This concept refers to how long your muscle is under strain or resisting the weight during your set. For example, if you were doing a Tricep pushdown, it might take you 2 seconds to push down and 1 second to let the weight go back to its starting position. Let’s say you were doing a set of 12, meaning the total time under tension for each rep is 3 seconds, if you are doing a set of 12 then your set total time under tension is 36 seconds. Breaking the terminology apart, TIME is the period during your set where your muscle is contracting, and TENSION is the force that is produced to contract, move and hold the weight.
It has been found there are three different ranges, which can help target your goals when you are lifting.
Strength: 1-30 seconds
Hypertrophy: 30-70 seconds
Muscular Endurance: 70-100 seconds
Now, is this necessarily something you should be focusing on when you are going about your workouts? Nope! It is more important to focus on form, intensity and on the muscles being utilized in your set. You can only focus on so many things when you are lifting. Having the need to count out seconds just to ensure you reach a target zone wouldn’t benefit you at all! Instead, you could be focusing on maintaining proper form, which not only moves the muscle properly but can also prevent injury.
I mean when you watch professional bodybuilders train, what do you notice? Are they tracking their time under tension? Nope, instead, they are solely focused on maintaining good form and intensity during their sets.
Remember, YOU control the weight and not the other way around.
Explode on the positive part of the movement, which will allow maximum activation of your fast twitch muscle fibers. Your body is comprised of two different types of skeletal muscle fibers: slow-twitch and fast-twitch. Slow twitch is activated in times the body is going through any type of endurance feats such as long-distance running. Fast twitch muscles are activated and utilized when your body needs powerful bursts of energy to move like sprinting.
So, you are exploding on the positive part of your rep, upon reaching the top of the movement, squeeze and hold the contraction for at least one second. Control the negative, which is the movement when the weight is lowered back down to the starting position.