Eccentrics and Isometrics, Used Deliberately
Introduction
Almost all training is thought about in terms of lifting the weight. The lowering phase is executed by inertia, and the holding phase is never trained at all. Yet these are two forms of contraction with distinct properties and quite specific applications.
They aren't techniques for everyone or forever. They're tools for particular problems: a tendon that hurts, a sticking point, an injury that limits range.
The phase you ignore is the one that can produce the most force. It's worth deciding what to do with it.
Eccentrics: the lowering phase
In an eccentric contraction the muscle produces force while lengthening: you lower a weight, decelerate in a lunge, walk down stairs.
It has a striking property: you can produce considerably more eccentric than concentric force. You can lower a weight under control that you couldn't lift.
What the evidence shows. Roig and colleagues' meta-analysis found that eccentric training produces greater strength and mass gains than concentric, with one important condition: when intensity is high. At equivalent intensities the differences shrink considerably.
The cost. It produces more muscle damage and more delayed soreness, especially at first. That demands slow progression and no high volume at the outset.
How to apply it without special equipment:
- Control the lowering, always. Two to three seconds on the eccentric phase of your usual exercises. It's the simplest thing, it's free, and it's probably all most people need.
- Assisted eccentrics on exercises where the concentric is the limiter: pull-ups jumping to the top and lowering slowly, dips the same.
- Single-leg eccentrics, going up with two and down with one, on leg press or step-ups.
What is not advisable is overloaded eccentrics — lowering more weight than you can lift — without partners or proper equipment. It's the highest-risk application and the least necessary.
Isometrics: holding without moving
In an isometric contraction you produce force without the joint moving: a plank, holding a half squat, pushing against something immovable.
They have three applications where they genuinely contribute.
1. Tendon pain. The most interesting one. Rio and colleagues' work showed that sustained isometric sets produced an immediate reduction in pain in patellar tendinopathy, with an effect lasting hours. They're widely used as a way to train when the full movement hurts.
2. Sticking points. If you always fail at the same point of a lift, holding load at that specific angle develops strength there. With one caveat: isometric gains are quite angle-specific — they improve mainly within a narrow range around the trained position, not across the whole movement.
3. When movement is limited. After an injury, with pain in certain ranges, or without equipment. They maintain stimulus when the alternative would be not training.
How to do them. Sets of 20 to 45 seconds at high effort, or maximal pushes of 3 to 5 seconds against an immovable resistance. Three to five sets.
An important caution
Sustained isometrics at maximal effort raise blood pressure markedly, more than equivalent dynamic work, especially if you hold your breath.
If you have uncontrolled hypertension, cardiovascular disease, glaucoma or aneurysms, discuss this with your doctor first. And in any case: breathe during the isometric, don't hold your breath.
Curiously, low-intensity long-duration isometric training appears in recent meta-analyses as one of the forms of exercise that most reduces resting blood pressure over the medium term. These are different things: the acute effect raises it, the chronic adaptation lowers it.
When to use each
| Situation | Tool |
|---|---|
| Normal training | Control the eccentric, 2-3 seconds |
| Tendon that hurts | Sustained isometrics |
| Always failing at the same point | Isometric at that angle |
| Injury limiting range | Isometric in the pain-free range |
| Can't do the concentric yet | Assisted eccentric |
Common mistakes
Dropping the weight in free fall. The most common way to waste half of every rep.
Introducing eccentrics at high volume immediately. The delayed soreness they produce is considerable; start with two sets.
Expecting isometrics to transfer across the whole range. They improve mainly near the trained angle.
Doing isometrics while holding your breath. Unnecessary and cardiovascularly risky.
Using them as a substitute for dynamic training. They're complements with specific indications, not a program.
Conclusion
The eccentric is the phase that can produce the most force and the one nearly everyone wastes. Isometrics are the most useful tool when something hurts or when you always fail at the same point.
Start with what costs nothing and helps everyone: control the lowering of your sets over two or three seconds for the coming weeks. And if you have a tendon that bothers you — patellar, Achilles, elbow — try three 30-second isometric holds before your session: it's among the best effort-to-relief interventions available.
References
- Roig, M., et al. (2009). The effects of eccentric versus concentric resistance training on muscle strength and mass in healthy adults: A systematic review with meta-analysis. British Journal of Sports Medicine, 43(8).
- Douglas, J., et al. (2017). Chronic adaptations to eccentric training: A systematic review. Sports Medicine, 47(5).
- Rio, E., et al. (2015). Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy. British Journal of Sports Medicine, 49(19).
- Oranchuk, D. J., et al. (2019). Isometric training and long-term adaptations: Effects of muscle length, intensity, and intent. Scandinavian Journal of Medicine & Science in Sports, 29(4).
- Edwards, J. J., et al. (2023). Exercise training and resting blood pressure: A large-scale pairwise and network meta-analysis. British Journal of Sports Medicine, 57(20).