Eccentric training explained simply

When you lower yourself into a squat, walk down a flight of stairs, or decelerate after a jump, your muscles are working actively while lengthening. This is called eccentric muscle action and is a natural part of almost every movement.

⠀

Eccentric training is used in general strength training, sport, and rehabilitation. It can allow the muscles to produce high levels of force at a relatively low energy cost, but it can also cause considerable soreness if the load is increased too quickly. The effect therefore depends on how the training is prescribed, which muscle or tendon is being loaded, and what the goal of the programme is.

⠀

The muscle works while it lengthens

A muscle can produce force in several ways. The difference lies in what happens to the muscle’s length while it is generating force.

During concentric muscle action, the muscle shortens. This happens, for example, when you lift a dumbbell during a biceps curl or rise from a chair.

⠀

During isometric muscle action, the muscle develops force without any substantial change in joint position. Planks and wall sits are common examples.

⠀

During eccentric muscle action, the muscle produces force while it lengthens. This occurs during the controlled lowering phase of an exercise.

The three main forms can be summarised as follows:

Type of muscle action	What happens to the muscle?	Example
Concentric	The muscle shortens	You rise from a squat
Isometric	Muscle length changes very little	You hold a static squat
Eccentric	The muscle lengthens while producing force	You lower yourself into a squat

⠀

It is important to understand that the muscle is not relaxing during the eccentric phase. It is working actively to control or slow the movement.

⠀

The muscles function as the body’s braking system

Eccentric muscle action is especially important when the body needs to slow down, absorb force, or control gravity.

When you walk downstairs, the thigh muscles work eccentrically to prevent the body from dropping uncontrollably onto the next step. When you land after a jump, the muscles around the hips, knees, and ankles work eccentrically to absorb the impact.

Eccentric work is used when you:

• walk or run downhill

• lower a weight under control

• decelerate before changing direction

• land after a jump

• sit down on a chair

• slow the arm after throwing

• control the body on stairs

⠀

Without sufficient eccentric capacity, many movements would become fast, uncontrolled, and more demanding on the joints. The ability to brake is therefore just as important as the ability to create forward movement.

⠀

Eccentric strength is often greater than concentric strength

Muscles can usually tolerate greater force during eccentric work than during concentric work. You can therefore often lower a heavier load than you are able to lift.

This is explained by several mechanisms. When the muscle lengthens while generating force, both active contractile structures and passive elastic components contribute to the total force. The protein titin and other connective tissue structures may also contribute to resistance when the muscle fibres are stretched.

⠀

The microscopic interactions between actin and myosin also behave differently during lengthening than during shortening. As a result, relatively high force can be produced without the same level of motor-unit recruitment.

Eccentric strength may therefore be substantially greater than concentric strength, but the difference varies according to:

• which muscle is tested

• movement speed

• joint angle

• training background

• measurement method

• familiarity with eccentric work

⠀

This is one reason why specialised eccentric training can create a very high mechanical load. The same property also means that the training must be introduced carefully.

⠀

High force requires relatively little energy

Eccentric muscle action has a lower metabolic cost than concentric action at the same force level. In other words, the muscle can produce or resist a large amount of force without using a proportionally large amount of energy.

Oxygen consumption, heart rate, and ventilation may therefore be lower during a mainly eccentric task than during concentric work with a similar mechanical load.

⠀

This can be useful in rehabilitation. People with reduced cardiovascular fitness may in some cases achieve a meaningful muscular training stimulus without placing the same demand on the heart and lungs as conventional exercise.

This has made eccentric training relevant for:

• older adults with reduced muscle strength

• people with low physical capacity

• some patients with cardiac or respiratory disease

• people rebuilding muscle after inactivity

• athletes seeking a high mechanical load

⠀

A lower energy cost does not mean that the training always feels easy. The local muscular load can still be high even when breathing and heart rate remain relatively moderate.

⠀

Why does eccentric training often cause soreness?

Unfamiliar eccentric exercise is one of the most common causes of delayed-onset muscle soreness, often referred to as DOMS. Pain and stiffness usually appear several hours after training and may peak one to three days later.

⠀

During unfamiliar eccentric loading, force is not always distributed evenly across all muscle fibres. Certain sarcomeres and structures may experience particularly high mechanical stress. This can produce microscopic changes in muscle tissue and trigger a local inflammatory and repair response.

Common reactions after unfamiliar eccentric training include:

• tenderness during movement or pressure

• stiffness

• temporary loss of strength

• reduced range of motion

• mild swelling

• a heavy feeling in the muscles

⠀

Soreness does not necessarily mean that the training was more effective. Severe soreness can reduce movement quality, impair the next session, and make it harder to maintain training volume.

The goal should therefore not be to become as sore as possible, but to apply a load the body can adapt to.

⠀

The body learns to tolerate the load

When the same eccentric activity is repeated after sufficient recovery, soreness usually becomes less pronounced. This is often called the repeated bout effect.

