Eserhaut Drake A, DeLeo Joseph M, Provost Jessica A, Ackerman Kathryn E, Fry Andrew C
Jayhawk Athletic Performance Laboratory - Wu Tsai Human Performance Alliance, University of Kansas, Lawrence, KS, United States.
Female Athlete Program - Wu Tsai Human Performance Alliance, Boston Children's Hospital, Boston, MA, United States.
Front Physiol. 2025 Feb 17;16:1538465. doi: 10.3389/fphys.2025.1538465. eCollection 2025.
The purpose of this study was to analyze changes in skeletal muscle oxygen saturation (SmO) kinetics during exercise in female rowers both acutely and longitudinally in relation to blood lactate (BLa). We also aimed to determine the agreement and statistical equivalence between physiological thresholds derived from SmO and BLa kinetics.
Twenty-three female NCAA Division I rowers were tested throughout the 2023-2024 academic year. Of these, 11 athletes completed at least two near-infrared spectroscopy (NIRS)-equipped GXTs, with physiological data analyzed for longitudinal changes. A 7x4-min discontinuous GXT protocol was performed by all athletes. First and second SmO breakpoints (SmOBP1 and SmOBP2) were estimated via piecewise linear regression modeling, and BLa thresholds (LT and LT) were calculated using ADAPT software. Paired-samples t-tests assessed differences, and equivalence was tested using two one-sided tests (TOST). Agreement was determined using Bland-Altman analysis yielding mean differences (MD) and 95% limits of agreement (LoA). Intraclass correlation coefficients (ICC) were also calculated.
No difference was found between SmOBP2 and LT (MD = -5.76W [95% LoA = -38.52 to 22.25W], p = 0.134), moderate-to-good levels of agreement (ICC = 0.67 [95% CI: 0.36-0.85], p < 0.001), and no statistical equivalence (p = 0.117). This was not the case for SmOBP1 and LT, with NIRS significantly underestimating LT (MD = -8.14W [95% LoA = -38.90 to 27.37W], p = 0.026), poor-to-moderate agreement (ICC = 0.24 [95% CI: -0.13-0.58], p = 0.10), and no statistical equivalence (p = 0.487). Additionally, SmO recovery kinetics (SmOresat) during 1-min rest intervals increased in response to graded increases in exercise intensity (p < 0.001, η = 0.71), with higher intensities appearing to blunt this effect (step 6 - step 7: MD = -0.16%⋅s, p = 0.69). No statistically significant changes were observed in LT's or SmOBP's throughout the 2023-2024 season.
In female collegiate rowers, NIRS may be a tool that compliments BLa testing when determining the second lactate threshold (i.e., LT). However, significant inter-individual variablility exists between SmOBP2 and LT2 paired with a lack of statistical equivalence suggest the two are not interchangeable. While not a standalone replacement, if used in combination with traditional BLa testing methods NIRS may be a complimentary tool that helps inform individual athlete training zone prescription.
本研究旨在分析女子赛艇运动员运动期间骨骼肌氧饱和度（SmO）动力学的急性和纵向变化，并将其与血乳酸（BLa）进行关联分析。我们还旨在确定从SmO和BLa动力学得出的生理阈值之间的一致性和统计等效性。
23名美国国家大学体育协会（NCAA）一级女子赛艇运动员在2023 - 2024学年接受了测试。其中，11名运动员完成了至少两次配备近红外光谱（NIRS）的递增负荷运动试验（GXT），并对生理数据进行纵向变化分析。所有运动员均执行了7×4分钟的间断性GXT方案。通过分段线性回归模型估算第一和第二SmO断点（SmOBP1和SmOBP2），并使用ADAPT软件计算BLa阈值（LT和LT）。配对样本t检验评估差异，并使用双侧单侧检验（TOST）检验等效性。使用Bland - Altman分析确定一致性，得出平均差异（MD）和95%一致性界限（LoA）。还计算了组内相关系数（ICC）。
SmOBP2与LT之间未发现差异（MD = -5.76W [95% LoA = -38.52至22.25W]，p = 0.134），一致性水平为中度至良好（ICC = 0.67 [95% CI：0.36 - 0.85]，p < 0.001），且无统计等效性（p = 0.117）。SmOBP!和LT的情况并非如此，NIRS显著低估了LT（MD = -8.14W [95% LoA = -38.90至27.37W]，p = 0.026），一致性为差至中度（ICC = 0.24 [95% CI： - 0.13 - 0.58]，p = 0.10），且无统计等效性（p = 0.487）。此外，在1分钟休息间隔期间，SmO恢复动力学（SmOresat）随着运动强度的分级增加而增加（p < 0.001，η = 0.71），较高强度似乎会减弱这种效应（第6步 - 第7步：MD = -0.16%·s，p = 0.69）。在整个2023 - 2024赛季中，LT或SmOBP未观察到统计学上的显著变化。
在女子大学赛艇运动员中，NIRS可能是在确定第二个乳酸阈值（即LT）时补充BLa测试的一种工具。然而，SmOBP2和LT2之间存在显著的个体间变异性，且缺乏统计等效性，这表明两者不可互换。虽然不是独立的替代方法，但如果与传统的BLa测试方法结合使用，NIRS可能是一种辅助工具，有助于为个体运动员的训练区域处方提供信息。
