The Science Behind Time Under Tension: Building Through Slow Movements (Part 2)
In last week’s weeks blog, we covered the basics of higher vs. lower reps for muscle growth. Now, let's dive deeper into one of the key components of building muscle—Time Under Tension (TUT). This principle explains how long your muscles are engaged during each set and why it matters.
Why TUT Matters
When you slow down your movements during exercise, especially during the lowering (eccentric) phase, you keep your muscles under tension for a longer time. The more time they spend working, the more you trigger growth responses in the muscle fibers.
Higher Reps: More reps usually mean more time under tension. When you’re lifting for 12-20 reps, your muscles are working for a longer duration, which builds endurance and can still promote hypertrophy, particularly in slow-twitch fibers.
Lower Reps: While heavier weights in lower rep ranges don’t create as much TUT, they do engage more muscle fibers at once. This results in more force production, which helps you build strength and power. Over time, that strength can translate into the ability to lift heavier weights for more reps, which ultimately leads to more muscle growth.
Moving slower during exercises increases time under tension (TUT), which plays a significant role in muscle growth for a few key reasons:
Here’s what happens on a cellular level when you slow down:
1. Mechanical Stress and Muscle Fiber Activation
Moving more slowly during exercise, especially during the eccentric phase, creates mechanical stress. This leads to tiny microtears in the muscle fibers, particularly in the sarcomeres (the basic contractile units of muscle).
These microtears activate the body’s repair mechanisms, which then lead to stronger, thicker muscle fibers as they heal.
Slower movements also target slow-twitch fibers, which respond well to prolonged efforts. Though these fibers aren't as large as fast-twitch fibers, they can still hypertrophy (grow) when under sustained tension.
2. Activation of Satellite Cells for Repair and Growth
Microtears in muscle fibers signal the body to activate satellite cells, which are special cells that play a major role in muscle recovery and growth.
These cells migrate to the damaged site, fuse with muscle fibers, and help repair them by donating their nuclei. This increases the muscle's ability to produce more proteins, which leads to muscle hypertrophy (growth).
3. Boosting Protein Synthesis
After satellite cells are activated, the muscle fibers start repairing themselves by producing actin and myosin—the proteins responsible for muscle contraction.
Slow, controlled movements also activate the mTOR pathway, a key regulator of muscle growth. This pathway signals the muscle to ramp up protein synthesis, which strengthens and enlarges the fibers.
4. Metabolic Stress and Cellular Swelling
The longer your muscles work, the more metabolic stress builds up. This is caused by the accumulation of byproducts like lactate, which sends growth signals to your muscle fibers.
As your muscles swell from increased blood flow during prolonged tension (the “pump”), the muscle cells stretch, further promoting growth.
5. Hormonal and Inflammatory Responses
Slower movements also lead to the release of key anabolic hormones, such as testosterone, growth hormone (GH), and IGF-1, which play crucial roles in muscle recovery and growth.
Muscle damage from slower movements triggers an inflammatory response, which is necessary for repair. This helps your muscles rebuild stronger.
How to Use TUT to Your Advantage You don’t have to lift heavy to build muscle! By increasing time under tension with lighter weights and slowing down your movements, you can still achieve significant gains. Here’s why:
Increased Time Under Tension: Lighter weights allow for more reps and longer sets, increasing TUT and promoting muscle growth through metabolic stress and fiber activation.
Volume Over Weight: Focusing on more reps and sets (overall volume) can stimulate muscle growth even when the weights are lighter. Bodybuilders and athletes often use a mix of high and low rep ranges to maximize volume and target different muscle fibers.
Understanding Time Under Tension (TUT) is crucial for maximizing muscle growth, but knowing how to apply it effectively in your workouts is just as important. While simply slowing down your movements can increase TUT, incorporating specific techniques like pause reps and negative reps can take your training to the next level.
Transition to Different TUT Methods:
If you’ve mastered the basics of increasing TUT by performing exercises at a slower tempo, consider adding more variety with these advanced techniques:
1. Start with Slow Reps:
Why: This is the simplest way to begin experimenting with TUT. By extending both the concentric and eccentric phases, you’ll engage your muscles for a longer duration.
How to Implement: Try performing your regular sets with a 3-second lift and a 3-second lower. Focus on maintaining control and form throughout the entire movement.
2. Move to Pause Reps:
Why: Once you’re comfortable with slow reps, pausing at the most challenging point of the movement adds a new level of difficulty. It forces your muscles to work without the aid of momentum, increasing strength and stability.
How to Implement: Add a 1-2 second pause at the bottom of a squat, at the midpoint of a bench press, or just before locking out a deadlift. Start with lighter weights and focus on engaging the target muscles during the pause.
3. Incorporate Negative Reps:
Why: Negative reps emphasize the eccentric (lowering) phase, where muscles are strongest. This can significantly boost muscle growth and strength.
How to Implement: Use a weight slightly heavier than your usual load and focus on a slow 4-6 second lower phase. You might need a spotter for safety when using this method with heavy weights.
