The effect of acute fatigue on somatosensory function differs between trained and untrained individuals

This study aims to investigate the changes in somatosensory function and the differences in upper and lower extremities before and after acute fatigue, as well as during the 10-minute recovery period, through incremental load testing in different populations. A total of 22 trained male participants (TG, n = 22, age: 23.5 ± 2.2 years; height: 177.8 ± 5.8 cm; weight: 77.5 ± 8.0 kg) and 19 untrained male individuals (NTG, n = 19, age: 23.2 ± 2.3 years; height: 178.9 ± 5.9 cm; weight: 78.7 ± 10.9 kg) were assessed at various time points during the incremental load testing (Pre vs. Post vs. 10 min) using two-point discrimination threshold tests on the index finger and thigh, as well as knee joint position sense testing. There were no significant differences (p > 0.05) in joint position sense between groups, whereas significant differences (p < 0.05) in two-point discrimination thresholds in the lower limbs were observed. Significant differences (p < 0.05) were observed between groups in the two-point discrimination thresholds in the right upper limb, while no significant differences (p > 0.05) were found in the left upper limb. The stability of the two-point discrimination threshold in the lower limbs of participants in the training and non-training groups exhibited significant correlations (p < 0.05) with their VO2max, carbon dioxide production (VCO2), MET, energy consumption, and duration. The training and non-training groups demonstrated significant differences (p < 0.05) in two-point discrimination thresholds and joint position sense at different time points (Pre vs. Post vs. 10 min). This study employed an incremental load fatigue paradigm with a 10-minute recovery observation window and introduced two-point discrimination stability as an exploratory variable. The findings indicate that somatosensory responses to acute fatigue differ between trained and untrained individuals, and aerobic power capacity represents an important associated factor.