Nordic Curls: Benefits for Sprinting, Injury Prevention, and Training Integration

Do Nordic Curls Help with Sprinting?

Yes, Nordic curls are a highly effective and evidence-backed exercise for strengthening the hamstrings, which are crucial for sprinting performance, significantly contributing to both injury prevention and improved force production during the sprint cycle.

Understanding Sprinting Biomechanics and Hamstring Function

Sprinting is a complex, high-velocity movement requiring powerful contributions from the entire lower kinetic chain. The hamstrings – a group of three muscles (biceps femoris, semitendinosus, and semimembranosus) located on the posterior thigh – play a pivotal role throughout the sprint stride, particularly during the following phases:

• Terminal Swing Phase: As the leg swings forward, the hamstrings eccentrically contract to decelerate the lower leg, preparing it for ground contact. This phase involves immense eccentric forces, and weak hamstrings are a primary limiting factor and injury risk here.
• Initial Stance Phase: Upon ground contact, the hamstrings contribute to hip extension and knee flexion, helping to propel the body forward and absorb impact.
• Propulsive Phase: While quadriceps and glutes are primary drivers, hamstrings assist in generating force through hip extension.

Their dual role as hip extensors and knee flexors, especially under high eccentric load during the terminal swing, makes their strength and resilience paramount for sprinters.

The Nordic Curl: A Hamstring Powerhouse

The Nordic hamstring curl (NHC) is a bodyweight exercise that specifically targets the eccentric strength of the hamstrings. Performed by kneeling with the ankles secured and slowly lowering the torso forward, resisting gravity primarily with the hamstrings, it creates an exceptionally high eccentric load.

This exercise is unique because:

• High Eccentric Load: Unlike many traditional hamstring exercises (e.g., leg curls), the NHC places a maximal eccentric load on the hamstrings, mimicking the high-force demands encountered during the terminal swing phase of sprinting.
• Functional Movement Pattern: While not identical to sprinting, it trains the hamstrings in a stretched position under load, which is highly relevant to their function during high-speed running.
• Muscle Activation: Research consistently shows high hamstring muscle activation during Nordic curls, particularly in the biceps femoris, which is the most commonly injured hamstring muscle in sprinters.

Evidence-Based Benefits of Nordic Curls for Sprinting

The scientific literature strongly supports the inclusion of Nordic curls in a sprinter's training regimen:

• Hamstring Strain Injury Prevention: This is arguably the most well-documented benefit. Numerous studies and meta-analyses have shown that regular Nordic curl training significantly reduces the incidence of hamstring strain injuries in athletes across various sports, including sprinting. This reduction is attributed to increased eccentric strength and changes in muscle fascicle length, making the hamstrings more resilient to damage.
• Improved Sprint Performance: While the direct link to maximal speed improvement can be complex and multifactorial, Nordic curls contribute indirectly and directly:
  • Enhanced Deceleration Capacity: Stronger hamstrings can more effectively decelerate the lower leg in the terminal swing, allowing for a more precise and powerful ground contact.
  • Increased Stride Length and Frequency: By improving the hamstrings' ability to handle high eccentric forces, athletes may be able to tolerate greater stride lengths and maintain higher stride frequencies without increased injury risk.
  • Greater Force Production: Stronger hamstrings contribute to overall lower limb power, which translates to more effective ground force application.
• Targeted Eccentric Strength Development: Sprinting, especially at top speeds, involves very high eccentric forces. The Nordic curl is one of the most effective ways to specifically train and adapt the hamstrings to these forces, leading to better injury resistance and potentially improved performance.

Integrating Nordic Curls into a Sprint Training Program

For optimal benefits, Nordic curls should be systematically integrated into a well-rounded sprint training program.

• Progression: Start conservatively. Many individuals cannot perform a full Nordic curl initially. Use regressions such as assisted Nordic curls (using a band or partner assistance) or partial range of motion. Gradually progress to full bodyweight repetitions.
• Frequency and Volume:
  • For injury prevention, 2-3 sets of 3-5 repetitions, 1-2 times per week, is a common and effective protocol.
  • For strength development, higher volumes (e.g., 3-4 sets of 5-8 repetitions) might be used, but adequate recovery is crucial due to the exercise's intensity.
• Periodization: Integrate Nordic curls during general preparation phases to build foundational strength. Reduce volume or frequency during peak competition phases to minimize fatigue and allow for maximal sprint performance. They can also be used during in-season maintenance.
• Placement in Workout: Due to their high intensity and fatiguing nature, Nordic curls are often performed at the beginning of a session after a thorough warm-up, or on a separate training day dedicated to strength. Avoid doing them immediately before high-intensity sprint sessions.
• Complementary Exercises: Nordic curls should not be the sole hamstring exercise. Include other exercises that target the hamstrings and glutes through different ranges of motion and force vectors, such as Romanian Deadlifts (RDLs), Glute-Ham Raises (GHRs), good mornings, and various sprint drills themselves.

Important Considerations and Potential Drawbacks

While highly beneficial, consider the following:

• High Intensity: Nordic curls are extremely challenging. Proper progression and coaching are essential to avoid overtraining or injury.
• Form Over Reps: Maintain strict form throughout the movement. Losing control or arching the lower back can reduce effectiveness and increase injury risk. Focus on a slow, controlled eccentric phase.
• Individual Variation: Not all athletes will respond identically, and some may find the exercise too difficult or uncomfortable initially.
• Not a Standalone Solution: Nordic curls are a powerful tool but are only one component of a comprehensive sprint training program that includes speed work, strength training, plyometrics, mobility, and recovery.

Conclusion

Nordic curls are an invaluable exercise for sprinters, offering significant benefits in hamstring injury prevention and contributing to overall sprint performance by enhancing eccentric strength and power. By systematically integrating them into a periodized training program, sprinters can build more resilient, powerful hamstrings, ultimately leading to a more robust and faster athlete.