How much weight should one lift?
For weight loss, science has found that lifting between 60-80 percent of one’s rep max is the best way to stimulate muscle growth, which is what helps one lose fat. (In weight training, “one rep max” is the maximum amount of weight one can lift in a single repetition for a given exercise). Here’s more from about.com.
The problem is that most people don’t think much about how much weight they need, much less go through the process of figuring out one rep max for every exercise they’re doing. In fact, many gymgoers lift the same weights week after week, which is just one way to keep their bodies from changing.
So how does one figure out how much to lift if he doesn’t know his one rep max? Typically, if he lifts 60-80 percent of max, he could do anywhere from 10-20 reps. Lifting at 80 percent and above takes him down to the lower rep range, which is where he’ll be if he’s trying to gain size. That means keeping his reps somewhere between eight to 16, if he’s lifting for weight loss and fitness. The weights are determined by the number of reps a person is doing.
For a beginner, he should choose a weight he can only lift 16 times. He doesn’t need to go to complete failure, but make sure he’s challenging his body.
Let him begin with one set of each exercise, slowly working his way up to two-three sets (i.e., adding a set each week). When he’s added sets and has a solid foundation (after six-eight weeks), let him add more weight so that he can only do eight to 12 reps.
Continue to progress by letting him add a rep each week until he reaches the max reps (no more than 16). Increase the weight and let him drop his reps back down to eight to 12.
The important thing to remember when it comes to strength training is that a person must give his muscle more weight than it can handle—that’s how muscles grow. The challenge of lifting heavy is just as much a mental game as it is a physical one and, if a person hasn’t pushed his body’s limits in a while, just the act of lifting weights may be all he can handle. If he’s consistent with a basic program and is building a solid foundation of strength, he’ll be ready for the next step—lifting heavy and pushing his muscles to their limits. A person will be amazed at the changes in his body.