Older Runners vs Older Sprinters

As mentioned before, body fat levels are the same for sprinters/runners from a competitive distance of 100 meters up to 10,000 meters.  Yet looking at the physiques of sprinters versus distance runners, you do see one main difference: muscle mass.  Sprinters are generally more muscular, and as distances increase you generally see the amount of muscle mass decline.  This makes sense, as more muscle is needed to produce speed for short sprints, and less muscle mass(but more muscle endurance) is needed for the slower speeds of distance running.

I thought it would be interesting to find out if this relationship of distance versus muscle mass held up through the aging process.  Using two separate papers (one and two), I was able to compare older endurance runners versus older sprinters.

I chose to compare the body composition for the 60-69 age range.  Here is the comparison:

	Height(cm)	Weight(kg)	Body Fat (%)
Sprinters	172.7	71.2	13.6
Endurance Runners	171	66.7	14

Body fat levels between the two groups are similar, but you can see the big difference is in total weight.  Sprinters weigh about 10 pounds more than the endurance runners.  Given the similar levels of body fat, you have to conclude that this difference is primarily muscle mass.

There could be some self-selection here, with individuals who are naturally more muscular choosing sprinting instead of distance running.  There's no way to tell for sure with these studies since they are cross-sectional analyses.  But my bet is that sprint training leads to increased muscle mass and maintenance of this muscle mass across the lifespan.