An expert answers frequently asked questions to start your clients on the right track.
Weight training is an extremely beneficial form of exercise but can be confusing if you’ve never done it. Jason R. Karp, MS, PhD student, college lecturer and track and field coach, answers frequently asked questions to start you on the right track. (Ask a personal trainer to set up a program specifically for you.)
You may have heard that you shouldn’t lift weights on consecutive days, but there really is nothing wrong with lifting weights every day. Some experts just recommend that, to give your muscles time to adapt, you not work the same muscle groups 2 days in a row.
Whether or not you need to lift weights every day depends on your fitness goals. For basic strength gains, you need to lift weights only two or three times per week. If you are a more advanced weight trainer, lifting weights more often is fine; you can even organize your training program into “easy” days and “hard” days.
Whether or not your muscles become bigger (hypertrophy) depends on three basic factors: genetics, gender and training intensity.
The genetic influence on muscle size is mostly a matter of your predominant type of muscle fiber. The muscles of people with predominantly fast-twitch muscle fibers hypertrophy more easily than the muscles of people with predominantly slow-twitch muscle fibers.
In terms of gender, men have greater amounts of testosterone and other hormones that influence protein metabolism than women. Therefore, men experience more muscle hypertrophy with strength improvement.
Training intensity is the only factor you can control. Generally, if you want bigger muscles, the load you lift should weigh at least 80 percent of the greatest amount of weight that you can lift at any one time (called a one-repetition maximum, or 1 RM). If you do not want bigger muscles, keep your load below 80 percent of your 1 RM.
Free weights (dumbbells and barbells) keep the resistance on a muscle constant throughout a joint’s range of motion (ROM); weight machines vary the resistance on the muscle throughout the joint’s ROM. A joint’s ROM contains points where a muscle is stronger and points where it is weaker, and a muscle’s weakest point limits the amount of weight the muscle can lift. Therefore, the constant resistance of free weights is a strong enough training stimulus only for the weakest joint positions. In contrast, weight machines place more stress on muscles at the angles at which the muscles can produce greater force, providing optimal resistance at every point in the entire ROM.
Of course, most weight machines allow movement in only one plane. Free weights allow movement in all three planes. With weight machines, only the major muscles required to perform a movement are used, whereas the added “burden” of balancing free weights in three planes at once forces recruitment of other functional muscles.
If you are new to weight lifting, you should probably use weight machines first to train the major muscles and use free weights later to train more specific movements.