After the first exposure, adaptations occur that make the muscle more resistant to a similar load later.

These adaptations may include:

• better distribution of force across muscle fibres

• altered recruitment of motor units

• structural changes in the muscle

• stronger connective tissue

• an increased number of sarcomeres in series

• more efficient movement control

⠀

The effect may last for weeks or months, but it gradually weakens if the load is not repeated. This is an important reason why eccentric training should be introduced gradually rather than avoided completely.

⠀

Eccentric training can increase strength and muscle mass

Both eccentric and concentric training can increase strength and muscle mass. Eccentric training may, however, produce some specific adaptations, especially when it is performed with high loads or through a large range of motion.

Eccentric training may contribute to:

• increased maximal strength

• increased muscle cross-sectional area

• improved force absorption

• greater strength at long muscle lengths

• better control during lowering phases

• changes in muscle architecture

⠀

Some research suggests that eccentric training may increase fascicle length more than concentric training. Fascicles are bundles of muscle fibres, and greater fascicle length may be relevant for force production at long muscle lengths and high movement speeds.

This is particularly relevant for muscles that are often injured while producing high force in a lengthened position, such as the hamstrings during sprinting.

⠀

Eccentric training is not automatically superior to conventional strength training. The effect depends on training volume, intensity, range of motion, exercise selection, and effort.

⠀

A slow lowering phase is not always the same as heavy eccentric training

Eccentric training is often associated with lowering a weight very slowly. A slow lowering phase increases time under tension and may improve control, but it does not necessarily maximise eccentric force.

If the load is light, a very slow lowering phase may mainly increase local fatigue. Specialised eccentric overload, by contrast, uses a load greater than the person can lift concentrically.

⠀

Several forms of eccentric training are used in practice:

Controlled lowering phase

The weight is lowered over two to five seconds using a load that can also be lifted again.

⠀

Eccentric overload

The load during the lowering phase is greater than during the lifting phase. This can be performed with a training partner, machines, or specialised equipment.

⠀

Unilateral eccentric work

The weight is lifted using two arms or legs and lowered using one side. This is often used in rehabilitation.

⠀

Flywheel training

A flywheel stores energy during the concentric phase. That energy must then be absorbed during the eccentric phase.

⠀

Eccentric training at long muscle lengths

The muscle is loaded while relatively lengthened, as in the Nordic hamstring exercise or deep split squats.

⠀

The most appropriate variation depends on the training goal and the individual’s experience.

⠀

Tendons need progressive load, not only eccentric work

Eccentric training has long been used for tendinopathies, particularly in the Achilles and patellar tendons. The classic Alfredson protocol for Achilles tendinopathy made eccentric heel lowering widely known.

⠀

It was previously common to suggest that the eccentric phase itself had a unique healing effect. More recent research presents a more nuanced picture.

The central principle appears to be that the tendon is exposed to sufficient and progressive load over time. Eccentric training, heavy slow resistance training, and other progressive loading approaches can all be effective.

In tendon rehabilitation, loading may help to:

• increase tendon load tolerance

• improve muscle strength around the tendon

• reduce pain over time

• improve function

• prepare the tendon for activity-specific demands

⠀

Eccentric training is therefore a useful tool, but it is not necessarily the only or best option for everyone.

⠀

The load should be adjusted according to symptom irritability, the duration of the condition, and the activities the person needs to return to. A runner and a sedentary person may require very different progressions.

⠀

The Nordic hamstring exercise is a well-known example

The Nordic hamstring exercise is one of the most studied eccentric exercises in sport. The athlete kneels with the ankles fixed and controls the forward fall of the upper body using the hamstrings.

⠀

The exercise loads the hamstrings eccentrically at long muscle lengths. Systematic reviews have shown that injury-prevention programmes including the Nordic hamstring exercise can substantially reduce the incidence of hamstring injuries.

Possible explanations include:

• increased eccentric knee-flexor strength

• increased fascicle length

• better capacity at long muscle lengths

• greater tolerance of high force

• improved preparation for sprinting demands

⠀

The exercise can, however, cause considerable soreness when first introduced. It is therefore sensible to begin with a low number of repetitions and increase the volume gradually.

The Nordic hamstring exercise is not the only useful exercise for the posterior thigh. Hip-extension exercises, Romanian deadlifts, and sprint training provide other important loading profiles.

⠀

Eccentric work is central to running and jumping

During running, several muscles work eccentrically in every landing phase. The calf muscles control ankle movement, the quadriceps control knee flexion, and the hip muscles help stabilise the pelvis and trunk.

⠀

During sprinting, the hamstrings work eccentrically towards the end of the swing phase. The muscle must slow the lower leg before the foot contacts the ground.

