Why Do High Repetitions Cause Muscle Definition?

Young woman training in the gym

A high number of reps and sets are often reflective of a strength training workout that’s designed to develop muscle size and definition. Building definition requires that your muscles handle a significant amount of workload, which in turn will stimulate the muscle-building process. After you’ve completed a high-repetition workout, give your muscles 48 to 72 hours of recovery time or you’ll limit your size increases.

Building Muscle Size

When your muscles get bigger and build definition, it’s due to your individual muscle fibers increasing in size. The fibers increase in size when they’re forced to handle workloads that they’re not normally used to. A larger workload causes the fibers to become overloaded and damaged, which in turn activates satellite cells, which are designed to help repair and build muscle tissue. In addition, your immune system is stimulated and begins the process of muscle healing.

The Right Reps

A high number of reps helps to provide enough of a workload to overload your muscles. Helen M. Binkley of the National Strength and Conditioning Association notes that six to 12 reps is adequate for stimulating muscle growth, while strength and conditioning specialist Lee E. Brown says sets for muscle-building can include up to 20 reps. Both professionals suggest at least three sets of each exercise.

Weight’s Impact

The number of reps alone isn’t the only component to an effective muscle-building workout. If you were to do 20 reps of every exercise with a weight that’s too light, you won’t adequately overload your tissues. Joseph A. Chromiak of the National Strength and Conditioning Association stresses the importance of completing each set to near failure or failure. This means you shouldn’t be able to complete more than 20 reps with the weight you’re using. If you can, it’s time to select a heavier weight.

Changing It Up

To keep your muscles from hitting a plateau, you should routinely change up the number of reps you’re performing of each exercise. You can follow a classic, linear periodization workout program, which involves progressively changing the reps and weight you’re using every two to four weeks. You can also use an undulated periodization program, which allows you to regularly increase and decrease the reps and weight you’re doing.

Other Factors

You'll see better definition improvements if you simultaneously follow a nutrient-dense, low-fat, high-protein eating plan. Consume a snack of lean protein and carbohydrates within 30 minutes after completing each workout and get 0.65 to 0.80 grams of protein for every pound you weigh each day. In addition, include both multi-joint and isolation exercises into your workout. Multi-joint exercises, such as squats and the bench press, are better for putting on mass, and isolation exercises help you increase definition.