My weights workouts last up to two hours. Is that too long?
Michael Latimer, by email

Jason Anderson replies: Enthusiasm is to be applauded but two hours is far too long to be working out. After 40 minutes of intense activity, levels of cortisol (the body’s destructive catabolic hormone) increase and you start to burn muscle instead of building it. Also, the body’s ability to produce force becomes limited by neurological and muscular fatigue. From a neurological perspective the ability of your nervous system to control your body decreases, which could lead to a nasty injury. From a muscular perspective, on the other hand, your ability to lift enough weight to stimulate muscle growth decreases, which means you’re wasting your time. Limit your workout to 40 minutes of intense muscle-building exercise and you’ll get better results, faster.