Eccentric strength training for speed and muscle strain prevention

Running fast isn't just about pushing the ground hard. Sprinting requires the athlete to produce force, absorb impact, slow down segments of the body and reorganize the stride in fractions of a second. With each running cycle, the hamstrings — a muscle group in the back of the thigh, formed mainly by the biceps femoris, semitendinosus and semimembranosus — need to control the leg as it moves forward, brake knee extension, help with hip extension and withstand tension at high speed. Therefore, many posterior strains occur when the muscle is stretched and being stressed at the same time, especially in the final phase of the leg swing during running. In this context, eccentric strength is not a gym detail; It is specific protection for the moment when the athlete most needs to resist speed.

Eccentric contraction is when the muscle produces force while lengthening. In squats, this happens on the way down; in the stiff-legged deadlift or Romanian deadlift, it happens when the hips go backwards and the hamstrings stretch under load; in Nordic exercise, it happens when the athlete tries to control the fall of the torso forward using the hind legs. This is different from the concentric phase, when the muscle shortens to overcome the load, such as rising from a squat or pulling the body back. For speed sports, the eccentric phase is crucial because the body doesn't just need to speed up; you also need to brake and absorb forces without losing alignment. An athlete who accelerates well but cannot control deceleration, landing, change of direction, or the final phase of the stride is leaving too much tissue exposed to too much tension.

The Nordic hamstring exercise, known as Nordic Hamstring Exercise, is one of the most studied examples of eccentric training. In it, the athlete remains kneeling, with their ankles fixed, and slowly lowers their torso forward trying to resist gravity with their hind legs. The slower and more controlled the descent, the greater the eccentric demand. This exercise became famous because it does not require complex equipment and attacks a very important adaptation: increasing the eccentric strength of the knee flexors. Systematic reviews show that programs that include Nordic can significantly reduce the risk of posterior injuries in sports such as football and other sprinting modalities, with a meta-analysis in the British Journal of Sports Medicine showing a reduction of up to 51% in the injury rate when exercise is part of the preventive program. (British Journal of Sports Medicine⁠)

But Nordic is not valuable just because it “strengthens”. It can also change muscle architecture. Muscle architecture is the way the muscle is internally organized: fascicle length, pennation angle and muscle thickness. Fascicles are small bundles of muscle fibers aligned within the muscle, as if they were cables within a larger rope. When we talk about increasing the length of the long biceps femoris fascicles, we are talking about an adaptation that can allow the muscle to better withstand tension at greater lengths. A meta-analysis on eccentric training in the long biceps femoris found an increase in fascicle length, an increase in muscle thickness and a reduction in the pennation angle after eccentric training, in addition to an improvement in the eccentric strength of the hamstrings. This supports the logic that the goal is not just to “feel the burn”, but to build a muscle that is more structurally prepared for sprinting and deceleration. (PMC⁠)

For speed, this matters because sprinting is a violent event for the hindquarters. During high-speed running, the hamstrings need to handle high forces at long muscle lengths, especially at the end of the swing phase. Recent reviews on injury mechanisms highlight that posterior strains often occur at this time, when there is high eccentric demand, rapid stretching and the need for precise neural activation. (PMC⁠) VETOR interprets this in a practical way: if the sport requires the muscle to be strong while stretched, the training needs to prepare the muscle to be strong while stretched. Therefore, exercises such as Nordic, stiff-legged deadlift, Romanian deadlift, glider leg curl, eccentric leg curl, posterior bridge with slide and squats with controlled descent can be used as preventative and performance blocks.

The controlled descent in the squat also has value, but with a different function than the Nordic. When the athlete performs a squat with 3 to 5 seconds of descent, he trains eccentric hip, knee and ankle control, improves position perception, increases time under tension and reduces the chance of “falling” into ranges that he cannot control. This doesn't mean that every workout has to be slow. Speed ​​athletes still need sprinting, jumping, explosive lifting and rapid force production. The point is that the controlled eccentric builds brake, fabric and control so that power is expressed more safely. Reviews on eccentric training in young athletes indicate benefits in strength, jumping, sprinting and change of direction, especially with methods such as Nordic and flywheel, which is an inertia equipment where the athlete accelerates a wheel and needs to brake the return of the load. (PMC⁠)

In the VETOR method, eccentric training needs to be dosed because it is expensive. Strong eccentrics generate a lot of muscle damage, delayed pain and residual fatigue, especially when the athlete is not yet adapted. Therefore, it makes no sense to put heavy Nordics on the day before maximal sprints, races, hard rolls, games or speed training. For beginners, 1 to 2 times a week, with low volume, may be sufficient: 2 sets of 3 to 5 controlled repetitions of assisted Nordic, light stiff-legged deadlift with slow descent, controlled step-down or bridge with slide. For intermediate and advanced players, the volume can increase gradually, but always respecting the quality of execution, pain, recovery and sports calendar. The objective is not to destroy the hamstrings; is to build the ability to absorb force without tearing.

