Last week I posted a picture of the Dutch BMX cycling team doing box squats. I was asked at that time to comment on the exercise. In the spirit of Eric Carr’s suggestion I will always head these observations as Exercise Comments. Also recognize that this is my opinion based on my experience and research where available.
I assume the rationale for using the box squat with this group of athletes was to work on basic strength in the acceleration phase of the start. The BMX rider must go from a dead stop up to top speed in a very short period of time. There is fairly high resistance during this time, hence the assumption that this would be more concentric strength dominant. All of that being said I would not use the box squat for this. I think traditional squatting starting with bodyweight moving across a spectrum to heavy external resistance would be more appropriate. When they could handle 5 to 6 sets of 4 reps with a relatively heavy load then I would introduce six second isometric hold squats (holding at bottom position) and exploding out. Following that I would progress to squat jump with no counter movement with about 50% of body weight for three to four sets of six. The last step in the progression would be de loading squats with a heavy sandbag. Sandbag on the lowering and drop off on the jump.
Personally I have never used box squats because I have always felt that there are better ways to accomplish the objective of what box squats are supposed to do. In my opinion the loading on the spine when on the box is not worth the risk. I know this is a very popular exercise in certain schools of training, but I think there are better ways to achieve starting strength.