Hamstrings and Running: Functions, Importance, and Optimization

How Do You Use Hamstrings When Running?

The hamstrings are critical, multi-functional muscles in running, primarily acting to extend the hip during the push-off phase and eccentrically decelerate the lower leg during the swing phase, preventing hyperextension of the knee and preparing for foot strike.

Anatomy of the Hamstrings

The hamstring group consists of three posterior thigh muscles: the biceps femoris (long and short heads), semitendinosus, and semimembranosus. Originating from the ischial tuberosity (with the exception of the short head of the biceps femoris), these muscles cross both the hip and knee joints, inserting onto the tibia and fibula. This biarticular nature is key to their diverse roles in locomotion, including running.

The Running Gait Cycle: A Hamstring Perspective

Running is a complex interplay of muscular contractions and joint movements, divided into two main phases: the stance phase (when the foot is on the ground) and the swing phase (when the foot is in the air). The hamstrings are active throughout both.

Stance Phase

• Initial Contact to Mid-Stance: As the foot lands, the hamstrings engage eccentrically to help control knee flexion and absorb impact, working synergistically with the quadriceps.
• Mid-Stance to Terminal Stance (Push-off): This is where the hamstrings, particularly the semitendinosus and semimembranosus, contribute significantly to hip extension. Alongside the gluteus maximus, they powerfully drive the body forward, propelling the runner. The biceps femoris also contributes to hip extension and external rotation of the tibia.

Swing Phase

• Initial Swing: Following toe-off, the hamstrings concentrically contract to flex the knee, lifting the foot off the ground and bringing the heel towards the buttocks. This action helps clear the ground and shortens the limb, making it easier to swing forward.
• Mid-Swing: The hamstrings remain active, helping to control the forward momentum of the lower leg.
• Terminal Swing: As the leg extends forward in preparation for the next foot strike, the hamstrings engage strongly in an eccentric contraction. This crucial action decelerates the forward swing of the tibia, preventing excessive knee extension and preparing the leg for a controlled landing. Without this eccentric braking, the knee would snap into hyperextension, leading to instability and potential injury.

Hamstring Actions During Running

Beyond the gait cycle phases, we can categorize hamstring actions by their primary biomechanical roles:

• Hip Extension: During the push-off phase, the hamstrings contract concentrically to extend the hip, propelling the runner forward. This is a powerful, propulsive action.
• Knee Flexion: In the initial swing phase, the hamstrings concentrically contract to flex the knee, lifting the foot and clearing the ground.
• Knee Deceleration (Eccentric Control): In the terminal swing phase, the hamstrings eccentrically control the forward momentum of the tibia, preventing hyperextension of the knee and preparing for foot strike. This eccentric strength is paramount for injury prevention and efficient running.
• Pelvic Stability: The hamstrings, along with other core and hip muscles, contribute to stabilizing the pelvis during the running gait, maintaining an upright posture and efficient force transfer.

Importance of Strong, Flexible Hamstrings for Runners

The multifaceted role of the hamstrings underscores their importance.

• Enhanced Performance: Strong hamstrings translate to more powerful hip extension, leading to faster acceleration and higher top-end speeds. Efficient eccentric control improves running economy and reduces braking forces.
• Injury Prevention: Weak or inflexible hamstrings are a common source of running-related injuries.
  • Hamstring Strains: Often occur during the eccentric braking phase of terminal swing or powerful concentric hip extension, especially when the muscle is fatigued or unprepared.
  • Knee Pain: Poor hamstring function can alter knee mechanics, contributing to conditions like patellofemoral pain syndrome.
  • Pelvic Instability & Low Back Pain: Weak hamstrings can lead to compensatory movements and increased stress on the lower back.

Optimizing Hamstring Function for Runners

To maximize running performance and minimize injury risk, runners should focus on both hamstring strength and flexibility.

• Strength Training:
  • Concentric Strength: Exercises like Romanian Deadlifts (RDLs), good mornings, and hip extension machines target the hip extension function.
  • Eccentric Strength: Nordic hamstring curls, glute-ham raises, and single-leg RDLs are excellent for building eccentric strength, crucial for deceleration and injury prevention.
  • Knee Flexion Strength: Hamstring curls (seated or lying) directly target knee flexion.
• Eccentric Training: Prioritize exercises that emphasize the lengthening contraction under load, as this directly translates to the demands of terminal swing.
• Flexibility and Mobility:
  • Dynamic Stretches: Leg swings and walking lunges with a reach can prepare the hamstrings for activity.
  • Static Stretches: Post-run or as part of a dedicated flexibility routine, static stretches like seated hamstring stretches or standing toe touches can improve range of motion.
• Proper Running Form: Maintaining an appropriate stride length and avoiding overstriding can reduce eccentric load on the hamstrings and improve overall efficiency.

Common Hamstring Injuries in Runners

Runners are particularly susceptible to hamstring injuries due to the high forces and rapid changes in muscle length experienced during the gait cycle.

• Hamstring Strains: These range from mild pulls (Grade 1) to complete tears (Grade 3) and are often associated with sudden acceleration, sprinting, or the eccentric demand of terminal swing.
• Proximal Hamstring Tendinopathy: An overuse injury affecting the tendons where the hamstrings attach to the ischial tuberosity, characterized by deep buttock pain, especially with sitting or hip flexion activities.

Prevention involves a balanced training program that includes strength, eccentric loading, flexibility, and gradual progression of running volume and intensity.

Conclusion

The hamstrings are far more than simple knee flexors; they are sophisticated, multi-purpose engines for running. Their ability to generate powerful hip extension for propulsion and provide crucial eccentric braking to control leg swing makes them indispensable to efficient and injury-free running. Understanding their intricate roles and actively training them for both strength and flexibility is paramount for any runner looking to optimize performance and longevity in the sport.