Most people who exercise regularly have never thought about whether their muscles are shortening or lengthening during a given movement. But the direction a muscle moves while under load is one of the most important variables in training, determining how much muscle damage is produced, how much strength is gained, how much soreness follows, and which specific athletic qualities are developed.
Understanding the difference between eccentric and concentric exercise is not an academic exercise. It directly changes how you programme your training, why certain exercises produce results that others do not, and how to use specific loading strategies to target the adaptations most relevant to your goals.
What Eccentric and Concentric Mean
Concentric contraction: A muscle contraction where the muscle shortens while producing force. The classic example is the upward phase of a bicep curl: as you curl the weight toward your shoulder, the bicep shortens while contracting. Concentric contractions overcome an external resistance.
Eccentric contraction: A muscle contraction where the muscle lengthens while producing force. Using the same bicep curl example, the lowering phase where you control the weight back to the starting position is eccentric: the bicep is still contracting and producing force, but the force is insufficient to overcome gravity and the muscle is lengthening under load.
Isometric contraction: A third type where the muscle contracts without changing length. Holding a plank, holding the bottom of a squat, or pausing mid-curl are all isometric contractions. These are covered in separate articles on this site.
A simple way to remember the distinction:
- Concentric: the muscle gets shorter (think: con-centric, coming to the centre)
- Eccentric: the muscle gets longer (think: eccentric means different, and this is the often-overlooked phase)
Almost every resistance training exercise involves both types within the same movement. The squat involves a concentric push upward and an eccentric lower downward. The push-up involves a concentric push and an eccentric lower. The deadlift involves a concentric pull from the floor and an eccentric lower back to the starting position.
The Physiological Differences
Force production:
One of the most significant and most counterintuitive findings in exercise science is that muscles can produce more force eccentrically than concentrically. The maximum eccentric strength of a muscle is approximately 20 to 40 percent greater than its maximum concentric strength.
This occurs because eccentric force production combines active muscular force with the passive elastic contribution of the tendons and the titin protein filaments within the muscle, which act as springs that resist lengthening. The concentric contraction relies only on the active muscular component.
Practical implication: This force differential means that the eccentric phase of an exercise is actually the more mechanically demanding phase for the muscle, even though it often feels easier. The weight that barely can be lifted concentrically can typically be lowered eccentrically with control.
Muscle damage:
Eccentric contractions produce significantly more micro-damage to muscle fibres than concentric contractions at the same load. The stretching of the muscle under tension during eccentric loading produces micro-tears in the myofibrils (the contractile units of muscle) at a rate that concentric contractions do not replicate.
This muscle damage is the primary cause of delayed onset muscle soreness (DOMS), which is why muscles are significantly sorer after activities dominated by eccentric loading (running downhill, the lowering phase of heavy squats, starting a new exercise programme) than after purely concentric activities.
Metabolic cost:
Concentric contractions have a higher metabolic cost than eccentric contractions for the same force output. Eccentric contractions are more mechanically efficient because the elastic energy contribution reduces the metabolic demand. This is why walking downhill (primarily eccentric for the quads) requires less oxygen than walking uphill (primarily concentric) at the same speed.
Neural drive:
Fewer motor units are required to produce the same force eccentrically as concentrically because each motor unit is contributing more force through the passive elastic component. This lower neural demand during eccentric loading is one reason the post-exercise neural fatigue from eccentric training is different in character from concentric training.
Why Eccentric Exercise Deserves More Attention
Most recreational training programmes emphasise the concentric phase and neglect or rush through the eccentric phase. This is a significant missed opportunity because the eccentric phase produces the majority of the training adaptations that make exercise valuable.
Muscle growth: The eccentric phase is the primary driver of muscle hypertrophy. Research has consistently found that eccentric-only training produces greater muscle growth than concentric-only training at the same load. When the eccentric phase is performed slowly and with control (rather than dropped quickly), it produces the most significant hypertrophic stimulus.
Strength development: Because muscles can produce more force eccentrically than concentrically, training the eccentric phase specifically with supramaximal loads (loads greater than the concentric maximum) overloads the muscle in a way that concentric training cannot. This is the basis of eccentric overload training used in advanced strength programmes.
Injury prevention: Eccentric strength is specifically relevant to injury prevention because many common sports injuries occur during the eccentric phase of movement. Hamstring strains during sprinting occur when the hamstring is eccentrically controlling the leg swing. Patellar tendinopathy is related to insufficient eccentric quad strength during landing. Achilles tendinopathy is related to insufficient eccentric calf strength during the loading phase of running. Training eccentric strength specifically reduces the risk of all these injuries.
Tendon health: Eccentric loading produces specific adaptations in tendon structure that concentric loading does not. Collagen synthesis and tendon stiffness both improve more with eccentric protocols, which is why eccentric exercise is the primary treatment for most tendinopathies.
