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Chunmei Cao, Yu Liu, Weimo Zhu and Jiangjun Ma

Background:

Recently developed active workstation could become a potential means for worksite physical activity and wellness promotion. The aim of this review was to quantitatively examine the effectiveness of active workstation in energy expenditure and job performance.

Methods:

The literature search was conducted in 6 databases (PubMed, SPORTDiscuss, Web of Science, ProQuest, ScienceDirect, and Scopuse) for articles published up to February 2014, from which a systematic review and meta-analysis was conducted.

Results:

The cumulative analysis for EE showed there was significant increase in EE using active workstation [mean effect size (MES): 1.47; 95% confidence interval (CI): 1.22 to 1.72, P < .0001]. Results from job performance indicated 2 findings: (1) active workstation did not affect selective attention, processing speed, speech quality, reading comprehension, interpretation and accuracy of transcription; and (2) it could decrease the efficiency of typing speed (MES: –0.55; CI: –0.88 to –0.21, P < .001) and mouse clicking (MES: –1.10; CI: –1.29 to –0.92, P < .001).

Conclusion:

Active workstation could significantly increase daily PA and be potentially useful in reducing workplace sedentariness. Although some parts of job performance were significantly lower, others were not. As a result there was little effect on real-life work productivity if we made a good arrangement of job tasks.

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Yeou-Teh Liu, Tsung-Yu Hsieh and Karl M. Newell

Recent studies have shown more than one time scale of change in the movement dynamics of practice. Here, we decompose the drift and diffusion dynamics in adaptation to performing discrete aiming movements with different space-time constraints. Participants performed aiming movements on a graphics drawing board to a point target at 5 different space-time weightings on the task outcome. The drift was stronger the shorter the time constraint whereas noise was U-shaped across the space-time conditions. The drift and diffusion of adaptation in discrete aiming movements varied as a function of the space-time constraints on performance outcome and the spatial, temporal, or space-time measure of performance outcome. The findings support the postulation that the time scale of movement adaptation is task dependent.

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Cheng-Feng Lin, Hui Liu, William E. Garrett and Bing Yu

Small knee flexion angle during landing has been proposed as a potential risk factor for sustaining noncontact ACL injury. A brace that promotes increased knee flexion and decreased posterior ground reaction force during landing may prove to be advantageous for developing prevention strategies. Forty male and forty female recreational athletes were recruited. Three-dimensional videographic and ground reaction force data in a stop-jump task were collected in three conditions. Knee flexion angle at peak posterior ground reaction force, peak posterior ground reaction force, the horizontal velocity of approach run, the vertical velocity at takeoff, and the knee flexion angle at takeoff were compared among conditions: knee extension constraint brace, nonconstraint brace, and no brace. The knee extension constraint brace significantly increased knee flexion angle at peak posterior ground reaction force. Both knee extension constraint brace and nonconstraint brace significantly decreased peak posterior ground reaction force during landing. The brace and knee extension constraint did not significantly affect the horizontal velocity of approach run, the vertical velocity at takeoff, and the knee flexion angle at takeoff. A knee extension constraint brace exhibits the ability to modify the knee flexion angle at peak posterior ground reaction force and peak posterior ground reaction force during landing.

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Cui Zhang, Qipeng Song, Wei Sun and Yu Liu

Daily stair activities have become increasingly challenging for older adults with deterioration in physical and cognitive capabilities. However, the dynamic stability of older adults during stair descent under a concurrent dual-task condition remains undetermined. The gait and dynamic stability variables of 40 healthy older adults were measured under single- and dual-task conditions during stair descent. The step length, step width, and single support time did not significantly increase (p > .05) under the dual-task condition during stair descent. The medial–lateral center of mass velocity significantly increased (p < .003), whereas the medial–lateral margin of dynamic stability value significantly decreased (p < .006) at the landing and initial single support under the dual-task condition during stair descent. The self-regulatory ability of healthy older adults under the dual-task condition during stair descent was underestimated. Dual tasking displayed a positive impact on the anterior–posterior dynamic stability of healthy older adults.

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Xiao Bao, Jie-Wen Tan, Ying Long, Howe Liu and Hui-Yu Liu

Objective: To study the effect of intermittent hypoxia training (IHT) for dizziness. Design: A single-blind, randomized controlled trial. All participants were recruited from a rehabilitation department in an acute university-affiliated hospital. Intervention: Participants with dizziness were randomly assigned to 2 groups (IHT group and control group). The Dizziness Handicap Inventory, Activities-specific Balance Confidence Scale, and Vertigo Visual Analog Scale were conducted at baseline, end of the fourth week. Results: Among 52 subjects, there were18 males and 34 females, ages 35 to 62 years old (mean [SD] = 46.9 [7.93]). Time length since onset ranged from 12 to 34 months (20.2 [7.15] mo). Dizziness Handicap Inventory, Activities-specific Balance Confidence Scale, Vertigo Visual Analog Scale scores, and attack frequencies of dizziness were improved after IHT intervention in the end of the fourth week. There were significant differences between the IHT group and the control group in the Dizziness Handicap Inventory, Activities-specific Balance Confidence Scale, Vertigo Visual Analog Scale scores, and attack frequencies of dizziness at the end of the fourth week (P < .05). No adverse events occurred during the study. Conclusion: IHT could improve dizziness after intervention at the end of the fourth week. IHT could be the effective method for treating dizziness.

