Fatigability and Recovery Differences Between the Sexes
by Doug Stewart
A lot of discussion exists around the performance differences between the sexes, and whether females are better suited for longer ultra-endurance exercise than men. Tiller et al., explored the question of whether sex differences confer an advantage for females, for example. A lot of research has studied the differences in fatiguability between the sexes, following a bout of long duration low-intensity exercise. However, a recently published paper explores these differences in fatigability and recovery from endurance exercise that follows a bout of higher-intensity running, in this case a 5km time trial.
16 recreationally active people took part in the study (8 female, 8 male, average age 23 years old). It involved running a 5km time trial on a treadmill, along with maximal strength tests (knee-extensor) prior to and after the time trial. During the treadmill run, heart rate was recorded, along with rate of perceived exertion, every kilometre.
Overall, the male participants ran the 5km 15% faster (around 29 minutes compared to around 35 minutes) than the female participants. Throughout the trial, HR rose each kilometre, as did the rating of perceived exertion, for both men and women.
On the baseline maximum strength test, the males produced a higher force than the female participants. In the strength test immediately following the 5km time trial, the percentage decrease in maximum strength was higher in the males – i.e., they lost more force than the females.
The participants completed 3 further strength tests at 10 minutes, 20 minutes and 30 minutes after the end of their 5km time trial. In the test 10 minutes following the time trial, the female participants again demonstrated significantly less of a drop in power versus the male participants. However, in the 20 minute and 30 minute post time trial tests, there was no significant difference in performance, versus baseline, between the sexes.
Below you can see the average decrease (and individual participant data) for the strength tests.
Source: Pons et al., 2023
Overall, the results suggest that the female participants experienced less fatigue and maintained a greater percentage of their maximal force up to 10 minutes after the time trial relative to males.
It is worth highlighting these are young recreationally active participants, so not athletes, and that only one measure of strength was assessed (a maximal force test of the knee extensor). Different tests, different levels of athletic ability, or different age groups may reveal different results. However, this experiment does suggest that there are differences between the sexes in response to a 5km time trial, supporting the research showing similar impacts in longer bouts of low-intensity running, and highlighting the importance of tailoring training to the individual and not using generic advice.
References:
Pons, M. S., Hunter, S. K., & Ansdell, P. (2023). Sex differences in fatigability and recovery following a 5 km running time trial in recreationally active adults. European Journal of Sport Science, 1-16.