Oshita Kazushige, Myotsuzono Ryota
Department of Human Information Engineering, Okayama Prefectural University, 111 Kuboki, Soja-shi, Okayama, 719-1197, Japan.
Department of Sports Science, Kyushu Kyoritsu University, 1-8, Jiyugaoka, Yahatanishi-ku, Kitakyushu-shi, Fukuoka, 807-8585, Japan.
Osteoporos Sarcopenia. 2021 Dec;7(4):146-152. doi: 10.1016/j.afos.2021.10.002. Epub 2021 Oct 26.
This study aims to investigate the association between skeletal muscle mass index (SMI) and physical activity among female university students who had exercise habituation in junior and high school.
The body composition of 120 Japanese female students was measured using the bioelectrical impedance analysis (BIA) method, and their physical activity level (PAL) was measured using a factorial method. Based on the 'Dietary Reference Intakes for Japanese' (DRIs-J), according to the Ministry of Health, Labour and Welfare, PAL (24-h energy consumption/basal metabolic rate) classifications were defined as low-PAL (PAL < 1.6), moderate-PAL (1.6 ≤ PAL < 1.9), and high-PAL (1.9 ≤ PAL < 2.2), respectively.
Individuals with low-PAL had a significantly lower SMI, especially for the lower limb muscles, than individuals with moderate-PAL or higher. More than 50% of the individuals with currently low-PAL corresponded or tended to correspond to the SMI cut-off value defined by the Asian Working Group for Sarcopenia or the 2017 National Health and Nutrition Survey of Japan. Therefore, more than half of the female students with currently low-PAL, even those with an exercise habituation in the past, corresponded to the cut-off value for muscle loss in sarcopenia diagnosis, particularly in the lower limbs.
These results suggest that it is important to maintain a moderate or higher level of physical activity in the DRIs-J classification, even for young women who used to exercise in the past, to maintain muscle mass accordingly.
本研究旨在调查初中和高中有运动习惯的女大学生骨骼肌质量指数（SMI）与身体活动之间的关联。
采用生物电阻抗分析（BIA）法测量120名日本女学生的身体成分，并采用析因法测量她们的身体活动水平（PAL）。根据厚生劳动省的《日本膳食参考摄入量》（DRIs-J），PAL（24小时能量消耗/基础代谢率）分类分别定义为低PAL（PAL<1.6）、中等PAL（1.6≤PAL<1.9）和高PAL（1.9≤PAL<2.2）。
低PAL个体的SMI显著低于中等PAL或更高的个体，尤其是下肢肌肉。目前低PAL个体中超过50%符合或倾向于符合亚洲肌少症工作组或2017年日本国民健康与营养调查定义的SMI临界值。因此，目前低PAL的女学生中，超过一半，即使是过去有运动习惯的学生，符合肌少症诊断中肌肉量减少的临界值，尤其是在下肢。
这些结果表明，即使对于过去曾锻炼的年轻女性，在DRIs-J分类中保持中等或更高水平的身体活动以相应维持肌肉量也很重要。
