Eh i don't know much about it, but i went to boxing 2-3 years ago and got told when you do exercises, you injure your muscles. When you get proteins they build up faster and gets stronger/bigger, so it might be best to exercise Monday-Wednesday-Friday and put a day or two more in when you've done it for a really long time. But hell i dunno it might not be true it's just what i've heard..