Concentric, Eccentric & Isometric Training - What's the Difference?

Concentric, eccentric, and isometric movement: Understand the differences and master them all

Strength training is about more than just lifting weights up and down.

Imagine you're on your final set of bench press, and you can't quite finish that last rep. Two things are likely to happen. First, your spotter will jump in before the bar crushes you. Second, you'll feel like that last rep was a failure.

In strength training, we often focus on getting the weight up—completing the rep. But if your goal is to build strength, there’s more to it than just full repetitions.

Each rep has three phases:

• Concentric – when your working muscles shorten.
• Eccentric – when your working muscles lengthen.
• Isometric – when your working muscles are under tension but without shortening or lengthening.

All three phases play a crucial role in muscle development. Let’s go over why:

What do concentric, eccentric, and isometric mean?

Concentric phase
The concentric phase—this is the actual lift—is when you generate force and work against gravity. It's also the phase where you activate the most muscle fibers at once. Training concentrically, especially with a focus on explosive power, improves your ability to generate force quickly, which enhances performance in many sports and daily movements. Trying to lift the weight as fast as possible, even if it moves slowly, helps you recruit more explosive muscle fibers—contributing to both muscle growth and better neuromuscular coordination.

Eccentric phase
The eccentric phase occurs when you lower the weight—like when the bar moves down toward your chest in a bench press. Here, your muscles are working to control the movement while being lengthened. You're usually stronger in this phase than in the concentric one. It’s also where you have the most control over the weight—yet we often pay the least attention to it.

Isometric phase
The isometric phase—when your muscles contract without changing length—is especially valuable for building stability and endurance. It trains your ability to hold positions under load, which is crucial for injury prevention and control during heavy lifts. Isometric training is also gentle on the joints and can be a good alternative to the other movement types during rehab. Holding a weight at the bottom of a squat or the top of a press strengthens the entire movement chain and improves your body's ability to manage heavy loads with precision.

Why is the eccentric phase especially important?

Understanding the phases of a lift allows you to train smarter. The eccentric phase demands more from your muscles, creates higher mechanical tension, and strongly contributes to muscle growth. It also strengthens tendons and joints, which improves stability and reduces injury risk.

There’s a clear link to everyday life, too: everything from walking downstairs to catching yourself when you slip involves eccentric muscle contractions.

Note: The eccentric phase causes more micro-damage to muscles—which is good for growth but may increase soreness. Make sure you allow enough recovery after workouts with a lot of eccentric work.

How to use the phases in your training

To get the most out of every repetition, keep the following in mind:

Lower the weight slowly and with control (eccentric)
Push up explosively (concentric)
The slow eccentric movement helps reduce joint stress, while the explosive concentric movement activates more muscle fibers, especially the fast-twitch type II fibers.

Use eccentric training to break through plateaus

It’s estimated that people can handle 20–30% more weight during the eccentric phase compared to the concentric. We can use this to our advantage by doing:

Slow negative reps (4–5 seconds lowering)
Heavier weight during the eccentric portion with help from a spotter (e.g., negative pullups or bench press)
These methods are intense and require more recovery, so don’t overdo them. But they can be highly effective for breaking through training plateaus.

Periodize your tempo

To vary your training and avoid plateaus, try changing the tempo of your reps. For example, use the following model:

• 50–60% of training: controlled but regular speed
• 10–20%: slow eccentric phases
• 10–20%: explosive concentric phases

Example periodization:

• 4 weeks normal tempo
• 1 week focused on slow eccentric reps
• 1 week focused on explosive lifts
• 1 deload week

This structure helps you develop methodically, avoid stagnation, and reduce injury risk.

Bottom line

To get the most from your strength training, we should view all types of muscle activity as beneficial—not just complete reps.

• Remember, each rep can have three phases:
• Slow lowering
• Pause with control
• Powerful drive upward

Each rep is its own action. It can be done sloppily and mindlessly, or with precision and focus. The results will reflect that. With the right planning and variation, training becomes more fun, builds more muscle, and keeps your body healthy longer.

So next time you lift, don’t just ask yourself how heavy—ask: how am I going to lift today?