At some point in your fitness journey, there’s a good chance you’ll reach the maximum capacity of the dumbbells, kettlebells, or weight plates you have access to at your neighborhood (or home) gym. The issue? You require these increasingly heavy tools to continue enhancing your strength and muscle development.

At least, so you believed: Increasing your duration of muscle contraction can aid in advancing your workouts without the need to increase the amount of weight. So how does it work? Here, a fitness expert shares the advantages of extending your duration of muscle contraction and how to utilize this resistance-training technique during your own workouts.

What Is Duration of Muscle Contraction?

Simply put, duration of muscle contraction refers to the length of time your muscles spend contracting against an external resistance, says Tessia De Mattos, P.T., D.P.T., C.S.C.S., a physical therapist and strength and conditioning coach in New York. The slower you lower into and rise out of a squat, for example, the longer the duration of muscle contraction, she says. “The total time that your muscles are contracting is much longer than if you were going at a regular pace,” she adds. You can increase the duration of muscle contraction by lengthening the concentric (when your muscle fibers shorten) or eccentric (when your muscle fibers lengthen) portions of a movement, says De Mattos. Or, you can get the job done by spending more time in an isometric position — holding still so there’s neither lengthening nor shortening of the muscle, research shows. (

The Advantages of Increasing Duration of Muscle Contraction

Though increasing duration of muscle contraction during your workout is fairly simple, it can be a valuable tool to utilize during your strength training routine.

May Enhance Muscle Strength and Hypertrophy

By slowing down your reps and increasing your duration of muscle contraction, you might observe more muscle gains. In fact, a small 2012 study found that performing leg extensions with slow lifting movements until fatigue led to greater increases in muscle protein synthesis rates than when the same exercise was performed quickly. During muscle protein synthesis, cells rebuild damaged muscle with amino acids, which may ultimately encourage muscle hypertrophy (aka growth), says De Mattos. Similarly, research published in 2016 found that slowing down the eccentric portion of a movement increases muscle activation and production of blood lactate — a sign of fatigue within a working muscle, which itself promotes hypertrophy, according to information from UC Davis Health.

In theory, increasing duration of stress, especially during the downward part of movements, should cause you to tire more quickly, she explains. There are many valid reasons as to why it should help enhance your power, but research hasn’t caught up, says De Mattos.

Establishes Favorable Motion Patterns

Aside from potential benefits, slowing down your pace can assist you in cultivating body awareness and learning the correct mechanics of a new movement, which can be particularly advantageous for fitness beginners, says De Mattos. “If a person has never exercised before or they have no previous experience with being active, their body awareness probably isn’t great,” she adds. “[Increasing duration of stress] is an excellent method to learn how to move.” Even intermediate gym-goers can gain insights by decelerating their repetitions. For example, intentionally performing a squat slowly may reveal in the mirror that your knees are collapsing inward or extending too far past your toes — form errors that may go unnoticed if you always perform rapid-fire repetitions, she explains. “It gives you the chance to correct that before you develop bad habits,” she adds.

Supports Tendon Health

While you can increase duration of stress during both the lifting and lowering phases of movements, De Mattos suggests slowing down the latter phase, as doing so may promote tendon health. “There’s a lot of research that supports the fact that tendons, which connect the muscle to the bone, really respond well to slow, controlled lowering — they respond really well to that,” she says. In fact, controlled lowering and heavy, deliberate resistance training have both been found to improve symptoms and tendon structure in people recovering from chronic tendon conditions.

How to Employ Duration of Stress During Strength Workouts

Increasing duration of stress is as simple as prolonging the time spent executing each repetition of a given exercise. However, there are still a few pointers you should bear in mind when incorporating it into your resistance-training sessions.

Utilize Bodyweight or Loaded Exercises

Since all exercises have lifting and lowering phases, you can increase your duration of stress by performing any of your preferred movements, says De Mattos. You might slow down your squats, leg extensions, or Romanian deadlifts to strengthen your lower body, or your bench presses and bent-over rows to achieve the same effect for your upper body, she adds. Alternatively, you can extend the duration of stress by briefly holding a position midway through an exercise, such as during a repetition of the superman or Bulgarian split squat.

Plus, you don’t have to utilize weights in order to experience the sensation of burning. “It’s an excellent method to elevate the difficulty of [a bodyweight exercise] for yourself,” states De Mattos. “Suppose you’re simply doing activities at home and you don’t have access to the gym — incorporating tempo, experimenting with the speed at which you perform, whether fast or slow, is an excellent way to introduce variety and advance yourself.” If you do decide to incorporate weights, opt for a load that is lighter than what you would typically use for regular repetitions, she recommends. “If you’re increasing the amount of time your muscles are under tension while simultaneously performing a weighted exercise, it will undoubtedly feel much more challenging.”

Count to Five

To execute an efficient time-under-tension workout, you’ll want to devote approximately five seconds to each repetition, according to De Mattos. “Anything longer than that will feel like agony,” she jests. If you desire to push your boundaries, strive for six seconds per repetition, as research published in Sports Medicine has discovered that this timeframe has the greatest impact on improving muscle strength. To ensure that you genuinely work within this timeframe, consider having someone count aloud using Mississippis or set a timer, suggests De Mattos. Without this sense of accountability, you may cheat on your repetitions and end up working for only half the necessary time required to induce muscle fatigue and hypertrophy, she explains.

Don’t Skip Rest Breaks

When extending the time under tension, it is crucial to allow your body ample rest time between sets. “If you’re engaging in strength or hypertrophy training, you should provide your muscles with sufficient rest time — at least one minute between sets,” says De Mattos. “If you’re returning to the next set faster than that, it signifies either it wasn’t challenging enough or you’re attempting to elevate your heart rate as if you were participating in a HIIT class, focusing on improving cardiovascular health and endurance rather than strength.” In other words, just like with your repetitions, avoid rushing through your rest breaks.