During jumping and landing, the muscles must absorb large forces within a short period of time. Eccentric capacity is therefore important in sports involving:

• sprinting

• jumping

• changing direction

• rapid deceleration

• landing

• contact with opponents

⠀

Good eccentric strength alone does not prevent every injury. Technique, total workload, recovery, and the specific demands of the sport must also be considered.

⠀

Downhill running creates particularly high eccentric load

When running downhill, the muscles must slow the body more with every step. The quadriceps are exposed to substantial eccentric loading as the knee bends after foot contact.

This explains why many people experience much more soreness after downhill running than after a similar run on flat terrain.

⠀

Downhill running can be used as specific training, but it should be introduced gradually. Too much too soon may lead to:

• severe soreness

• reduced strength for several days

• altered running technique

• longer recovery needs

• irritation of already sensitive tissue

⠀

Runners preparing for events with a large amount of downhill running should therefore adapt to this type of load well in advance.

⠀

Older adults may particularly benefit from eccentric capacity

The ability to produce eccentric force is important in daily activities such as sitting down, walking downstairs, and controlling the body when balance is disturbed.

In older adults, reduced eccentric strength may contribute to difficulty with:

• walking downstairs safely

• sitting down under control

• slowing a movement

• managing uneven surfaces

• recovering balance

• controlling the body after a misstep

⠀

Eccentric training may therefore be relevant for function and fall prevention. Its relatively low energy cost may also be beneficial for people who do not tolerate high cardiovascular loads.

The training still needs to be adapted to balance, movement control, pain, and overall health.

⠀

How eccentric training can be used in practice

Most people do not need specialised equipment. The eccentric phase can be emphasised by controlling the lowering portion of common exercises.

Examples include:

• slow lowering in a squat

• controlled step-down from a box

• slow lowering during calf raises

• Romanian deadlifts

• negative pull-ups

• slow lowering in a biceps curl

• lunges with a controlled descent

• Nordic hamstring exercises

• slow lowering during push-ups

⠀

A simple approach is to use two to four seconds during the lowering phase. The load should remain controlled enough for technique to be maintained.

A possible progression is:

• begin with a low volume and few exercises

• use a moderate load

• perform two to three controlled sets

• increase repetitions first

• increase load afterwards

• introduce specialised overload later

• allow sufficient recovery between unfamiliar sessions

⠀

Progression should be slower for people who are not accustomed to strength training or who have a painful condition.

⠀

More soreness is not the goal

Eccentric training can be effective without causing severe soreness. Soreness says little about training quality and is not required for strength development.

If the training causes so much soreness that the person cannot walk normally, work, or complete the next planned session, the dose was probably higher than necessary.

Signs that the volume should be reduced include:

• soreness that limits daily function

• clear strength loss lasting several days

• worsening movement quality

• increasing joint or tendon pain

• needing to cancel several sessions

• persistent swelling or sharp pain

⠀

A moderate and temporary response can be normal. The load should still be adjusted according to function rather than a goal of producing as much discomfort as possible.

⠀

When eccentric training requires extra caution

Eccentric training is safe for most people when appropriately prescribed, but certain situations require greater caution.

The load should be assessed carefully in cases of:

• acute muscle or tendon injury

• recent surgery

• substantial swelling

• severe or unexplained pain

• marked muscle weakness

• neurological conditions

• previous rhabdomyolysis

• prolonged inactivity

• medication affecting muscle function

• significant cardiac or respiratory disease

⠀

After surgery, loading must follow the restrictions set by the surgeon or treating healthcare professional. During muscle or tendon rehabilitation, training should be matched to tissue tolerance and the stage of recovery.

Severe muscle pain, marked swelling, substantial weakness, and dark urine after intense exercise may indicate serious muscle breakdown and require urgent medical assessment.

⠀

Summary

Eccentric training means that a muscle develops force while lengthening. This occurs when the body slows a movement, such as during the lowering phase of a squat, while walking downstairs, or when landing after a jump. Eccentric work allows the muscles to handle high force at a relatively low energy cost and can contribute to increased strength, muscle growth, improved braking control, and greater load tolerance. It is used in strength training, sport, and rehabilitation, but it is not automatically better than other forms of strength training. The load should be increased gradually because unfamiliar eccentric exercise often causes soreness and temporary strength loss.

⠀

Sources

• Douglas, J., Pearson, S., Ross, A. & McGuigan, M. (2017). Eccentric exercise: Physiological characteristics and acute responses. Sports Medicine, 47(4), 663–675.

• LaStayo, P. C., Marcus, R. L., Dibble, L. E., Wong, B. & Pepper, G. (2014). Eccentric exercise in rehabilitation: Safety, feasibility, and application. Journal of Applied Physiology, 116(11), 1426–1434.

• Van Dyk, N., Behan, F. P. & Whiteley, R. (2019). Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: A systematic review and meta-analysis of 8459 athletes. British Journal of Sports Medicine, 53(21), 1362–1370.

⠀