Say you train your entire body on Monday. Should you do it again on Tuesday, or wait until Wednesday? The answer is that your body requires a minimum of 48 hours to fully recover after exercise, sometimes even longer. Physiological processes at the cellular level require rest and nutrients before you can train that same muscle group again. A good rule of thumb: If you're even slightly sore, you're not ready to train that bodypart again. If you're an advanced bodybuilder and split up your workout into, for example, one day for upper body and another for lower body, you can train on consecutive days as long as you don't repeat the same workout. As a beginner, you don't want to go more than 96 hours (four days) without training the same muscle group again. Timing too infrequently results in submaximal gains. The answer for the beginner, then, is to train every 2-3 days (or three times a week). A Monday - Wednesday - Friday (or similar) schedule is ideal.
