THE IMPORTANCE OF THE HIP EXTENSOR AND HIP FLEXOR MUSCLES IN SPRINTING
The hip extensors and the hip flexors are the strongest muscle groups within the lower extremity. The extensors are the primary movers, by acceleration, of the body’s center of gravity. The prime movers of the hips are also responsible for generating the most force during sprinting. Studies by Ralph Mann and others indicate that the bulk of forward propulsion and power generation in sprinting comes from the proximal musculature of the pelvis.
The hip extensors are dominant in the back swing and the first half of the stance phase, and the hip flexors are dominant power generators in the second half of the stance and early swing phases. According to famed track coach, Tom Tellez, the athlete who can best utilize the hips joints will be more successful in sprinting. The most important phase in each stride for all athletes is the push-off the ground. The amount of ground contact force generated affects the length and rate of each stride, acceleration speed, and maximum mph speed. During this action, the body is stretched upward from the ground and the origin of the motion occurs at the hip joint. “The hip acts as a crank to deliver the force to the ground. This force is then returned to the center of the mass lifting it up off the ground.” During foot placement, the hips continue to extend. The foot (ankle) is placed directly under the knee joint with the shin perpendicular (right angle) to the ground.
Research indicates that there is a strong relationship between hip flexion and hip extension strength relative to body weight when strength is assessed from an upright position. There also appears to be a cause-effect relationship between enhanced hip flexion/extension strength and sprinting speed (Guskiewicz, et. al., Isokinetics and Exercise Science, Vol. 3, No. 2, 1993, The Relationship Between Sprint Speed and Hip flexion/Extension Strength in Collegiate Athletes). The hip musculature may be more important than knee musculature in evaluating sprinting speed.
The Hip Flexor Muscles
In spite of the importance of the hip flexor muscles to sprinting and other movement patterns in sports, this muscle group is one of the most neglected in strength training. While exercises for the leg extensor muscles are common, hip flexor exercises are rare. The main muscles involved in hip flexion are the psoas major and the iliacus (the ilopsoas muscles). The rectus femoris, one of four quadriceps, crosses the hip joint and also operates as a hip flexor and knee extensor. The deepseated ilopsoas muscles are difficult to strengthen with free weights and receive little attention in the weight room. The truth is that strong hip flexor muscles are critical for high performance in team sports and utilized anytime the thigh is brought up toward the abdomen or the abdomen is moved toward the thigh. Executing a powerful kick of the ball in football, rugby and soccer requires simultaneous knee extension and hip flexion. Strong hip flexors also play a role for ball carriers who are moving forward with opponents holding on. Hockey and lacrosse players also must skate and run through contact. The baseball player taking the first few steps out of the box or off a base will benefit from strong hip flexors. And, of course, sprinters who need extremely strong hip flexors.
Training the Hip Flexors. The two most commonly used exercises to develop hip flexor strength are incline sit-ups and hanging leg raises. With body weight providing the resistance, strength gains are limited. A multi-hip machine is available that allows the athlete to push against a padded roller swinging on an arc with the thigh. If the position of the hip joint could be maintained, heavier weights could be used. The MyoQuip HipneeFlex is designed to strengthen both hip and knee flexors simultaneously from full extension to full flexion. Decreasing resistance occurs throughout the movement to provide the correct loading to both sets of flexors. Kevin O’Neill, MS, CSCS provides a list of additional exercises to strengthen the hip flexor muscles:
Spread Eagle Sit-ups–Start by lying on your back. Spread your legs with locked knees and hook both feet on the vertical support beams of a power rack. Now complete a straight leg sit up. To add resistance, use a weight or dumbbell.
Hanging Knee/Leg Raises–While hanging from a pull-up bar, keep your upper body straight, bend your legs and bring both knees to your chest. You can also keep your legs straight and bring the toes to the ceiling with the legs parallel to the floor. For added resistance, hold a dumbbell with your feet.
Incline/Flat Bench Leg Raises–This exercise is similar to the one above, except, you adjust the angle to make it slightly easier. Lie supine while holding on to a bench behind your head. Complete either a straight or bent leg raise.
Cable/Band Knee Drive–Attach an ankle cuff cable to the low cable pulley. Place both hands on a a bench or box in front of you. Your body should resemble a sprinter leaving the blocks. Make sure you are far enough away to maintain tension on the cable. With a flat back, drive the knee forward and up in front of your chest. Stay in control of the weight on the negative phase so it doesn’t jerk your leg at the end of the repetition. Focus on keeping the ankle cocked in dorsi-flexion. You can also use a band instead of the cable which forces you to accelerate through the movement.
Lying Cable Knee Drive–While lying on your back attach your ankle cuffs to the low cable pulley and bring both knees to the chest.
Forward Sled Dragging–Using the sled strap attachment, place a loop around each foot. Proceed to walk straight ahead.
SOURCE: National Association of Speed and Explosion, Sports Speed News Bulletin Volume 5, Issue 22 (May, 2009)