Age-related slowdown: run vs. bike vs. swim
A paper in last month’s International Journal of Sports Medicine takes a look at how much you slow down as you age, comparing the three triathlon disciplines. Researchers in France crunched data from the top ten finishers in each age group at the 2006 and 2007 world championships, for both Olympic-distance and Ironman triathlons. Since a picture is worth 1,000 words:
The top graph is for Olympic-distance, while the bottom graph is for Ironman. What sticks out is that cycling declines more slowly than running and swimming, and the researchers suggest a bunch of different explanations for this. One is that running and swimming rely more on fast-twitch muscle fibres, which atrophy more quickly than slow-twitch fibres. Another is simply that running is harder on the body, so older athletes have to spend less time running to avoid injuries, while cyclists are able to maintain higher training volumes as they age. There are also more subtle possibilities, such as the idea that identical declines in your power output would affect running more than cycling (since running speed is directly proportional to mechanical power, but cycling speed only proportional to the cube root of mechanical power).