Fast Reps vs Slow Reps

Last updated on February 23rd, 2022 at 06:04 pm

You may have noticed that some people are inclined to perform their reps as quickly as possible, while others take their time to execute each rep. The level of your progress could be affected by the speed at which you perform each repetition. To understand what’s best for you, let’s dig deep into the benefits of each approach. 

Exercise Tempo

When it comes to training, a significant variable such as the exercise tempo should be highly considered. This means the speed at which you perform each rep (i.e., how fast you lift or lower resistance), whether this is lifting weights in the gym or doing pull ups in calisthenics. The tempo can be broken into three elements: concentric, eccentric, and isometric components of a motion.

Firstly, concentric contraction is when the muscle shortens as the muscle produces tension while the insertion moves towards the origin. This occurs at the beginning of the exercise, for example, the upward phase in bicep curls, also known as the positive portion for an exercise. 

Eccentric contraction is a portion of a movement where the muscle controls movement against gravity and resistance by increasing the length during contraction. A simple example is the lowering down phase of chin ups. A recent study conducted by Hryvniak et al, (2021) suggests that more fast-twitch (type II) muscle fibers are recruited during eccentric contractions, which in simple terms are designed for short, explosive bursts of energy.

Lastly, isometric contraction occurs when the muscle length remains the same when tension is produced, no joint or limb motion occurs. For example, when doing push ups, holding your body static at the bottom phase of a push up. According to the Principles of Sports Rehabilitation, this element of exercise tempo is often commonly used during the rehabilitation phase of injuries as muscles are rarely injured during this type of contraction.

Altering the tempo or speed at which these phases are executed will determine your overall results after training for a while. It is also important to consider your fitness goal to understand which approach would work best for you. Let’s now find out the benefits of both. 

Slow Rep Training

Performing slower reps during the eccentric (negative) portion of the movement will increase the time under tension on your muscles than faster reps. This will reduce the momentum invol ved in the movement and cause mechanical damage and metabolic fatigue which leads to achieving muscular hypertrophy.

An empirical study suggests that slow speed resistance training resulted in about 50% greater increase in strength for both men and women than regular speed training. For example, using the 2-1-3 tempo where you take 2 seconds on the concentric, 1 second on the isometric, and 3 seconds on the eccentric. This puts high emphasis on the eccentric which is the standard procedure to slow reps.

For beginners, performing slower reps with easier progressions where less load is placed on the targeted body such as doing knee push ups or using lighter weights if you’re weight lifting is a safe approach as it enables you to focus on form before moving on to more challenging progressions or weight, which prevents any unnecessary injuries. 

Fast Rep Training

In contrast, executing repetitions at a fast tempo is associated with increasing max strength, explosive power, and speed. For example, if you’re looking to improve your one-rep max in pull ups, dips, squats, or even increase your explosive power in the vertical jump, this approach would be ideal for you. 

This will develop the fast-twitch (type II) muscle fibers in your body which are used when the body is required to produce sudden and more powerful forces, but for shorter durations and fatigue quicker. 

Additionally, you can perform more reps with a faster tempo due to lower time under tension which places less metabolic stress on your muscles. Note that lower time under tension on your muscle with fast reps does not impede muscle growth. Sakomoto and Sinclair (2006) support that faster movement speeds assist in individuals being able to do more repetitions.

Typically, fast reps are often performed during the concentric portion of the exercise, such as doing a rep max in a pull up or a dip as you will need to execute that rep quickly against resistance. On the contrary, doing a one-rep max at a slow tempo would almost be impossible for you to do – Not highly advised!

Which is Better: Slow Rep or Fast Rep?

Tempo is an important resistance training variable, which should be highly considered during the planning and execution of your training program. While utilizing fast or slow repetition has its benefits, Pat Chadwick suggests that you employ a combination of the two throughout your training to get stronger and maximize muscular hypertrophy. 

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