Anzai Miho, Hioki Maya, Sawa Maria, Takahashi Hitoshi, Michishita Ryoma
Graduate School of Sports and Health Science, Fukuoka University, Fukuoka 8140180, Japan.
Faculty of Health Care and Medical Sports, Department of Rehabilitation, Teikyo Heisei University, Chiba 2900170, Japan.
Med Int (Lond). 2025 Apr 30;5(4):38. doi: 10.3892/mi.2025.237. eCollection 2025 Jul-Aug.
The present study aimed to investigate the association of physical activity and with or without regular exercise habits with lower limb muscle thickness, intramuscular adipose tissue (IntraMAT) and muscle strength in healthy young collegiate women, focusing on muscle thickness and IntraMAT using ultrasound tomography. The study participants included 20 healthy young collegiate women (age, 20.7±1.0 years). Physical activity was measured using a uniaxial accelerometer, and lower limb muscle thickness and IntraMAT were measured using ultrasound tomography. Muscle strength was measured as the maximum voluntary contraction force during isometric knee extension. The present study examined the association of physical activity with lower limb muscle thickness, IntraMAT and muscle strength, depending on whether the participants followed an exercise habit or not. Single correlation analysis revealed no significant correlation between the physical activity level and muscle thickness or muscle strength in all the participants. However, in the participants without regular exercise habits, the number of step counts and physical activity levels, particularly the time spent performing moderate- to vigorous-intensity activity, were positively associated with vastus lateralis muscle thickness (P=0.018 and P=0.048), and tended to have higher echo intensity of rectus femoris (P=0.056). These results suggest that a reduction in the time spent performing moderate- to vigorous-intensity physical activity may affect lower limb muscle thickness in healthy young collegiate women without regular exercise habits. In addition, the results suggest that a lack of exercise habits may influence the increase in IntraMAT in healthy young collegiate women.
本研究旨在调查健康年轻女大学生的身体活动以及有无规律运动习惯与下肢肌肉厚度、肌内脂肪组织（IntraMAT）和肌肉力量之间的关联，重点是使用超声断层扫描来研究肌肉厚度和IntraMAT。研究参与者包括20名健康年轻女大学生（年龄20.7±1.0岁）。使用单轴加速度计测量身体活动，使用超声断层扫描测量下肢肌肉厚度和IntraMAT。肌肉力量通过等长伸膝时的最大自主收缩力来测量。本研究根据参与者是否有运动习惯，研究了身体活动与下肢肌肉厚度、IntraMAT和肌肉力量之间的关联。单因素相关分析显示，所有参与者的身体活动水平与肌肉厚度或肌肉力量之间均无显著相关性。然而，在没有规律运动习惯的参与者中，步数和身体活动水平，特别是进行中等到高强度活动的时间，与股外侧肌厚度呈正相关（P=0.018和P=0.048），股直肌的回声强度也有升高趋势（P=0.056）。这些结果表明，在没有规律运动习惯的健康年轻女大学生中，减少进行中等到高强度身体活动的时间可能会影响下肢肌肉厚度。此外，结果表明缺乏运动习惯可能会影响健康年轻女大学生IntraMAT的增加。
