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Eccentric training

Also called eccentric exercise, eccentric resistance training, eccentric loading

Training in which muscles work while they are lengthened, as when lowering a weight. What it asks of muscles and tendons, and what studies found about strength, size, soreness and hamstring injury.

Region
Across the body
Updated
September 30, 2026
Reviewed
September 30, 2026 · how entries are checked

What it is

Working while lengthening

Muscle can contract in two ways, by shortening (concentric) or by lengthening (eccentric)2. The two differ a great deal in how force is made, in how much force is possible, and in energy cost2. In an eccentric contraction, a force on the muscle is larger than the force it produces, so the muscle and tendon lengthen while working1. The muscle absorbs energy from the load, so this work is also called negative work1.

Eccentric contractions are part of most everyday and sporting movements1. They hold the body up against gravity, absorb shock and store elastic energy before a shortening contraction1. Running downhill and walking down stairs are two examples in which the thigh muscles that straighten the knee do more eccentric work1.

The forms it takes

One review groups the ways of producing eccentric work into three kinds7:

  • Strength and conditioning exercises with body weight, outside loads or both7.
  • Isotonic (constant-load) or isokinetic exercises; isokinetic machines hold a limb to a fixed speed7.
  • Purpose-built eccentric ergometers (exercise machines)7.

These can target small or large muscle groups, with little or no muscle damage or pain, according to another review7. Accentuated eccentric loading is one variant: the lowering phase uses a heavier load than the lifting phase8. A review of 22 studies in youth athletes found two methods used most often9. They were the Nordic hamstring exercise and flywheel training, which uses a spinning wheel for resistance9.

What it loads

More force for less effort

Reviews state that eccentric contractions produce more force than isometric or concentric ones, at a lower metabolic cost1,2. In isolated muscle, lengthening force can reach close to 1.8 times the maximum held (isometric) force2. In living people it is lower, about 1.2 times, probably because the nervous system holds it back2. One review states that titin, a giant protein, working with actin, another muscle protein, can explain linear force rises seen in lengthening experiments10.

Fewer motor units, the nerve cells and the muscle fibres they switch on, are recruited in eccentric contractions2. They also fire at a lower rate than in shortening contractions2. One review puts the metabolic cost at about four times lower than the same exercise done concentrically1.

Heart and lungs on an eccentric cycle

A meta-analysis, which pools several studies into one answer, compared eccentric and concentric cycling across 21 studies11. At the same power, eccentric cycling gave lower oxygen use, breathing, heart rate, blood lactate and felt effort11. When the two were matched for oxygen use instead, eccentric cycling strained the heart and circulation more7,11. Heart rate, blood pressure and the heart’s output rose more7,11. Stroke volume, the amount of blood the heart pumps out with each beat, was lower7,11.

Load on a tendon: one example

One laboratory study compared eccentric squats with a free weight on a decline board and on flat ground12. Patellar tendon force was 25–30% greater on the board12.

Damage and soreness

A review states that eccentric exercise the body is not used to causes muscle damage and delayed-onset muscle soreness1. A review states that damage is generally accepted to begin with uneven stretching of sarcomeres, the small repeating units that make a muscle fibre contract1. Eccentric work at longer muscle lengths produced more signs of damage than at shorter lengths1. Soreness typically appears 12–24 hours after, peaks between 24 and 72 hours, and is gone within 5–7 days1. How sore a muscle feels matches other damage markers poorly1.

A review notes that older adults are more vulnerable to exercise-related muscle damage1. It reports that thigh muscle samples taken after eccentric cycling showed more disordered sarcomeres at ages 59–63 than at 20–301.

The repeated bout effect

Repeating a similar bout causes less damage, which is called the repeated bout effect13. After the repeated bout, muscle proteins in the blood rise less, and there is less soreness and swelling1. Strength and range of motion also recover faster1. Protection appears after a single bout, but seems more complete after several sessions1.

