Need some information

I’m posting this on behalf of one of my friends who also happens to be a coach. His players have on Tuesday and Thursday mornings a speed training class. He’s looking for some “scientific explanation” on why his pitchers should not do it on the day they pitch. I know it just makes sense not to, because of energy spent, but he likes physical evidence in hand. Any help would be great, thanks!

Depleting glycogen stores…may not be a problem if there is enough time between the session and the game (assuming the player is getting enough food in their body). There is also muscle breakdown with any physical exertion which takes time to repair…this breakdown won’t be as significant as it would for a hard lifting session, but the legs won’t be as fresh as they would be otherwise. Will it negatively effect the pitchers? Maybe, slightly, maybe not at all…but why not just do your 15-20 minutes of speed work after the game?