Department of Physical Therapy, Showa University School of Nursing and Rehabilitation Sciences, 1865 Tokaichiba-cho, Midori-ku, Yokohama, Kanagawa, 226-8555, Japan.
Division of Health Science Education, Showa University School of Nursing and Rehabilitation Sciences, Yokohama, Japan.
Sci Rep. 2024 May 22;14(1):11676. doi: 10.1038/s41598-024-61529-x.
Peak oxygen uptake (VO), evaluated as exercise tolerance, is a strong predictor of life prognosis regardless of health condition. Several previous studies have reported that peak VO is higher in those with a greater decrease in muscle oxygen saturation (SmO) in the active muscles during incremental exercise. However, the skeletal muscle characteristics of individuals exhibiting a greater decrease in SmO during active muscle engagement in incremental exercise remain unclear. This study aimed to clarify the relationship among muscle strength, muscle endurance, and skeletal muscle oxygenation dynamics in active leg muscles during incremental exercise. Twenty-four healthy young men were included and categorized into the non-moderate-to-high muscular strength and endurance group (those with low leg muscle strength, endurance, or both; n = 11) and the moderate-to-high muscular strength and endurance group (those with both moderate-to-high leg muscle strength and endurance; n = 13). All participants underwent cardiopulmonary exercise testing combined with near-infrared spectroscopy to assess whole-body peak VO and the change in SmO at the lateral vastus lateralis from rest to each exercise stage as skeletal muscle oxygenation dynamics. A linear mixed-effects model, with the change in SmO from rest to each stage as the dependent variable, individual participants as random effects, and group and exercise load as fixed effects, revealed significant main effects for both group (P = 0.001) and exercise load (P < 0.001) as well as a significant interaction between the two factors (P < 0.001). Furthermore, multiple-comparison test results showed that the change in SmO from rest to 40%-100% peak VO was significantly higher in the moderate-to-high muscular strength and endurance group than in the non-moderate-to-high muscular strength and endurance group. Maintaining both muscle strength and endurance at moderate or higher levels contributes to high skeletal muscle oxygenation dynamics (i.e., greater decrease in SmO) during moderate- or high-intensity exercise.
峰值摄氧量（VO），作为运动耐力的评估指标，是预测生命预后的强有力指标，无论健康状况如何。几项先前的研究报告称，在递增运动中，主动肌的肌肉氧饱和度（SmO）下降较大的人群中，峰值 VO 较高。然而，在递增运动中主动肌参与时 SmO 下降较大的个体的骨骼肌特征尚不清楚。本研究旨在阐明递增运动中主动腿肌的肌肉力量、肌肉耐力和骨骼肌氧合动力学之间的关系。共纳入 24 名健康的年轻男性，分为非中高强度肌肉力量和耐力组（腿部肌肉力量、耐力或两者均较低；n = 11）和中高强度肌肉力量和耐力组（腿部肌肉力量和耐力均为中高强度；n = 13）。所有参与者均进行心肺运动测试并结合近红外光谱技术，以评估全身峰值 VO 和股外侧肌 SmO 从休息到每个运动阶段的变化，作为骨骼肌氧合动力学。以 SmO 从休息到每个阶段的变化为因变量，个体参与者为随机效应，组和运动负荷为固定效应的线性混合效应模型显示，组（P = 0.001）和运动负荷（P < 0.001）均有显著主效应，以及两个因素之间存在显著的交互作用（P < 0.001）。此外，多重比较检验结果表明，中高强度肌肉力量和耐力组从休息到 40%-100%峰值 VO 的 SmO 变化显著高于非中高强度肌肉力量和耐力组。在中高强度运动中，保持肌肉力量和耐力处于中等或较高水平有助于提高骨骼肌氧合动力学（即 SmO 下降幅度较大）。
