If you’re just starting out in the world of fitness, one of the key concepts you should begin to grasp as soon as possible is TUT training (from the English acronym time under tension), which is precisely that: the amount of time a muscle or specific muscle group is active and under tension during an exercise. Something essential for increasing your strength without weights.
If you’ve ever heard a coach talk about ‘time under tension’ as the reason your legs burn during a squat or your core during an extremely slow push-up, you might not be excited to learn more about the training principle. But understanding it will help you appreciate its nature and learn to use it to reap great benefits.
Time under tension (TUT) refers to the total time spent performing an exercise during which the muscle produces tension. And when exactly is a muscle under tension? To answer the question, it helps to understand the three types of contractions a muscle undergoes during exercise: concentric, isometric, and eccentric. The concentric is when a muscle shortens, the isometric is when there are no changes in muscle length, and the eccentric is when the muscle lengthens.
An example: the biceps curl. The upward movement of this exercise is the concentric contraction. Lowering the weight is the eccentric phase of the movement, when the biceps lengthen. Finally, imagine holding a dumbbell halfway through a curl with the elbow bent at 90 degrees. Your biceps are working to hold the weight, but the muscle does not change length: that is an isometric contraction.
A muscle under tension
A muscle is under tension during all three contractions. The time under tension represents the total time spent in all these phases for a set or training session. Therefore, several factors determine the time under tension in a workout: the total exercise time, the number of repetitions and sets you perform (that is, training volume) and finally the duration of each repetition.
You can play with all three factors to increase the time of use in any training session. However, when people talk about ‘time under tension training’, it often refers to playing with the time spent on each repetition. Time under tension can be easily manipulated by increasing or decreasing the time spent in any of the three contraction phases.
The benefits of TUT training
In a nutshell, playing with time under tension adds variety to your workouts and makes them more challenging. Increasing TUT can help raise the difficulty of your workload and your overall strength without necessarily changing the weight you use. And it can be especially useful for those who don’t have much equipment available or who want to challenge themselves without the need to use bulky weights.
Time under tension is a great concept to apply to bodyweight training, which is ideal when you travel and don’t have weights at your disposal. Adjusting time under tension within a set is a good way to create variety in the workout and challenge muscular endurance and strength.
Woman exercising outdoors.
If you feel stuck in your training, especially regarding your strength progress, adding the stimulus of time under tension can give your body the boost it needs to keep adapting. It can also help you train your mental fortitude. TUT isn’t just an excellent way to vary your training; it also offers you a mental challenge to slow down.
TUT training and muscle growth
If increasing time under tension presents you with the same challenge as lifting heavier weights, it surely helps you develop your muscles. Hypertrophy is the process of increasing the size, density, and shape of skeletal muscles, often through resistance training.
A high training volume (28-30 sets per muscle per week) is generally better for inducing muscle growth than a lower volume (6-10 sets per muscle per week). Furthermore, a high training volume tends to result in a greater time under tension (TUT) overall.
However, if you look more closely at time under tension per repetition or during each phase of the movement, the benefit is less clear. Neither slow nor fast repetitions seem to make a difference in hypertrophy, according to studies. However, it may be beneficial to adopt a half-and-half approach.
Research shows that eccentric movements favor hypertrophy more, which would support the theory that eccentric time under tension can help promote muscle growth. Although there is not yet definitive scientific evidence to prove it, it seems the best tempo for hypertrophy could be a combination of a slower movement in the eccentric phase with a faster movement during the concentric phase. For example, for a biceps curl, this would involve lowering the weight slowly and raising it quickly again.
