Time Under Tension refers to how long a muscle is under stress during a set of weight lifting. The number of seconds it takes you to complete a set is your total time under tension. It is directly related to the tempo you are using for your concentric and eccentric movements of each repetition. So, if you are counting two on the way up, one at the top, and three on the way down, your time under tension is five seconds per rep. After 10 reps, you have a total time under tension of 50 seconds. Multiply that number by the number of sets you are doing of that exercise, and then, add together the value of every exercise of your workout. This will give you your total time under tension. For best results, it is recommended to reach 30-70 seconds per set.
Why is any of this important?
Working to improve your time under tension will enhance your metabolic response. The longer your muscle remains under tension, the greater the release of growth hormone your body will experience, and thus, your muscle definition will increase. Furthermore, longer time under tension results in increased metabolic rate because you will be creating a higher degree of micro tears in the soft muscle tissue, and the body will need to expend more calories repairing those micro tears. The muscle—subsequently– learns to deal with a higher level of fatigue over time.
Increasing time under tension will result in new muscle growth. In 2012, a study was performed to determine the effects of increased time under tension on protein synthesis. Researchers took needle biopsies of the right and left leg muscle tissue from men who performed longer, slower reps on one leg and faster reps on the other. After six hours, the rate of protein synthesis was elevated by 114 percent in the leg that performed slow contractions versus only a 77 percent increased rate in the leg that performed faster repetitions. Furthermore, after 30 hours, mitochondrial protein synthesis rates were increased to 175 percent in the leg that performed slower contractions versus 126 percent in the leg performing faster contractions.
This study supports how time under tension leads to increased muscle growth. It is important to try and maintain a steady tempo throughout the exercise. It is also ideal to spend more time on the eccentric movement than the concentric. The eccentric portion of the movement, i.e., the lowering, is when your muscle is lengthening. (Think of a bicep curl, for instance. The pulling up of the dumbbells is the concentric while the lowering back to place is the eccentric part of the movement). Slowing down during that portion of the repetition will cause more muscle tears and encourage more muscle growth.
Incorporating a focus on increasing time under tension into your regular workouts will stimulate muscle growth at a much more efficient pace. More muscle growth equals higher metabolic rate and leaner mass.
