RESEARCH REVIEW

Eccentric Muscle Actions and How the Strength and Conditioning Specialist Might Use Them for a Variety of Purposes

Original article by Cowell, John F; Cronin, John; Brughelli, Matt

Background

Eccentric training, focusing on the lengthening phase of muscle contraction, is gaining traction in strength and conditioning, rightfully so. I've been drawn to this area over the past year, and I've found this 2012 article to be a valuable resource. Despite being over a decade old, its insights into the unique physiological and mechanical benefits of eccentric muscle actions are still applicable. It lays out the diverse applications of this training method, from tendon remodelling to increasing muscle fibre length, and explores how supra-maximal loads can push athletes beyond their concentric limits and elicit valuable neuromuscular adaptations. It's a great starting point for anyone interested in the power of eccentrics.

What the authors did

The article reviews the existing literature and synthesises the findings to offer practical insights for sports practitioners. They provide case studies as well as recommendations for eccentric loading parameters.

What the authors found

• Eccentric loading has a demonstrable effect on remodelling tendon structure.

• Adopting eccentric loading parameters could help prevent surgical interventions in athletes suffering from tendinopathies. 

• Shifting optimal muscle length through eccentric training to produce peak force at greater muscle lengths, decreasing injury risk.

• Supra-maximal eccentric (SME) and accentuated eccentric loading (AEL) strength training produces greater strength and hypertrophy gains compared to concentric training.

• Eccentric capacity affects stretch-shortening cycle efficiency through contraction coupling, eccentric velocity tolerance, and utilisation of elastic energy.

What does this mean?

Tendon Rehabilitation:

• It increases the “lengthening” strength of the muscle-tendon complex to help attenuate landing forces, reducing strain on the tendons during contact movements.

• Stimulates collagen synthesis and fibril organisation, which promotes tendon remodelling.

• Enhances tendon stiffness and tensile strength.

Muscle Length-Tension Curve Shift:

• Eccentric loading through long muscle lengths extends the muscle’s optimal length for tension.

• Athletes with hamstring injury history demonstrated 12.7 degrees shorter optimum muscle length on the injured limb, compared to noninjured.

• Reduces susceptibility to strain injuries by enabling force production at greater muscle lengths.

• Nordic curls and similar exercises consistently shift the length-tension relationship.

Supra-Maximal & Accentuated Eccentric Training:

• SME involves loads that exceed the athlete’s concentric 1RM entirely—typically 110-130% of 1RM. Some evidence suggests athletes may be up to 60% stronger eccentrically than concentrically.

• AEL involves loading above concentric 1RM during the eccentric phase

• After 6 weeks of training twice per week, an AEL group showed a 29% increase in hamstring strength compared to 19% in the standard group.

• After 10 weeks of training, the elbow extensor strength of an SME group increased by 24%, compared to 15% in the standard group.

• Significant mechanical stress is placed on muscles and connective tissues, which can increase injury risk if not implemented properly.

• Enhances force production and muscle architecture through targeted overload.

Stretch-Shortening Cycle (SSC) Efficiency:

• Improves contraction coupling and eccentric velocity tolerance.

• Eccentric training improves SSC by enhancing preactivation

• Increases tendon and MTU stiffness, increasing the utilisation of elastic energy and enhancing reactive strength.

• Contributes to greater explosiveness and performance in plyometric movements.

Limitations

• The vast majority of the literature reviewed was conducted on untrained populations.

• Eccentric training often requires high levels of stability or utilises single-joint exercises which neglect synergistic muscle groups. (Although there is merit to this in specific scenarios.)

• The training regimes did not reflect those seen in practice, with training sessions every day or biweekly sessions with little longitudinal data.

• Set and rep schemes often did not match those commonly employed in practice.

Coach's Takeaway

Understanding how tendons adapt requires recognising their viscoelastic properties and mechanical strain thresholds. Eccentrics offer an effective way to meet the load and velocity required for remodelling, benefiting both healthy and degenerative tendons. Tempo eccentrics can be highly beneficial in tendon rehab, but only if the load is heavy enough to stimulate tenocytes. A common and detrimental pitfall in rehabilitation is using a load that is simply too light to elicit positive change.

Fascicle length increases have been hypothesised as key to improving the length-tension relationship, but until recently, evidence was lacking. Andrews et al. (2024) provided the first direct human data showing serial sarcomere additions in the bicep femoris after 9 weeks of eccentric training, with the most hypertrophy occurring in the distal region.

Nordics are the poster child for eccentric hamstring work and injury reduction strategies, and while they have their place, I’ve got some reservations. They’re often touted as a fix for hamstring strains that typically occur during the late swing phase of sprinting, but the hip and knee angle during Nordics doesn’t quite match that of sprint mechanics. Plus, they’re notoriously hard to standardise, progress, and regress. Athletes tend to “bail” right at the end of the movement—arguably the most important part for driving fascicle length and distal hypertrophy.

My preference? A 2-down-1-up seated hamstring curl at 100-120% of concentric 1RM. For those sticking with Nordics, band-assisted full-range contractions are a good option, progressing by gradually removing assistance over time.

Eccentric training can be a game-changer, but it often gets sidelined due to worries about overloading or DOMS—and I get it. As Luke Storey recently wrote for Sportsmith, “...although eccentric contractions…have an effect on muscle damage, DOMS is exacerbated most by unaccustomed exercise. If the body is not used to something, it will certainly freak out over the subsequent 24-48 hours—whether that’s the result of eccentrically dominant exercise or something else.”

I couldn’t agree more. In my own practice, I’ve seen that the more exposure athletes have to eccentrics, the less their bodies overreact, which aligns with the classic principle of progressive overload.

Final thoughts

Eccentric training is finally gaining the attention it merits, and every coach should understand its potential. However, safe and effective implementation requires careful planning and a solid understanding of the underlying principles. This review is a good introduction, but it only provides a glimpse into the broader scope of eccentric training applications and considerations. For anyone looking to dive deeper, Matt Handford's An Essential Guide to Eccentric Training and Pete Burridge's A Practical Guide to Eccentric Training are both excellent resources and articles I frequently refer back to.

Thanks for reading!

~ Murray

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