TUT – Time Under Tension

Calculating the time under tension should not pose a problem for anyone. I'll use a specific example to explain how to do this. After performing a series on your chest, you let the weight drop for 3 seconds, then you lift it without holding it for 2 seconds, and start the next repetition immediately. It took you 5 seconds (tempo 3 0 2 0). Assuming the series consisted of 12 repetitions, your TUT is 60 seconds (5 × 12). As you can see, the fundamental effect on TUT has two factors: the tempo and the number of repetitions. Modifying either of them automatically modifies TUT.

Depending on the particular training aim, we can apply a suitable duration of maintaining tension. To augment strength, our set should last approximately 20 seconds. To attain functional hypertrophy, it is advised to keep the muscles under tension for a span ranging from 20 to 40 seconds.

Many of us go to the gym with the aim of increasing our muscle mass. Studies indicate that manipulating only this parameter can help us achieve this goal. It turns out that performing 6 sets of 12 repetitions at a weight of 35% CM with a slow tempo results in greater muscle growth than performing 3 sets of 12 repetitions with a fast tempo and a weight of 70%. Increasing the time under tension at the same training volume leads to greater hypertrophy. This is very useful information for those who, for various reasons, cannot lift heavy weights but still wish to improve their appearance.

As we observe, only the modification of the duration of maintaining stress allows us to influence the results of our training. However, this is not the only factor that determines how we shape our body. Muscle development is influenced by three main mechanisms: their mechanical stress, damage, and metabolic stress. Using a sufficiently high weight causes an increase in mechanical tension within the muscles, which promotes the development of fast-twitch muscle fibers that determine muscle size. Prolonging the eccentric phase in each repetition intensifies the damage to muscle tissue, which manifests itself in the form of muscle pain (DOMS) after training. Increasing TUT leads to an increase in metabolic stress through a restriction of oxygen access, enhanced perfusion (muscle pump), and an accumulation of metabolic by-products such as lactic acid. Only by combining these three elements in a single training does the body receive the right stimulus for development.

Apart from the appropriate speed, the weight employed also impacts muscle tension. There is a close connection between TUT and the weight used during training. Increasing the weight results in faster exhaustion, which shortens the time under tension. Conversely, prolonging the time can be achieved by decreasing the weight. One technique that utilizes this dependence is the so-called drop sets. Many fitness enthusiasts focus on training with the maximum possible load, while forgetting about proper technique and experiencing muscle strain. Often, instead of muscle force, they use inertial force, leading to a loss of desired muscle tone. Measuring TUT for such executed sets is pointless. In such situations, it is better to decrease the weight and concentrate on working the muscles, rather than unconsciously swinging the weight and counting repetitions.

There are two ways to achieve this: the most obvious is setting a stopwatch to a specific number of seconds and performing exercises until the counter stops. The second, recommended and more efficient method is to use a pace that best suits each repetition. This allows for a more intense focus on the movement, especially in the eccentric and concentric phase. Managing movement and maintaining muscle tension for the set amount of time is a crucial aspect, especially in strength training. This approach to exercises has already been described by Joe Weider as the "rule of continuous muscle tension".

Tracking TUT for the entire training session allows us to precisely determine how long our muscles have actually worked. Applying this parameter can be a form of training progression for us. For example, instead of increasing the weight, we can extend the total TUT from week to week within a given training cycle. In this way, we increase the volume. Extending the time under tension results in increased metabolic stress, which leads to a higher production of anabolic hormones. A higher TUT means more work done by the muscles, which translates into their better development. It also means a greater consumption of glucogen, a higher number of minor muscle injuries, an increase in the muscle pump effect, and more burned calories. Using only the recommended number of repetitions and selecting the right weight does not always make training effective if we do not use the right tempo and determine the right time under tension. This parameter allows us to focus on muscle tension, which is one of the most important factors influencing the final training result. It enables us to utilize the time spent in the gym more effectively and achieve our goals faster.