論文

This study investigated whether whole-body vibration (WBV) coupled with low-velocity exercise (EX) for 13 weeks retains muscle performance gains after 5 weeks of subsequent detraining compared with the results of an identical EX program without WBV. Thirty-two untrained healthy adults (22-49 years of age) were randomly assigned to groups that performed EX with or without WBV (EX-WBV and EX, respectively; n = 16 per group). The following outcome variables were evaluated: countermovement jump height; maximal isometric, concentric, and eccentric knee extension strengths; local muscular endurance; and lumbar extension torque before, during, and after the 13-week training period, and after 5 weeks of detraining. Compared with the EX group, significantly higher increases in countermovement jump height and isometric and concentric knee extension strengths were detected in the EX-WBV group after the 13-week training period. However, detraining caused significant declines in these 3 muscle performance tests only in the EX-WBV group (-4.8, -10.2, and -17.2%, respectively), resulting in no significant differences between the test and control groups after the detraining period. After detraining, all examined variables showed significantly better performance compared with pretraining (p < 0.05) and did not significantly differ from midtraining (7 weeks) in both groups (p > 0.05). These results suggest that muscle strength in the lower extremities, particularly isometric and concentric contractions, and muscle power might be more susceptible to short-term detraining effects when exercise is combined with WBV. Thus, it is necessary to perform regular exercise to maximize the benefits of WBV on muscle strength and power during the early stages of training in previously untrained individuals.

本研究は定期的に太極拳練習を行っている男女を対象に脳波(Electroencephalogram:EEG)によるポジティブ感情(積極快)と、質問紙調査によるフロー体験の関係を調査した。積極快と質問紙調査で得られたフロー値との相関は、上級者では有意な相関が見られたが、初心者では有意な相関が見られなかった。さらに、同対象者に対して2年間の縦断研究を行ったところ、上級者は積極快の切片がすでに高く2年間に有意な変化は見られなかったが、初心者は積極快の切片は低かったため2年間に有意な変化が見られた。(著者抄録)

The effects of resistance training (RT) combined with whole-body vibration (WBV) on muscle fitness, particularly muscle hypertrophy and neuromuscular performance, are not well understood. We investigated the effects of WBV in healthy, untrained participants after a 13-week RT course by performing magnetic resonance imaging and by measuring maximal isometric (with electromyography) and isokinetic knee extension strengths, isometric lumbar extension torque, countermovement-jump, knee extension endurance, and sit-ups. Thirty-two individuals (22-49 years old) were randomly assigned to RT groups with (RT-WBV, n=16) or without WBV (RT, n=16). Following the RT course, significantly higher increases in the cross-sectional areas of m. psoas major (vs baseline values) and erector spinae muscle (vs the RT group) were observed in the RT-WBV group (+10.7%, P<0.05; +8.7%, P<0.05) compared with the RT group (+3.8%, P=0.045; 0.0%). Higher increases from baseline were also observed in maximal isometric force, concentric knee extension torque, countermovement-jump, and maximal isometric lumbar extension torque in RT-WBV (+63.5%; +76.7%, +15.0%, and +51.5%, respectively; P<0.05) than in those of RT (+25.6%, P=0.001; +17.8%, P=0.18; +11.3%, P=0.001; and +26.4%, P<0.001, respectively). The WBV-induced increases in muscle hypertrophy and isometric lumbar extension torque suggest a potential benefit of incorporating WBV into slow-velocity RT programs involving exercises of long duration.

The mechanism of insulin resistance in obesity is not fully understood. In muscle cells, the number of insulin receptor, the function of glucose transporter 4 and the activity of tyrosine kinase decrease. The rink of body fat accumulation and insulin resistance in muscle is thought through free fatty acid and tumor necrosis factor alpha secreted in adipose tissue. Thiazolidinediones (TZDs) are useful to reduce insulin resistance especially in obesity. TZDs seem to cause small weight gain, but to reduce visceral fat in 12-24 weeks. In longer period, it hasn't been studied very much. There are some unsolved problems. So now, targets of TZDs are obese diabetes failed in other medicines. When using TZDs, be cautious of excess eating and physical inactivity. [References: 23]