Go slower for strength training gains

To maximize strength training benefits, you sometimes need to take it slow. A form of training called time under tension, or TUT, focuses on the amount of time muscles are activated during an exercise, rather than the number of repetitions or amount of weight.

“Many people don’t realize how fast they go through their exercises,” says Corey Goldman, a physical therapist with Harvard-affiliated Spaulding Rehabilitation. “TUT forces you to slow the tempo and make controlled movements, so you can keep your muscles engaged longer and stimulate muscle growth.”

What happens with time under tension

Each repetition (rep) in strength training has three phases: concentric (lifting the weight), isometric (holding the weight still), and eccentric (lowering the weight). How long it takes to perform the rep equals your TUT.

For example, at a typical pace, a repetition might take one second for lifting and one second for lowering, with no pause in between, which equals two seconds of TUT. However, if you slow your tempo and take two seconds to lift, add a one-second pause, and take two seconds to lower, your TUT more than doubles. Those extra seconds add up. The idea is that over time, the added stress from prolonged muscle tension can lead to greater muscle growth.

Other benefits of time under tension

TUT has many other benefits. Training muscles to sustain contractions for longer periods can increase their stamina. This comes in handy when you’re performing repetitive and prolonged activities, like lifting and carrying items and walking, running, or cycling for long distances.

“Going slower helps you be mindful of how your body moves, making it easier to maintain proper form,” says Goldman. “You can avoid injury and execute each rep to its full potential.” If your workouts feel stagnant or your progress has hit a plateau, introducing TUT can add a new challenge.

Finding your tempo

No single tempo works for everyone. A review of previous studies, published in the March 2024 issue of the Journal of Functional Morphology and Kinesiology, looked at the evidence and suggested that any tempo up to eight seconds per rep is beneficial.

Goldman recommends starting with a 3-1-3 tempo: three seconds to lift, a one-second hold, and three seconds to lower. “It’s easy to follow, and it creates a smooth flowing rhythm like a metronome beat,” says Goldman. If keeping track of your tempo is challenging, or if it’s difficult to slow your pace, a training partner or personal trainer can count out loud for you.

How to perform time under tension

TUT can be applied to practically any type of strength training exercise, even vertical movements like squats, lunges, and pull-downs. You can use TUT with free weights or gym machines.

Be aware that a slower tempo tires out muscles more quickly, so at first you may need to use lighter weights or do fewer reps than usual. “Always keep in mind that it’s not how much you lift or how many reps you do, but how long you keep your muscles engaged,” says Goldman.

He suggests starting with a familiar exercise like a biceps curl. Use enough weight so you can complete no more than 10 reps at a 3-1-3 tempo. Increase the weight by 10% to 15% next time, and gradually build up to your usual weight. Aim to complete six to 10 reps of TUT per set; lower or increase the weight as needed to stay in this range. As you add more TUT exercises to your workouts, focus on different muscle groups to prevent muscle imbalance and protect against strains and injuries.

Remember that TUT is just one tool of many that can aid in strength training. “TUT is not something you have to do all the time — or should,” says Goldman. “But adding TUT occasionally to your regular workouts is a great way to give your muscles an extra boost.”

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