Q: i run with a hundred pounds in my backpack everday then i do 15 decline and regular pushups with the weighted backpack on will this help build strenght and muscle in my legs and chest

A: That's a pretty hardcore routine! Yes, that certainly will get you pretty far as far as leg and chest muscle development. I do want to warn you that running with loose 100 pounds of weights in your backpack can lead to serious lower back injuries as well as knee and ankle problems. For that reason it certainly wouldn't be my first choice of exercise. Be on a lookout for lower back pain and do NOT try to exercise through it.

As an alternative to running you can do lunges with those same 100 pounds in your backpack. Check out my Exercises page to see about lunges and other leg exercises. You can do squats with the backpack as well. Both lunges and squats are very very effective strength builders, though they will not have quite the same endurance training effect you get with running. However if you keep up what you're doing now you're virtually certain to develop lower back problems, so I'd switch to lunges and squats for strength training and continue running without weights if you want to have good cardio endurance in addition to strength.