Reps

A rep is a single execution of one exercise. if you do a set of 10 bicep curls consecutively, that's 10 reps. During your first week or two, keep the weights very light so that you can complete about 15 reps in good form. This is a change for you to practice good form while you work on your neuromuscular coordination and lean the proper 'feel' for the movement. Developing that feel with become even more critical later on because it will tell you if an exercise is working.

After that initial break-in period, to build size and strength you want to do 8-12 reps per set (after your warm-up set of 15 reps, which you should do at the start of each exercise). Use a weight that allows you to do the recommended number of reps and still reach muscle failure.

Muscle failure means that you cannot do any more reps with good form. If you can't do eight strict reps, the weight's too heavy. If you can do more than 12, the weight's too light. Adjust the weight for your next set. (Note: The numbers eight and twelve are not arbitrarily derived. Exercise scientists have conducted numerous tests and have found that working with a weight about 70% of your one-rep maximum produces the fastest results. Most bodybuilders can lift about 70% of their one-repetition maximum 8-12 times).

Though you don't have to train to muscle failure to grow, you need to come pretty close. Bodybuilders call this intensity. How do you know if you're close to working at 100% intensity? Simple: If you can do another rep with good form, do it! If you can do still another, do it.

After you build you base, you may want to experiment with a program that alternates periods of high reps (which build muscle endurance) to medium reps (builds muscle mass) with low reps (builds strength and power) and back up again. This is called cycling. The idea here is to progress to a higher level of strength each cycle. (Note: Advanced strength athletes like powerlifters use slightly different training methods, most notably the number of reps, that do bodybuilders. You'll get stronger as you build muscle, but training to maximuse strength isn't identical to the type of training that maximizes mass.)