Dr. Pierce's Tip of the Week - Archive

The Science of Repetitions
January 16, 2004

First of all, there is no magic number. As you'll learn, repetition protocols should change given the condition of your training age, the nature of the exercise and the goal. Learning a little about the principles behind repetition prescription will give you a better idea of how to apply this to your own workouts. The following general principles about repetition selection are based upon practical scientific research and empirical evidence from the work with elite athletes at the Poliquin Performance Center. The amount of weight you lift in relation to your one-repetition maximum (1 RM) determines how much tension a muscle produces. And the preponderance of credible research shows the level of tension imposed upon a muscle is critical for obtaining a strength or hypertrophy (muscle gain) response. The number of repetitions you select will influence all other loading parameters: sets, speed of contraction, rest intervals and exercise selection. The bottom line& Strength researchers have found a relationship between maximum number of repetitions, intensity and the desire training effect see chart below:

Reps: 1-5 % of Maximum: 100-85.6% Training Effect: Relative strength increases through enhanced neural drive with no hypertrophy.

Reps: 6-8 % of Maximum: 93.1-78.6% Training Effect: Optimal compromise between maximal strength and hypertrophy gains.

Reps: 9-12 % of Maximum: 76.5-70.3% Training Effect: Best hypertrophy gains leading to increased maximal strength.

Reps: 13-20 % of Maximum: 68.8-60.6% Training Effect: Strength-Endurance gains and lower hypertrophy gains.

When you plan your workout you should determine the desired training effect and select a repetition bracket to suit your goal. If you want to gain size, you would select a weight that enables you to complete between 6 and 12 repetitions. If you want to gain strength with minimal hypertrophy you would select a weight you are able to lift between 1 and 5 reps, and if you want to increase your endurance with again minimal hypertrophy you would select the bracket of repetitions between 13 and 20.

***Keep in mind the ability to perform repetitions at a given percentage will vary from muscle group to muscle group. For example at 70% of maximum you may able to perform 40 repetitions on the leg press but only 12 repetitions on a bicep curl.

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