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Feng-Tzu Chen, Su-Ru Chen, I-Hua Chu, Jen-Hao Liu and Yu-Kai Chang

This study examines the effect of a 12-week multicomponent exercise intervention on metacognition among preadolescents with obesity. Seventy-five preadolescents were randomly assigned to either a multicomponent exercise group or a reading control group. An exercise intervention consisting of a jumping rope was utilized to develop multifaceted fitness features, with each session lasting for 75 min and three sessions being conducted per week for 12 weeks. Results revealed significant interactions between group and time point for cardiovascular fitness, muscular endurance, flexibility, and power, as well as for Tower of London task measures, including total move score, total executive time, and total planning-solving time, with better postintervention performances achieved by the exercise group. Positive correlations between the physical fitness and metacognition measurements were also observed. These findings suggest that the multicomponent exercise benefits metacognition in obese preadolescents, with exercise-associated changes in multifaceted fitness features mediating the relationship between exercise and metacognition.

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Yu-Qian Liu, Yan-Zhong Chang, Bin Zhao, Hai-Tao Wang and Xiang-Lin Duan

Some athletes are diagnosed as suffering from sports anemia because of iron deficiency, but the regulatory mechanism remains poorly understood. It is reported that hepcidin may provide a way to illuminate the regulatory mechanism of exercise-associated anemia. Here the authors investigate the hepcidin-involved iron absorption in exercise-associated anemia. Twelve male Wistar rats (300 ± 10 g) were randomly divided into 2 groups, 6 in a control group (CG) and 6 in an exercise group (EG, 5 wk treadmill exercise of different intensities with progressive loading). Serum samples were analyzed for circulating levels of IL-6 by means of enzyme-linked immunosorbent assay (ELISA). The expression of hepatic hepcidin mRNA was examined by real-time polymerase chain reaction analysis. The protein levels of divalent metal transporter 1 (DMT1), ferroportin1 (FPN1), and heme-carrier protein 1 (HCP1) of duodenum epithelium were examined by Western blot. The results showed that the amount of iron and ferritin in serum were lower in EG than in CG (p < .05). The levels of IL-6 and white blood cells were greater in EG than in CG (p < .01). The expression of DMT1, HCP1, and FPN1 was significantly lower in EG than in CG (p < .01). The mRNA expressions of hepatic hepcidin and hemojuvelin in skeletal muscle were remarkably higher in EG than in CG. The data indicated that inflammation was induced by strenuous exercise, and as a result, the transcriptional level of the hepatic hepcidin gene was increased, which further inhibited the expression of iron-absorption proteins and led to exercise-associated anemia.

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Bo Hu, Xiaoyu Liu, Chenggang Wang, Sufeng Yin, Liqun Yu, Tianzhe Zhang, Jianhui Wu, Yinping Chen, Yao Zheng and Fumin Feng

Objective:

To examine the association and relative contribution of different levels of physical activity (PA) with metabolic syndrome (MS).

Methods:

The cluster sampling method was used to recruit 8,750 communitybased individuals between 40 and 60 years of age. MS was defined according to the International Diabetes Federation, 2005. PA was estimated with the International Physical Activity Questionnaire, and three levels of PA (low, moderate, vigorous) were used to classify the individuals. The risk factors of MS were comprehensively collected, and logistic regression methods were used to measure the association between PA and MS. Population-attributable risks and their 95% confidence intervals (CI) were calculated based on the regression model.

Results:

Approximately 30.4% (2,661) of the participants were MS patients. The percentage of individuals with vigorous levels of PA was 46.2% and 43.5% and with low levels of PA was 11.3% and 11.3% in non-MS and MS group, respectively. Individuals with vigorous PA had an odds ratio (OR) of 0.78 (95% CI: 0.66, 0.91) for MS compared with those with low PA, and the OR for individuals with moderate PA was 0.85 (95% CI: 0.73, 1.01). Moderate and vigorous PA levels decreased risk of MS by 18.3%, with approximately 11% of that decrease due to vigorous PA.

Conclusions:

Vigorous PA levels were consistently associated with a reduced risk of MS; however, a protective role of moderate PA was not found. The population-attributable risk for vigorous PA was about 11% for all MS risk factors.

Open access

Yang Liu, Yan Tang, Zhen-Bo Cao, Jie Zhuang, Zheng Zhu, Xue-Ping Wu, Li-Juan Wang, Yu-Jun Cai, Jia-Lin Zhang and Pei-Jie Chen