Why Concentric Exercise Also Matters
Despite the emphasis on eccentric benefits above, concentric training has specific and irreplaceable roles:
Power development: While eccentric strength is greater than concentric strength at slow speeds, the velocity at which concentric contractions can be performed without load is much higher than eccentric contractions. Explosive, high-velocity concentric movements (jumps, throws, sprints) develop the rate of force development and concentric power that are essential for athletic performance.
Skill acquisition: Many movement patterns are learned more effectively through concentric emphasis (the upward phase of a movement) before the eccentric loading is added. Learning the concentric pattern first allows the correct motor program to be established before the additional demand of controlled eccentric loading is added.
Metabolic conditioning: The higher metabolic cost of concentric contractions makes concentric-dominant training more effective for cardiovascular fitness and caloric expenditure. Circuit training and metabolic conditioning programmes that emphasise continuous concentric movement produce greater cardiovascular and metabolic adaptations than slow, eccentric-focused training.
Plyometric performance: Explosive concentric power, developed through plyometrics and sprint training, is the final output quality in the stretch-shortening cycle. The eccentric loading phase stores the elastic energy, but it is the rapid concentric extension that produces the jump height, sprint speed, or throw velocity.
Exercises That Emphasise Each Type
Eccentric-Dominant Exercises
Eccentric-only deadlift (lowering phase):
Use a load that exceeds the concentric maximum. With the assistance of training partners (for the concentric lift) or from a rack position, lower the bar very slowly (5 to 8 seconds) back to the floor. This supramaximal eccentric overload produces the greatest eccentric stimulus available.
Nordic hamstring curl:
The athlete’s ankles are fixed and the body lowers forward from the kneeling position. The hamstrings eccentrically control the entire bodyweight through the lowering phase. This is the most effective eccentric hamstring exercise and the primary evidence-supported intervention for hamstring strain prevention.
Eccentric calf lower (on a step):
Rise onto both toes, transfer weight to one foot, and lower the heel slowly below the step over 3 to 4 seconds. The eccentric calf lower is the primary rehabilitation exercise for Achilles tendinopathy and the most effective exercise for developing Achilles tendon stiffness.
Slow-tempo lowering in any compound exercise:
Any exercise where the lowering phase is performed with a 3 to 5-second count emphasises eccentric loading. A 4-second squat descent, a 3-second chin-up lowering, or a 4-second push-up lowering all produce greater eccentric stimulus than the same exercises performed at normal tempo.
Running downhill:
The quads eccentrically control the body during each footstrike on a downhill surface. This is why significant quad soreness follows downhill running and why downhill running is used to specifically develop quad eccentric strength in some trail running programmes.
Plyometric landing phase:
The landing from a jump is almost entirely eccentric as the quads, glutes, and calves absorb the landing impact. Training the landing mechanics of plyometric exercises with emphasis on slow, controlled landings develops eccentric strength specifically.
Concentric-Dominant Exercises
Sled push and pull:
The sled provides resistance only in the direction of push or pull. There is no eccentric loading phase because the sled does not resist the return movement. This makes sled training almost purely concentric, producing muscular fatigue and strength development with minimal muscle damage and soreness.
Why this matters: Athletes returning from injury can perform sled work to maintain strength and conditioning without the muscle damage of eccentric training, allowing them to train hard during recovery periods.
Concentric-only press on cable machine:
Release the weight stack at the top of a pressing movement (rather than controlling the return) and reset before each concentric press. This isolates the concentric stimulus.
Cycling:
Cycling is primarily concentric: the downstroke of each pedal revolution is a concentric quad extension. The return phase provides minimal eccentric loading. This is why cycling produces minimal DOMS compared to running, even at the same cardiovascular intensity.
Swimming:
The propulsive phases of swimming strokes are primarily concentric. The recovery phase provides little eccentric resistance from water. This is another reason swimming is used for athletic conditioning during injury recovery: it maintains cardiovascular and muscular fitness with minimal muscle damage.
Box jumps (jump phase):
The jump phase of a box jump is entirely concentric. When step-down is used rather than jumping back down, the eccentric landing phase is also eliminated. This is why box jumps with a step-down are used in some programmes to develop explosive concentric power without the cumulative eccentric damage of repeated jump landings.
Olympic lifts (concentric emphasis):
The pull phases of Olympic lifting movements are primarily concentric. The catching phase introduces some eccentric loading but the dominant training stimulus is the explosive concentric extension.
How to Programme Eccentric and Concentric Work Together
The standard approach: equal emphasis
In most resistance training programmes, each exercise involves equal emphasis on both phases. A natural tempo of 2 seconds concentric and 2 seconds eccentric is the baseline from which modifications can be made.
