Effects of Vibration Resistance Exercises on EMG and Skeletal Muscle Hemodynamics.

Objectives: Past studies show that vibration can stimulate muscle activity and improve muscle performance. However, further verification is needed on the effects of different vibration frequencies combined with different muscle strength exercise intensities on EMG activity and skeletal muscle hemodynamics. Methods: We recruited 27 male college athletes for 40%, 60%, and 80% maximum voluntary contraction (MVC) tests at the vibration frequencies of 0 Hz, 10 Hz, 20 Hz, and 30 Hz. We collected EMG activity signals using wireless EMGs and skeletal muscle hemodynamic parameters using a near-infrared spectrometer. Results: At an 80% MVC intensity of the rectus femoris, the mean, peak, and area of EMG at 30 Hz were significantly increased, compared with those at 0 Hz. At a 40% MVC intensity with vibration frequencies of 10 Hz, 20 Hz, and 30 Hz, the HHb of skeletal muscles was significantly increased, while the O2Hb and TSI were significantly decreased, compared with those at 0 Hz. Conclusions: We conclude that high frequency and strongly vibrated muscle strength exercise can improve EMG activity, while vibration and low-intensity muscle strength exercise could increase the oxygen consumption of skeletal muscles.

Relationships between different types of physical activity and metabolic syndrome among Taiwanese workers.

This study aimed to investigate the relationships between different types of physical activity (PA) and metabolic syndrome (MetS). In this cross-sectional study, 3,296 Taiwanese workers were enrolled. A self-reported questionnaire was used to assess nutritional health behavior and PA levels related to occupation, leisure time, and commuting. Anthropometric measures, blood pressure and biochemical determinations of the blood were also obtained. Multiple logistic regression was used to evaluate the adjusted odds ratios (ORs) and 95% confidence intervals (CI) of MetS and its components associated with different types of PA. The prevalence of MetS was 16.6% in workers. Compared with a low level of leisure-time PA, a high level of leisure-time PA showed a significantly lower risk of high triglycerides (OR 0.73, 95% CI 0.61-0.87) and MetS (OR 0.76, 95% CI 0.62-0.95). Compared with a low level of occupational PA, a high level of occupational PA represented a significantly lower risk of both abdominal adiposity (OR 0.64, 95% CI 0.49-0.84) and high triglycerides (OR 0.71, 95% CI 0.55-0.90). However, commuting PA levels were not significantly associated with MetS and its components. In conclusion, occupational PA as well as leisure-time PA could be important for the prevention of MetS.