The Difference Between Concentric and Eccentric Motion in Strength Training

UNDERSTANDING MUSCLE CONTRACTIONS

In strength training, every movement involves muscle contractions. These contractions fall into two primary categories: concentric and eccentric. Concentric motion occurs when a muscle shortens as it contracts. Eccentric motion happens when a muscle lengthens under tension. Both are essential, but eccentric training offers unique advantages, especially for tendon health and injury recovery.

CONCENTRIC VS ECCENTRIC: THE BASICS

Concentric contractions are what most people associate with lifting. For example, in a bicep curl, the concentric phase is when you lift the dumbbell upward, shortening the biceps. In a tricep pushdown, the concentric phase is when you extend your arms downward, shortening the triceps.

Eccentric contractions occur during the lowering phase. In the bicep curl, this is when you slowly lower the dumbbell back down, lengthening the biceps under control. In the tricep pushdown, the eccentric phase is when you allow the bar to rise back up, resisting the motion as your triceps lengthen.

WHY ECCENTRIC TRAINING MATTERS

Eccentric training places greater mechanical stress on the muscle and connective tissue. This stress stimulates more muscle damage, which leads to greater adaptation during recovery. Eccentric movements also require less energy than concentric ones, allowing for higher loads to be used with less fatigue.

From a tendon perspective, eccentric loading is especially beneficial. Tendons are made of collagen fibers that respond well to slow, controlled tension. Eccentric movements increase tendon stiffness and promote collagen remodeling, which is critical for healing and long-term durability.

TECHNICAL BENEFITS FOR TENDON RECOVERY

When tendons are injured, they often become disorganized at the cellular level. Eccentric loading helps realign collagen fibers and restore tensile strength. It also improves blood flow to the tendon, which is typically limited. This makes eccentric training a cornerstone of rehabilitation protocols for conditions like patellar tendinopathy, Achilles tendinitis, and tennis elbow.

PRACTICAL APPLICATIONS

To incorporate eccentric work, slow down the lowering phase of your lifts. Use a three to five second descent on exercises like squats, curls, and pushdowns. You can also use techniques like eccentric-only reps, where you assist the concentric phase and focus entirely on the lowering portion.

CLOSING THOUGHTS

Concentric motion builds strength and power. Eccentric motion builds resilience, control, and tendon integrity. For lifters focused on longevity, injury prevention, and recovery, eccentric training is not optional. It is essential.