The eccentric emphasis approach:
Slow the eccentric phase to 3 to 5 seconds while maintaining a normal concentric phase. This increases the eccentric stimulus, muscle damage, and hypertrophic adaptation from each set. Appropriate for:
- Muscle building phases
- Injury prevention emphasis
- Tendinopathy rehabilitation
- Athletes wanting to develop eccentric strength without adding sets
The concentric emphasis approach:
Accelerate the concentric phase to maximum speed while performing a controlled but normal-tempo eccentric. This emphasises the power development and rate of force development adaptations. Appropriate for:
- Power and explosiveness development
- In-season training where muscle damage must be minimised
- Metabolic conditioning phases
The eccentric overload approach:
Use loads that exceed the concentric maximum, possible through:
- Partner-assisted concentric phase (the partner helps lift the load) followed by unassisted eccentric lowering
- Bands that reduce the effective load during the concentric phase but provide full load during the eccentric phase
- Rack-based eccentric-only work where the bar is set at the top position and only lowered
Appropriate for:
- Advanced strength athletes targeting specific eccentric strength deficits
- Rehabilitation from specific tendinopathies where eccentric overload is the evidence-supported treatment
- Strength athletes attempting to break through a plateau
Weekly structure:
Avoid scheduling two consecutive sessions with high eccentric emphasis. Eccentric muscle damage requires 48 to 72 hours to resolve adequately. A programme that includes one eccentric-focused session followed by a concentric-emphasis or metabolic session before the next eccentric session allows adequate recovery.
Sport-Specific Applications
Sprinters:
Hamstring eccentric strength is the primary injury prevention target. Nordic hamstring curls 2 to 3 times per week during the off-season and once per week during the competition season directly reduce hamstring strain rates. Concentric-focused sprint training and plyometrics develop the explosive concentric power of each stride.
Runners:
Downhill running and eccentric calf lowering develop the eccentric strength that absorbs landing impact during running. Insufficient eccentric calf and quad strength is the primary cause of shin splints and Achilles tendinopathy during mileage build-up periods.
Basketball and volleyball players:
Landing mechanics training that emphasises slow, controlled eccentric landings develops the quad and glute eccentric strength that prevents ACL injuries during landing from jumps. The explosive concentric phases (jump initiation) are developed through plyometrics.
Swimmers:
The primarily concentric nature of swimming means that dryland eccentric training provides an important complement to pool training. Eccentric shoulder and rotator cuff work prevents the shoulder overuse injuries that are endemic in competitive swimming.
Weightlifters and powerlifters:
The lowering phase of every lift represents an eccentric overload opportunity. Tempo prescriptions that slow the eccentric phase (commonly 3 to 4 seconds) are used to develop additional hypertrophy and tendon strength. Eccentric overload with accommodating resistance (bands and chains) is used in advanced programmes.
Frequently Asked Questions
Why am I more sore after downhill running than flat running?
Downhill running creates sustained eccentric loading of the quadriceps as they control the body during each footstrike on the decline. This eccentric loading produces significantly more muscle damage than the primarily concentric demand of flat running, producing the pronounced quad soreness that follows long downhill sections. The same mechanism explains why step descent produces more soreness than step ascent.
Should I always control the lowering phase of exercises?
In most strength training contexts, yes. A controlled eccentric phase (2 to 4 seconds) produces more muscle damage, greater hypertrophic stimulus, and more complete strength development than dropping the weight quickly. However, in power and speed training contexts, the eccentric phase may be performed at higher speed to emphasise the stretch-shortening cycle and power transfer. The appropriate tempo depends on the training goal.
Is eccentric training safe for beginners?
Eccentric training is safe for beginners when introduced gradually. The greater muscle damage from eccentric-focused training produces significant DOMS in people who are new to it, which can be demotivating and may temporarily limit function. Beginners should start with normal tempo training and gradually introduce eccentric emphasis over several weeks to allow the muscle and connective tissue to adapt.
What is the difference between negative reps and eccentric training?
Negative reps is the common gym term for eccentric-only training, where only the lowering phase is performed. Technically, all resistance training involves an eccentric phase, but the term negative reps typically refers to intentionally emphasised or supramaximal eccentric loading. Eccentric training is the broader term that encompasses all approaches to emphasising the lengthening phase of muscle contraction.
Can eccentric training help with chronic tendinopathy?
Yes, significantly. Eccentric loading protocols are the most evidence-supported conservative treatment for most tendinopathies. The eccentric calf lower for Achilles tendinopathy (Alfredson protocol), the eccentric quad loading for patellar tendinopathy, and the eccentric wrist extensor loading for lateral epicondylalgia all have strong research support and produce better outcomes than rest alone in most cases.