I was fortunate to be in Les Gets, France in 2019 to watch the UCI MTB World Cup races. It was very interesting to contrast the men’s and women’s body types. The women are all very slight and quite short. I happened to stand next to Yolanda Neff in line for the restroom and she is tiny. On the other hand the men are all fairly tall and pretty built, including upper body.
As a short MTB master racer this got me thinking. Why do top UCI MTB men and women seem to have such different builds? The World Cup courses feature lots of steep climbs, so I can see why being small with a large watts/kg ratio would be an advantage. But the men are pretty big (by professional cyclist standards.) Are they just that much more powerful?
I’m not sure about the women but for the men, i don’t think it’s that they are that much more powerful (i.e. to get same w/kg) but they accept a lower w/kg because of differently valued tradeoffs vs. roadies. Specifically that the physical demands of MTB weigh in favor of a relatively stronger and more durable upper body even at the expense of w/kg, all else equal. So a bigger dude with lower w/kg can still be successful.
@EG1, welcome to the community! That must have been so exciting to watch the Les Gets race in person!
It does seem that we see the need for additional upper body durability as @BikerBocker said reflected in the data. There is an interesting 2018 study that highlighted differences among Olympic and World Champion XCO racers compared to their non-champion counterparts. These champions showed overall greater weight and upper arm muscle area, among other parameters. This would highlight the need for upper body durability.
A few other anthropometric averages from other studies on female off-road cyclists:
Wilbur et al. - including world champions
162cm // 57.5kg
Stapelfeldt et al. - national team level
169cm // 63kg
Impellizzeri & Marcora - national and international level
167cm // 52.5kg (+/- 3kg)
In terms of being more “powerful,” then we have to account at least partly for men having more lean tissue than women. A 2007 study showed that some of those differences in peak power between males and females could be accounted for by lower leg volume in females, and another study suggested that the rate of lower limb fat accumulation was greater in females than in males during puberty (males actually saw increased lean tissue, while females experienced an increase in lower-limb fat relative to muscle). There have been other suggested factors as well, relating to metabolic and hormonal changes that could potentially influence peak power production.
Sánchez-Muñoz C, Muros JJ, Zabala M. World and Olympic mountain bike champions’ anthropometry, body composition and somatotype. J Sports Med Phys Fitness. 2018 Jun;58(6):843-851. doi: 10.23736/S0022-4707.17.07179-1. Epub 2017 Apr 28. PMID: 28462576.
Doré E, Martin R, Ratel S, Duché P, Bedu M, Van Praagh E. Gender differences in peak muscle performance during growth. Int J Sports Med. 2005 May;26(4):274-80. doi: 10.1055/s-2004-821001. PMID: 15795811.
Perez-Gomez J, Rodriguez GV, Ara I, Olmedillas H, Chavarren J, González-Henriquez JJ, Dorado C, Calbet JA. Role of muscle mass on sprint performance: gender differences? Eur J Appl Physiol. 2008 Apr;102(6):685-94. doi: 10.1007/s00421-007-0648-8. Epub 2007 Dec 15. PMID: 18084774.
Impellizzeri FM, Marcora SM. The physiology of mountain biking. Sports Med. 2007;37(1):59-71. doi: 10.2165/00007256-200737010-00005. PMID: 17190536.