Understanding Fatigability: Why Women Generally Outperform Men in the Gym
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Chapter 1: Introduction to Sex Differences in Gym Fatigability
Did you know that women tend to experience less fatigue during workouts compared to men? This is a fascinating fact that many in the fitness community often discuss.
In the realm of strength training, it is widely recognized that female athletes can maintain their performance with shorter rest periods between sets and can execute more repetitions at a similar intensity than their male counterparts. As a coach, I've observed this phenomenon repeatedly; female clients typically require less downtime and thrive on shorter breaks during their workouts.
For clarity, I will use "female" and "male" throughout this discussion, as these terms are prevalent in current research. However, it's essential to recognize that findings may differ when considering transgender and non-binary individuals, though research in this area is still developing.
Scientific studies consistently reveal that women are less prone to fatigue, and a pivotal study conducted in 2019 shed light on the underlying cause: blood flow.
Section 1.1: Insights from Research on Fatigability
In a study by Ansdell et al., researchers examined the differences in fatigability through low-intensity isometric knee extensions. While these specific exercises may not be commonplace in most gym routines, the findings were significant.
The results indicated that female lifters outperformed their male peers by approximately 10% in terms of the weight lifted over time. Additionally, women could sustain muscle contractions during the isometric exercises for more than double the duration of their male counterparts.
The research involved nine female and nine male participants, which might seem limited, but small sample sizes are typical for detailed experimental research. The study aimed to determine each participant's critical intensity—the maximum workload they could maintain throughout the day—and how quickly they would fatigue.
Over seven lab sessions, participants became accustomed to the testing equipment and procedures. The initial visit assessed baseline neuromuscular function, including maximal voluntary contraction (MVC).
Section 1.2: Key Findings from the Study
To equalize the fatigue levels between genders, female participants had to exert themselves at a higher intensity. The findings suggested that women demonstrated greater strength endurance at intensities ranging from 40% to 80% MVC.
To illustrate, during the highest intensity tested, males averaged a time to task failure of 217 seconds at 61% MVC, while females were close behind with an average of 216 seconds at 71% MVC.
During the supramaximal trial (critical intensity + 10%), female participants exhibited a time to task failure that was more than double that of the males.
This study not only confirmed the existing observations regarding fatigability differences between genders but also highlighted variations in blood flow during both submaximal and supramaximal trials. During the supramaximal test, levels of oxygenated hemoglobin in the quadriceps decreased for male participants, while it increased for females. Conversely, the increase in deoxygenated hemoglobin was much more pronounced in males.
Main Takeaways
The primary conclusion is that females generally exhibit lower levels of fatigue than males, driven largely by differences in blood flow and oxygen delivery. Women appear to excel at directing blood and oxygen to the necessary areas during exercise.
This ability may relate to differences in muscle fiber composition and body size. Typically, women are smaller, which shortens the distance that oxygen must travel to reach working muscles. Previous research has indicated that the disparity in fatigability is more significant when males are stronger than females; however, when matched for strength, the differences diminish.
It's also worth noting that female athletes with greater size and strength may require longer rest periods than those who are smaller and less powerful. Additionally, females tend to possess a higher proportion of Type I muscle fibers, which contributes to their superior performance in endurance activities.
Caveat: Beyond Sex Differences
While biological sex influences fatigability, it is not the sole determining factor. Individual characteristics such as size, strength, training history, and workout intensity all play crucial roles in how exhausting a workout may be for each person.
The first video titled "Sex Differences in Neuromuscular Fatigue and Performance: Why Does it Matter?" by Prof. Hunter delves into the implications of these differences in greater detail.
The second video, "Sex differences in the physiology of exercise: An integrative perspective," provides a comprehensive overview of how these physiological differences manifest in various exercise contexts.
Pennie Varvarides is an inclusive strength and flexibility coach who helps clients over 30 develop functional movement. Follow Pennie on Instagram or TikTok @superpennie for more insights.