Time Under Tension Explained: How To Use TUT Training To Build Muscle Growth

Welcome to Time Under Tension (TUT) training - a simple, science-backed method that’s all about how long your muscles are working during a set, not just how much you’re lifting. Because when it comes to building muscle, the secret might just be slowing things down.

Loved by bodybuilders, PTs, and everyday gym-goers to feel the burn longer, TUT is a hypertrophy hack that can help you break through plateaus and get more from each rep.

In fact, slowing down your reps can lead to greater muscle fibre activation and increased protein synthesis, which are key drivers of muscle growth as demonstrated in a study that found that slow-tempo reps (6 seconds per rep) led to greater muscle protein synthesis compared to fast reps, even when total volume was matched [1].

So whether you’re trying to put on size or train more efficiently, TUT could be the switch up your routine needs. In this guide, we’ll break down exactly what TUT is, how it works, and how to apply it to your own training (without needing a stopwatch or a degree in biomechanics).

What Is Time Under Tension (TUT) Training?

Time Under Tension (TUT) is exactly what it sounds like — the total time your muscles are actively held under tension during a rep. Instead of racing through reps, it's about creating controlled, intentional movement by slowing down each phase of the movement and the total duration of a rep - including the lowering (eccentric), pause (isometric), and lifting (concentric) phases.

So instead of doing 10 quick bicep curls in 15 seconds, a TUT-focused set might have you doing 6 slower reps over 45 seconds.

TUT and Hypertrophy Explained: How Slowing Down Your Reps Builds Muscle

Time Under Tension (TUT) promotes muscle growth by increasing the amount of time your muscles are actively working during a set. The longer they’re under strain, the greater the challenge placed on your muscle fibres, especially the slow-twitch fibres most associated with hypertrophy and muscular endurance.

When you lift with intent and control, TUT training increases metabolic stress, causing small tears in muscle fibers, stimulating growth-promoting hormones - all key ingredients for boosting hypertrophy (the process of increasing the size of your muscles through resistance training). A 2006 study by Tanimoto & Ishii found that even when using lighter loads, slow and continuous reps still led to significant muscle gains, confirming that it’s not just what you lift, but how you lift it [2].

Newer research suggests that using a rep tempo between 2 to 8 seconds can maximise hypertrophy, especially when both the concentric (lifting) and eccentric (lowering) phases are controlled [3]. That means you don’t need to fly through reps for gains—in fact, the opposite is often more effective.

Slowing things down might feel strange at first, but lifters regularly report improved muscle activation and mind-muscle connection when slowing the tempo. One user on Reddit noted, “I started slowing my reps down and immediately felt more engagement in muscles I’d been struggling to grow.” Another shared that adding TUT to their final set helped them break plateaus without stressing their joints.

TLDR? Here’s why that slower approach works so well:

1. Enhanced Muscle Fiber Recruitment

Moving slowly through each rep forces your muscles to stay engaged for longer, activating more fibres across the full range of motion. This greater recruitment means your muscles work harder with each rep, boosting muscle growth.

2. Increased Metabolic Stress

TUT extends the time your muscles spend under tension, creating more metabolic stress—a proven driver of muscle growth. This type of stress encourages the release of growth factors and muscle-building hormones, supporting muscle repair and protein synthesis, even without heavy weights.

3. Eccentric Focus for More Damage and Growth

Slowing down the eccentric (lowering) phase of each rep maximises (intentional) muscle damage and time under load. Research shows that eccentric contractions cause more microtrauma than concentric ones, which your body then repairs to build back bigger and stronger [4]. This makes slow, eccentric-focused reps a powerful hypertrophy tool.

Training at home or using lighter equipment? You can still see real progress by playing with tempo. Try our dumbbell workout plans or kettlebell workouts to see how.

4. Stronger Mind-Muscle Connection

When you slow down, you give your brain time to connect with the muscles you’re training. The extra time allows you to focus on the muscle being worked, improve your form, and deepen the contraction. Over time, this stronger mind-muscle connection makes your training more effective and reduces wasted reps.

Focusing on core development? The slow tempo of TUT can be a game-changer for ab exercises, helping you really feel each contraction. Try our kettlebell core workout if you’re looking to level up your ab workout with free weights.

How To Use TUT In Your Workouts

Time-under-tension training doesn’t mean abandoning your usual workouts; it just means adjusting the tempo. Here’s how:

• Target a TUT range of 30–70 seconds per set. That’s the sweet spot for hypertrophy. If a single rep takes 5 seconds to complete, then you should aim for around 8–12 reps per set.

