How Time Under Tension Can Help You Unlock More Strength Gains

The phrase “time under tension” might sound like something involving engineering or stress, but it's actually a fitness term. “You may hear the term ‘time under tension’ when it comes to strength workouts since the concept is simply the amount of time a specific muscle or muscle group is active and under tension during an exercise,” says Peloton instructor Katie Wang.

If you’ve ever heard an instructor call out “time under tension” as the reason for some leg-burning squat pulses or an excruciatingly slow push-up rep, you might not be excited to hear more about the training principle—but understanding it will help you appreciate its torturous nature and learn to use it yourself to score some hefty benefits. Everything you need to know about time under tension training, ahead.

What Is Time Under Tension?

Time under tension (often abbreviated to TUT) refers to the total time spent performing an exercise where the muscle is producing tension, explains Alex Rothstein, exercise science program coordinator at the New York Institute of Technology.

When is a muscle under tension, exactly? It helps to understand the three types of contractions a muscle performs during exercise, Rothstein says: concentric, isometric, and eccentric. Concentric is when a muscle is shortening, isometric is when there is no change in muscle length, and eccentric is when the muscle lengthens. Consider a bicep curl, for example. The upward movement of a bicep curl is the concentric contraction or phase. (Put your hand on your bicep as you curl, and you should feel the muscle shortening.) Lowering the weight is the eccentric phase of the movement; your bicep muscle is lengthening. Finally, imagine holding a dumbbell halfway in a curl with your elbow bent at 90 degrees. Your bicep is working to hold the weight, but the muscle isn’t changing in length: that’s an isometric contraction. 

A muscle is under tension during all three of these contractions. “Time under tension represents the total amount of time spent in all of these phases for a given set or workout session,” Rothstein explains. As such, several factors determine the amount of time under tension in a workout: the total amount of time you’re exercising; the number of reps and sets you’re doing (i.e., the training volume); and the amount of time each rep takes.

You can play with all three factors to increase the TUT in any workout. However, when people talk about “time under tension training” or “time under tension workouts,” they’re often talking about playing with the amount of time spent on individual reps. “Time under tension can be manipulated quite easily by either increasing or decreasing the amount of time spent in any of the three contraction phases,” Rothstein explains. For example, “I often like to play with tempo, holds, and pulses to increase time under tension in my Peloton workouts,” Katie says.

The Benefits of Playing with Time Under Tension

Simply put, playing with time under tension adds variety to your workouts and makes them more challenging. “Increasing your time under tension can help increase the difficulty of your workload and your overall strength without necessarily having to change the weight you are using,” Katie says. 

TUT can be especially helpful for people who don’t have very much equipment available or who want to challenge themselves without cumbersome weights. “It's a great concept to apply with bodyweight workouts—which is ideal when you’re traveling and don't have weights readily available,” Katie adds. “Adjusting the time under tension within the set is a nice way to create variety in the workout and challenge muscular endurance and strength.”

Reminder: You need to keep challenging yourself with your workouts to keep seeing gains. Exercise puts your body under stress, so your body adapts to better handle the challenge. To keep promoting adaptations, you need to keep increasing the amount of stress you’re putting your body under, according to the National Academy of Sports Medicine (NASM). This is the training principle of progressive overload in a nutshell: it’s the process of gradually increasing the demand placed on the body over time. Typically, it’s done by increasing the amount of weight you’re lifting or the number of reps you’re doing, but adding more time under tension is just another way of boosting the difficulty, Rothstein says.

If you feel stuck in a workout plateau, especially regarding your strength progress, adding a new stimulus, like more time under tension, can give your body the push it needs to keep adapting. It can help train your mental toughness, too. “Not only is it a great way to mix up your workout, but it also provides a mental challenge to slow things down in your workouts,” Katie says.

How Time Under Tension Workouts Affect Muscle Growth

If increasing time under tension challenges you the same way lifting heavier weights does, it surely helps you build bigger muscles, right? Sort of. Let’s get into it.

What Is Hypertrophy?

Muscle hypertrophy is the process of increasing the size, density, and shape of skeletal muscles, often through resistance training, according to NASM. Hypertrophy can result from many different types of exercise (especially if you’re a beginner), but you can also train for hypertrophy specifically. Hypertrophy training usually includes doing high volumes of training with light-to-moderate weights. According to NASM, the optimal set, rep, and intensity ranges for muscle hypertrophy is –5 sets of 6–12 reps using a weight around 75–85 percent of your one-rep max (aka 1RM, the maximum amount of weight you can lift for a single rep).

