The Effect of a KN95 Mask on High-Intensity Interval Training Performance, Physiological Response, and Perception.

The purpose of this study was to assess the effect of a KN95 mask on the performance, physiological response, and perception of high-intensity interval training (HIIT). Twenty college-aged participants (Male: 10, Female: 10) completed a two-visit, crossover, counterbalanced study. The HIIT workout included four 1-minute "all-out" intervals at 3.5% of body mass with 4-minute rest intervals, performed with or without a KN95 mask. Following HIIT, participants remained on the cycle ergometer for a 15-minute recovery period. For each interval, peak power and average power were recorded. Throughout the HIIT workout and recovery, heart rate, blood lactate, muscle oxygenation, perceived exertion, and perceived recovery were measured. All data were assessed using trial×time ANOVAs with post hoc pairwise comparisons. Alpha level was set to p<0.05. All data are presented as mean±standard deviation. No significant interactions were noted for peak power (p=0.432), average power (p=0.674), blood lactate (p=0.533), perceived exertion (p=0.221), perceived recovery (p=0.333), or muscle oxygenation (p=0.991). A significant main effect of trial was noted for heart rate during recovery, with higher heart rate during the masked trial compared to control. A KN95 mask did not affect performance, physiological response, or perception during HIIT, though it led to elevated heart rate during recovery. These results suggest KN95 masks may not impair HIIT performance but can influence short-term post-exercise heart rate recovery.