In 15 sedentary men, eccentric exercise repeated two weeks later changed all damage measures less, with a similar effect across nine muscle groups14. There is little agreement on why the effect happens13. One review weighs nerve, connective tissue and cell-level explanations, and concludes no single theory is likely to explain them all13.

One review looked at ways of avoiding damage and soreness from eccentric work1. It called repeated sessions of submaximal work, made harder step by step, the most useful approach described so far1.

How the body adapts

Strength

In a meta-analysis of 27 trials of maximal isokinetic training in healthy adults, the two modes gave these strength gains15:

Strength measuredEccentric-only trainingConcentric-only training
Eccentric27%1510%15
Concentric13%1514%15
Isometric18%1517%15

The eccentric strength gain differed between the two; the concentric and isometric gains did not15. The longer the training lasted, the larger the eccentric-only advantage for eccentric strength15. A review of 18 trials in healthy people under 65 found similar eccentric strength gains after the two, 19% each16. It found larger concentric strength gains after concentric training, 16% against 9%16.

Another meta-analysis of 20 trials compared the two3. Gains after eccentric training seemed more tied to the speed and type of contraction trained than gains after concentric training3. Total and eccentric strength rose more when eccentric work was done at higher intensity than the concentric training3. A review of 40 studies covered adults aged 17–3517. It found eccentric loads not limited by concentric strength appear better than traditional resistance training for measures linked to strength, power and speed17.

Nine trials covered 276 athletes and healthy people18. In them, flywheel training with eccentric overload beat conventional resistance training for strength, power, size, jumping and running speed18. In 49 studies, accentuated eccentric loading gave long-term changes similar to constant-load resistance training in strength, jump height, fascicle angle and length, and cross-sectional area8.

Muscle size: reviews disagree

Pooled studies point in different directions on muscle growth, or hypertrophy3,4:

  • In a 2009 review of 20 trials, high-intensity eccentric training increased muscle girth more than concentric training3.
  • In a 2017 review of 15 studies of healthy adults, eccentric work had the larger effect, but the difference was not statistically significant19.
  • In a 2025 review of 26 trials of 682 healthy adults, growth did not differ between the two, with very low certainty4.
  • In a 2017 review of 40 studies (ages 17–35), eccentric work matched or beat other modes for cross-sectional area (muscle size across)17.

In the 26-trial review, subgroups favoured eccentric training for upper-limb muscles and for programmes of 8 weeks or less4. One review concluded that when the two are matched for load or work, size rises similarly but through different changes in structure2. Changes in muscle protein building after the two kinds of exercise seem very similar2.

Fascicle length and what drives it

One review reported its authors’ ultrasound findings: eccentric training lengthened fascicles (bundles of muscle fibres) more2. Concentric training changed pennation angle, the angle at which fibres lie against the muscle’s line of pull, more2. In adult athletes, hamstring fascicles lengthened with eccentric training (a pooled mean difference of 0.90 cm) and shortened with concentric training5. Across 27 trials in adults, eccentric exercise improved joint flexibility by a moderate amount20. Flexibility was measured as range of motion (how far a joint moves) or fascicle length20.

One review looked at the mechanism, sarcomeres added in series. Its meta-analysis found no effect of eccentric training on the number of sarcomeres in series in animals, and too few human studies to judge21. It concluded that high force at long fibre lengths seems to be the key stimulus for adding sarcomeres21. By that review, eccentric work does not seem to be a key driver21.

Tendons

A review of 40 studies in adults aged 17–35 reported changes in tendon tissue17. These may relate to how much strain the tendon was put under17. One trial had 36 active volunteers22. In the 11 who did six weeks of eccentric decline squats with a 6-second lowering phase, the patellar tendon thickened about 21.8%22. The tendon overview gives the wider picture of how tendons respond to load.

