Welcome to part 3 of our Muscle Building Series. This time we will be looking at Training Intensity and explaining how we gauge this appropriately during workouts at Train.

What is Training Intensity?

Training Intensity describes the amount of load (also known as resistance or weight) and effort you use during each exercise.

As with most training variables there seems to be an ideal intensity range that generates the most effective muscle growth. If training intensity is too high, overtraining is likely to occur meaning increase risk of injury and a slower rate of muscle growth slower. If your training intensity is too low then your muscles will not be stimulated enough to be forced to adapt and grow.

From the research, it is clear that muscle growth can occur from a broad range of intensities. However, strength can only be increased by training with high intensities and short sets. (1,2)

As mentioned in part two of our series a mixture of exercises using short and long sets should be used to maximise muscle growth. High-intensity short sets of 5 to 8 reps can be used to ensure 100% recruitment of muscle fibres. Moderate intensity longer sets of 15-20 (ideally failure) can be used cause muscle protein synthesis. Both of which are fundamental principles for muscle growth. (3)

How to measure training intensity and ensure you have the right amount?

Traditionally intensity was measured as a percentage of the maximal weight that can be lifted for a single repetition.  You may see it written on a program in shorthand like so – 70% of 1RM. An example of this would be that if someone could Bench Press 100kg for 1 repetition then their 70% of 1RM would be 70kg.

Using a percentage of 1RM may be good for elite lifters and athletes, however, we find it time consuming as it involves regular testing and it is difficult to measure correctly for most exercises.

At Train we prefer to measure Training Intensity by the amount of effort required to complete a set. We use the Reps To Failure scale (RTF) (4) to determine if the adequate intensity is being used.

How to use RTF

After each set, we ask clients to score the amount of effort used. Scores range between 0-4 and depend on the amount of reps they feel they still have in the tank after the set was completed.

RTF  Score Table

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The ideal scores will depend on the type of exercise, the order of the exercise within the workout and the general energy level of the client.

What score is right?

We generally use heavy compound movements at the beginning of most sessions. These require short sets of 5-8 repetitions and we’d hope to reach a score of 3 to 1. The score should get lower as the sets go on. Example – score of  3/2 after the first set, 2/1  after second set and 1 after the final set.

During heavy lifts the aim is to avoid working to failure as for most clients this is too taxing and can lead to overtraining.  The training weight and intensity can be changed between sets to bring about the desired level of effort.  If the score is higher than 4 it is not included as a working set and the weight is adjusted.

We then move on to exercises that involve moderate loads and more reps. These exercises use rep ranges of 10-12 and our aim is to work to an RTF score of 1 or 0 if it is the last exercise for that body part and the client is feeling good.

The final part of each session normally involves isolation movements and exercises using higher reps. Typically we always aim to work to failure with theses exercises and aim for that to occur between 15-20 reps. We try to avoid using more than 20 reps as this has been showed to provide fewer gains in muscle (5)

Key Points

  • Use high intensity and low reps at the begin of your workout.
  • Use moderate intensity and high reps during the latter stages of your workout.
  • Only work to failure when using high rep sets.

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If you found this helpful and you’d like to learn more you can find the first two parts of our series below:

How often you should train a muscle (Frequency) 

How many sets and reps you should you use (Volume)


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1) – Effects of different volume-equated resistance training loading strategies on muscular adaptations in well-trained men.

2) – Muscular adaptations in response to three different resistance-training regimens: Specificity of repetition maximum training zones 

3 – Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men

4 – http://www.lookgreatnaked.com/blog/a-better-way-to-gauge-intensity-of-effort-during-resistance-training/

5 – Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones.