These days lots of endurance athletes are supplementing their endurance training with CrossFit workouts, or are interested in doing so. Whenever one of these athletes comes to me for coaching, I try to talk him or her out of it. I do this not because I think CrossFit is intrinsically bad or because I believe that CrossFit negatively affects endurance performance. Rather, these persuasive efforts are based on the fact there are simply more effective ways for endurance athletes to strength train and cross-train.

It is an obvious point, but worth mentioning nevertheless, that CrossFit was not created to serve as supplemental training for endurance athletes. There is no reason, therefore, to expect CrossFit to do the job especially well. As a supplemental training modality for endurance athletes, CrossFit has several drawbacks:

First, CrossFit workouts are very intense. Endurance fitness and performance improve most when high-intensity work accounts for about 20 percent of total training time. Incorporating CrossFit into an endurance training program therefore reduces the amount of high-intensity training an athlete can do in his or her actual sport and increases the risk of overtraining. Traditional strength workouts that avoid sustained elevation of heart  rate do not compete against endurance training in this way.

Second, CrossFit workouts are highly taxing, generating significant levels of fatigue and muscle damage and thereby often compromising performance in subsequent endurance workouts.

Third, many of the strength exercises done in CrossFit workouts are not functionally specific to endurance sports. Handstand push-ups, for example, are a waste of time for cyclists and runners. Look at the physiques of top competitive CrossFitters. Do you want to haul around all that beef in your next race?

Fourth, CrossFit workouts do not include any of the corrective exercises that endurance athletes need to do in order to iron out muscle imbalances and strengthen important stabilizing muscles so they can swim, bike, and run more efficiently and with less risk of injury. Nobody wants to watch athletes do side planks on television, but no strength workout for endurance athletes is complete without such exercises.

Fifth and finally, many CrossFit workouts involve the use of rowing machines. Rowing is great exercise, but it doesn’t do much for most types of endurance athletes. Runners in particular who want to supplement their running with nonimpact endurance training are better off choosing an activity that is much more similar to running itself, such as outdoor elliptical biking.

There, I’ve said my piece.