Abstract
The purpose of this study was to investigate the effects of sex on muscle hypertrophy and strength gain induced by body mass-based resistance training in older adults.
Eighteen older adults (7 men: age 69±2 years, height 1.68±0.04 m, body weight 64.9±6.0 kg; 11 women: age 68±4 years, height 1.55±0.07 m, body weight 51.6±7.2 kg) participated in this study. All subjects carried out resistance exercises without adding any external weight to their body mass (i.e., body mass-based resistance training). They performed 2-3 sets of 10-15 repetitions 3-4 days/week for 18 weeks. They were instructed to complete the concentric and eccentric phases of each repetition over 3-4 s and performed 3-6 exercises. The maximum voluntary isometric strength in knee extensors and flexors was a fixed knee joint angle of 90°. A knee joint angle of 0° corresponded to full knee extension. Muscle thicknesses were measured via B-mode ultrasound using a 5-18 MHz scanning head. Subjects were tested before (PRE), during (MID) and immediately after (POST) the training period. For strength and muscle thicknesses, a repeated measures ANOVA on time (PRE, MID and POST) with a between subject factor of group was used.
The values of the maximal isometric strengths for both knee extension and flexion were significantly (p<0.05) higher in men. Muscle thickness of the posterior of the thigh was also significantly (p<0.05) thicker in men, whereas there was no difference in muscle thickness of the anterior of the thigh. Body mass and the body mass index did not change after the training period. Significant main effects of time (p<0.05) were observed for muscle thicknesses and strength of the thigh. Maximal isometric knee extension strength significantly (p<0.05) increased MID and POST training in both men and women. Significant improvements were observed POST training for maximal isometric knee flexion strength and the muscle thicknesses of both the anterior and posterior of the thigh in both groups. For all variables, there were no significant interactions of time and sex, which means that the effects of muscle hypertrophy and strength gain were the same between older men and older women in the present study.
In conclusion, body mass-based resistance training can increase muscle hypertrophy and strength gain for both older men and women. The present results suggest that there are no differences in the training effects based on sex in this age group.
© 2018 The Juntendo Medical Society. This is an open access article distributed under the terms of Creative Commons Attribution License (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original source is properly credited.
