Why Repetitions are an Important Training Variable

There are four training variables that require manipulation during a workout in order to make significant gains in the gym. An easy way to remember them is with an acronym known as FITT. The FITT Principle, as it is referred to, stands for training frequency, intensity, timing and type (specificity). These variables are controlled for during each training session and over the length of the training program. Frequency is the number of sessions per week, intensity is the load expressed as resistance, time is simply duration of a workout and finally type is the activity.

With that said, to reach any fitness goal, the rules of overload and progression should be followed in a given workout. Each of these are key training principles that refers to the amount of load or resistance and the way that load should be increased respectively.

The Importance of a Repetition

You can perform hundreds of repetitions in a given workout. The speed of a repetition, total number of repetitions and the volume, all play an important role in muscular development. Variations in either will have a direct correlation on the nervous and muscular systems via the corresponding training stimulus. Let’s break down each one of these.

Repetition Speed or Tempo and TUT

A repetition has three distinct phases, an upward, isometric and lowering phase. As a result, we have the ability to increase or decrease time under tension (TUT) by manipulating the tempo (speed) for a given repetition. For example, a workout with a prescribed tempo of 1/1/2 would mean, a 1-second upward (concentric), 1-second isometric and a 2-second lowering (eccentric) phase. Therefore, in this case, each one takes 4-seconds to complete. In other words, 4-seconds x total repetitions = TUT. If we use 8 repetitions as an example, we would have 32-seconds of TUT. A good range to shoot for is about 30-50 seconds of TUT/set. Research has demonstrated the importance of TUT and the key may be in the cumulative effect of TUT for an entire workout (all sets) versus to a single set.

Repetition Tempo x Total # Repetitions = TUT

Quantity of Repetitions

One of the first things you learn when strength training is a higher number of repetitions stimulates muscle endurance while a lower number builds strength. Here is nice graph, showing the importance of a repetition scheme on a specific training goal, as seen in the NSCA manual.

TRAINING GOALREPETITIONSINTENSITY (% 1-RM)
Strength Endurance>12<67%
Hypertrophy6-1267-85%
Maximum Strength<6>85%
Power
-Single-repetition event
-Multiple-repetition event

1-2
3-5

80-90%
75-85%
Source: NSCA Essentials of Strength Training and Conditioning (3rd ed.) 2008.

Exercise Volume (sets x repetitions x load)

The volume is the quantity of work that someone does in a training session. In regard to strength training, this is the number of repetitions multiplied by the number of sets and weight lifted. For example, performing four sets x 8 using 40-lbs. dumbbells equates to a volume of 32 x 40 or 1280. In addition, volume can also be expressed in terms of distance, time, number of throws, or even number of jumps, etc. For example, when performing medicine ball throws for 35-seconds, volume can be quantified by time. Volume can also be expressed in terms of distance, such as sprinting for 100-meters or running a certain number of miles, like a 5k. An inverse relationship exists between the intensity of an exercise and its volume.

The Value of this Information Moving Forward

During your next workout pay attention to how you execute each repetition in each set you perform. Be more aware of the tempo for each repetition; have an idea of the cumulative TUT post workout. Are you less than 30-seconds/TUT/set like many who train? Is your total TUT changing from one workout to the next based on your training goals? If you know you move through your repetitions quickly, that fine (especially training for power), maybe slow down that final phase of each repetition. The lowering or eccentric phase is important because you can typically handle more weight, so slow things down to challenging your muscles more often, keeping the concept of TUT in the back of your mind. Stay strong with Jefit.