The Optimal Number of Repetitions

optimal number of repetitions

What is the optimal number of repetitions for your training goals? That is an important question that most people who start working out ask themselves. Usually, people do 3 sets of 10 repetitions. But why do they do this? We will discuss sets in another article. In this one, we discuss repetitions.

Let’s get some facts straight first. How many repetitions are best for you depends on your goals. And the number of repetitions always correlates with the type of resistance you should use. For example, heavy weight lifters have a different repetition pattern than body builders. And a jogger will have another repetition pattern. This article focusses on explosive power, sub-maximum power and endurance power.

The Optimal Number of Repetitions and Your Goals

Before you read any further, think about the goals you want to achieve in your exercise. Do you mostly want to improve absolute strength? For example, bench press over 100 kilograms (kg)? Do you mostly want hypertrophy? For example, get bigger arm muscles? Do you want to improve your muscle endurance by lifting weights to make lifting easier in your job? 

different types of muscle fibres
You have different types of muscle fibre in your body

The Optimal Number of Repetitions and Different Types of Muscle Fibre 

There are three types of muscle fibres in your muscles. The numbers are a little susprising: 

  • 1 slow twitch 
  • 2a oxidative glycolytic 
  • 2b fast twitch

Let’s look into these a little more.

Type 1 muscle fibre

These muscle fibres use oxygen as their fuel. This can be sustained over long periods of time but they produce almost no muscle growth hormone (MGH). Type 1 is activated most when repetitions are high (>20) over a longer period of time. For example, when you do mutiple exercises or walk and do cardio activities. 

Type 2a muscle fibre

Type 2a muscle fibres use glycolytics as fuel, which is stored in the muscle. It can be sustained for over 1 minute or 6-20 reps. When your body runs out of this glycolytics, you can feel sore. These fibres produce the most MGH. 

Type 2b muscle fibre

Type 2b muscle fibres are the opposite from type 1 muscle fibres. They use phosphat as fuel, which is also stored in the muscles. It produces the maximum amount of strength but only for a couple of seconds (10 seconds or 1 to 3 reps). They are for great outbursts. However, they do not produce al lot of MGH because the muscles lack time to do that under tension. 

What Does This Mean

Let’s compare muscle fibres for each type to running athletes to help you visualise it.

  • 1: long distance runners > 1 km
  • 2a: 200m/400m sprint 
  • 2b: 100m sprint 

In the case of repetitions it is bit harder to visualise. You could simplify them into these 3 groups: 

  • First group:  type 1 muscle fiber: endurance strength range between 15 to 30 repetitions between 50-70% of 1 repetition maximum (1RM) 
  • Second group: type 2a muscle fiber: sub maximal/hypertrophy strength range between  6 to 15 repetitions with 70-90% of 1RM 
  • Third group: type 2b muscle fiber: maximum strength range between 1 to 5 repetitions with 90-99% of 1RM. 

Note: 1RM is the maximum strength you can produce in 1 repetition, this is your absolute strength. 

the optimal number op repetitions. push ups.

How to Start with a Different Number of Repetitions

If you want to start training you should begin with group 2. This is a safe way to start and get used to your exercises. Generally, you start with a lower weight (50% of 1RM) and concentrate on execution. Because repetitions with a lower weight improve execution. Ten to fifteen repetitions should be enough. Don’t start with group 3 if you are not used to working out. If you do too many repetitions your muscles need to recover for a longer period of time, even if you use a low weight. Once you perfect your execution and have gotten used to training you can start increasing the weight or the repetitions and choose the group you want to train.

The Optimal Number of Repetitions 

To best you can do is focus on all 3 types of muscle fibre. This means training according to a split schedule that includes endurace, maximum strength and sub-maximum strength. Include exercises with a high number of repetitions and a low weight and also exercises with a low number of repetitions and a high weight. If your goal is hypertrophy and it starts getting hard to increase your weight or to add more reps to your exercise you should change your training. You can focus on type 1 in one week and type 2b in the next. Then rotate this schedule for a while. This will stimulate an increase in repetitions and weight. 

Example 1

Your goal is to do a 100kg bench press with 10 to 12 reps. For months, you get stuck on 95 kg and  3 sets of 8 reps. So, the first week you will do 95kg (75% 1 RM) with 3 sets of 8 reps. The second week, you decrease in weight to 75 kg (60% 1RM) but increase to 3 sets of 20 to 25 reps. This helps your body to increase in reps all over. In the third week, you increase the weight  to 120kg (95% 1RM) and do 3 to 5 reps. This increases your absolute strength. As time goes by, you will notice your regular 3 sets of 8 reps 95 kg becomes more easy and you can start increasing reps and weight to progress to your goal.

Example 2

Your training schedule includes 3 exercises for your chest: bench press, chest press and push ups. On the bench press you perform 95% 1RM with a few reps, on the chest press you perform 75% 1RM with 10 reps and with push ups you will perform more than 20. By doing this, you activate all muscle fibres in your chest and will make the muscle strong in strength, sub-maximum strength and endurance. 


To get the best results, you should train all of the muscle types. Why? That way, your muscles get an all-round training. Also, by training all the muscle types you will achieve the greatest improvement. Group 1 and 3 contradict each other. Group 1 helps to increase the weight in group 3. And group 3 helps to increase the number repetitions in group 1. They both increase performance of group 2. 

Either way, if you are a beginner you should start low in group 2 and improve your execution. Whatever you level, just keep going, and you will find your optimal number of repetitions. Let us know if you need any help!

1: Morree JJ de, Jongert MWA, Poel G van der. Inspanningsfysiologie, oefentherapie en training. Houten: Bohn stafleu van Loghum; 2011. 150-159.

2: Burgerhout WG, Mook GA, Morree JJ de, Zijlstra WG. Fysiologie leerboek voor paramedische opleidingen. Amsterdam: Elsevier gezondheidszorg; 2010. 73-77 

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