Effect of Menstrual Cycle on Perceived Exertion and Running Economy During Treadmill Running

Abstract

Running coaches often use ratings of perceived exertion (RPE) to communicate to athletes the level of intensity for a workout. The menstrual cycle is a factor for female athletes that may alter one's perception of RPE. PURPOSE: The purpose of this study was to investigate how the menstrual cycle affects RPE during treadmill running. A secondary purpose of this study was to explore how the menstrual cycle affects running economy (RE). More specifically, the two purposes of this study were to compare male and female RPE during a VO2max test and 80% sub maximal tests and to examine how the menstrual cycle affects female RPE and RE. METHODS: Ten experienced (average VO2max 59.8 ml·kg-1 · min-1) runners, (7 F, 3 M) participated in this IRB approved study. All participants were tested to determine their VO2max. Individual testing protocol was designed for 80% of maximum effort in which participants ran a series of 4 sub maximal runs on a treadmill over 4 weeks. Female participants charted their menstrual cycle, based on basal body temperature. RESULTS: A 2 (sex) x 4 (cycle) mixed ANOVA was performed to analyze the changes in performance during the 80% sub maximal running series. There was no significant main effect of basal body temperature between the days prior to menstrual cycle: F(4,24) =1.261, p = 0.313, partial h2 = 0.174. There was no significant main effect of respiratory exchange ratio (RER) on cycle: F(3,24) = 0.835, p = 0.488, partial h2 = 0.095. There was no significant main effect of RPE on cycle: F(3,24) = 2.746, p = 0.065, partial h2 = 0.256. There were no significant main effects of VO2 on cycle, F(3,24) = 1.243, p = 0.316, partial h2 = 0.135, or of RE on cycle, F(3,24) = 1.085, p = 0.374, partial h2 = 0.119. There was a significant main effect of gender on 80% of VO2max: F(1,8) = 23.466, p = 0.001, partial h2 = 0.746. CONCLUSIONS: All 7 female participants perceived working the hardest cycle week 1, (pre-menstrual phase). On average, men perceived working harder than females and were less variable then females during the 4 testing weeks. The mean average RER for women across the 4 weeks of testing was 0.983 while men averaged 0.972. The results suggest across the 4 cycle weeks, women were actually working slightly harder based on RER, however RPE data suggest they perceive to work slightly less. RPE and RE did not relate with the lowest RPE being the most economical for females. Interestingly, men displayed the lowest RPE averages during cycle week 2 and 3, at which point they were the most economical. The possibility of implementing an individualized training protocol based on the runner's menstrual cycle may lead to improvements that would not have been achieved without taking this into consideration.