Time under tension: what is it, and could it help you grow muscle?

Man holding a kettlebell doing a squat outdoors on a running track
(Image credit: Shutterstock)

Time under tension (TUT) is an approach predominantly found in weightlifting, but not exclusively. As the name suggests, it refers to the time muscles spend activated (or under contraction) during an exercise. 

By increasing the amount of time a muscle is held under tension when working with the best adjustable dumbbells, weights, or your body weight, you could benefit from hypertrophy, which is the process of building muscle. Doing so could add more challenge and resistance during an exercise, which could help build muscle without lifting heavier weights

If you’re considering adding the time under tension technique to your strength training program, we cover what time under tension means, the potential benefits, and whether it could help you grow muscle mass. 

What is time under tension?

As mentioned, TUT uses tempo to make your muscles work harder through the same amount of resistance. It involves slowing down an exercise and performing it for longer, extending the total time worked. The technique is also used during high-rep endurance training to improve muscular endurance. 

Many coaches program exercise tempo in three stages — the concentric phase (when muscles shorten or contract), the eccentric phase (when the muscle lengthens), and the pause between them. 

For example, a bicep curl programmed at a 4-1-4 tempo would mean lifting the weight for four seconds (concentric loading), pausing for one second, then lowering the weight (eccentric loading) for four seconds. 

Adding a longer pause adopts isometric contraction — placing muscle under stress without shortening or lengthening.  

Does time under tension for hypertrophy work? 

During exercise, your muscles work hard, and muscle fibers micro-tear. It was thought lactic acid build-up was the reason for next-day delayed-onset muscle soreness (DOMS), but we now know these micro-tears are the most likely cause.

When this sort of "injury" happens to muscles, the body will send necessary healing to the area, and you’ll also produce the growth hormone, helping muscles adapt and grow stronger. It’s how you build muscle mass — essentially, you break it down to build it up stronger — a process called hypertrophy. 

However, different tempos suit different styles of training. To develop power (think a sprinter or high jumper), you’ll focus on fast and powerful movement that recruits your fast-twitch muscle fibers, responsible for quick bursts of movement. For endurance sports and hypertrophy training, a slower tempo will recruit the slow twitch fibers (or sometimes a mix of both), responsible for more sustained periods of exercise.

Person holding two dumbbells during bicep curl close up

(Image credit: Getty images/ Unknown)

But does TUT work? Some research supports adopting the time under tension technique when working out with weights. One example is an excerpt from the Science and Development of Muscle Hypertrophy: "evidence indicates that TUT plays a role," but we should also consider the "context of the resistance training variables comprising a given routine." 

The body of work suggests total TUT for a muscle group is most relevant — that could be in a session or over time across a week — and a longer TUT (60 seconds or more) per set could be "beneficial for targeting hypertrophy of Type I muscle fibers.’"

Another 2016 study found that doubling the eccentric loading time compared with concentric had positive impacts on growth. But before focusing on rep duration or increasing volume for muscle growth, make sure you lift weights with good form and focus on the correct range of motion to maximize the benefits.

Time under tension workout 

If you plan to try TUT training, start by following a strength training program and spend 35 to 60 seconds on each set. For example, if you timed a bench press at 4-1-4 for 6 reps per set, you’d hit 54 seconds. You might need to lift slightly lighter than usual to achieve a longer set, but it also shouldn’t feel easy.

Another way to achieve time under tension during a high-intensity workout is using a complex workout. By grouping exercises into one longer working set without rest, you can reach the same goal of working muscles for longer toward fatigue. This five-move barbell complex workout strengthens muscles and boosts your metabolism in 20 minutes. 

You could also follow the same format for bodyweight exercises like squats and push-ups. We love this calisthenics workout for developing muscle and trying out functional training

If you’re looking for more creative ways to adopt time under tension for muscle growth, add more reps to increase overall training volume or supersets to target and fatigue one muscle group. This Arnold Schwarzenegger workout builds full-body strength in just four moves and uses cluster supersets to work muscles harder. Performing the moves back-to-back will increase overall reps and work muscles longer to build strength and mass. 


Time under tension techniques could help build muscle mass alongside progressive overload — training regularly and adapting your routine incrementally as you improve, like adding weight. Protein is also a big player in building lean muscle, so focus on ample protein intake as part of a balanced diet to support gym gains alongside sleep and recovery time. Already a protein pro? Here are the best protein shakers we swear by. 

If you’re currently suffering from injury, seek advice from your physician before engaging in new exercise regimes. 

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Sam Hopes
Senior Staff Writer - Fitness

Sam Hopes is a level III qualified fitness trainer, level II reiki practitioner, and senior fitness writer at Future PLC, the publisher of Tom's Guide. She is also about to undertake her Yoga For Athletes training course. Having trained to work with mind and body, Sam is a big advocate of using mindfulness techniques in sport and fitness, and their impact on performance. She’s also passionate about the fundamentals of training and building sustainable training methods.  When she's not writing up her experiences with the latest fitness tech and workouts, you’ll find her writing about nutrition, sleep, recovery, and wellness.