Concentric exercises are movements where a muscle shortens as it generates force. Every time you curl a dumbbell upward, push yourself off the ground in a push-up, or stand up from a squat, the working muscles are performing a concentric contraction. This is the “lifting” phase of most exercises, and it’s one of two main types of muscle action you perform during any strength movement (the other being eccentric, where the muscle lengthens under load).
How Concentric Contractions Work
Inside your muscles, contraction happens through a process called cross-bridge cycling. When your brain signals a muscle to fire, calcium ions flood into the muscle fibers and trigger tiny protein filaments (actin and myosin) to grab onto each other and slide together, like interlocking fingers pulling inward. Each cycle of grabbing, pulling, and releasing requires one molecule of ATP, your body’s energy currency. As millions of these cycles happen simultaneously, the entire muscle fiber shortens, the sarcomere (the smallest contractile unit) gets shorter, and you produce movement.
This process continues as long as there’s enough calcium signaling and energy available. When the signal stops, calcium is pumped back out, the filaments release, and the contraction ends.
Common Examples in the Gym
Almost every exercise has a concentric phase. Identifying it is simple: it’s the portion of the movement where you’re working against gravity or resistance, and the target muscle is getting shorter.
- Bicep curl: The concentric phase is curling the weight up toward your shoulder. Your bicep shortens as it contracts.
- Squat: The concentric phase is standing up from the bottom position. Your quadriceps and glutes shorten to drive you upward.
- Bench press: Pushing the bar away from your chest is the concentric phase for your chest and triceps.
- Pull-up: Pulling your body upward is the concentric phase for your lats and biceps.
- Calf raise: Rising onto your toes is the concentric phase for your calf muscles.
In each case, the opposite direction (lowering the weight, descending into the squat, bringing the bar back to your chest) is the eccentric phase, where the same muscles lengthen while still producing force to control the movement.
Concentric vs. Eccentric Contractions
The distinction between concentric and eccentric isn’t just academic. The two types of contraction differ in energy cost, muscle damage, and even how your nervous system recruits muscle fibers.
Concentric contractions are far more metabolically expensive. In a cycling study comparing concentric and eccentric pedaling at the same workload, oxygen consumption was about 65% lower during the eccentric bout. Heart rate was roughly 35% lower as well. This tracks with animal research showing that energy cost during eccentric contractions can be around 70% lower than concentric. In practical terms, the “lifting” portion of any exercise burns significantly more energy than the “lowering” portion.
Motor unit recruitment also differs. Research recording individual motor units in hand muscles found that 18 out of 21 units were recruited during the concentric phase and increased their firing rate as the shortening movement progressed. During the eccentric phase, those same units decreased their firing rate or shut off entirely. A small number of high-threshold units showed the opposite pattern, activating only during the eccentric phase. This means your nervous system handles the two phases with partially different strategies.
One of the most practical differences: concentric contractions cause less muscle damage and less delayed-onset muscle soreness (DOMS). Movements that lengthen the muscle under load are the primary drivers of the soreness you feel 24 to 72 hours after a tough workout. Concentric-only training produces considerably less of this effect.
Muscle Growth From Concentric Training
Concentric contractions do build muscle, but they appear to stimulate growth differently than eccentric contractions. Research on concentric-only versus eccentric-only training has found that eccentric work tends to produce slightly greater overall gains in muscle mass. More interesting is how the muscle grows. Concentric-only training primarily adds contractile units side by side (increasing the muscle’s pennation angle, which is the angle at which fibers attach to the tendon). Eccentric-only training adds contractile units end to end, increasing the length of each muscle fiber.
In practice, most people train with both phases in every rep, which is the most effective approach. But understanding this distinction matters if you’re designing a program with a specific goal, like building width in a muscle versus increasing its functional range.
Why Concentric Strength Matters for Performance
For athletes, concentric force production is directly tied to explosive power. A study on female volleyball players found that concentric rate of force development at 100 milliseconds, along with squat strength and squat-jump height, explained over 50% of the variance in change-of-direction performance. The ability to produce force quickly during the shortening phase of a movement, particularly right after an eccentric braking action, is what allows athletes to accelerate, jump, and cut effectively.
This is why plyometrics, Olympic lifts, and jump squats are staples in athletic training. They all emphasize rapid, powerful concentric contractions, often immediately following an eccentric load.
Concentric-Focused Training in Rehabilitation
In physical therapy settings, concentric-focused exercises are sometimes prioritized early in rehab because they produce less muscle fiber damage than eccentric work. When someone is recovering from an injury, excessive eccentric loading can delay structural and functional recovery. Starting with concentric-dominant movements lets the muscle rebuild strength without as much inflammatory stress.
As recovery progresses, eccentric loading is gradually reintroduced, since it’s important for tendon health, full-range strength, and injury prevention. But the lower soreness and damage profile of concentric training makes it a practical starting point when tissues are still healing.
How to Emphasize the Concentric Phase
If you want to focus more on concentric work in your training, there are a few straightforward strategies. Lift the weight explosively on the way up while taking only a controlled (not exaggerated) lowering phase. Use movements where the eccentric component is minimized, like sled pushes, rowing machine sprints, or battle ropes. Drop the weight at the top of a deadlift rather than slowly lowering it. Some machines, particularly cable systems, also allow you to load the concentric phase more heavily.
For general fitness and muscle building, though, you don’t need to isolate concentric work. The standard approach of lifting and lowering in a controlled manner gives you the benefits of both contraction types in every set. Understanding the concentric phase simply helps you train with more intention, knowing exactly which part of the movement is doing what for your body.