Influence of deception of task duration on the sex-specific physiological responses to RPE-clamp cycle ergometry

Purpose: The purpose of this study was to examine the sex-specific influence of expected exercise duration on the physiological responses to RPE-clamp exercise anchored to RPE 15 with participants being deceived into believing the RPE-clamp exercise would last for 20-, 30-, or 40-min, but all trials were 30-min.

Methods: Twelve males and 12 females completed a graded exercise test followed by randomly ordered RPE-clamp trials at RPE15 on the Borg 6-20 scale where subjects were deceived into expecting exercise to last for either 20-, 30-, or 40-min, but the actual duration for each trial was 30-min. Separate 2 (Sex [Male vs. Female]) × 3 (Deception [20-min, 30-min, 40-min]) × 11 (Time [0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 min]) mixed model analyses of variance (ANOVAs) with appropriate follow-up ANOVAs, and Bonferroni-corrected pairwise comparisons, were used to examine changes in volume of oxygen uptake ( $\dot{V}{O}_2$ ), heart rate (HR), respiration rate (RR), power output, and muscle oxygen saturation (%SmO₂).

Results: Females, but not males, demonstrated lower power outputs when expected duration was 40-min compared to 20-min after approximately half of the exercise bout. $\dot{V}{O}_2$ , regardless of Sex, was also lower when expected duration was 40-min (62.47 ± 5.59% $\dot{V}{O}_{2max}$ ) compared to 20-min (66.35 ± 5.79% $\dot{V}{O}_{2max}$ ). There was no effect of expected duration on HR, RR, or %SmO₂, but females demonstrated significantly higher HR (86.06 ± 5.93%HR_max) and RR (74.81 ± 7.26%RR_max) compared to males (79.52 ± 4.96%HR_max; 62.31 ± 5.80%RR_max).

Conclusions: RPE-clamp exercise performance in females, but not males, may be influenced by the expectation of exercise duration.