Tilp Markus, Mosser Nina, Schappacher-Tilp Gudrun, Kruse Annika, Birnbaumer Philipp, Tschakert Gerhard
Institute of Human Movement Science, Sport and Health, University of Graz, Graz, Austria.
Institute of Electronic Engineering, FH JOANNEUM, University of Applied Science, Graz, Austria.
Front Physiol. 2025 Feb 24;16:1465344. doi: 10.3389/fphys.2025.1465344. eCollection 2025.
There is a well-established relationship between the respiratory compensation point (RCP) and local muscular breakpoints determined from near-infrared spectroscopy (NIRS) and electromyography (EMG). However, these breakpoints have not yet been compared both in locomotor and non-locomotor muscles simultaneously in single-leg cycling exercise. Therefore, the aim of the study was to investigate the relationship and agreement between systemic and local breakpoints in locomotor and non-locomotor muscles.
Data from twelve physically-active participants (25.5 ± 3.9 years, 176.1 ± 11.6 cm, 71.2 ± 9.4 kg, 4 females) who completed a continuous single-leg step incremental cycling test (10 W min) with their right leg were included in the analysis. Ventilation and gas exchange were recorded to determine RCP. Surface EMG (sEMG) and NIRS signals were measured from both vasti lateralis muscles and breakpoints were determined from root mean Q square sEMG and deoxygenated hemo- and myoglobin signal m[HHb].
There was no significant difference in the power output at RCP (127.3 ± 21.8 W) and local muscular breakpoints both from the locomotor (m[HHb]: 119.7 ± 23.6 W, sEMG: 126.6 ± 26.0 W) and non-locomotor (m[HHb]: 117.5 ± 17.9 W, sEMG: 126.1 ± 28.4 W) muscles. Breakpoints also showed significant (p < 0.01) correlations (r = 0.67-0.90, ICC = 0.80-0.94) to each other with weaker correlations in the non-locomotor muscle (r = 0.66-0.86, ICC = 0.74-0.90). Despite the strong correlations, high individual variability and weak limits of agreement (up to -32.5-46.5 W) and substantial absolute differences (10.2-16.7 W) were observed which indicates that these breakpoints cannot be used interchangeably.
These findings offer further insights into the mechanistic relationship between local and systemic physiological response to exercise with increasing workload. We conclude that, despite strong correlations, local muscular breakpoints do not have to coincide with systemic boundaries of physiological domains.
呼吸补偿点（RCP）与通过近红外光谱（NIRS）和肌电图（EMG）确定的局部肌肉断点之间存在着既定的关系。然而，在单腿骑行运动中，尚未同时对运动肌和非运动肌的这些断点进行比较。因此，本研究的目的是探讨运动肌和非运动肌中全身断点与局部断点之间的关系和一致性。
分析纳入了12名身体活跃的参与者（年龄25.5±3.9岁，身高176.1±11.6厘米，体重71.2±9.4千克，4名女性）的数据，他们用右腿完成了连续的单腿逐步递增骑行测试（每分钟10瓦）。记录通气和气体交换以确定RCP。从双侧股外侧肌测量表面肌电图（sEMG）和NIRS信号，并根据均方根sEMG以及脱氧血红蛋白和肌红蛋白信号m[HHb]确定断点。
RCP时的功率输出（127.3±21.8瓦）与运动肌（m[HHb]：119.7±23.6瓦，sEMG：126.6±26.0瓦）和非运动肌（m[HHb]：117.5±17.9瓦，sEMG：126.1±28.4瓦）的局部肌肉断点之间无显著差异。断点之间也显示出显著（p<0.01）的相关性（r = 0.67 - 0.90，组内相关系数ICC = 0.80 - 0.94），非运动肌中的相关性较弱（r = 0.66 - 0.86，ICC = 0.74 - 0.90）。尽管相关性很强，但观察到个体差异很大，一致性界限较窄（高达-32.5 - 46.5瓦）且绝对差异较大（10.2 - 16.7瓦），这表明这些断点不能互换使用。
这些发现为随着工作量增加，局部和全身对运动的生理反应之间的机制关系提供了进一步的见解。我们得出结论，尽管相关性很强，但局部肌肉断点不一定与生理领域的全身界限一致。
