Dewei Mao

Strategies of stepping over obstacles: The effects of long-term exercise in older adults

BACKGROUND Stepping over obstacles challenges stability and is a leading cause of falls in older adult populations. As walking and Tai Chi (TC) exercise have been suggested practices for older adults for fall prevention, the purpose of this study was to evaluate the obstacle-crossing strategies of long-term TC practitioners and exercise walkers. METHODS Thirty healthy older women (average age: 65.7 years) with either TC (n=15) experience (average experience: 8.2 years) or walking exercise (n=15; average experience: 8.8 years) participated in this study. We used three trial conditions: (1) normal walking, (2) crossing a 15cm (20% of leg length) obstacle, and (3) crossing a 23cm (30% of leg length) to assess obstacle-crossing strategy. Sagittal plane obstacle-crossing kinematic parameters and plantar pressures were used to evaluate the obstaclecrossing strategy. A MANOVA assessed differences between groups. RESULTS Individuals with a TC background crossed the obstacle significantly faster with a significantly longer step relative to the exercise walkers. Plantar pressure profiles between the two groups also differed. Exercise walkers showed greater plantar pressure in the forefoot; TC practitioners demonstrated greater medial heel plantar pressure during obstacle-crossing. CONCLUSIONS Our results suggest that obstacle-crossing strategies were affected by the type of longterm exercise. The strategies each group used had important attributes that affect stability during obstacle-crossing. Future studies are needed to understand how obstacle-crossing strategies are adopted and how exercise may influence the strategy used.

Effects of Exercise on Ankle Proprioception in Adult Women during 16 Weeks of Training and Eight Weeks of Detraining

This study evaluates the effects of training and detraining on ankle proprioception in terms of kinesthesia in adult women. Sixty participants were randomly assigned to three groups. Tai Chi and Brisk Walking Groups went through a 16-week training period followed by an eight-week detraining period. The ankle plantar-flexion, dorsal-flexion, inversion, and eversion kinesthesia were measured every four weeks. The ankle kinesthesia in plantar/dorsal flexion of both exercise groups decreased, but the Tai Chi Group decreased more and sooner than the Brisk Walking Group. The training effects of Tai Chi exercise were retained but diminished during the detraining. The training effects of Brisk Walking exercise were not retained. The kinesthesia of ankle inversion and eversion remained unchanged after training. The results suggest that Tai Chi exercise is more effective in training ankle proprioception in plantar and dorsal flexion and in retaining the training effects compared with Brisk Walking exercise.

Effects of Backpack Weight on Posture, Gait Patterns and Ground Reaction Forces of Male Children with Obesity during Stair Descent

This study investigates the effects of backpack weight on posture, gait pattern, and ground reaction forces for children with obesity in an attempt to define a safe backpack weight limit for them. A total of 16 obese (11.19 ± 0.66 years of age) and 21 normal body weight (11.13 ± 0.69 years of age) schoolboys were recruited. Two force plates and two video cameras were used. Multivariate analysis of variance with repeated measures was employed. Obese children showed increased trunk and head forward inclination angle, gait cycle duration and stance phase, decreased swing phase, and increased ground reaction force in the medial-lateral and anterior-posterior directions when compared with male children with a normal body weight. The changes were observed even with an empty backpack in comparison with normal body weight children and a 15% increase in backpack weight led to further instability and damage on their already strained bodies.

Effect of 1-year regular Tai Chi on neuromuscular reaction in elderly women: a randomized controlled study

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.

Test–retest reliability of a new device for assessing ankle joint threshold to detect passive movement in healthy adults

Abstract This study aimed to evaluate the test–retest reliability of a new device for assessing ankle joint kinesthesia. This device could measure the passive motion threshold of four ankle joint movements, namely plantarflexion, dorsiflexion, inversion and eversion. A total of 21 healthy adults, including 13 males and 8 females, participated in the study. Each participant completed two sessions on two separate days with 1-week interval. The sessions were administered by the same experimenter in the same laboratory. At least 12 trials (three successful trials in each of the four directions) were performed in each session. The mean values in each direction were calculated and analysed. The ICC values of test–retest reliability ranged from 0.737 (dorsiflexion) to 0.935 (eversion), whereas the SEM values ranged from 0.21° (plantarflexion) to 0.52° (inversion). The Bland–Altman plots showed that the reliability of plantarflexion–dorsiflexion was better than that of inversion–eversion. The results evaluated the reliability of the new device as fair to excellent. The new device for assessing kinesthesia could be used to examine the ankle joint kinesthesia.

