I wouldn't worry about muscle loss... if your protein intake is high enough and of course getting your good fats in and running gear (not sure if your natural or not), the whole overtraining thing i think is bullshit. Prepping for nationals I averaged 2-3 hours a day, sometimes going 10-15 days straight training doing giant sets and up to 3 hours of cardio per day everyday, sleeping less than 4 hours a night, working (as a personal trainer conveniently enough) 14-16 hours 6x per week AND eating roughly 1000 calories in the final weeks and I have never been so ripped and full in my life. Basically if you have all your ducks in a row, keep training as intensly as possible on your working sets. If you feel an injury coming on, maybe its time to pick a different variation of the exercises your doing, sometimes thats all it takes to get things going again. I know I get bored with my routines very often and like to change them up and even make new exercises. I don't think theres a whole lot you can do wrong. In my experience, the body can take a shit load of a beating on very minimal fuel and you will be ripped to shit. keep atter dude, take the extra time between sets if you need it. unless you're doing timed sets dont worry. I use the rule of thumb for breaks: whenever my breathing comes back to normal i start my next set. (taken from Craig Bonnett)