Annoyingly, I will never be able to out-lift my boyfriend. And it’s not through lack of trying.
Women and men take part in separate events in almost every competitive sport. And rightly so; we are built very differently - men are typically bigger, faster and stronger than women, so it wouldn’t be a fair contest if this was not acknowledged. But does this mean that women and men should therefore train differently? Or should everybody with the same fitness goal train in exactly the same way, regardless of sex?
This is a much-debated topic in the fitness industry, and I think one of the reasons it is so controversial is because we actually don’t have that much evidence when it comes to women and exercise. Women are severely underrepresented in the sports science research; according to a review of 5,261 sports and exercise science research studies, 66% of participants were male and 34% were female. Even more worryingly, just 6% of studies looked specifically at females, whereas almost five times as many studies (31%) focused exclusively on males (Cowley et al., 2021). So before we even begin to answer this question, it’s clear that we need more female-specific sports science research to better understand how women respond to training. But until then, what do we already know about the physiological responses to exercise in women versus men?
Men can build more muscle
Let’s start with a basic fact about human biology: men and women have different hormonal profiles. The most noteworthy difference here is that men have approximately 15 times more testosterone than women (Handelsman et al., 2018). Not only does testosterone influence the development of male sex organs, it is also responsible for increased muscle and bone mass. This makes building muscle FAR easier for men than for women. Even if a woman and a man exercised and ate in exactly the same way, the man would build more muscle because of the difference in their testosterone levels. To illustrate this, one study found that after a six month strength training intervention men built approximately twice as much muscle as women (Ivey et al., 2000). Given the importance of muscle mass and bone density for health, particularly as we age, I would argue that this difference alone makes resistance training even more essential for women than men, because it’s harder for women to build muscle.
Men have stronger upper bodies
In addition to the hormonal differences between women and men, there are also striking anatomical differences. Women have around 52% less muscle mass in their upper bodies than men (Miller et al., 1993). Women also carry a higher proportion of their weight on their lower bodies, and tend to have a higher body fat percentage – this is an evolved characteristic necessary for childbearing. These sex differences in muscle distribution mean that men have a natural strength advantage when it comes to upper body exercises such as pull ups, press ups and bench pressing. Given these differences, I would typically expect men to perform more advanced versions of upper body exercises (e.g. unassisted pull ups, full press ups, heavier bench pressing) than I would expect of women.
Women can handle more volume and less rest
Research suggests that women can handle more volume and require shorter rest periods than men. There are a few reasons for this; the female sex hormone oestrogen, the greater distribution of type 1 (slow-twitch) muscle fibres and a typically higher body fat percentage all favour higher rep ranges, less rest and more exercises within a session. Men on the other hand are better suited to more explosive efforts, and typically require longer rest periods than women as a result of their testosterone, increased type 2 (fast-twitch) muscle fibres and lower body fat percentages.
I would caveat this by saying that I think it’s important for women and men to incorporate high and low rep ranges into their training because there are physiological benefits to both, however I would bear in mind these natural sex differences and take advantage of somebody’s natural strengths in order to optimise their training.
Men have a higher aerobic capacity
We know that men tend to outperform women at aerobic capacity work, as measured by VO2 max (maximal oxygen uptake). The reason for this relates to another anatomical difference between men and women - men have naturally larger airways, lungs and hearts (LoMauro & Aliverti, 2018), so blood and oxygen can be transported around the body more efficiently during maximum exertion. On average, a woman’s VO2 max is 70-75% that of a man’s of the same age (Kenney et al., 2012), although this will of course vary depending on training history. Given this difference, I would expect men to favour more high-intensity aerobic training (e.g. sprinting, tempo running etc.), whereas women would probably favour more lower intensity aerobic work (e.g. longer, slower efforts). That being said, it is important to work on ones’ weaknesses, so the opposite type of training shouldn’t necessarily be avoided!
Women have more hormonal fluctuations
Lastly but perhaps most importantly, we must remember that women have a more variable hormonal profile than men due to their menstrual cycle. Women also experience life changes characterised by fluctuating hormone levels such as pregnancy and the menopause. Since hormones have a dramatic effect on energy levels and strength, women generally experience far greater variation in these factors on a daily, weekly and monthly basis than men, who typically have a more steady release of hormones. In my experience as a woman working with women I know that hormones are one of the most crucial factors to consider in a woman’s training programme. During certain times of the month women often feel low in energy whereas other times they feel upbeat and strong. There has been some interesting research in this area looking at specifically which types of exercise are most suited to which phase of the menstrual cycle (McNulty et al., 2020). It is critical to take these hormonal fluctuations into account when training a woman of any age, and be aware that last-minute adjustments to a session may need to be made depending on which phase a woman is at in her cycle, and crucially, how she is feeling that day.
My final thoughts
We can’t deny that there are enormous hormonal and anatomical differences between men and women, so just like you wouldn’t expect both sexes to eat in exactly the same way it seems unreasonable to expect them to train in exactly the same ways. The differences needn’t be huge, and I’m definitely not saying women should train with pink 1kg dumbbells and men with 40kg dumbbells, however there should be some subtle differences in exercise selection, rep range, training frequency and recovery. Ultimately, we need more research to be carried out on women who exercise to better understand how our bodies respond to different training stimuli. But until then we must use the limited knowledge we’ve got and make appropriate allowances for sex differences in exercise.
References
Cowley, E., Olenick, A., Mcnulty, K. & Ross, E. (2021). “Invisible sportswomen”: The sex data gap in sport and exercise science research. Women in Sport and Physical Activity Journal, 29, 1-6. 10.1123/wspaj.2021-0028.
Handelsman, D. J., Hirschberg, A. L., & Bermon, S. (2018). Circulating testosterone as the hormonal basis of sex differences in athletic performance. Endocrine Reviews, 39(5), 803–829. https://doi.org/10.1210/er.2018-00020
Ivey, F.M., Roth, S.M., Ferrell, R.E., Tracy, B.L., Lemmer, J.T., Hurlbut, D.E., Martel, G.F., Siegel, E.L., Fozard, J.L., Jeffrey Metter E., Fleg, J.L., & Hurley, B.F. (2000). Effects of age, gender, and myostatin genotype on the hypertrophic response to heavy resistance strength training. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 55(11). M641-8. doi: 10.1093/gerona/55.11.m641. PMID: 11078093.
Kenney, W.L., Wilmore, J.H., & Costill, D.L. (2012). Physiology of sport and exercise (5th ed). Champaign.
LoMauro, A., & Aliverti, A. (2018). Sex differences in respiratory function. Breathe, 14(2), 131–140. https://doi.org/10.1183/20734735.000318#
McNulty, K.L., Elliott-Sale, K.J., Dolan, E. et al. (2020). The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis. Sports Medicine, 50, 1813–1827. https://doi.org/10.1007/s40279-020-01319-3
Miller, A.E., MacDougall, J.D., Tarnopolsky, M.A., & Sale, D.G. (1993). Gender differences in strength and muscle fiber characteristics. European Journal of Applied Physiology and Occupational Physiology. 66(3), 254-62. doi: 10.1007/BF00235103. PMID: 8477683.