Time under Tension (TUT) is a widely used time-based metric that prioritizes increasing the duration of repetitions and sets rather than weight lifted. This method was popularized in the 90s and was widely accepted and adopted as opposed to progressive overload. However, critics were quick to refute TUT and some even label it as a “myth.”
Time under tension is a fitness principle and is not a myth. It is a timing-based metric used with other fitness principles like progressive overload, metabolic fatigue, and cell swelling to enable adequate muscle growth.
Time under tension provides a good alternative to traditional methods of training. However, it is important to learn and discern the proper ways to use time under tension and how to incorporate it properly into an existing fitness program.
What is Time Under Tension?
Time Under Tension refers to the amount of time it takes to complete a repetition and/or set. For repetitions, people measure TUT with ratios like 3:1:1 or 5:1:5. These three numbers represent the number of seconds used to execute the three phases of the repetition. Sometimes, a fourth number is added to the ratio to represent the amount of time in seconds to rest before performing another repitition.
Repetitions of any exercise consist of three parts: eccentric phase, isometric phase, and concentric phase.
The eccentric phase is where the muscles become shorter and the muscle fibers are squeezed together. To illustrate, in a bench press this is where the barbell comes in contact with the chest.
The isometric phase is the transition between the eccentric and the concentric phase.
The concentric phase is where the muscles elongate. In a bench press this is when the arms are elongated as the person lifts the barbell away from their body.
TUT ranges from 20 to 70 seconds. The common standards for strength, muscle mass, and endurance are 20 seconds, 40-70 seconds, and 70 seconds or more, respectively. People often use TUT as an alternative to counting repetitions in a set. In its heyday, this method of training led to the methodical timing of lifts.
People believe that increasing TUT will lead to a greater increase in muscle mass. Thus, instead of the conventional repetition counting, people began to alter the amount of time in seconds they devote to each phase of the workout. A 3:1:1 repetition will increase strength, while a 5:1:5 repetition is best for reaching muscle hypertrophy.
Scientific studies also support the TUT claim, stating that it helps in increasing protein synthesis essential for muscle growth. There is a popular belief that the eccentric phase of the repetition produces greater micro-trauma to the muscles than the concentric phase, leading to more muscle growth. This led people to double the time devoted to the eccentric phase of the repetition (hence 3:1:1 and 5:1:5).
TUT also altered the isometric phase of the workout, stating that pausing for one second before transitioning between the eccentric and concentric phase removes the potential for momentum and forces the muscle to execute the exercise. Resting for one second in between the eccentric and concentric phase also mentally activates the muscles and helps engage more muscle fibers.
Is it Better to Lift Slowly to Increase TUT?
The TUT fitness philosophy comes from the understanding that lactic acid build-up is a good indicator of muscle growth. Lactic acid build-up occurs when the muscles are worked beyond their normal capacity, and a burning sensation begins in the muscles during the lift. The TUT prescribes that people must slow down their lifts to activate the lactic acid build-up better in the muscles.
The TUT method activates Delayed Onset Muscle Soreness (DOMS) and with greater intensity than traditional rep-counting workouts. It also has longer muscle recovery time than traditional workouts, which further convinced people on the effectiveness of the TUT method for building muscle.
Several benefits of TUT include the ability to focus on form to help prevent joint injuries. The slow, albeit controlled movement that’s associated with TUT also promotes more purposeful movements and greater mind-body connection. This subsequently leads to better breathing, better body alignment and posture, and greater muscle control.
Slower lifts also create greater tension in the eccentric phase of the lift. According to the TUT training philosophy, slower lift result in more tension in the muscles and allows you to reach hypertrophy faster with less effort.
The Process of Muscle Growth
The most accepted explanation for the muscle growth process includes only three mechanisms: progressive overload, metabolic fatigue/stress, and muscle damage or cell swelling.
Most fitness experts would subscribe to the principle of progressive overload which aims to overwork the muscles towards metabolic fatigue to deplete its energy and signal anabolic growth for muscle gain through recovery from muscle damage. In this process, three crucial variables contribute to muscle development: frequency, intensity, and volume.
Frequency indicates the number of repetitions in a set; Intensity represents the amount of weight; Volume represents the total volume of weight lifted during the entire set.
Training volume, which is the combined values of weight x repetitions x sets, is one of the most important variables to assess the effectiveness of a routine. Volumes that do not reach beyond the capacity of the muscles do not effectively engender muscle growth.
Another important factor for muscle growth is mechanical tension. This represents the amount of stress the muscles experience during each repetition. A common adage among traditional fitness experts is that muscles do not know repetitions or cannot experience time; they only experience external stress or pressure. Thus, in terms of traditional fitness training, mechanical tension is a more important factor than time under tension for muscle growth.
Time Under Tension vs Progressive Overload
TUT is not a myth, but the foundations of its claims on muscle growth are contested widely in the fitness world. Training using time under tension is important for muscle growth, but it ignores other factors of muscle growth like mechanical tension and progressive overload. The TUT method relies solely on applying pressure to the muscle for longer duration without considering progressively overloading the muscles and applying optimal mechanical tension.
One of the primary basis for the perceived success of TUT is the longer and more painful DOMS, but traditional fitness experts say that people should never use pain as an indicator of workout success or failure. Truth be told, there is no scientific explanation for why DOMS occur. However most people subscribe to the beliefs above that micro-tears in the muscles result in Delayed Onset Muscle Soreness.
The flawed foundation of the TUT method is also exposed in scientific research as some have shown negligible improvement in strength and size in using TUT as compared with traditional methods. Other studies also show that faster paced training is more effective because of the higher peak force and training volume. There are also established scientific literature on the positive relationship between hypertrophy and training volume, while there are none for lifting tempo and muscle development.
Contrary to TUT, the best method to achieve higher training volume is through progressive overload coupled with explosive repetitions. This method takes advantage of the inverse relationship between the amount of tension and the amount of time for the lift. This means that people can only lift heavier weights for a shorter period of time before reaching muscle fatigue. Thus, people use explosive reps to stave muscle fatigue longer and perform more lifts using heavier weight.
The main flaw in TUT is its focus on lift tempo and lack of consideration for progressive overloading. The method prescribed in TUT of lifting slower reduces the total amount of training volume per set because lifting slower will force the individual to scale down on the weight in order to adhere to time per set/rep. Therefore, despite inducing DOMS, the total “work” being done by the muscle is reduced.
The main goal of TUT is to work the muscles longer by altering the timing of lifts. In terms of promoting muscle growth, progressive overload is the most widely accepted and time-tested method.