The relationship between climatic condition, sex, and degree of slowing in the marathon

Abstract

Purpose: Degree of slowing over the course of a marathon may be affected by a number of variables, including sex and climatic conditions. Differences in substrate metabolism, thermoregulation, and pacing strategy may exist between sexes, and contribute to differences in the degree of slowing. The purpose of this study was to examine the degree of slowing (first vs. second half time in a marathon) between sexes and environmental conditions (warm vs. cold weather) and to determine if respiratory exchange ratio (RER) during a submaximal steady state run in a laboratory was associated with degree of slowing in the marathon. Methods: Degree of slowing was assessed in 167 recreational runners (123 females and 44 males). Anthropometric measures were taken and a submaximal 6-minute treadmill run was completed before the marathon to measure RER. Effective temperature during the marathon was calculated for two different years (2014, cool weather vs. 2015, warm weather). Results: Degree of slowing differed between cool (14.1 ± 12.0%) and warm weather (22.0 ± 16.5%; P < 0.05) and between males and females (20.6 ± 14.8% vs. 17.0 ± 14.8%, P < 0.05). Females had a lower RER (0.87 ± 0.05 vs. 0.89 ± 0.05, P < 0.05). Both sex (P = 0.001) and weather (P = 0.034) significantly affected degree of slowing, but there was no interaction between sex and weather (P = 0.756). There was no relationship between degree of slowing and RER or anthropometric measures, with the exception of height in the whole population (P = 0.023) and in women (P = 0.017). Conclusion: Males slow more than females during the marathon, and warm weather leads to greater degree of slowing in both. The difference in pacing between males and females during a marathon can't be explained by differences in RER or thermoregulation in warm conditions.