4. Combining Techniques:
For an even greater challenge, try combining these methods. For example, use a slow eccentric phase, followed by a pause, then a controlled concentric phase. This combination maximizes TUT and hits your muscles from all angles.
Finding What Works Best for You
Experiment with each method to see what feels most effective for your training goals. You don’t have to incorporate all these techniques at once; start by adding one method per workout and gradually build from there.
By varying how you use TUT with these advanced techniques, you can keep your workouts challenging and dynamic, ensuring continuous progress and adaptation.
Example Weekly Workout Plan Using Time Under Tension, Pause Reps, and Negative Reps
This workout plan incorporates a mix of traditional time under tension (TUT) techniques, pause reps, and negative reps to maximize muscle growth and strength. Each workout focuses on different muscle groups and integrates various TUT strategies. Adjust weights to allow for the longer time under tension and additional challenge.
Day 1: Upper Body – Push (Chest, Shoulders, Triceps)
Pause Bench Press
4 sets of 6-8 reps
Technique: Lower the bar slowly for 3 seconds, pause for 2 seconds just above the chest, then press up explosively.
Incline Dumbbell Press – Slow Tempo
3 sets of 8-10 reps
Technique: 3-second eccentric (lowering) phase and 1-second concentric (lifting) phase.
Overhead Shoulder Press – Negative Reps
4 sets of 6-8 reps
Technique: Press up normally, then take 4 seconds to lower the weights back to starting position.
Cable Tricep Pushdowns – Pause Reps
3 sets of 10-12 reps
Technique: Pause for 2 seconds at full extension, focusing on squeezing the triceps.
Day 2: Lower Body – Quads & Hamstrings
Back Squats – Pause Reps
4 sets of 6-8 reps
Technique: Lower for 3 seconds, pause for 2 seconds at the bottom, then explode up.
Romanian Deadlifts – Negative Reps
3 sets of 8-10 reps
Technique: 4-second eccentric phase, keeping tension on the hamstrings throughout.
Leg Press – Slow Tempo
4 sets of 10-12 reps
Technique: 3-second eccentric phase, 1-second concentric phase.
Walking Lunges – Time Under Tension
3 sets of 12-16 reps per leg
Technique: Move slowly, taking 3 seconds to lower into each lunge, no lockout at the top.
Day 3: Active Recovery or Rest
Day 4: Upper Body – Pull (Back, Biceps)
Pull-Ups – Negative Reps
4 sets of 4-6 reps
Technique: Explosive pull-up, then 5-second descent.
Bent Over Rows – Slow Tempo
4 sets of 8-10 reps
Technique: 3-second lowering phase, 1-second lifting phase.
Seated Cable Rows – Pause Reps
3 sets of 10-12 reps
Technique: Pause for 2 seconds at full contraction, squeezing shoulder blades together.
Dumbbell Curls – Slow Tempo
3 sets of 12-15 reps
Technique: 3-second lifting and lowering phase.
Day 5: Lower Body – Glutes & Core
Hip Thrusts – Pause Reps
4 sets of 8-10 reps
Technique: Pause for 2 seconds at the top, squeezing glutes.
Bulgarian Split Squats – Negative Reps
3 sets of 10-12 reps per leg
Technique: Lower for 4 seconds, then come up explosively.
Cable Kickbacks – Slow Tempo
3 sets of 15-20 reps
Technique: 3-second eccentric phase.
Hanging Leg Raises – Time Under Tension
3 sets of 10-15 reps
Technique: Move slowly with control, 3-second eccentric phase.
Day 6: Full Body – Compound Movements
Deadlifts – Negative Reps
4 sets of 4-6 reps
Technique: Control the lowering phase for 4 seconds.
Barbell Front Squats – Pause Reps
4 sets of 6-8 reps
Technique: 3-second descent, 2-second pause at the bottom.
Push-Ups – Slow Tempo
4 sets to failure
Technique: 3-second eccentric phase, 1-second hold at the bottom.
Hollow Body Holds – Time Under Tension
4 sets of 30-45 seconds
Technique: Maintain a tight core throughout.
Day 7: Active Recovery or Rest
Tips for Implementing this Plan:
Warm Up: Start each session with a 5-10 minute warm-up to increase blood flow and prepare your muscles.
Intensity: Use weights that allow you to complete the set with proper form but are challenging enough to fatigue the muscles within the specified rep range.
Rest: Take 60-90 seconds between sets to recover, but keep the intensity up to maximize TUT benefits.
Progression: Increase weight, reps, or sets each week to apply progressive overload and continue making gains.
This plan blends different TUT methods throughout the week, providing a comprehensive approach to muscle growth and strength development.
Key Takeaway
Incorporating slower movements and focusing on time under tension, especially during the eccentric phase, can lead to greater muscle growth—even with lighter weights. By understanding the science behind muscle fiber activation, protein synthesis, and metabolic stress, you can design workouts that maximize hypertrophy without always needing to lift heavy.
Give this approach a try during your next workout, and feel the difference as your muscles spend more time working toward your growth goals!
Until next time,
Robyn
P.S. – If you missed part 1 of this series, check out last week’s blog about “High Vs Lower Reps” on the blog page :)