Time Under Tension – You’re doing it Wrong

Time under tension (TUT) training concepts have been around for years, however, the interpretation of time under tension and how it is best utilised in a training sense is often misinterpreted in its application despite being appropriately explained in the literature.

Tension can loosely be defined as:

The pulling force exerted by both ends of a string, cable, chain or in this instance, muscle tissue. 

When more force is exerted, a greater tension reading occurs and a measurement in newtons can be achieved, of which is an international system of unit measurement to describe force.

Similarly, tension can simply be a reference to the state of something being stretched, just like a barbell with weight does on the pectoral muscles during the eccentric (lowering of the weight) phase of the bench press.

So in essence, tension is the stretch effect placed on the muscle when under load. However, what many forget to recognise is that with greater weight, greater tension is achieved.

Let's think about a rubber band with a 100g weight attached to it. The 100g of weight will apply tension to the rubber band and cause it to stretch ‘x’ amount, of which the tension on the rubber band could be measured in newtons. Now, this weight is easy for the rubber band to maintain and it should have no issue maintaining this tension for an extended period of time.

Eg: Its tension is far greater

Don’t worry I understand we are not rubber bands, however, it does make a simple analogy to explain the weight tension relationship, remembering that tension is a measurement of force measured in newtons, of which time is not a part of the equation.

So I ask you, what provides more tension…

A 40kg bench press completed with excessively slow eccentrics and concentric phases causing failure to occur at 12 reps

Or

An 80kg bench press completed with controlled eccentrics and a powerful concentric phase to maximise muscle fibre recruitment that also fails at 12 reps?

Both place tension on the muscle, of which is then completed over time, however, option B creates FAR more mechanical tension on the tissue despite the time it is under that tension being less.

Now given that the primary benefits of training are achieved by an increase in training volume, frequency and intensity (which is a measurement of strength and therefore more tension) not time under load, which out of the two scenarios do you think will elicit the greater results?

The muscle that is being stretched the most, is the muscle that is being activated the most. Remember, tension is a measurement of the stress of a force placed on a muscle causing it to stretch.

So... regardless of the training modality, the same fundamentals for muscular hypertrophy remain the same. Exercise choice, speed of repetitions and rest periods have little effect when compared to intensity, frequency and volume. 

Some important definitions:

• Myofibrillar hypertrophy refers to the increase in actual muscle tissue size and requires mechanical tension (load, volume, frequency) to illicit a positive response.
• Sarcoplasmic hypertrophy refers to the increase in muscle content and can be achieved through both nutritional and training methods whereby the goal is to flood the cell with nutrients (carbs) and metabolic waste, which is what misinterpreted TUT achieves.

Remember… just because it burns and causes muscle pain the next day, doesn’t mean it's and effective growth stimulus.

Tension is a measurement in newtons, without reference to time. Place more tension through the muscle by increasing the load placed through it and you will get far better hypertrophy compared to submaximal loads lifted at snail speed just to feel the burn.

But does the research agree?

In a nutshell, traditional TUT, whereby the eccentric phase is done at a slow pace with a momentary pause and a slow concentric phase appears to show no benefit for hypertrophy when compared to a traditional resistance program (1). What is interesting about TUT though is its proposed effects on muscle hypoxia, which is hypothesised to be a result of the lack of waste removal due to the consistent length of muscle contraction, and its apparent positive effects on hypertrophy in a similar fashion to that of blood flow restriction training (2).

So while the mechanical load is diminished in a traditional TUT set, which may not benefit maximum myofibrillar hypertrophy, the metabolic waste accumulation may help with sarcoplasmic hypertrophy and in the absence of traditional weight training, may be a good alternative to try an illicit a similar growth response.

I would, however, suggest that the same hypoxic effect could be achieved using a heavier load for 25+ reps versus a lighter load for 10 slow reps. The time the muscle is under tension would be similar, however, the tension achieved by the heavier load for higher reps would more than likely have greater total benefits.

Take away the slower reps, add more weight to the bar and work on the 3 key principles for muscle growth, which are volume, intensity and frequency.