• Use tempo notation. A 3-2-1 tempo means 3 seconds to lower the weight (eccentric), 2-second pause at the bottom, and 1 second to lift (concentric).

• Apply it strategically. Try TUT in your last set, burnout sets, or accessory lifts where you want to boost muscle fatigue.

• Track your tempo. Count each second, use a metronome app (to practice tempo-keeping), or focus on breathing to keep things consistent.

Best Exercises To Try Time Under Tension

TUT works best with movements that allow for control, isolation, and a strong mind-muscle connection. Think isolation/accessory exercises like bicep curls that you add on to your workouts after your big compound lifts. Chest and back movements also respond especially well to time under tension, as slowing down during a push-up or row can massively increase pec or lat engagement. These exercises are ideal because they’re easy to slow down without compromising form, and make a noticeable difference.

For Biceps: Dumbbell Bicep Curl

This classic arm day isolation move becomes much more effective when slowed down. Applying TUT increases the time the biceps are under strain, especially during the eccentric (lowering) phase, leading to greater muscle fiber recruitment. It also prevents momentum from doing the work, forcing your muscles to stay active throughout the full range.

For Glutes: Bulgarian Split Squat

This unilateral lower-body exercise is already challenging, and when slowed down, it becomes a masterclass in stability, control, and quad engagement—prepare to fight the shakes! TUT training helps build deep strength in the glutes, hamstrings, and quads while also enhancing balance. Slowing the tempo also reduces reliance on momentum and encourages proper knee tracking and hip alignment.

For Chest: Push-Up

Slowing down a push-up shifts it from a bodyweight staple to a serious upper-body builder. Time under tension used here increases chest, triceps, and core activation, especially during the eccentric lowering phase. It’s also a great way to make push-ups harder without adding external load—ideal for home training or hotel workouts!

For Hamstrings: Romanian Deadlift (RDL) – Slow Eccentric

The RDL is all about hamstring and glute engagement. By focusing on a slow eccentric (when you lower the weight), you increase stretch and tension in the posterior chain. This not only stimulates more muscle growth but also improves mobility and joint health over time. The controlled tempo also reduces the risk of injury from jerking or overextending.

For Shoulders: Cable Lateral Raise

Lateral raises can be easy to cheat- swinging the weight or rushing reps, you know the drill. But under TUT, the delts stay activated through the entire lift. Slowing down the tempo eliminates momentum, keeps constant tension on the side delts, and helps isolate the muscle more effectively for size and shape.

Example TUT Workouts

While you can dedicate an entire workout to TUT training, it’s also an effective technique when used as an accessory at the end of a session, especially after your heavier compound lifts. This approach lets you hit the big movements with maximum effort, then finish with slower, controlled exercises to fatigue the target muscles and drive additional growth.

Example: Lower-Body TUT Finisher

1. Walking Lunges - 2x12 steps each leg @ 3-1-2 tempo

2. Leg Extensions (Quads) - 2x12 @ 3-1-3 tempo

3. Bodyweight Glute Bridge Hold - 2x30 seconds (continuous tension, no rest at the bottom)

Rest: Keep rest minimal - about 30–45 seconds between sets to maintain the burn and maximize time under tension without turning it into another full-leg workout.

Example: Full Body TUT Workout

1. Dumbbell Chest Press - 4×10 @ 3-1-2 tempo

2. Bulgarian Split Squats - 4×8 each leg @ 3-1-2 tempo

3. Bicep Curls - 4x10 @ 3-1-2 tempo

4. Cable Lateral Raise- 4×12 each side @ 3-0-3 tempo

5. Push-Ups (burnout finisher) - 3 sets to failure @ a slow 3-1-2 tempo

Rest: 60–90 seconds between sets. Focus on form and tempo, not load.

Optional: Beginners can reduce time or reps. Advanced lifters can combine TUT with dropsets or supersets for added burn.

How Does TUT Differ From Traditional Lifting?

Traditional reps are typically geared toward building strength, power, or volume. The tempo is often moderate or fast, which can be great for developing explosive strength but might not always fully activate the muscle through its full range of motion. TUT training, on the other hand, slows things down. The tempo is more controlled, placing continuous stress on the muscle and increasing time spent under load—something that’s been linked to better hypertrophy outcomes.

