What exactly is Time under Tension?
Time under tension (TUT) is a way of calculating the total amount of work you place on a muscle. When you talk about time under tension, this essentially refers to how much time the muscles are under stress. Time under tension (TUT) refers to the total time a muscle resists weight during each set. TUT, is one of the most important triggers for muscle hypertrophy or growth
As an example, a set of incline dumbbell flyes, with a 4-1-2 cadence, would mean that the dumbbells are lowered towards the chest (eccentric phase) over four seconds, then held at the bottom of the movement for one second, then pushed back up (concentric phase) over two seconds. If I performed 10 reps this would translate into a time under tension (TUT) of 70 seconds. If you increased the speed of those reps to about three seconds, then it would take you only 30 seconds to complete a 10-rep set. Although the number of reps and the amount of weight are the same, the second set might not increase your muscle mass to the same level as the first. And that’s the basis of time under tension training.
Time under Tension (TUT) Set Time
Research shows that the best way to gain muscle strength is by performing 1-6 reps per set; for muscle growth (bodybuilding), your ideal rep range is 8-12; and for muscle endurance, 15-30 reps prove most beneficial. The problem is that all these ranges assume that each rep takes about four seconds to complete. If you extrapolated those figures, you’d assume that the best time under tension (TUT) set ranges are 4-24 seconds for strength, 32-48 seconds for growth and 60-120 seconds for endurance. However, strength coaches and training experts have tweaked those values based on their own experience.
Time under Tension (TUT) Studies
In 1989, a team from the University of Texas Southwestern Medical Center at Dallas conducted a study where they analyzed 156 training variables for exercise-induced increases in muscle mass in cats. The variable which demonstrated the highest correlation to increases in muscle mass was the lift time. Next on the list was the amount of weight lifted. Basically, slow lifting movements with relatively heavy weights resulted in the greatest muscle mass gains. According to the researchers, “The slow lifting style may minimize the role that momentum plays in completing the lift, thereby maintaining the need for tension development throughout the range of movement.” As long as the stimulus was sufficient and progress was made over time, muscle mass increased. However, the paper did indicate that a critical level in the amount of weight lifted was necessary for hypertrophy. In this particular study, it was a minimum of 30 percent of the cat's body weight
Sure, we're not cats, so if you do not believe in the results of this 25 year old study, we can turn to two additionally studies.
Wernborn et al. took aim at the same variables in humans in a massive 2007 review study titled “The influence of frequency, intensity, volume and mode of strength training on whole muscle cross-sectional area in humans.” After analyzing hundreds of studies, the researchers concluded that performing sets to failure with moderately heavy loads—at least 60 percent of 1RM, with highest rates occurring around the 70-85 percent of 1RM mark, yielded the greatest hypertrophy (muscle growth) results. The review clearly indicated that maximal loads are not necessary for hypertrophy, but also that training should be performed close to maximum effort in at least one set. Equally important, Wernborn et al concluded that the total duration of muscle activity per session may be a more critical factor than the total reps in inducing hypertrophy (muscle growth).
In a 2012 study in the Journal of Physiology titled, “Muscle time under tension during resistance exercise stimulates differential muscle protein sub-fractional synthetic responses in men”, Burd et al., also looked at time under tension (TUT) and maximum muscle hypertrophy (muscle growth). The study confirmed the value of time under tension (TUT) in stimulating hypertrophy (muscle growth) with a conclusion that increasing muscle time under tension during exercise may be important in optimizing muscle growth.
Using Time under Tension (TUT) to Maximize Muscle Growth
So how do we put time under tension (TUT) into action in our training routines? When it comes to tension, it's all about finding the sweet spot between “too high” and “too low.” If you are training for muscle growth or hypertrophy, then typically each set you perform should have a total time under tension (TUT) of between 40-70 seconds per SET using a moderately heavy load of 70-85 percent of 1RM, or a weight that allows you to achieve between 5 and 12 reps maximum, is ideal.
Breaking this down to time under tension (TUT) per rep, the best approach for maximal growth is to for a moderate pace of 4-6 seconds per repetition, with a time under tension that ranges from 24 seconds (4 seconds x 6 reps) to 60 seconds (6 seconds x 10 reps) per set.
Using Time under Tension (TUT) to Maximize Strength
If pure strength is your goal, then each set (1-6 reps) would have a total time under tension (TUT) of no more than about 20 seconds.
Rest between Sets
The rest periods between sets are another area where time plays an important role in muscle growth (hypertrophy). If you don't rest enough, then of course fatigue will hinder your performance on the next set. But resting too long isn't ideal either. The goal is sufficient, but not complete recovery. So what does sufficient mean? After looking at the research, I'm convinced that sufficient recovery occurs when rest intervals are at least two minutes in length, but generally not more than three minutes. If you are less conditioned, then when rest intervals up to 5 minutes between sets may be warranted until you bring your conditioning up.
From a neuromuscular perspective, studies show that it may actually be more beneficial to take advantage of the neural excitation from the previous set than to wait for fatigue to diminish altogether. Up around the 5 minute mark, neural activation often declines to a point where carryover is more or less lost for the next set.
A number of studies have shown that rest intervals of 3 minutes allow good recovery from fatigue while still taking advantage of neural excitation from the previous set. This rest interval with maximum load has shown to lead to maximal increases in testosterone and GH levels, conducive for optimal growth. There are studies that show that using this approach occasionally can result in GH increases of twenty-fold, about the same level that is released early in sleep so using this type of protocol has great potential to build muscle and reduce body fat at a high rate.
