The age and sex distribution of the 190 runners consistently within the 25th and above the 75th percentile each year was similar to that of Figure 1, with 23 female runners and 167 male runners.
Examining the graph above, I would think that men responded more positively than women. But to see that they both responded similarly is interesting.
The time of day also influences endurance performance [Citation6Hobson RM, Clapp EL, Watson P, et al. Exercise capacity in the heat is greater in the morning than in the evening in man. Med Sci Sports Exerc. 2009;41(1):174–180. [Crossref], [PubMed], [Web of Science ®], [Google Scholar],Citation24Bessot N, Nicolas A, Moussay S, et al. The effect of pedal rate and time of day on the time to exhaustion from high‐intensity exercise. Chronobiol Int. 2006;23(5):1009–1024. [Taylor & Francis Online], [Web of Science ®], [Google Scholar]], with previous literature on the topic reporting conflicting results. Hobson et al. [Citation6Hobson RM, Clapp EL, Watson P, et al. Exercise capacity in the heat is greater in the morning than in the evening in man. Med Sci Sports Exerc. 2009;41(1):174–180. [Crossref], [PubMed], [Web of Science ®], [Google Scholar]] demonstrated in a laboratory setting that endurance performance in warm conditions was superior in the morning than the evening, while other laboratory studies conducted in cool conditions reported that endurance performance was better in the evening than the morning [Citation24Bessot N, Nicolas A, Moussay S, et al. The effect of pedal rate and time of day on the time to exhaustion from high‐intensity exercise. Chronobiol Int. 2006;23(5):1009–1024. [Taylor & Francis Online], [Web of Science ®], [Google Scholar],Citation25Reilly T, Baxter C. Influence of time of day on reactions to cycling at a fixed high intensity. Br J Sports Med. 1983;17(2):128–130. [Crossref], [PubMed], [Google Scholar]] or were the same for both the morning and evening
The laboratory settings can be controlled and it is different than the field study. The field study (done in the natural world) can be controlled, but not in the way the laboratory settings can be controlled. So, this might affect the results.
dry bulb temperature (Tdb) and wet bulb temperature (Twb)
Dry bulb temperature: Temperature measured by regular thermometers. Wet bulb temperature: Temperature measured by regular thermometers wrapped in wet wicks.
Source: United Metal Products
As absolute humidity is often the main factor that influences marathon performance [Citation30Brotherhood JR. Heat stress and strain in exercise and sport. J Sci Med Sport. 2008;11(1):6–19. [Crossref], [PubMed], [Web of Science ®], [Google Scholar],Citation31Brocherie F, Girard O, Pezzoli A, et al. Outdoor exercise performance in ambient heat: time to overcome challenging factors? Int J Hyperthermia. 2014;30(8):547–549. [Taylor & Francis Online], [Web of Science ®], [Google Scholar]], mean values of absolute humidity experienced by each runner were also calculated to better elucidate the environmental parameters’ influence on marathon performance.
It is interesting to know how humidity can have an effect on marathon performance. After doing some research, I found out that when we run, our body produces sweat to reduce the core temperature of our body. Through evaporation, our body cools off by releasing heat energy. But when the humidity is high, evaporation gets affected (it lessens), resulting in the heat energy not being released from our body. This leads to dehydration, fatigue, and more. Thus affecting the marathon performance.