Anatomy Of A Rep!

The repetition is the single most basic, but at the same time, the most fundamental factor in bodybuilding.

It's pretty easy to determine that the sport of bodybuilding is completely based on and around muscles... exhausting them, feeding them, and then finally resting them so they can grow bigger and stronger.

As you probably already know, each of these factors must be combined in the correct ratio to each other to ultimately acquire true, lean muscle mass. Once you consider yourself to be fairly established in this sport (having most of the bugs worked out of your nutrition, supplementation, and training), it should be one of your goals to try and improve, starting with the basic fundamentals.

The Rep

Let's begin by taking a closer look at the repetition, and see how we can seize every possible benefit from it. This will be the first step towards reaching your ultimate goal... and if you're like me, it's shredded mass.

The repetition is the single most basic, but at the same time, the most fundamental factor in bodybuilding. No aspect of training is more important than the rep. You perform hundreds, maybe thousands of reps each week, so why not take the time to actually understand what's happening and try to improve your reps?

Never really thought about it, did ya? Improving the basic fundamentals of bodybuilding, such as the repetition, will enable you to build muscle much more efficiently and even reduce the chances of becoming injured.

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From a mechanical perspective, a repetition is made up of three distinct phases:

  • Concentric phase (lifting the weight)
  • Transition or peak contraction phase (mid-point)
  • Eccentric phase (lowering the weight)

You've probably heard me say it before, but I'll say it again, the mind-muscle connection is essential. Instead of thinking of the rep as a 3 phase movement, try to get your head into your muscle and feel it working.

A common false belief is that a muscle contracts only during the concentric phase, and relaxes during the eccentric phase, but in actual fact a muscle contracts during both phases of an exercise. This alone addresses that emphasis should be placed on the eccentric (negative) phase of a rep.

To View Negative Rep Articles, Click Here.

To better illustrate this, the working muscle shortens during the concentric phase and lengthens during the eccentric phase. While performing barbell curls for example, the biceps shorten on the concentric phase, while they lengthen and stretch out on the eccentric phase.

If the muscle was relaxed on the eccentric phase of a rep, the weight would simply fall uncontrolled towards the ground. Admit it, we all do it now and then, some more than others... Make it your prime goal to put an end to this horrible habit!

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An exercise's range of motion consists of the concentric and eccentric phases. Movements that do not utilize the body's full range of motion will limit the number of muscle fibers recruited and will decrease flexibility in the long run. Contrary to popular belief, exercising through a full range of motion is safe and will not cause injuries as long as the rep is performed at a medium-slow pace and always under full control. Getting sloppy is where you'll meet your adversary: an injury.

Also, avoid conserving energy during a rep. When you lock out at the top or during the transition phase, you temporarily shift the load from the target muscle to the joint. Go for the peak contraction. To make the most progress, you have to apply optimum stress to the muscle for the entire set, beginning to end... Your rest comes then at the end of the set, not half-way through.

The Three Phases

On that note, let's get into the goodies and learn a little about what happens, and how to make it better.

The Concentric Phase

During the concentric phase of a rep, the working muscle shortens, pulling the bones on each side of the joint together. For example, your forearm and upper arm come together when you perform a dumbbell curl.

If the weight being lifted is fairly light, a large percentage of muscle fibers remain inactive. However, if the weight is heavy, the muscle will recruit as many fibers as possible to meet the demands placed on it. The more muscle fibers that you activate during a set will result in greater strength and size gains - that is if all the other factors such as nutrition and recovery time are properly addressed.

When performing a rep, use a speed which is completely controlled with no swinging. This will avoid letting momentum do some of the work for you and allow for maximum muscle fiber recruitment. Breathing is also an important aspect of your quality rep. Exhale during the concentric phase, and inhale on the eccentric phase.

The Transition Phase

At the end of the concentric contraction, a muscle is in its shortest position. I recommend that you pause here for half a second to contract the muscle and achieve the very important peak contraction. Along with heavy weights, rely on training principles such as peak contraction, isolation, supersets, etc.

The Eccentric Phase

This will ensure that the highest number of muscle fibers are stimulated during a set. Remember: The further you bring a set past failure, the more muscle fibers are recruited... resulting in more growth. The goal of a bodybuilder is to use the least amount of weight possible to provide optimal muscle-building stimulation.

This second half of the rep is known as the eccentric phase. This phase of a rep is just as important as the concentric phase for promoting muscle growth, but many bodybuilders treat it as the inferior half of the rep. Although fewer muscle fibers are used than during the concentric contraction, more stress is placed on each of the activated muscle fibers and that translates into a higher percentage of the muscle fiber being damaged. This being a good thing, of course!


Before you begin a set, there are a few aspects which must be in-check to ensure that you get off to a good start. First of all, make sure your body is in proper alignment so you are in the optimum position to get the most out of your set. Maintaining proper bio-mechanical alignment and posture will also add to the effectiveness of your set. Stay tight to maximize stability and power.

Now that you may have a better understanding of the dynamics of a rep, apply your knowledge to every rep of every set. After one or two workouts, watch your workouts become more intense, your post-workout soreness will increase, but most importantly your muscle will become more striated, harder and bigger... by simply improving one of the basic fundamentals of bodybuilding!

"Expecting your best every time produces more failure than success!"