Why ‘Time Under Tension’ Is the Latest in Efficient Fitness Trends

This shift in the focus is what some pro trainers are calling the next frontier in fitness.

The concept is referred to as “time under tension,” or TUT for short. Sebastien Lagree, creator of the Lagree Method (the megaformer workouts that are mega-challenging) is a huge proponent of this concept. “TUT is the amount of time a muscle is working during an exercise set,” he explains. Instead of counting reps—something Lagree says is “actually useless” because of so many variables in personal speed and performance day to day, rep to rep—“you time the muscle contraction, and that becomes the new measure of gain.”

Rob Darnbrough, co-founder of Smart Fit Method, wholeheartedly agrees. “Time under tension is when the muscle is being fully challenged throughout the entire range of motion,” he says.

This works both during the concentric phase—when the muscle shortens—and eccentric phase—when the muscle lengthens. (Think of a biceps curl: When you bring the weight up and in, that’s a concentric contraction; when you lower the weight back down, that’s the eccentric contraction.) The aim is for both of those phases to have sufficient tension to fatigue the muscle.

“If you are locking up your joints or taking breaks during the designated time you’ve allotted for the exercise, you are not using the time under tension method,” says Heather Perren, senior master trainer at Lagree and co-founder of Lagreeing at Home. “Time under tension is exactly what the name implies: You are keeping the muscles under tension for the entire duration. No breaks!”

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The benefits of time under tension

Efficiency is really the name of the game here. In theory, the concept cuts down on “wasted time” during workouts. (One might argue that the mental health and recovery benefits of down time during a workout aren’t necessarily wasted, but for the sake of minimizing input for maximum output, we’ll take it.)

“Strength training comes down to three things,” says Darnbrough. “Mechanical load, muscle damage, and metabolic stress.” Applying the appropriate amount of time under tension will increase the results you get from each of those factors.

“The body doesn’t care how many sets or reps you did,” Darnbrough continues. “It only matters how much time the muscle is truly under tension.”

The experts at Lagree Method point out that TUT forces your muscles to work harder, and therefore optimizes muscular strength, endurance, and growth. “It’s a great way to give your body a challenging, high-intensity workout,” says Perren. “Because TUT is done keeping time, not reps, you can slow the pace down, which also makes your workout safer.”

Lagree himself also adds that TUT is a “more accurate measure of improvement over just counting repetitions.” You can't simply speed up your way through the challenge or abuse momentum—when you're able to spend more time contracting a muscle, you truly know it's getting stronger.

How to apply time under tension to your workouts

TUT can be used in any type of strength workout, including Pilates, megaformer workouts, and classic weight lifting and strength training.

“In Pilates, this is why we emphasize slow movements,” says Adriana Vargas, master Pilates trainer and founder of Live+Love Pilates in La Jolla, California. “Not only does it allow you to focus on your form and your breath, but also muscle connection and tension. The pace of the motion—or control—with that specific resistance is very important, as it will allow you to focus and build those long lean muscle fibers that we develop with Pilates practice.”

Lagree says this concept has been a part of his method for nearly 20 years. His classes use a minimum of one minute for exercises involving core and upper body, and a minimum of two minutes for the lower body exercises. “We never count repetition in class, we only keep track of time,” he says. “You can easily incorporate TUT in other forms of exercise by using a stopwatch instead of counting reps to failure. Each time you perform a move, try to increase the set so it takes a little longer than the previous time.”

If you’re using hand weights, dumbbells, or a traditional gym machine, Darnbrough says TUT can be achieved by “slowing down the movement,” and essentially holding it where you feel the burn for a little longer.

Looking for a general guidepost? An ideal time under tension is between 90 seconds and two and a half minutes for most exercises, says Darnbrough. “This will increase muscle damage and hypertrophy, strength and metabolic conditioning.”

Ready to get stronger? Try testing out time under tension with the Arnold Press: