The CrossFit Endurance prescription calls for more intensity and less weekly mileage for runners. At first, this may seem to be more appropriate for younger athletes, but a current research indicates that runners are more prone to unfavorable body composition changes as they get older. The paper concludes that active individuals must therefore increase their training mileage as they get older. ). Among the runners who maintained their activity levels as they got older, it was calculated that avoiding unfavorable body composition changes would necessitate the men would annually boosting their training distance by 4.5km per week and women by 6.2 km (there’s wiggle room here) to maintain a constant body weight and favorable body composition.
Here’s how BMI and waist circumference looks when plotted against age, for the average runner in this survey:
Not too pretty. However, it’s shocking to read the scientists who performed this study suggesting that the answer is an increase in training mileage. If gaining muscle and losing fat are part of our long-term plans, this isn’t a game we can realistically win, because our training mileage can’t go upwards forever. Plot these numbers over a decade or two and it becomes fairly obvious that simply increasing the distance is a very bad idea.
Conversely, the CrossFit Endurance model tells us that intensity can (and should) get higher as weekly mileage gets lower, and a conjugate system of weight training and assistance will do far more than simply adding laps around your town. This has obvious implications for the runner who wants to continue being competitive (or even smashing records) in their later years, but also for anyone programming for a masters athlete or even the local soccer mom at your box. Why? Because you can not continuously increase the mileage on your clients or athletes forever – because they’ll either get hurt or get rid of you.
Here’s a copy of the full study, if you’re interested in reading it, and this is the abstract: