the navicular and talus bones. Previous studies have reported that a medial heel wedge is effective in the management of musculoskeletal injuries. However, it remains unclear the effect of a medial heel wedge on the weight-bearing responses of footarch bones in vivo. To clarify the effects of a medial heel wedge on the weight-bearing response of hindfoot valgus and the total weight-bearing responses of the navicular and talus bones is necessary to understand how best to treat musculoskeletal injuries clinically. The purpose of our study was to clarify the effects of a medial heel wedge on the weight-bearing response of hindfoot valgus and the total weight-bearing responses of the navicular and talus bones.METHODS Twenty-five healthy males were analyzed. We obtained MRI scanning of the right foot under non-loading (NL) and full weight-bearing (FW) conditions. Participants wore two insole types, a flat insole and a medial heel wedge. To evaluate the weight-bearing response in hindfoot valgus, the hindfoot alignment view (HAV) was measured. We also measured navicular and talus bone positions and calculated the total positional changes of the navicular and talus bones (ΔTPCN, ΔTPCT) from the vertical and medial displacements using the Pythagorean theorem.RESULTS Significant interactions were observed with the HAV. Under both NL and FW conditions, the HAV was smaller on the medial heel wedge than on the flat insole. In addition, the ΔTPCN was significantly smaller on the medial heel wedge than on the flat insole. However, no significant differences were observed for ΔTPCT.CONCLUSIONS Our results suggest that use of a medial heel wedge decreases hindfoot valgus values under both NL and FW conditions and stabilizes the total weight-bearing response of the navicular bone.

The Effects of Brazilian Jiu-Jitsu on Body Composition, Health Fitness, Functional Movement Screening in non-Elite Healthy Young Adults

OBJECTIVES Brazilian Jiu-Jitsu (BJJ) has grown massively in recent years, but its positive effects in non-elite population has not been analyzed. The purpose of current study was to exam the effects of BJJ on body composition, health fitness components, and functional movement screening (FMS) in healthy young adults.METHODS Combined exercise program was composed of aerobic and resistance exercises. All participants were randomly assigned either into BJJ exercise group (BJEG, n=10, 28.10±2.64 years) or combined exercise group (CEG, n=10, 28.20±3.43 years). Exercise intervention was conducted for ninety minutes per session, three times per week for twelve weeks.RESULTS Body fat (%) and muscle mass (kg) were significantly improved in both groups. Muscle strength in upper and lower extremity, muscle endurance, flexibility, power were significantly improved in both groups. Cardiorespiratory fitness in BJEG was significantly improved. Also, FMS total score and deep squat score showed significant improvement in both groups.CONCLUSIONS BJJ is an effective exercise for health and fitness management purpose in non-elite healthy young adults.

Effectiveness of Kinesio Taping for Dynamic Postural Stability in Adolescent Athletes with Chronic Ankle Instability: A Pilot Study

OBJECTIVES To determine the effectiveness of K-tape on dynamic postural stability of the injured limb in adolescent athletes with chronic ankle instability (CAI) by measuring reach distance with the modified Star Excursion Balance Test (mSEBT).METHODS Twenty volunteers (20 females [17.78 ± 1.22 yrs], height [163.89 ± 7.69 cm], mass [62.51 ± 9.81 kg]) with CAI. Four strips of K-tape were applied to the injured limb. Participants completed 4 trials of testing (2 with tape, 2 without tape) using the mSEBT as the assessment tool. We applied 4 strips of K-tape to the injured limb and then tested postural stability using the mSEBT to see if there was an increase of reach distance in the mSEBT. Measuring reach distance in Anterior (AN), Posteromedial (PM), Posterolateral (PL) on the injured limb with K-tape and without K-tape condition. We measured the reach distances and then normalized the distance to account for height differences. A repeated measures t-test was used for this study.RESULTS There is no statistically significant different between the condition with K-tape and without K-tape in the reach distances on the mSEBT in adolescent athletes with CAI.CONCLUSIONS Based on the results, there appears to be no improvement of reach distance using the mSEBT in adolescent athletes with CAI. Therefore, clinicians need their thoughtful consideration for applying K-tape to improve dynamic postural stability in adolescent athletes with CAI.

Energy System Contribution during 1500M Running in Untrained and Endurance-Trained Asian Male College Students

OBJECTIVES To compare the aerobic and anaerobic energy system contribution during 1500m running between collegiate untrained (UT) and endurance trained (ET) subjects.METHODS Five Asian UT (age: 23.8 ± 0.4 yrs, body fat %: 15.9 ± 5.7 %, height: 174.0 ± 4.1 cm, weight: 65.5 ± 4.1 kg) and 5 Asian ET male participants (age: 24.4 ± 3.9 yrs, body fat %: 12.9 ± 6.9 %, height: 169.4 ± 5.1 cm, weight: 60.6 ± 8.1 kg) participated in this study. Participants attended 3 sessions to determine their body composition, submaximal and maximal oxygen consumption (VO_2max) test, 1500m track running session (RS) and 1500m treadmill RS. The maximally accumulated oxygen deficit (MAOD) method was used to calculate energy system contribution.RESULTS The times for the 1500m track run for the UT and ET were 428.0 ± 48.7 and 331.6 ± 14.0 seconds (p=0.004) respectively. There were no significant differences in VO₂ between the 1500m track and treadmill RS indicating the participants ran to their personal best times for both trials. The mean VO_2max(mL•kg^-1•min^-1) were significantly different between UT (45.1 ± 5.0) and ET participants (58.3 ± 2.2) (p=0.002). The mean relative contributions of the aerobic and anaerobic energy system during 1500m running were significantly different for the UT, 65.4 ± 7.0%, 34.6 ± 7.0 and ET, 75.7 ± 1.5%, 24.3 ± 1.5 % (p =0.011).CONCLUSIONS The point of equal contribution of the aerobic and the anaerobic systems occurred after thirty to forty seconds of intensive exhaustive running after which the aerobic contribution continues to increase while the anaerobic contribution decreases with increasing duration. By the end of 60th second of exhaustive running, the ET mean aerobic contribution is 71.5% compared to the UT’s 58.6%. This finding suggests a greater reliance on the aerobic energy system by the ET.