Kinetic changes in sweat lactate following fatigue during constant workload exercise

• Published in: Physiological reports Vol. 10; no. 2; pp. e15169 - n/a
• Main Authors: Okawara, Hiroki, Sawada, Tomonori, Nakashima, Daisuke, Maeda, Yuta, Minoji, Shunsuke, Morisue, Takashi, Katsumata, Yoshinori, Matsumoto, Morio, Nakamura, Masaya, Nagura, Takeo
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.01.2022; John Wiley and Sons Inc; Wiley
• Subjects: Adult; Athletes; Body composition; COVID-19; Cross-Sectional Studies; Ethics; Exercise Test; Fatigue; Humans; Lactic Acid; Male; Medical research; Original; Physiology; Sensors; sports; Sports facilities; Sweat; sweating; Workload; Workloads; Young Adult; lactic acid; physiology; fatigue; sports; sweating
• ISSN: 2051-817X
• DOI: 10.14814/phy2.15169

It is useful to investigate various physiological responses induced by fatigue in athletes. Moreover, wearable noninvasive sensors, including sweat sensors, are compatible with fatigue evaluation because of their ease of use, and ability to measure repeatedly and continual data. This cross‐sectional study aimed to clarify how sweat lactate elimination curves obtained during constant workload exercise changed following fatigue. Seventeen recreationally trained males (average age, 20.6 ± 0.8 years) completed two consecutive constant workload exercise tests (at 25% peak power) with rest intervals; the participants were encouraged to perform Test 1 until exhaustion and Test 2 only for 10 min. Subjective fatigue (numerical rating scale with face rating scale), sweat lactate, and sweat rate were measured for 10 min in each test. Subjective fatigue was compared using the Wilcoxon signed‐rank test and time to each constant value between Tests 1 and 2 was compared using paired t‐test. Subjective fatigue significantly increased during Test 2 compared with that during Test 1. After Test 1, the sweat lactate elimination curve demonstrated a leftward shift, as proved by the significantly sooner observation of the peak and constant values of sweat lactate (2, 3, and 4 μA) (p < 0.01). Our preliminary results suggest that the sweat lactate elimination curve is different in the fatigue state. Further research may provide insight in the application of this curve to the evaluation for fatigue. Graphical To evaluate the changes in sLA after fatigue using a wearable sLA sensor, comparing the sweat lactate elimination curve during constant workload exercise between in fatigued state and notfatigued in twenty healthy recreationally trained males was performed. As a results, a leftward shifted curve was detected, which suggest the possibility of taking insight in the application of this curve to the evaluation for fatigue by further research.