The Overlooked Half of Every Rep
Every repetition has two phases: the concentric (lifting the weight) and the eccentric (lowering the weight). Most lifters focus entirely on the concentric. They heave the weight up, then let gravity do the work on the way down.
This is a mistake. Research shows the eccentric phase may be the more important half of the rep for building muscle and strength.
What the Research Shows
A 2017 systematic review examined studies comparing eccentric-only versus concentric-only training. The findings clearly favored eccentrics:
- Eccentric training produced approximately 10% greater total strength gains
- Muscle hypertrophy was equal or greater with eccentric emphasis
- These benefits occurred despite eccentrics feeling "easier" in terms of cardiovascular demand
Why Eccentrics Build More Muscle
Several mechanisms explain the superiority of eccentric training:
1. Higher Force Production: Your muscles can handle 20-40% more weight during the lowering phase than they can lift concentrically. This means eccentrics expose your muscles to greater mechanical tension, the primary driver of hypertrophy.
2. Fewer Motor Units, More Stress: Because eccentrics are "easier" neurally, fewer motor units are recruited to control the same load. This means each active motor unit experiences greater stress, potentially enhancing the growth stimulus at the fiber level.
3. Muscle Damage and Repair: Controlled eccentric contractions cause more microscopic muscle damage than concentrics. While excessive damage is counterproductive, moderate damage triggers robust repair processes that result in bigger, stronger muscles.
4. Unique Muscle Adaptations: Eccentric training increases muscle fascicle length (adding sarcomeres in series), which may improve force production at longer muscle lengths and reduce injury risk.
Practical Ways to Emphasize Eccentrics
You don't need special equipment. Here's how to incorporate eccentric emphasis into your training:
1. Slow Eccentrics (Tempo Training):
Instead of dropping the weight, lower it for 3-4 seconds. For a bench press: 1 second up, 3-4 seconds down. This simple change dramatically increases time under tension and eccentric stress.
2. Negative Reps:
Load the bar heavier than your 1RM (typically 105-120%) and have a spotter help you lift it. Then lower the weight slowly on your own over 4-6 seconds. Use sparingly: 2-3 negative reps at the end of your last set.
3. Accentuated Eccentrics:
Use weight releasers or have partners add extra weight for the eccentric portion only. The load is heavier on the way down, lighter on the way up.
4. Eccentric Isometrics:
Lower to the bottom position slowly, pause for 2-3 seconds, then lift. This combines eccentric stress with isometric tension at the stretched position.
Exercise Selection for Eccentrics
Some exercises are better suited for eccentric emphasis:
Excellent for eccentrics:
- Romanian deadlifts (controlled lowering)
- Nordic hamstring curls
- Negative pull-ups (jump up, lower slowly)
- Dumbbell flyes
- Lying leg curls
Use caution:
- Conventional deadlifts (difficult to control eccentrically)
- Olympic lifts (not designed for slow eccentrics)
- Any exercise where form breaks down under slow tempos
Recovery Considerations
Eccentric training causes more muscle damage, which means:
- Expect more DOMS (delayed onset muscle soreness), especially when first implementing
- You may need slightly longer recovery between sessions for the same muscle group
- Start conservatively and increase eccentric emphasis gradually
The soreness decreases as you adapt. After 2-3 weeks of consistent eccentric work, your muscles become more resistant to damage (the "repeated bout effect").
Sample Eccentric-Emphasis Workout
Chest and Triceps (Eccentric Focus):
- Bench Press: 4 sets x 6-8 reps (4 seconds down, 1 second up)
- Incline Dumbbell Press: 3 sets x 8-10 reps (3 seconds down)
- Cable Flyes: 3 sets x 12 reps (3 seconds down, 2-second squeeze)
- Close-Grip Bench: 3 sets x 8 reps + 2-3 negative reps on final set
- Overhead Tricep Extension: 3 sets x 10-12 reps (3 seconds down)
The Bottom Line
Stop ignoring the lowering phase. Research shows that emphasizing eccentrics leads to greater strength gains and at least equal muscle growth. The simplest change you can make is slowing down your negatives to 3-4 seconds.
Your muscles don't know how much weight is on the bar. They only know tension. Eccentrics let you create more tension with the same or even less weight, making them one of the most efficient tools for building muscle.
Reference
Douglas J, Pearson S, Ross A, McGuigan M. Eccentric Exercise: Physiological Characteristics and Acute Responses. Sports Med. 2017;47(4):663-675. PMID: 27647157