It is well known that eccentric exercise induces muscle damage that is characterized by a prolonged decrease in muscle strength and range of motion, development of delayed onset muscle soreness, and swelling. Therefore, the present study aimed to compare the acute effects of hold-relax stretching (HRS) with those of static stretching (SS) on muscle strength and soreness. The participants comprised 28 male volunteers randomly assigned to either the HRS group (N = 14) or the SS group (N = 14). Initially, the participants of both groups performed 60 maximal eccentric contractions of the knee extensors. Two and four days after this exercise, each group performed either HRS or SS for 60 s at a time and repeated them six times for a total of 360 s. Muscle strength and soreness during stretching and contraction were measured before and immediately after HRS and SS. The results showed that the muscle soreness observed after eccentric contraction significantly decreased immediately after both HRS and SS were performed two and four days later. In addition, there were no significant changes in muscle strength immediately after both HRS and SS were performed two and four days later. The rate of change in muscle soreness after HRS was significantly higher than that after SS two days post eccentric contractions. These results suggest that while both HRS and SS can effectively decrease muscle soreness, the effect of HRS on muscle soreness was larger than the effect of SS.

Resistance training is a treatment for muscle weakness and muscle atrophy. Although previous studies reported that muscle strength increased via changes in neural adaptation after low-intensity resistance training with skin cooling (SC), the effects of the training on both muscle strength and muscle thickness were unclear. Therefore, this study investigated the effect of low-intensity training of the triceps brachii with SC on muscle strength and muscle thickness. Volunteers were 12 healthy men, with one arm randomly assigned to SC and the other to control groups. Elbow extension exercises were performed for 8 weeks, and 1 repetition maximum (RM) and muscle thickness of triceps brachii were measured before and after training. Resistance exercise was performed thrice a week using a dumbbell adjusted to 50％ of 1 RM for both the groups. The SC side used an ice bag secured to the triceps brachii during training. There were no significant interaction effects of 1 RM and muscle thickness of triceps brachii；however, both variables significantly increased after training in both the SC and control groups. Muscle strength and muscle thickness increased after the 8-week training program with SC. No significant differences were observed between the groups.

Resistance training is a treatment for muscle weakness and muscle atrophy. Although previous studies reported that muscle strength increased via changes in neural adaptation after low-intensity resistance training with skin cooling (SC), the effects of the training on both muscle strength and muscle thickness were unclear. Therefore, this study investigated the effect of low-intensity training of the triceps brachii with SC on muscle strength and muscle thickness. Volunteers were 12 healthy men, with one arm randomly assigned to SC and the other to control groups. Elbow extension exercises were performed for 8 weeks, and 1 repetition maximum (RM) and muscle thickness of triceps brachii were measured before and after training. Resistance exercise was performed thrice a week using a dumbbell adjusted to 50％ of 1 RM for both the groups. The SC side used an ice bag secured to the triceps brachii during training. There were no significant interaction effects of 1 RM and muscle thickness of triceps brachii；however, both variables significantly increased after training in both the SC and control groups. Muscle strength and muscle thickness increased after the 8-week training program with SC. No significant differences were observed between the groups.