Validation of aerobic threshold assessment using a sweat lactate sensor during arm crank exercise by healthy adults

Assessment of the aerobic threshold (AeT) using a sweat lactate sensor has been validated primarily during lower limb exercise. This study aimed to examine whether sweat-based AeT assessment is also applicable during upper limb exercise. In this cross-sectional study, 27 healthy young individuals performed an incremental arm crank ergometer test while sweat lactate levels were continuously monitored using a wearable sensor attached to the forehead. Expired gas variables, sweat rate, and heart rate were simultaneously recorded. Correlation analyses were conducted between the lactate threshold in sweat (sLT) and the ventilatory threshold (VT1). Sweating was observed in all participants, and the sLT was successfully identified using the sensor. Strong correlations were observed between sLT and VT1 (workload: r = 0.904, exercise time: r = 0.859, both p < 0.01). Furthermore, no significant differences were observed between the heart rates at sLT and VT1. These findings demonstrate that sLT corresponds closely with VT1 during arm crank exercise, supporting the robustness of sweat-based AeT assessment across different exercise modalities.