It’s not always about reps. 

This is the oft-forgotten truth about muscle-building and your workouts. In general, we often default to counting reps and sets in our training, thinking the more reps and sets of work we pile up, the better we’re doing at creating muscle-building stimulus.

But what you’re actually chasing with all those reps is something called “time-under-tension,” and this is actually the true secret to building muscle. What is time under tension? It’s literally the amount of time during which a muscle is “tensing” or straining during a rep.

Take a biceps curl, for example. Stand holding the dumbbells, arms relaxed, and your biceps aren’t under tension. But once you begin the curling motion, biceps literally “tense.” They stay tensed as you curl up and flex, and as you lower back to the starting position, they’re tense, too. It’s not until you’re fully relaxed that you release them from this tension.

Even when you’re piling up reps during a workout, you shouldn’t simply blindly be chasing total reps. Instead, you’re doing all those reps to accumulate total “time under tension” during a set. The more time you keep your muscles under tension with a challenging weight, the more you’re subjecting them to the muscle-building stimulus you need for growth.

Using Time-under-tension

Once you understand time under tension, you begin to understand why you can’t just rush reps, and why form matters so much on just about every exercise. If you speed through, say, 15 reps of bodyweight squats in 15 seconds, then your legs are under actual tension for barely 15 seconds. That’s not nearly as much muscle-building stimulus as they need, depending on your training goals.

Slow things down, and that all changes. Imagine lowering into a squat, and doing so slowly, taking 3 seconds to lower your butt to the ground. Suddenly, quads and hamstrings must tense up to control your body to the ground. Do 10 reps this way, and you’re getting 30 seconds of time under tension, and also developing better body control.

All of this requires proper form. Go back to the bicep curl. If you lift weights beyond what your biceps can handle and you have to “cheat” the weight upwards, then your biceps face less actual “tension” because your body and momentum did the work instead of your biceps. Stand with the weights, tighten your abs and glutes so your torso doesn’t move, and curl the weights upwards slowly, then lower them slowly, and your biceps face a truer challenge.

All of this is key to your training. If you’re aiming to build muscle, especially if you’re just starting out, learn to master time under tension and make it the prime goal in every workout. Aim for 30 to 40 seconds of time under tension in every set. You’ll get that in the 3-move total-body workout below.

Directions: Do this workout 4 to 5 days a week for a month. Focus on form and focus on timing. Each exercise has a time attached to it; work at that pace to pile up time under tension.

On days you don’t do this workout, aim to do an “active rest” session, going for a 20-minute walk or run. Aim to stay active seven days a week. Your body is meant to move!

Warm up for this workout with 1 minute each of planks, reverse lunges, and bodyweight squats. Then jump into your session.

Exercise 1: Tempo Goblet Squat

Stand holding a kettlebell, dumbbell or other weight at your chest, core tight, glutes squeezed, feet about shoulder-width apart. Bend at the knees and hips and lower into a squat. Take 3 seconds to do this. Pause when your thighs are parallel with the ground. Hold for 1 second, then press back up. That’s 1 rep. Do 4 sets of 10. Each set, you’ll pile up 40 seconds of time under tension.

Exercise 2: Paused Pushup

Get in pushup position, core tight, wrists slightly wider than your shoulders. Lower into a pushup, taking 2 seconds to lower your chest an inch from the ground. Pause for 1 second. Press back up. That’s 1 rep. Do 4 sets of 10. Each set, you’ll pile up 30 seconds of time under tension.

Exercise 3: Negative-focused Dumbbell Row

Stand with feet shoulder-width apart, and hinge forward, keeping your shoulders higher than your hips. Grasp a weight in your right hand, and let your arm hang naturally. Stabilize yourself against a bench or wall with your left hand. Row the dumbbell toward your rib cage, pausing at the top. Take 5 seconds to lower, lowering with complete control. That’s 1 rep. Do 3 sets of 10 per side. You’ll pile up 50 seconds of time-under-tension each set.

Exercise 4: Halfway Paused Bicep Curl

Stand holding dumbbells in your hands, core and glutes tight. Without moving your upper arms, curl the biceps toward your chest, pausing at the top. Lower the dumbbells with control, pausing when your forearms are parallel with the ground. Hold for 2 seconds here, then lower all the way. That’s 1 rep. Do 3 sets of 10. You’ll pile up 20 seconds of time under tension when your forearms are parallel with the ground, and a bit more tension during the rest of each set, too.

Exercise 5: Goblet Romanian Deadlift

Stand with your feet shoulder-width apart, core tight, a kettlebell or dumbbell held in both hands. Keeping your core tight, push your butt back and lower the weight to the ground, taking 3 seconds to do this. Lower until you feel your hamstrings tighten, stopping before your back rounds. Pause for 1 second, then stand back up, squeezing your glutes. That’s 1 rep. Do 3 sets of 8. You’ll pile up 32 seconds of time-under-tension each set.