ORIGINAL ARTICLE   

Gazzetta Medica Italiana - Archivio per le Scienze Mediche 2022 November;181(11):833-40

DOI: 10.23736/S0393-3660.22.04780-5

Copyright © 2022 EDIZIONI MINERVA MEDICA

language: English

Relationship between sweat lactate secretion rate and blood lactate concentration during exercise near the lactate threshold

Takashi YAMAGATA ^{1, 2} ✉, Yasushi SHIGEMORI ³

¹ Department of Clothing, Japan Women’s University, Tokyo, Japan; ² Department of Health and Sports Science, Kawasaki University of Medical Welfare, Okayama, Japan; ³ Aisin Cosmos R&D Co. Ltd., Aichi, Japan

BACKGROUND: Wearable devices to monitor health are increasing in popularity, but metabolic parameters are not established. Blood lactate measurement helps to monitor exercise intensity for safety and effectiveness of exercise training. While sweat lactate is one potential substrate for monitoring exercise intensity instead of blood lactate measurement, whether sweat lactate may correlate with blood lactate concentration during exercise remains unclear. We aimed to assess whether secreted sweat lactate correlate with blood lactate level changes during rest and exercise at intensities near the lactate threshold.
METHODS: Nine young men performed 10 minutes of constant-load exercise at 85, 100, and 115% of the lactate threshold (in a randomized order) following 30 minutes of passive heating for measuring resting sweat in 25 °C and 63% relative humidity. Using an absorptive patch, sweat was collected from the forehead, and the lactate levels were measured. Blood lactate levels and sweat rate were assessed.
RESULTS: Blood lactate levels were significantly higher at 115% of lactate threshold than that at 85%. Sweat lactate secretion was not significantly different at rest, 85%, or 100% of the lactate threshold; however, it was significantly higher at 115% than at rest. During exercise, the blood lactate concentration positively correlated with sweat lactate secretion rate (r=0.63, P<0.05) with no differences in sweat rate among the three exercises.
CONCLUSIONS: Forehead sweat lactate secretion rate may provide useful noninvasive biomarker for monitoring exercise intensity near the lactate threshold.

KEY WORDS: Anaerobic threshold; Forehead; Lactic acid; Sweat