Most people assume that men have more strength than women. It’s true that trained men can generally lift heavier weights than women, but women may have an advantage when it comes to muscular endurance. Women are able to sustain isometric contractions for a longer period of time than men at sub-maximal intensities, meaning their muscles are more resistant to fatigue. Tell that to the power-lifting men at the gym!
Muscle Endurance: Is There a Gender Difference?
A number of previous studies looking at muscle endurance show that women have greater muscle endurance and their muscles are more resistant to fatigue than men’s. This is true with muscle contractions of low to moderate intensity but not at higher intensities where greater force is generated. Why is there a difference in muscular endurance between the two sexes?
Some research suggests that women have better muscle blood flow during isometric contractions than men. Men are able to generate more maximal force, but this may come at a price in terms of muscle endurance. The higher force they generate when they contract their muscles and their larger muscle mass reduces the flow of blood and oxygen to the muscle. This causes the muscle to fatigue more rapidly.
There’s also some evidence suggesting that women have greater muscle endurance because they’re able to recruit a greater number of synergistic muscle fibers to reduce fatigue. Women are also better able to use aerobic pathways for generating energy, which is the primary pathway used during muscle endurance exercise. Different hormone balances between men and women may also explain why women have greater muscular endurance and less resistance to muscle fatigue.
Muscle Endurance vs. Muscle Strength
Muscle strength and endurance are two different entities. Muscle strength is the maximal force a muscle can develop. It involves generating a large amount of force over a short period of time. As such, it relies on the anaerobic energy system for fuel. When weightlifters in the gym train to build strength, they use heavy weights that they’re only able to lift a few times. Strength training targets the fast-twitch muscle fibers and usually leads to an increase in muscle size over time. Building muscle strength and mass is the goal of powerlifters.
Muscle endurance is the ability to lift a sub-maximal weight repeatedly or to hold a sub-maximal muscle contraction for a sustained period of time. It involves repetitive or sustained contraction of muscle fibers, which requires a steady, continuous supply of energy. This comes from the aerobic energy system and primarily involves the slow-twitch muscle fibers.
Endurance training uses less resistance, but the resistance is sustained or repeated for long periods of time. Muscles adapt by becoming more efficient at using the aerobic system for generating energy so that the muscle can contract for a longer period of time. Training with lighter weights usually doesn’t cause a significant increase in muscle size.
Men have an advantage when it comes to muscle strength. The average man can generate a greater maximal force than a woman’s, but at sub-maximal loads, their muscles fatigue faster. So, trained men can lift heavier weights than women, but women excel from an endurance standpoint since their muscles are more resistant to fatigue. The good news is both men and women can develop their muscle strength and endurance through training.
Idea Fitness. “Fatigue Resistance: An Intriguing Difference in Gender”
Muscle and Strength Magazine. “Understanding Muscular Fitness”
Exercise and Sport Science Reviews. 29(3), 109-12.