It is also important not to sell the eccentric as absolute shielding. Posterior injury is multifactorial: it involves previous history, exposure to sprinting, fatigue, eccentric strength, hip strength, coordination, stiffness, sleep, weekly load, accelerations, decelerations, surface and inadequate return after injury. Nordic helps a lot, but it does not replace progressive sprinting, running technique, volume control and general preparation. Studies comparing Nordic and sprint training show that both can influence factors related to performance and risk, but in different ways: Nordic is strong for eccentric strength and posterior architecture, while sprint is irreplaceable for specific coordination, elastic rigidity and real application of force in running. (PMC⁠) In VETOR, the best strategy is not to choose between eccentric strength and sprint; is to integrate the two into the week without creating excessive fatigue.

The final rule is simple: a fast athlete needs an engine and a brake. The engine comes from strength, power, technique and elastic capacity. Brake comes from eccentric strength, joint control, stability, and progressive exposure to high speed. A strong hamstring only in slow gym movements may not survive the sprint. An athlete who only runs fast but never strengthens the muscle in a stretched position also leaves a gap. VETOR uses the eccentric as a bridge between bodybuilding and sport: Nordic for hamstrings, stiff-legged deadlift for hips, squats with controlled descent for global control, eccentric calf raises for ankle, step-down for knee and sprint progressions for specificity. Because real speed isn't just about those who accelerate more. It is the one who accelerates, absorbs, brakes, reorganizes and repeats without breaking.

Reliable sources and what they support

1. Nordic Hamstring Exercise and Hamstring Injury Risk — British Journal of Sports Medicine, 2019 This meta-analysis analyzed 8,459 athletes and concluded that programs that include Nordic exercise reduce hamstring injuries by up to 51%. It is one of the strongest sources to support the use of Nordic as a preventive tool in sprint sports.

2. Effect of Injury Prevention Programs that Include the Nordic Hamstring Exercise — Systematic Review and Meta-analysis, 2017 This review also concluded that preventive programs with Nordic reduce the risk of hamstring injuries, especially in football players. It supports the phrase that Nordic is a relevant preventive tool, but it should be part of a program, not an isolated solution.

3. Effect of Nordic Hamstring Exercise Training on Knee Flexors Eccentric Strength and Fascicle Length — Systematic Review and Meta-analysis, 2020 This meta-analysis concluded that Nordic has the potential to increase eccentric strength of the knee flexors and the length of the long biceps femoris fascicles. It is one of the best sources to explain why Nordic can change muscle architecture.

4. The Effects of Eccentric Training on Biceps Femoris Architecture and Eccentric Strength — Systematic Review and Meta-analysis, 2020 This review found that eccentric training increased fascicle length, increased muscle thickness and reduced pennation angle in the long biceps femoris. Supports the part of the article about structural adaptation, not just strength gain.

5. The Effects of Nordic Hamstring Exercise on Performance and Injury Prevention — Umbrella Review, 2024 Recent review that brings together evidence on Nordic, including performance, eccentric strength and factors associated with injury prevention. Useful for a modern and broad view of the topic.

6. Hamstring Injury Mechanisms and Eccentric Training-Induced Adaptations — 2025 This review explains that hamstring injuries often occur in the final swing phase of running, when there are high eccentric forces at long muscle lengths. Supports the biomechanical explanation of the article.

7. Sprint Versus Isolated Eccentric Training — Mendiguchia et al., 2020 This study compares the effects of eccentric training with Nordic and sprint training as complements to football. It is important because it shows that sprint and eccentric can act in different ways, reinforcing the VETOR idea of ​​integration, not replacement.

8. Eccentric Resistance Training in Youth Athletes — Systematic Review, 2023 Review supporting the use of eccentric training to improve strength, jumping, sprinting, and change of direction in young athletes. Good source to support that eccentric is not just prevention; it can also contribute to performance.

9. Hamstring Strain Injury Rehabilitation — 2021 Review on hamstring strain rehabilitation. She reinforces that eccentric exercises are common in rehabilitation to prepare athletes for high-speed running and correct deficits in strength and muscular structure. Useful for connecting prevention, return to sport and physical preparation.

In VETOR, eccentric strength is the fast athlete's brake. Sprinting requires the hamstrings to produce force while stretching, especially in the final phase of the stride. Therefore, exercises such as Nordic, stiff-legged deadlift, glider curl and squats with controlled descent are not just for “strengthening the posterior”; they help build muscle that is better prepared to absorb tension, protect tissue and transform speed into sustainable performance.