FAST REPS vs SLOW

Author: Jim Stoppani, PhD

If you're familiar with my training advice, then you know that I like change. I like to change up exercises, rep ranges, rest periods, training splits, and even the speed at which reps are performed. When it comestibles rep speed, most people stick with the tried and true slow and controlled pace of about 1-2 seconds on the positive and about 1-2 seconds on the negative. While this is the pace you should keep for most of the time, you should occasionally consider going much slower some of the time and much faster some of the time. Super slow reps can help you build more muscle, while fast and explosive reps can help you build more strength and power, which can help you build more muscle in the long run, and they can even help you to burn off more body fat.

Studies Confirmed

Scientists from the University of Sydney (Lidcome, NSW, Australia) had males and females follow a biceps training program for 6 weeks using different rep speeds to determine which rep speed on the one-arm biceps curl best increased strength and which rep speed best increased muscle size. One group did one-arm biceps curls using slow reps (3 seconds on the positive and 3 seconds on the negative part of the rep), while the other group did fast reps (less than 1 second on the positive and negative part of the rep). Each group trained with a weight that limited them to 6-8 reps on the one-arm biceps curl and trained three times per week. They found that the fast reps increased biceps strength by 46% over the 6 weeks, while slow reps only increased biceps strength by 40%. Slow reps on the other hand, increased biceps size by 3%, while the fast reps only increased size by 1%. In other words, fast reps appear to be best for increasing muscle strength, while slow reps are best for increasing muscle size. Slow reps may increase size better than fast reps due to a greater increase in growth hormone (GH) and testosterone levels. A Japanese study reported that subjects using slow reps raised GH and testosterone levels than those using faster reps.

Fast Reps = Fast Results

Fast reps likely increase muscle strength better because they utilize more of the fast-twitch muscle fibers within a muscle. These are the muscle fibers that can contract with great speed and strength. These muscle fibers also appear to burn more calories than slow-twitch muscle fibers. Researchers from Ball State found that weight-trained men doing squats with fast reps burned over 10% more calories than when they did squats with normal speed reps. The fast rep workouts also caused the men to burn 5% more calories at rest after the workout was over.

So be sure to change up your rep speeds just like you change up other aspects of your workouts. Keep normal-speed reps at the foundation of your training program, using them the majority of the time. However, also use fast reps for building strength and power, as well to drop body fat. Use slow reps to help encourage more muscle growth.