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Optimising Muscle Growth: Rethinking Training Volume for Better Results

Updated: Jul 20, 2023

Are you looking to maximise your muscle gains through weight training? Training volume plays a vital role in determining the amount of muscle growth you can achieve after a series of workouts. However, traditional methods of measuring volume might not be the most ideal approach. Let's explore a more effective way to gauge training volume for muscle building and boost your progress!

The Quest for the Ideal Training Volume

Counting the number of sets or using the volume load (sets x reps x weight) are common ways to measure training volume. However, we need to dive deeper to understand what truly triggers muscle growth.

Unlocking the Secret: High Threshold Motor Units

The mechanical stimulus that drives muscle growth lies in the activation duration of muscle fibers controlled by high threshold motor units. These are the powerhouse fibers responsible for significant muscle gains. So, if muscle building is your goal, focusing on the reps that activate high threshold motor units is crucial.

"Stimulating Reps"

To measure stimulating reps, we focus on the number of reps performed at a high level of motor unit recruitment and a slow contraction velocity. These are the reps that really make a difference!

Stimulating Reps in Action

Heavy loads (1-5RM), approximately 85% of 1RM, typically engage full motor unit recruitment for all reps in a set, and the slow movement speed triggers muscle activation. So, all the reps in these sets are likely to be stimulating reps.

Moderate (6-15RM) and light (15RM+) loads, however, don't involve full motor unit recruitment for all reps in a set. While moving with maximal intent, the muscle fibers don't shorten slowly. As the set progresses, motor unit recruitment increases gradually, while bar speed reduces due to fatigue.

Finding Your Sweet Spot

My preferred rep range is between 5 and 9 reps, for example.

Training Volume in Practice: A Real-Life Example

Let's say we're performing the leg press:

  • Set: 8 reps

  • Experience: The first 3 reps were moderately easy, but the last 5 were challenging, leading to failure on the 8th rep.

The Power of Stimulating Reps

In this case, you've done 5 stimulating reps that activate high threshold motor units, contributing to muscle growth.

Adjusting Your Training Volume

By focusing on stimulating reps and understanding their impact on muscle growth, you can make more informed decisions about your training volume. Adjust your workouts accordingly as you progress through your training phase.


Unlocking your muscle-building potential lies in understanding stimulating reps and their role in training volume. Tailor your workouts to activate high threshold motor units and watch your gains soar!

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