Muscle activation also differs, with research showing that manipulating tempo, even at the same volume and intensity, can result in greater mechanical tension, a key trigger of hypertrophy [5].

And while traditional reps depend heavily on load and rep count, TUT can help you recruit deeper muscle fibers by forcing more control and stability - giving you that ‘burning’ feeling.

Are There Limitations to TUT?

Training with time under tension is powerful, but it’s not perfect. Here are a few caveats to the method:

• Not ideal for pure strength goals. It’s harder to slow down the reps as the weights get heavier, and slower reps with lighter weights won’t provide enough overload to maximize strength development. Studies back this up, showing high-load training superior for strength gains when faster tempos and heavier loads are used, compared to slower, low-load training [6].

• Mentally fatiguing. Long sets require focus and discipline, and aren’t ideal if you’re short on time, like a lot of us are. It’s easy to try and rush… but that defeats the point.

• Is it a myth? No, but it’s not magic either. Studies and anecdotes show that TUT works best when combined with progressive overload, proper recovery, and good nutrition

Still, as a hypertrophy tool, it’s highly effective, especially for those training at home, dealing with joint issues, or seeking new intensity.

Final Takeaway: Why TUT Belongs In Your Training Toolbox

TUT isn’t a gimmick, it’s a hypertrophy strategy that teaches control, enhances muscle engagement, and builds strength without pushing yourself to the limits.

It helps you get more from every rep, activate stubborn muscles, and break through growth plateaus, especially when you don’t have access to heavy weights.

Think of TUT as a tool to complement your training, not replace it. Use it during accessory lifts, burnout sets, or as a way to bring more intent to your workouts.

Experiment with tempo in your next session and feel the difference.

Looking for your next workout to try TUT on? Whether it’s push, pull, or back and bi’s, we’ve got something for everyone on the Gymshark Training App. Download below!

References:

[1] Burd, N. A., Andrews, R. J., West, D. W., et al. (2012). Muscle time under tension during resistance exercise stimulates differential muscle protein sub-fractional synthetic responses in men. The Journal of Physiology, 590(2), 351–362. https://doi.org/10.1113/jphysiol.2011.221200

[2] Tanimoto, M., & Ishii, N. (2006). Effects of low-intensity resistance exercise with slow movement and tonic force generation on muscular function in young men. Journal of Applied Physiology, 100(4), 1150–1157. https://doi.org/10.1152/japplphysiol.00641.2005

[3] Loenneke, J. P., Wilson, J. M., & Pujol, T. J. (2023). The Role of Muscle Metabolite Accumulation in Promoting Muscle Hypertrophy: A Narrative Review. Journal of Functional Morphology and Kinesiology, 9(1), 9. https://doi.org/10.3390/jfmk9010009

[4] Schoenfeld, B. J., Ogborn, D., & Krieger, J. W. (2015). Effect of repetition duration during resistance training on muscle hypertrophy: a systematic review and meta-analysis. Sports Medicine, 45(4), 577–585. https://doi.org/10.1007/s40279-015-0304-0

[5] Wilk, M., Jarosz, J., Krzysztofik, M., Filip‑Stachnik, A., Białas, M., Rzeszutko‑Belzowska, A., Zając, A., & Staśtny, P. (2021). Contrast Tempo of Movement and Its Effect on Power Output and Bar Velocity During Resistance Exercise. Frontiers in Physiology, 11, 629199. https://doi.org/10.3389

[6] Schoenfeld, B. J., Peterson, M. D., Ogborn, D., Contreras, B., & Sonmez, G. T. (2015). Effects of low- vs. high-load resistance training on muscle strength and hypertrophy in well-trained men. The Journal of Strength and Conditioning Research, 29(10), 2954–2963. https://doi.org/10.1519/JSC.0000000000000958

[7] Mitchell, C. J., Churchward-Venne, T. A., West, D. W., Burd, N. A., Breen, L., Baker, S. K., & Phillips, S. M. (2012). Resistance exercise load does not determine training‑mediated hypertrophic gains in young men. Journal of Applied Physiology (1985), 113(1), 71–77. https://doi.org/10.1152/japplphysiol.00307.2012

Chaves, D. F. S., et al. (2020). The Role of Metabolic Stress and Exercise-Induced Hypoxia in Skeletal Muscle Adaptations: A Review. Frontiers in Physiology, 11, 629199. https://doi.org/10.3389/fphys.2020.629199