Time under Tension (TUT) Benefits
Greater Metabolic Response. The first big benefit you’ll get from monitoring your time under tension and then working to improve it is an enhanced metabolic response. The more time under tension (TUT) you’re placing that muscle under, generally the greater the growth hormone (GH) release will be.
Jump-starts the Metabolism. Additionally, if you have a large time under tension, you’ll also really jump-start the metabolism since you are making the body do so much work and will be creating quite a high degree of micro tears in the tissues, therefore this will cause the body to expend more calories once the workout is finished.
Forces Better Form. Studies show that people who perform faster reps tend to have poorer form, use momentum, and actually have higher incidence of muscle and joint injuries. Therefore slowing the rep speed down tends to improve form, which results in less incidence of injuries, and increased muscular development.
Helps Prevent and/or Reduce Joints Pain. Prolonging the time under tension (TUT) of any given rep reduces the mechanical stresses on joints, making it an attractive possibility for those suffering from orthopedic issues.
Helps Improve Muscle Endurance – Employing time under tension (TUT) training techniques help the muscles learn to deal with a higher level of fatigue (including lactic acid buildup). Since the more stress you place on the muscle with increasing the amount of time the muscle is under tension, the more you’ll deplete the muscle of the resources it has, the greater its ability to deal with fatigue will become. If you’re looking to fully deplete your muscle glycogen levels so that when you come out of that workout session and load up with carbs post-workout to evoke a huge muscle growth potential, increasing your total time under tension for each set, is one good way to do it (most people instead will typically the total number of reps per set to increase time under tension (TUT), rather than focusing on increase rep time to increase total TUT).
Keys to Success when Using TUT to Maximize Muscle Growth
Monitor Total Rep and Set Time. To monitor your rep speed and total time under tension (TUT) for every set, you need to watch the clock. If you train with a partner, have help you count off reps at the right speed, track total set time and keep you in your time under tension (TUT) window. If you train alone, try to estimate your time by counting off with the one-one thousand system: Count the time it takes to complete each rep and the set, starting with one-one thousand and counting up.
Do Not Stop Counting Reps. When you’re training for muscle mass, continue to shoot for 8-12 reps. But incorporating time under tension (TUT) training into your routine can allow you to widen that rep range to about 6-15 per set, as long as you stay within the time under tension (TUT) range of 40-60 seconds. So if you decide to perform six reps of barbell curls, you would need to slow down your reps to about seven seconds per rep for a total of 42 seconds of time under tension (TUT). If you did 15 reps of barbell curls, you’d need to keep the reps to about 3-4 seconds for a total of 45-60 seconds of time under tension (TUT).
Variance Is Key. Regardless of your training goals, it’s important to vary your reps and time under tension (TUT) times within the range of your goal so your body does not get used to a specific cadence, total TUT time per set. Other ways to use variance to your advantage is: (1) to not use time under tension (TUT) training techniques for every exercise or every set (2) Use TUT every third workout, etc.
Do Not Drop the Weight too much or Decrease Set Volume. Now that you can see that using a higher time under tension (TUT) is an effective strategy to bring about higher levels of muscular fatigue, one thing that you do want to note here is that this doesn’t mean you should go reducing your weight, or dropping your set volume. These are key mistakes that people trying to implement time under tension (TUT) make and it will really hold them back from progress. The goal of any muscle building workout program must always be to maintain heavy lifting, and total time under tension (TUT), so really try and ensure that you aren’t dropping the weight too much, and you’re not dropping your total volume too much to achieve a greater rep time under tension (TUT). Aim to use a moderately heavy load of 70-85 percent of 1RM, or a weight that allows you to achieve between 5 and 12 reps maximum. Think about total workout time under tension (TUT) and total load moved for each body part to maximize growth. Do your best to maintain your current set volume.
Do not forget to Other Important Factors. For time under tension (TUT) training techniques to be effective it is extremely important to eat to grow (get proper amounts of macros) get proper recovery/rest time, choose proper exercises, training frequency, and employ moderate to heavy lifting with increased resistance.
Bottom Line on TUT Training
At the end of the day, your muscles grow in adaptation to your training demands (frequency, intensity and volume). The time a muscle is under tension is a proven factor in stimulating optimal growth, and should be something to be considered to add to your training regimen if you are looking for ways to jump start your training and improve your muscle building results. Muscle time under tension (TUT) can help save your joints, improve your training form, allow you to develop strong neuromuscular pathways with your target muscles and help maximize muscle growth.
About the Author Jeff Behar
Jeff Behar, MS, MBA, is a well-known health, fitness, wellness author and anti aging, champion natural bodybuilder (2014 Masters Grand Prix Champion, 2015 California State Masters Champion), and a recognized health, fitness and nutrition expert with over 30 years of experience in the health, fitness, disease prevention, nutrition, and anti-aging fields.
As a recognized health, fitness and nutrition expert, Jeff Behar's has been featured on several radio shows, TV, and in several popular bodybuilding publications such as Flex, Ironman and in several highly regarded peer reviewed scientific journals. Jeff Behar is also the CEO and founder www.MuscleMagFitness.com and www.MyBesthealthPortal.com and a Medical Commentator on exercise for The American Academy of Anti-Aging Medicine, the worlds largest medical academy for anti-aging and regenerative medicine, provides medical professionals with the latest Anti-Aging, regenerative, functional and metabolic medicine.
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