Older adults and young athletes

A review states that many studies report older people keep a relatively preserved ability to produce eccentric strength1. It declines less with age than concentric or isometric strength1. Three reviews of older adults found these results23,24,25:

  • In 11 trials, a small but significant strength advantage over usual resistance training, with no significant difference in function, power or muscle size23.
  • In adults over 55 (19 papers), larger gains than concentric or usual exercise in timed up-and-go and two sit-to-stand tests, not the 6-minute walk24.
  • In 15 trials of 438 older adults, eccentric overload may improve leg strength and power. Against usual resistance training, a post-hoc analysis showed a trend towards it being at least no worse. Programmes of 8 weeks or more gave larger gains25.

A review of 22 studies covered athletes aged 18 or under9. It concluded its findings support eccentric training for improving strength, jumping, sprinting and changing direction in that group9.

Hamstring injury: two readings of the trials

In a meta-analysis of randomised trials in recreational to professional adult athletes, eccentric training reduced hamstring injuries by 56.8% to 70.0%5. In 15 studies of athletes, programmes with the Nordic hamstring exercise had a pooled risk ratio for hamstring injury of 0.4926. That was against programmes or usual training without it26.

A reanalysis kept only the five randomised trials of the Nordic hamstring exercise from an earlier 15-study meta-analysis6. It added one newer trial and found a pooled risk ratio of 0.596. Its confidence interval, the range that shows how precise a result is, ran from 0.27 to 1.296. Its authors judged the protective effect inconclusive and mostly based on trials at high risk of bias6.

Trials in people with tendon pain

Eccentric exercise has been studied in tendinopathy, local tendon pain that comes with activities that load it27. A review of Achilles and patellar tendinopathy found limited evidence, for the Achilles, that eccentric loading gives better outcomes than other loading programmes27. It found little evidence for isolating the eccentric part27.

One randomised trial had 58 people with long-lasting mid-portion Achilles tendinopathy28. Mid-portion means the part of the tendon more than 2 cm above where it attaches to the heel bone28. Twelve weeks of eccentric training and of heavy slow resistance training gave equally good improvements in symptoms28. Changes in tendon thickness did not differ between the two28. In 6 trials of 429 people with outer-elbow tendon pain, adding eccentric exercise to other approaches improved pain scores and strength over those approaches alone29.

Connections

Eccentric training works muscle and its tendon, which lengthen together under the load1. Exercise pages that use it include the Nordic hamstring curl, one of two methods used most often in a review of youth athlete studies9. They also include the decline squat, the eccentric heel drop, wrist extension and the wrist curl12,30,31,32.

The reviews above compared it with concentric or usual resistance training15,17. Plyometric training uses an eccentric action followed at once by a concentric one, as in repeated jumping33. Isometric training covers held (isometric) contractions, which make less force than eccentric work1,2.

Eccentric training loads

Eccentric training is used in

Eccentric training is compared with

Eccentric training is related to

Sources

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  2. Franchi MV, Reeves ND, Narici MV (2017). Skeletal Muscle Remodeling in Response to Eccentric vs. Concentric Loading: Morphological, Molecular, and Metabolic Adaptations.. Frontiers in Physiology. doi:10.3389/fphys.2017.00447 PMID 28725197
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  15. Spudić D, Nosaka K (2025). Eccentric-Only Versus Concentric-Only Isokinetic Strength Training Effects on Maximal Voluntary Eccentric, Concentric and Isometric Contraction Strength: A Systematic Review and Meta-analysis.. Sports Medicine - Open. doi:10.1186/s40798-025-00887-w PMID 40839186
  16. Vetter S, Schleichardt A, Köhler HP, Witt M (2022). The Effects of Eccentric Strength Training on Flexibility and Strength in Healthy Samples and Laboratory Settings: A Systematic Review.. Frontiers in Physiology. doi:10.3389/fphys.2022.873370 PMID 35574461
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  22. Abián P, Martínez F, Jiménez F, Abián-Vicén J (2020). Effects of Eccentric Single-Leg Decline Squat Exercise on the Morphological and Structural Properties of the Vastus Lateralis and Patellar Tendon.. International journal of environmental research and public health. doi:10.3390/ijerph17249410 PMID 33333987
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Every source the library cites

Changes

  • First published.