Both men and women have incredible potential when it comes to increasing their strength, hypertrophy, and power through resistance training. Over the last few decades, multiple studies have explored the potential differences that play roles in how the sexes adapt to certain forms of resistance training.
With a meta-analysis reciente, the authors looked at multiple studies comparing men and women and how they respond to resistance training from a strength and hypertrophy standpoint. It is well known that there are differences such as hormone levels, lean body mass, and muscle mass between the sexes, but how exactly do they influence training responses?
In the study, the authors analyzed and compared three key areas of performance, including: hypertrophy, upper body strength, and lower body strength. It is worth noting that most of the research included in this meta-analysis was on untrained individuals and resistance training variables varied slightly between different studies.
In regards to hypertrophy, the authors reviewed 10 different studies that met their criteria and suggested that hypertrophy adaptations were similar between the sexes within the research they reviewed.
Regarding lower body strength, 23 studies were considered and, like hypertrophy, both sexes responded similarly with respect to overall gains based on the strength markers used in the research. Although the gains in lower body strength are similar, upper body strength varied to a greater degree within the 17 included studies and greater increases were observed in women.
Factors to consider
Research to date has been light on comparing the sexes and some of the deeper physiological differences that might be at play with regard to how men and women respond to different forms of resistance training.
The above results are interesting, however it is worth remembering that a large number of the study populations tested were untrained. Considering this might suggest why untrained women saw greater increases in upper body strength. If this form of training was a novel stimulus and there was no previous exposure to upper body strength training, either through work, sport or lifestyle, then it makes sense that their upper bodies respond more quickly than men.
Neuromuscular considerations
At meta-analysis, the authors note that little is yet known about potential neuromuscular differences that might be at play between how different sexes adapt to various forms of training.
However, it is suggested that men have the potential to fatigue faster due to heavy training compared to women, but the exact reason why is still unclear. Also, men generally have a fitness ceiling larger than females, which might explain why females adapt more quickly to certain forms of novel stimuli (novice gains).
Muscle mass and hormonal issues
Between the sexes, men generally have higher lean body mass and total muscle mass compared to women, while women have higher percentages of body fat. Apart from these differences, the authors point out that one explanation between the discrepancies in the way in which the sexes respond to the different forms of training could be due to the differences in the muscle phenotype of each sex.
Essentially, the varied responses to resistance training could be due to how the muscle fiber composition varies between the sexes. Despite some studies suggesting that women have higher percentages of Type I fibers in the vastus lateralis and biceps brachii, which could be data used to suggest best training practices, there is still insufficient research on this topic to draw any conclusions.
When dealing with hormonal differences, men generally have higher androgen levels than women, which might suggest why women experience less change in muscle size with hypertrophy-oriented training. The authors also note that although men generally see greater increases in absolute hypertrophy and strength than women, the relative increase between the sexes is similar over time.
Another hormonal factor that was discussed is the differences that women may experience during their menstrual cycle. Research is still relatively light on the exact mechanisms that might be at play with regard to strength and hypertrophy adaptations during various parts of the cycle, but there are some suggestions as to where growth and fatigue most occur.
The authors also made reference to the fact that when it comes to muscular fatigue, the sex differences depend on the task being performed. However, it has been suggested that women experience less muscle fatigue when performing isolated contractions.