YMCA Boot Camp Shirt

My wife & I are doing Boot Camp at the local YMCA near our jobs. The workouts are freakin' unreal, it makes me hurt everywhere just thinking about it. This was the shirt design I can up with. No color yet, thought I would ask for suggestions?? The big piece will cover the full back and the smaller piece will be right under the neckline on the front. The shirts are Steel Grey and they are being printed dye-sub. Thoughts, suggestions, critiques, and any feedback welcome as always! Thx y'all!!