I have always incorporated distance running into my training, especially in the off-season, but recently someone told me that extensive aerobic exercise like distance running can slow down your reactions, which is not exactly a good thing if you’re a keeper. I know that sprinters refrain from doing long aerobic exercise, as it slows their sprinting time. Do you know if there is any concrete evidence to support this claim?
There has been research done and the basic principle is that goalkeeping is a fast twitch position and to reinforce that with fast twitch training. Longer, aerobic workouts can be construed as reinforcing medium twitch training and probably isn’t considered as productive as sprint and explosive exercises. Having said all that, I don’t think there’s anything wrong with keepers doing aerobic workouts. I actually encourage our keepers to do it. You need to balance distance work with sprints, but as long as they are done with moderation, I don’t see a problem.
If you’re looking for scientific reference, check sports medicine/training books/journals. My reference is the US Olympic Committee Strength and Condition Director.