Eccentric vs Concentric Training: Understanding Muscle Actions

Every rep you perform has two distinct phases, and most people completely ignore one of them. Understanding the difference between eccentric and concentric muscle actions—and training both intentionally—can unlock new gains in strength, muscle size, and injury resilience.

The Two Phases of Every Rep

Concentric Phase

The concentric phase is when your muscle shortens under load. This is the "lifting" part of most exercises:

Curling the dumbbell up during a bicep curl
Standing up from a squat
Pressing the bar up during bench press
Pulling yourself up during a pull-up

This is what most people focus on—moving the weight against gravity.

Eccentric Phase

The eccentric phase is when your muscle lengthens under load. This is the "lowering" part:

Lowering the dumbbell during a bicep curl
Descending into a squat
Lowering the bar to your chest during bench press
Lowering yourself from a pull-up

Many people let gravity do this work, dropping the weight quickly. That's a missed opportunity.

Why Eccentric Training Is Special

Research consistently shows that eccentric training offers unique benefits:

1. Greater Strength Gains

Your muscles can handle approximately 20-40% more weight during the eccentric phase than the concentric. This means eccentric training provides a stronger stimulus for strength adaptation.

2. More Muscle Damage (The Good Kind)

Eccentric contractions cause more microscopic muscle damage than concentric. This damage triggers the repair and growth process that builds bigger muscles. Controlled damage = controlled growth.

3. Better Tendon Health

Eccentric training is particularly effective for strengthening tendons. It's the gold standard treatment for tendinopathies like Achilles tendinitis, patellar tendinitis, and tennis elbow.

4. Improved Flexibility

Eccentric training lengthens muscles under load, improving flexibility while building strength. This is called "eccentric stretching" and it's more effective than passive stretching for some goals.

5. Lower Energy Cost

Eccentric contractions use less energy than concentric. You can do more work with less fatigue, making it efficient for building strength.

6. Injury Prevention

Strong eccentric control protects against muscle strains and tears. Most muscle injuries occur during the eccentric phase—when the muscle is lengthening while trying to decelerate a force.

The Science Behind the Difference

During concentric contractions, muscle fibers slide together and shorten. The muscle actively produces force to move a load.

During eccentric contractions, muscle fibers are pulled apart while trying to resist lengthening. The muscle acts as a brake, absorbing force rather than producing it.

This "braking" action creates unique mechanical stress on the muscle fibers and their surrounding connective tissue, triggering distinct adaptation signals.

How to Emphasize Eccentric Training

1. Slow Down the Lowering Phase

The simplest approach: take 3-5 seconds to lower the weight on every rep. This increases time under tension during the eccentric phase.

Example: During a bicep curl, take 4 seconds to lower the weight, 1 second to curl it up.

2. Eccentric-Only Training

Use a heavier weight than you could lift concentrically and focus only on the lowering phase.

Example: Load a leg press with 120% of your normal weight. Use both legs to push it up, then lower slowly on one leg. Reset and repeat.

This requires a partner or creative setups but provides an intense eccentric stimulus.

3. Accentuated Eccentrics

Add extra resistance during the lowering phase only.

Example: During dumbbell curls, use your free hand to press down slightly on the working arm as you lower the weight, adding resistance.

4. Yielding Isometrics

Hold a position for time, fighting against gravity. Your muscles work eccentrically to resist lengthening.

Example: Hold the bottom position of a squat for 30 seconds, maintaining tension.

Eccentric Training for Specific Goals

For Muscle Building (Hypertrophy)

Use 3-4 second eccentrics on most exercises
Focus on the stretch under load
Control the weight through full range of motion
Expect more soreness initially—this is normal

For Strength

Include occasional eccentric-only work at supramaximal loads (105-120% of max)
Use 4-6 second eccentrics on main lifts
Focus on maintaining perfect form during the descent

For Tendon Rehab

Slow eccentrics (3-5 seconds) are therapeutic for tendinopathies
Start with bodyweight and progress gradually
Example: Heel drops off a step for Achilles tendinitis
Consistency matters more than intensity

For Injury Prevention

Train eccentric strength in positions where injuries commonly occur
Example: Nordic hamstring curls to prevent hamstring strains
Focus on controlling deceleration in sport-specific movements

Sample Eccentric-Focused Workouts

Upper Body Emphasis

| Exercise | Eccentric Tempo | Sets × Reps | |----------|-----------------|-------------| | Pull-ups | 5 sec down | 3 × 5 | | Bench Press | 4 sec down | 3 × 8 | | Bent Rows | 3 sec down | 3 × 10 | | Bicep Curls | 4 sec down | 3 × 10 |

Lower Body Emphasis

| Exercise | Eccentric Tempo | Sets × Reps | |----------|-----------------|-------------| | Back Squat | 4 sec down | 3 × 8 | | Romanian Deadlift | 3 sec down | 3 × 10 | | Walking Lunges | 3 sec down | 3 × 8/leg | | Calf Raises | 4 sec down | 3 × 12 |

Concentric Training: When to Emphasize It

While eccentric training has unique benefits, concentric training is still essential:

For Power Development

Power requires rapid concentric contractions. Explosive jumps, throws, and Olympic lifts are concentric-dominant and essential for athletic performance.

For Skill Acquisition

Learning movement patterns is often easier when focusing on the concentric (lifting) phase first.

For Reduced Soreness

If you're returning from a layoff or need to minimize next-day soreness, concentric-focused training causes less muscle damage.

For Energy System Training

Concentric exercises like sled pushes, bike sprints, and rowing provide cardiovascular training without the muscle damage that impairs recovery.

Practical Application

For most people, the best approach is balanced:

Control every rep: Never drop or bounce the weight. Own the eccentric.
Vary your tempo: Some sessions use slow eccentrics (3-4 seconds), others use normal speed (1-2 seconds).
Include power work: Fast concentric movements like jumps, throws, or explosive lifts develop different qualities.
Match method to goal: Rehabbing a tendon? Emphasize slow eccentrics. Training for a sport? Include fast concentrics.
Progress gradually: Eccentric training causes more soreness initially. Introduce it slowly.

Common Mistakes

Dropping the Weight

The most common error. Lowering the weight with gravity cheats you out of half the exercise.

Too Much Too Soon

Aggressive eccentric training causes severe delayed onset muscle soreness (DOMS). Build up gradually.

Ignoring the Concentric

Eccentric-only training has its place, but most programs should include both phases.

Poor Eccentric Form

Form often breaks down during the lowering phase when fatigue sets in. Maintain the same technique throughout.

Key Takeaways

Every rep has concentric (shortening) and eccentric (lengthening) phases
Eccentric training provides unique benefits for strength, muscle size, and tendon health
Most people rush through the eccentric—slow it down to 3-4 seconds
Eccentric training causes more soreness initially; progress gradually
Balance both phases for complete training; emphasize one or the other based on your goals

The weight going down is just as important as the weight going up. Master both, and you'll see better results than ever.