The aim of the present study was to compare the effects of low-load, higher-repetition training (LLHR) with those of high-load, lower-repetition training (HLLR) on muscle strength, mass, and echo intensity in healthy young men. Fifteen healthy men (age, 23.1 ± 2.6 years) were randomly assigned to one of the two groups: LLHR or HLLR group. Resistance training on knee extensor muscles was performed 3 days per week for 8 weeks. One-repetition maximum (1RM) strength, maximum isometric strength, muscle thickness and muscle echo intensity on ultrasonography of the rectus femoris muscle were assessed every 2 weeks. Analysis of variance showed no significant group × time interaction, and only a significant main effect of time was observed for all variables. The 8-week resistance training increased 1RM, maximum isometric muscle strength, and muscle thickness by 36.2%–40.9%, 24.0%–25.5%, and 11.3%–20.4%, respectively, whereas it decreased echo intensity by 8.05%–16.3%. Significant improvements in muscle strength, thickness, and echo intensity were observed at weeks 2, 4, and 8, respectively. The lack of difference in time-course changes between LLHR and HLLR programs suggests that low-load training can exert similar effects on muscle mass and characteristics as high-load training by increasing the number of repetitions, even when not performed to failure.
1Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan.
2IMS Health Japan, Japan
3Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Japan
Corresponding author: Tome Ikezoe Human Health Sciences, Graduate School of Medicine, Kyoto University 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507,Japan. Telephone: +81-75-751-3967; Fax: +81-75-751-3909 E-mail: firstname.lastname@example.org
The authors declare that they have no conflict of interest.