Cyclists: adjusting saddle height and maintaining bone density
Two studies in the March issue of the Journal of Strength and Conditioning Research that may be of interest to cyclists:
First (and simplest), another study about cyclists and bone density. Lots of previous cross-sectional studies have found that cyclists seem to have lower bone density than non-athletes and people who do impact activities like running. This one, from UC San Diego, actually followed 19 male masters cyclists and 18 matched non-athletes for seven years. Sure enough, the cyclists started with lower bone density, and declined faster during the study. By the end of the study (when both groups had an average age of 57), 17 of the cyclists had osteopenia and six had more serious osteoporosis; in the control group, 11 had osteopenia and one had osteoporosis. The message: get some impact activity, do some strength training, and get your bone density checked periodically.
Second is a study about optimizing saddle height (using “saddle” rather than “seat” makes me snicker, but that’s what they use in the paper, so I’ll stick with it!) for both performance and injury prevention. Apparently there are two standard, well-studied approaches to setting saddle height. The Hamley method, based on research in the 1960s, recommends setting the distance between pedal and saddle as 109% of inseam, measured from ischium (hip bone) to floor. That’s based on optimizing performance. The Holmes method, on the other hand, suggests setting knee angle at the bottom of the stroke to between 25 and 35 degrees to avoid injury.
A useful aside in the paper, derived from the Holmes research: pain in the front of the knee usually means the saddle is too high low, pain in the back of the knee means it’s too low high. [Update March 6: Thanks to commenter Phil for catching the fact that the journal article had it backwards!]
Anyway, the problem is that these two methods don’t always coincide, mainly because people have very different ratios of upper leg to lower leg length. In this study, setting the seat at 109% of inseam led to knee angles ranging from 19 to 44 degrees, and only three of the 11 subjects (who were well-trained cyclists) fell into the 25-35 degree injury reduction zone. So which is best?
The researchers looked at anaerobic power (30 second sprints) and economy (15-minutes at 70% VO2max) for three different settings: 109% inseam, 25 degree knee angle, and 35 degree knee angle. Surprisingly, the 25 degree knee outperformed 35 degrees AND 109%, particularly for economy. These results in well-trained cyclists echoed earlier studies by the same group in casual cyclists. So they conclude that 25 degree knee angle is the best way to set saddle height, since it’s within the “minimize injury” range and also appears to optimize performance. Obviously if you’re a Tour de France racer, you’re going to optimize bike position in a much more sophisticated way, but this seems like a useful rule of thumb for the rest of us.