Cayot Trent E, Robinson Shara G, Davis Lindsay E, Bender Paul A, Thistlethwaite John R, Broeder Craig E, Lauver Jakob D
Department of Kinesiology, Health, and Sport Sciences, University of Indianapolis, Indianapolis, IN, USA.
Division of Mathematics, Computer, and Natural Sciences, Ohio Dominican University, Columbus, OH, USA.
Int J Exerc Sci. 2021 Apr 1;14(4):284-294. doi: 10.70252/HBRA1900. eCollection 2021.
The present investigation examined the ability of two threshold detection analyses (maximum distance, Dmax; modified maximum distance, mDmax) in identifying the near-infrared spectroscopy (NIRS) threshold, a lactate threshold (LT) estimate, from exercising tissue oxygen saturation (StO) responses. Additionally, the test-retest reliability of exercising StO and total hemoglobin concentration (THC) responses were examined at moderate and peak cycling intensities. Fourteen healthy, recreationally active participants performed maximal incremental step cycling tests (+25 W / 3 minutes) to volitional fatigue on two separate occasions while StO and THC of the vastus lateralis were monitored. Exercising blood [lactate] was collected during Session One. LT and NIRS thresholds (NIRS1, NIRS2) were then determined using Dmax and mDmax threshold analyses. Significant ( < 0.05), moderate correlations were detected between LT and NIRS1 when using Dmax (LT = 130 ± 49 W, NIRS1 = 136 ± 34 W, = 0.690), but not for mDmax (r = 0.487). No significant test-retest reliability for the NIRS thresholds were observed for Dmax (ICC = 0.351) or mDmax (ICC = 0.385). Exercising StO responses demonstrated good reliability (ICC = 0.841-0.873) while exercising THC responses demonstrated moderate-good reliability (ICC = 0.720-0.873) at moderate and peak exercise intensities. The results of this study suggest that neither the Dmax nor mDmax threshold analyses should be used to estimate the LT due to the unreliable detection of the NIRS threshold from session to session.
本研究考察了两种阈值检测分析方法（最大距离，Dmax；改良最大距离，mDmax）从运动组织氧饱和度（StO）反应中识别近红外光谱（NIRS）阈值（一种乳酸阈值（LT）估计值）的能力。此外，还在中等和峰值骑行强度下检验了运动时StO和总血红蛋白浓度（THC）反应的重测信度。14名健康的、有休闲运动习惯的参与者在两个不同的时间进行了最大递增阶梯式骑行测试（+25W/3分钟）直至自愿疲劳，同时监测股外侧肌的StO和THC。在第一次测试期间采集运动时的血乳酸。然后使用Dmax和mDmax阈值分析确定LT和NIRS阈值（NIRS1、NIRS2）。使用Dmax时，LT与NIRS1之间检测到显著（<0.05）中度相关性（LT = 130±49W，NIRS1 = 136±34W，r = 0.690），但mDmax未检测到（r = 0.487）。对于Dmax（ICC = 0.351）或mDmax（ICC = 0.385），未观察到NIRS阈值有显著的重测信度。在中等和峰值运动强度下，运动时的StO反应显示出良好的信度（ICC = 0.841 - 0.873），而运动时的THC反应显示出中等 - 良好的信度（ICC = 0.720 - 0.873）。本研究结果表明，由于不同测试间NIRS阈值检测不可靠，Dmax和mDmax阈值分析均不应被用于估计LT。