Bodybuilding is an excellent example of hypertrophic training. Bodybuilders typically follow a workout split that dedicates each lifting session to one or two muscle groups and do a moderate number of reps and sets of exercises that all target those same muscles. Overall, this results in a lot of time under tension for the targeted muscle groups.

Does Increasing Time Under Tension Help Build Muscle?

If you’re talking about the time under tension of a whole workout, then yes. High volumes of training (28−30 sets per muscle per week) are generally better for inducing muscle growth than lower volumes (6−10 sets per muscle per week), according to the American College of Sports Medicine (ACSM). And high volumes of training tend to result in higher TUT overall.

However, if you get more granular and look at the time under tension per rep or during each movement phase, the benefit is less clear. Neither slow nor fast-paced reps seem to make a difference in hypertrophy, according to a 2021 review published in Sports Medicine.

However, it may be beneficial to take a half-and-half approach. Research shows that eccentric movements are more conducive to hypertrophy, so it’s theorized that increasing the eccentric time under tension may help promote muscle growth. Though we don’t yet have definitive scientific evidence to prove it, the Sports Medicine review authors suggest that the best pacing for hypertrophy may be a combination of slower movement in the eccentric phase with a faster movement during the concentric phase. For example, with a bicep curl this would look like slowly lowering the weight and quickly raising it back up. 

How Long Should Time Under Tension Be?

More serious lifters may be curious about how to pace their reps for the best results, according to the time under tension principle. A review of research on TUT training published in the International Journal of Sports Medicine found that a wide range of repetition tempos can offer benefits and that the best one depends on your goals. 

For example, the researchers concluded that both a fast rep tempo (eccentric phase of 1–3 seconds; concentric phase less than one second) and a moderate-slow rep tempo (eccentric phase of 1.7–3 seconds; concentric phase also 1.7–3 seconds) significantly improve muscular strength (i.e., how much weight you can lift).

Similarly, to develop maximum power, another review published in the Strength and Conditioning Journal found that 4- to 8-second reps are suitable, depending on your ability level, as long as the concentric motion is quick or explosive (less than three seconds).

For hypertrophy, the International Journal of Sports Medicine review found that similar muscle growth occurred along a wide repetition tempo spectrum (0.5–8 seconds) when sets were performed to failure (when you physically can’t do any more reps). The Strength and Conditioning Journal review came to a similar conclusion; the researchers recommend a total rep time of eight seconds or less, but note that the optimal timing of each movement phase for maximizing hypertrophy is still not entirely clear. As explained above, it may be beneficial to perform a slower eccentric phase and faster concentric phase, though we can’t say for sure. 

So, if your goal is to build muscle, there’s (unfortunately) no one best answer to this question. In general, to encourage hypertrophy, muscle cells need to be under tension long enough to prompt the muscle to get bigger—usually around 40–70 seconds per set, NASM reports. So, whatever tempo you try, don’t speed through your sets too quickly.

Should You Try Time Under Tension Workouts?

Unlike more advanced lifting techniques like drop sets or density training, exercisers of any level can use time under tension to help spice up their training. “Everyone should give time under tension a try in their workouts,” Katie says. 

If it all sounds a little too complicated, rest assured: Time under tension isn’t something you need to pay attention to in your workout routine (especially if you’re following guided, instructor-programmed workouts like those on the Peloton App), though you may incorporate the technique without even realizing it.

How to Add Time Under Tension to Your Strength Work

Next time you’re powering through a workout and not feeling challenged enough, try slowing down your reps or adding pauses or isometric holds, Katie suggests. “Those are all ways you can increase the time under tension thus forcing your muscles to adapt and build strength in response to the new stimulus,” she says. 

Rothstein also recommends incorporating TUT into your workouts by first becoming aware of the cadence you typically use during strength sets. Then, “instead of just counting reps, try to set different tempos to each phase of the rep,” he says. For example, if you’re listening to music, you can try performing the concentric phase in two to five beats, pause for one to two beats, perform the eccentric phase for two to five beats, and count that as one rep. “This will most likely be slower than your regular pacing and will feel significantly harder to complete the normal number of reps,” he says. So, if you can’t lift as much weight or finish your set, don’t feel bad about it. It means you’re genuinely challenging yourself.

Takeaway

Whether you’re pressing to the beat during an Intervals & Arms Ride with Cody Rigsby or holding a plank during Pilates with Aditi Shah, time under tension is part of your workout. There’s no need to worry about manipulating TUT if you’re a beginner or following guided programs like Peloton’s. However, understanding the technique can help you realize the value of those brutal squat pulses and potentially help you level up your solo strength work. At the very least, playing with time under tension training gives you an excuse to slow down, be more mindful, and really feel the burn.