For the muscles to grow, in both strength and size, we focus on applying resistance by lifting weights. Typically, we focus on how much weight we can lift and how many times we can repeat the movement. For how much weight we can lift, we use the term load. For how many times we can repeat the movement, we use the term repetitions or volume. They are both important parameters and give you perspective of how much strength you currently have and what you can do to improve them.
Although those parameters are important, we need to include another metrics to appreciate better muscular growth (strength and size). It is called “Time Under Tension”. Time under tension means how much of stimulus we are placing on the muscles during exercise. More tension you can apply to the muscles better growth response you can have. However, too much tension can cause stress and may lead into inflammation and injury.
Benefit of Time Under Tension
If you ever worked with experienced trainers or coaches, you may have trained in tempo training. Major focus of tempo training or time under tension training is manipulation of the body under load. By adjusting the movement tempo, you are applying more tension or stimulus to the muscles in 1 repetition.
While benching, for example, you may have performed 3-5 seconds to lower the weight to the chest and 1 seconds to push the weight back. This is part of time under tension technique. In this example, you are spending 4-6 seconds per repetitions and if you are performing 6 repetitions, you have been applying stimulus to the muscles for 24-36 seconds. When you are performing 1 second lowering and 1 second push for 12 repetitions, you are applying 2 seconds worth of stimulus per rep and 24 seconds per set. In other words, with time under tension you can apply similar stimulus with fewer repetitions.
With controlled movement, another advantage you’ll find with time under tension is improvement in exercise technique along with less chance of injury.
3 Types of Muscle Contractions
In muscle contraction there are 3 different types, concentric contraction, eccentric contraction, and isometric contraction. Concentric contraction refers to shortening of the muscles. Eccentric contraction refers to lengthening of the muscles. Isometric contraction refers to tightening of the muscles while not joint movement is observed.
For example, when performing biceps curl, when the weight is being lifting from the elbow extended position to elbow flexed position, biceps muscles is in concentric contraction. When the movement is reversed from flexed elbow position to extended position, the biceps muscles is in eccentric contraction. When biceps muscles are tightened but joint movement is not there this is called isometric contraction.
Application of Time Under Tension
When applying time under tension, you can apply this in these 3 contraction patterns. For many of my clients, I focus on fast concentric contraction and slow eccentric contraction. Squat, for example, I often have my client descend in 3-5 seconds (slow) and ascend as fast as they can. Occasionally, I may have them pause for 2 seconds at the bottom position for isometric contraction. For the load, I may give them weight that they can perform in good form for 8-10 repetitions then reduce the volume to 6 repetitions. Ideally, repetition 1 and repetition 6 should be a same quality. If I’m having my client do several sets, their rep 1 of the first sets and rep 6 of the last set should be about the same. Muscle fatigue may kick in but should be able to manipulate the tempo.
Focus is not how many repetitions they can do with time under tension. It is more about how much stimulus I can provide to their muscles. Of course, if the load is too light, it may be difficult to provide the necessary stimulus for the muscles to grow. Volume also is not very important though if it is too less of the repetitions, you may not be able to stimulate the muscle well. When providing time under tension protocol, you should be aware of how you are performing in terms of exercise technique, feeling the muscle tensions, controlled breathing, and so on.
Time under tension does not a replacement for what you are currently doing. It is additional method that can improve your overall performance. If you are struggling to seeing results, see if you can play with timer under tension with your favorite exercises for 4-6 weeks.
Initially, don’t worry about how much time under tension you should work with. Start with changing tempo to slower pace than what you normally would do.
Not Just Load and Volume
For building strength and muscle mass, how much weight you can lift (load) and how many reps you can do (volume) is the starting point. As you get stronger, you will also need to think of how much stimulus you can place on your muscles.
Kota Shimada
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