The purpose of this study was to investigate the effects of different sitting postures, by change of seat height, on lower extremity muscle activation and maximum power during explosive bicycle pedaling exercises. The subjects performed 5 sec maximum pedaling exercises at three different seat heights.‘High’ seat height was defined as 95% of leg length, ‘Middle’ was 90% and‘Low’ was 85%.
The results were summarized as follows: A) At 3 revolutions, maximum power at‘High’ was significantly higher than that at‘low’. B) Pelvic angle at‘High’ was significantly higher than that at‘Low’. C) The maximum extension angle of the knee joint was a significantly high value in descend. ing order of‘High’, ‘Middle’ and‘Low’. D) mEMG of the Erector spinae and Biceps femoris at‘High’ was significantly higher than that at‘Low’. E) At‘High’, there was a significant correlation between maximum power of 3 revolutions and mEMG in the Gluteus maximus. In addition, maximum power at 3 revolutions tended to correlate with mEMG in the Biceps femoris and Vastus lateralis.
These results suggest that in explosive pedaling exercises, different sitting postures by change of seat height, have different influences on hip extension muscle activation and maximum power.

The purpose of this study was to prove the hypothesis that the effect of strength training is memorized and reinforced by retraining. Untrained university-age men participated in this training program. The retraining leg was subjected to 5 weeks of isometric training, 17 weeks of detraining and 5 weeks of retraining in knee extension. The contralateral training leg was subjected to 5 weeks of isometric training during the same period as the retraining phase of the retraining leg. Maximal isometric torque of knee extension increased after the 5-week training and remained at the trained level during the 17week detraining period. Torque gain by retraining of the retraining leg was 2.6 times greater than that of the contralateral training leg. These changes in isometric torque corres-ponded with changes in iEMG of the vastus lateralis. The cross-sectional area of the quadriceps femoris muscle did not change with training. Results support the hypothesis that the effect of strength training is memorized and reinforced by retraining. In addition, results show that these adaptations would be explained by recruitment and rate coding of motor units.

Pelvic floor trauma developing into pelvic frailty is a significant concern in urogynecology or orthopedics. The majority of women who have experienced vaginal childbirth are affected, to a certain extent, by some form of pelvic floor damage, thereby eliciting substantial alterations of functional anatomy in the pelvic cavity which are manifested as urinary incontinence or pelvic organ prolapse (e.g., uterine prolapse). With the above in mind, medical researchers, continence experts, and continence exercise practitioners in the research areas of sports medicine and rehabilitation medicine believe that the coordinated activity of pelvic floor muscles, in association with the abdominal muscles, is a prerequisite for urinary and defecatory continence. Since the pelvic floor forms the base of the abdominal cavity, stronger pelvic floor muscles are crucial in maintaining such capabilities. Opposing action of the abdominal and pelvic floor muscles ensures that exercises for one may also strengthen the other. Appropriate abdominal maneuverability or logical exercise training of the abdominal muscles may thus be beneficial in maintaining not only strength but also coordination, flexibility, and endurance of pelvic floor muscles and abdominal muscles. Such exercises, collectively known as pelvic floor muscle training, may be effective for long-term pelvic cavity care and also in rehabilitating cases of pelvic floor dysfunction. Further research is needed, however, in determining whether pelvic floor muscle function can be truly enhanced or maintained by such exercises in cases of pelvic floor dysfunction and/or decreased urinary continence.