Unlocking the Benefits of Varying Repetition Speed and Time Under Load for Optimal Fitness Results

Repetition Speed, Time Under Load (TUL), & Reps vs. TUL

How slow do I need to move during a set of an exercise? As slow as you can without the movement stuttering or creating a series of starts-and-stops. This will vary greatly between different people. Some individuals can accomplish moving so slowly that it takes them 30 seconds to complete 1 repetition. For other individuals that same repetition may take them 6 seconds to complete rather than 30 seconds.

The exercise we choose to do will have a big effect on the speed/cadence at which we go. For example, if we are doing a calf raise (short range of motion), going slow may be a 6-8 second repetition, whereas going slow on a pullover (long range of motion) may be a 30 second repetition. 

The duration of the exercise set from the moment you start moving until the point at which muscular failure is achieved is called Time under load (TUL). This is the best and most accurate way to track progress and fine tune weight progression. For most trainees, the TUL you are aiming for is between 45-90 seconds. While this is best for most, there are times longer or shorter TUL will be needed. Again, it will depend on the trainee, and is the job of the trainer to figure out what TUL is best! 

Why is TUL better than reps?

Because everyone’s repetition speed/cadence is different. Let's do some math!

Let’s take the pullover as the exercise for this example:

Trainee A: Repetition cadence is 30 seconds.

Trainee B: Repetition cadence is 8 seconds.

Trainee C: Repetition cadence is 16 seconds.

To achieve a TUL of 45-90 seconds the amount of repetitions needed are:

Trainee A: ~2-3 repetitions

Trainee B: ~5-11 repetitions 

Trainee C: ~3-6 repetitions

So, if we we track repetitions, and say we look for a rep range of 8-12 repetitions/set here is the TUL for each trainee:

Trainee A: 240-360 seconds or 4-6 minutes

Trainee B: 64-96 seconds or ~1-1.5 minutes

Trainee C: 128-192 or ~2-3 minutes.

While TUL and timing reps are better and easier to track, you can use reps too, but a trainer will need to know each client's repetition cadence to determine how many reps they need to achieve a TUL of ~45-90 seconds. 

Ultimately, the main goal is to achieve muscular failure as quickly and efficiently as possible without foregoing safety in the process. How you get there is up to the trainer. Keep in mind the metaphor “All roads lead to Rome''. Exercise is the same way, all methods of exercise will result in health and wellness benefits (assuming it is balanced with adequate recovery), but not all exercise methods are as efficient, safe, practical, or easy for everyone to adhere to.