Muscle oxygenation in vastus lateralis and gastrocnemius during incremental running exercise: effect of exercise intensity, VO2max, sex and age

Introduction. The aim of this study was to describe the effect of exercise intensity, maximum oxygen utilisation (V ̇O_2MAX), sex and age on vastus lateralis (VL) and gastrocnemius (Gn) muscle oxygenation measured using near-infrared spectroscopy (NIRS) during incremental running exercise to exhaustion, in a participant group having a large range of V ̇O_2MAX.Methods. Systemic cardiorespiratory responses (V ̇O_2, ventilatory thresholds), and variables of muscle oxygenation (Δ[HHb], Δ[O2Hb], ΔTSI) at VL and Gn muscles were collected continuously in thirty-six participants (11 women, 25 men; age: 34.110.7 yr; height: 1.750.1 m; weight: 70.216.6 kg; weekly training: 591374 min;) during an incremental running test (V ̇O_2MAX=52.511.9 mL·min-1·kg-1). Breakpoint analyses were used to compare systemic cardiorespiratory responses and patterns of muscle oxygenation. The effect of exercise intensity, V ̇O_2MAX, sex and age on Δ[HHb], Δ[O2Hb] and ΔTSI at VL and Gn were determined at 10% increments from 50% to 100% of V ̇O_2MAX.Results. The only predictor of V ̇O_2MAX was Δ[HHb] at VL, and gas exchange thresholds and muscle oxygenation breakpoints were not significantly correlated. There were no effects of V ̇O_2MAX or sex on the dynamics of muscle oxygenation. The effect of exercise intensity was significant for all variables at VL, and only for Δ[HHb] at Gn at 50% and 60% of V ̇O_2MAX. The magnitude of muscle oxygenation responses was significantly decreased in women compared to men, and there was no effect of age. Conclusion. Our results indicate that using NIRS oximetry, Δ[HHb] on vastus lateralis, but not gastrocnemius, is suitable to identify changes in exercise intensity and aerobic capacity in running, with a lower magnitude of response in women compared to men, and with no effect of age.<br>

引言：本研究旨在探讨运动强度、最大摄氧量（V̇O₂MAX）、性别与年龄对递增力竭性跑步过程中，股外侧肌（vastus lateralis, VL）与腓肠肌（gastrocnemius, Gn）的近红外光谱（near-infrared spectroscopy, NIRS）检测所得肌氧水平的影响，且研究对象的V̇O₂MAX跨度范围较大。
方法：本研究纳入36名受试者（女性11名，男性25名；年龄34.1±10.7岁；身高1.75±0.1m；体重70.2±16.6kg；周训练时长591±374min），在递增跑步测试（V̇O₂MAX=52.5±11.9 mL·min⁻¹·kg⁻¹）期间，连续采集全身心肺反应指标（V̇O₂、通气阈值）以及股外侧肌与腓肠肌的肌氧变量Δ[HHb]、Δ[O₂Hb]、ΔTSI。采用拐点分析法比较全身心肺反应与肌氧变化模式。以V̇O₂MAX的50%至100%为区间，按每10%的递增梯度，分析运动强度、V̇O₂MAX、性别与年龄对股外侧肌与腓肠肌的Δ[HHb]、Δ[O₂Hb]及ΔTSI的影响。
结果：本研究发现，仅股外侧肌的Δ[HHb]可作为V̇O₂MAX的预测指标，且气体交换阈值与肌氧拐点无显著相关性。V̇O₂MAX与性别均未对肌氧动力学产生显著影响。运动强度对股外侧肌的所有肌氧变量均存在显著影响，而仅在V̇O₂MAX的50%与60%负荷下，腓肠肌的Δ[HHb]受运动强度影响显著。女性受试者的肌氧反应幅度显著低于男性，而年龄未产生显著影响。
结论：本研究结果表明，采用近红外光谱血氧检测技术时，股外侧肌的Δ[HHb]而非腓肠肌的Δ[HHb]，可用于识别跑步运动中的运动强度与有氧能力变化，且女性的肌氧反应幅度显著低于男性，年龄无显著影响。