There are many factors that impact how much your muscles grow with weight training.

Is it Better to Do Short Reps or Long Ones?

by Brandi Junious

You want to get in shape, look great and stay healthy. You've also been told to lift weights to achieve this, and you should. But you may be afraid that strength training will leave you looking too bulky. This can be a common concern begging the question-- which is better, short reps or long reps? There are myths surrounding which method leaves you lean and which creates more bulk. However, knowing your goals and understanding how each type of rep affects your you muscles can help you decide which strength-training strategy is best for you.

The Myth

It is often believed that lifting light weights with short, fast reps leads to more lean, toned muscles, while lifting heavier weights with fewer, long reps will cause your muscles to bulk up. However, this commonly held belief is turning out to be not so true. According to the American Council on Exercise, you can get similar results whether you are lifting light weights at high reps or heavy weights at low reps. In fact, women can choose either strength training method without worrying about their muscles getting too big, since they generally do not have the high testosterone levels needed to get bulky, according to exercise physiologist Dr. Jason Karp. Muscle strength and growth doesn't depend on the number of reps or weight used, but instead relies on doing each set of training until your muscles are fatigued, he notes.

Lift to Failure

Women are able to lift different amounts of weight based on their present physical strength and body size. Therefore, it is more important to build a strength training routine around muscle fatigue or failure rather than a specific weight amount and number of reps. Your muscles can't get stronger or gain endurance unless you exercise them anaerobically. This means that you must choose a weight amount and number of reps that brings you to muscle fatigue or failure within 90 seconds. For women, this usually doesn't require a very heavy amount of weight and can be achieved with both short and long reps.

Short vs. Long Reps

While the maximum size your muscles can reach may rely on factors like testosterone and body type, the kind of training you do can affect your muscle strength, definition and endurance. Fast, short reps are power-oriented and build strength. They utilize fast twitch muscle fibers, which are primarily responsible for muscle size or definition. Slow, long reps take longer to complete, and primarily work the slow twitch muscle fibers that build endurance. Your goals should dictate which type of training you do; however, recommends doing a combination of the two to help develop both strength and endurance for a well-rounded workout.


You should always consult your doctor before starting any new exercise or strength-training routine to make sure you are healthy enough for the type of exercise you choose. Always use a spotter when weightlifting, especially when you are lifting heavier weights or attempting to increase the amount you normally lift. Use proper form when lifting weights and understand how to use all exercise equipment correctly before you begin. Stretch thoroughly before and after your workouts to prevent injury and reduce muscle soreness.

About the Author

Based in the Los Angeles area, Brandi Junious specializes in health-related articles. Her writing reflects her expertise in fitness and education. Junious is the author of children's book "A World Without Trees" and her work has appeared on Modern Mom, The Nest Woman, Chron Healthy Living and at Junious holds a bachelor's degree in psychology from the University of Southern California and a master's degree in Education.

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