Effects of Tai Chi Exercise on body stability among the elderly during stair descent under different levels of illumination

ABSTRACT The elderly are prone to stair descent falls under low illumination. Tai Chi, a traditional Chinese conditioning exercise, has been proved to improve body stability by altering body condition, gait, and proprioception. This study investigates whether Tai Chi exercise could improve body stability during stair descent under high and low illumination. Three groups of elderly women who practice Tai Chi, brisk walking, and no exercise were included. They descended from a simulated staircase. Tai Chi participants decreased horizontal velocity, centre of mass (COM) sway, and increased foot clearance compared with other participants, these movements could increase body stability; Compared with under high illumination, Tai Chi participants decreased horizontal velocity, loading rate, braking impulse, and increased inclination angle, COM sway, centre of pressure displacement under low illumination. Tai Chi participants were more sensitive to the difference in illumination, and took corresponding strategies to stabilize their bodies during stair descent.

Could Insoles Offload Pressure? An Evaluation of the Effects of Arch-supported Functional Insoles on Plantar Pressure Distribution during Race Walking

This study investigated the effectiveness of functional insoles on plantar pressure distribution during race walking so as to reduce the high plantar pressure and force on race walkers, who tend to suffer from overuse injury. A total of 20 male race walkers aged 21.19 ± 3.66 years and with a mean height of 178.85 ± 14.07 cm were recruited as participants. Each participant completed a race walking with functional or normal insoles. Plantar pressure insoles were used to collect vertical plantar pressure data. A two-way analysis of variance with a mixed design was used to determine the difference between the two conditions. Results showed that the use of functional insoles reduces the peak pressure and the impulse in the metatarsophalangeal joints and heels and thus suggest that functional insoles reduce the overuse injury risks of these parts. The first ground reaction force peak also decreased. This result suggested that functional insoles reduce the risks of foot and leg injuries.

Long-term Tai Chi exercise increases body stability of the elderly during stair ascent under high and low illumination

Abstract The effects of long-term Tai Chi exercise on body stability of the elderly during stair ascent under high and low illumination were investigated. Forty-five healthy elderly women were divided into three groups, namely, Tai Chi exercise group, brisk walking group and no-exercise control group. All the participants ascended a staircase, during which force platforms and a motion capture system collected the data. Under the high illumination, Tai Chi exercise participants exhibited higher loading rate and anteroposterior centre of pressure (COPap) displacement as well as a lower braking impulse than no-exercise group. Under the low illumination, Tai Chi exercise participants demonstrated higher COPap and mediolateral centre of pressure (COPml) displacements as well as lower braking and lateral impulses compared with no-exercise participants. The centre of mass (COM)ml sway in Tai Chi and no exercise participants were higher, the loading rates in Tai Chi and walking participants were higher, and the lateral impulse in no exercise participants was higher under low illumination than under high illumination. Thus, low illumination increases the risk of falling. Tai Chi participants increased their foot clearance, head inclination angle and COPap displacement under low illumination to increase their stability during stair ascent.

The effect of Tai Chi practice on brain white matter structure: a diffusion tensor magnetic resonance imaging study

ABSTRACT 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.

Effects of Tai Chi Chuan and Brisk Walking Exercise on Balance Ability in Elderly Women: A Randomized Controlled Trial

This study aims to investigate the effects of Tai Chi Chuan (TCC) and brisk walking (BW) on balance and training duration for the two exercises to significantly improve balance. A total of 48 elderly women were randomly divided into three groups. The TCC and BW groups completed a 60-min intervention training program with five sessions weekly for 16 weeks. Single-leg standing balance was tested every 4 weeks. Results showed that all the variables with eyes open improved on the eighth week (p < .05) in the TCC group and on the 12th week (p < .01) in the BW group. All variables with eyes closed improved on the 12th week (p < .01) in the TCC group and on the 16th week (p < .05) in the BW group. The results showed that 12 and 16 weeks of TCC and BW, respectively were essential to improve balance with eyes closed among the women aged 60-70 years.