The Coach Curtis Harwell Discusses More Fitness and Bodybuilding Myths

You should only rest 45 seconds in between sets

That's true if you're trying to improve cardiovascular health or lose some bodyfat. But in order to build muscle, you need to allow enough time for the muscle to recuperate fully (i.e. let the lactic acid buildup in your muscles dissipate and ATP levels build back up). In order to make muscles grow, you have to lift the heaviest weight possible, thereby allowing the maximum number of muscle fibers to be recruited.

If the amount of weight you lift is being limited by the amount of lactic acid left over from the previous set, you're only testing your ability to battle the effects of lactic acid. In other words, you're trying to swim across a pool while wearing concrete overshoes. When training heavy, take [at least!] two and three minutes between your sets. Notice I said, "when training heavy." The truth is, you can't train heavy all the time. Periodization calls for cycling heavy workouts with less intense training sessions in an effort to keep the body from becoming overtrained.