Eccentric means the lowering or lengthening phase of an exercise, when your muscle stretches under load rather than shortening. If you’re doing a bicep curl, the eccentric part is when you slowly lower the weight back down. Your biceps are still working, still under tension, but they’re getting longer instead of shorter. This phase is sometimes called “the negative,” and it plays a surprisingly large role in building strength, growing muscle, and preventing injury.
How Eccentric Contractions Work
Every repetition of most exercises has two main phases. The concentric phase is when the muscle shortens to move a load, like pressing a barbell off your chest. The eccentric phase is when the muscle lengthens while still resisting a load, like lowering that barbell back to your chest. During that lowering portion, an external force (gravity, a cable, your body weight) is overpowering what your muscle produces, so the muscle stretches while it contracts.
What makes eccentric contractions unusual is that your muscles are actually stronger during this phase. A large meta-analysis covering 335 studies found that eccentric muscle strength is roughly 40% greater than concentric strength. You can resist more weight on the way down than you can lift on the way up. This is why you can slowly lower a weight you couldn’t curl back up, and it’s the basis for several advanced training techniques.
Eccentric contractions also cost less energy in the moment. Compared to concentric work at the same volume, eccentric exercise produces lower heart rates, lower blood pressure, and lower ventilation rates. Your muscles store elastic energy during the stretch rather than burning through as much fuel. That combination of high force and low energy cost is one reason eccentric training shows up so often in both athletic programs and rehabilitation.
Why Eccentric Training Builds Muscle
Eccentric loading is one of the most potent triggers for muscle growth. When a muscle is both stretched and overloaded at the same time, it creates significant mechanical tension on the muscle fibers. That tension activates signaling pathways that ramp up protein synthesis, essentially telling your body to build the muscle back bigger and stronger.
The structural changes are worth understanding. Eccentric work stimulates your body to add new contractile units (called sarcomeres) both along the length and across the width of muscle fibers. This increases the muscle’s cross-sectional area and changes its internal architecture, producing real, measurable hypertrophy. Because eccentric contractions create greater mechanical tension than concentric ones, this remodeling process happens faster with eccentric-focused training than with lifting-only work.
The Link to Muscle Soreness
If you’ve ever been especially sore a day or two after a workout, eccentric loading was likely the main culprit. Delayed onset muscle soreness (DOMS) is closely tied to the lengthening phase of exercise. During eccentric contractions, the stretching isn’t perfectly uniform across all the tiny contractile units in a muscle fiber. The weakest segments absorb more of the stretch, which creates micro-level disruption in the muscle’s structure.
This isn’t necessarily a bad thing. That micro-disruption is part of the stimulus that triggers muscle repair and growth. But it does mean that if you dramatically increase the eccentric component of your training, or try a new eccentric-heavy exercise for the first time, you should expect more soreness than usual for the first few sessions. The effect diminishes quickly as your muscles adapt, a phenomenon known as the repeated bout effect.
Benefits for Tendons and Injury Prevention
Eccentric training does more than build muscle. It strengthens tendons by stimulating the cells within tendon tissue to increase collagen production and trigger remodeling. Higher eccentric loads create greater strain on the tendon, which over time increases tendon stiffness, elastic modulus, and even cross-sectional area. This is why eccentric exercises like slow heel drops off a step are a standard treatment for Achilles and patellar tendinopathy. The vibrations and oscillations that eccentric contractions produce within tendon tissue appear to have therapeutic effects that concentric contractions don’t match.
The injury prevention data is striking. The Nordic hamstring curl, a bodyweight eccentric exercise where you slowly lower yourself forward from a kneeling position, has been studied extensively in soccer players. One study found it reduced hamstring injuries by 51% per 1,000 hours of exposure. When implemented as a structured pre-training program, initial hamstring injuries dropped by as much as 92%, and recurrent injuries fell by 85%. The severity of injuries that did occur also decreased dramatically, with average time missed dropping from nearly 8 days to under 3.
Metabolic and Recovery Effects
Eccentric exercise feels easier in the moment because it uses less oxygen and energy during the session. But the aftermath tells a different story. Repairing the micro-disruption caused by eccentric loading requires significant energy. As much as 20% of resting metabolic rate can go toward protein resynthesis after a demanding session. This creates a prolonged elevation in your metabolic rate after the workout is over.
That post-exercise repair cost has some interesting metabolic benefits. Eccentric training improves glucose tolerance more effectively per unit of energy spent than concentric training does. It also reduces LDL cholesterol more efficiently per calorie burned. The mechanism is straightforward: more muscle fiber disruption means more repair, and more repair means more energy pulled from the bloodstream over the following hours and days.
Common Eccentric Exercises
Most exercises naturally include an eccentric phase. The key is knowing where it is so you can emphasize it. Here are some clear examples:
- Squat: The eccentric phase is the lowering portion, when your quads and glutes lengthen as you descend.
- Push-up: Lowering your chest toward the floor is eccentric for your chest and triceps. Pushing back up is concentric.
- Bicep curl: Lowering the weight back down is the eccentric phase for your biceps.
- Overhead press: Slowly lowering the weights by bending at the elbows is the eccentric portion.
- Heel drop: Rising onto your tiptoes is concentric for your calves. Lowering your heels below the level of a step, slowly and with control, is eccentric. This is a classic rehab exercise for Achilles tendon issues.
- Nordic hamstring curl: Kneeling and slowly lowering your torso toward the floor while your hamstrings resist gravity. Almost entirely eccentric.
- Running and jumping: Every landing involves eccentric loading on your quads, calves, and glutes as they absorb impact.
How to Emphasize the Eccentric Phase
The simplest way to get more out of eccentric training is to slow down the lowering portion of your reps. In many gym programs, tempo is written as four numbers representing seconds spent in each phase: eccentric, pause at the bottom, concentric, pause at the top. A tempo of 3-1-1-0 means you lower for 3 seconds, pause for 1 second, lift for 1 second, and skip the pause at the top. Increasing that first number to 4 or 5 seconds significantly increases the time your muscles spend under eccentric tension.
A more advanced approach is supramaximal eccentric training, where you load the eccentric phase with more weight than you could lift concentrically. Since your muscles can handle roughly 40% more force during the lowering phase, some protocols use loads of 120% of your one-rep max for the eccentric portion, with a partner or mechanical aid helping you through the concentric phase. This is typically reserved for experienced lifters and requires a spotter or specialized equipment.
For most people, simply controlling the lowering phase of every rep, taking 2 to 4 seconds instead of letting gravity do the work, is enough to capture the benefits. Eccentric-focused training doesn’t require special equipment or a completely new program. It requires attention to the half of every rep that most people rush through.