Prevention Of Hamstring Injuries: The Kinetic Chain Approach.

Hamstring injuries frequently happen during running and jumping activities, typically during either the late swing or early stance phase of the gait cycle.
Note: This is part two, click here for part one.

We have all seen it; an athlete pulls up on the field, grabbing the back of his or her leg. Hamstring injuries are quite common in the athletic world.

Many causative factors have been proposed including:

  • Poor flexibility
  • Inadequate muscle strength
  • Dyssynergic muscle contraction during running
  • Inadequate warm-up before exercise
  • Returning to activity before complete rehabilitation following injury. (1)

The purpose of this paper is to explain an approach to preventing these injuries by analyzing movement patterns and initiating specific exercises to address the deficiencies uncovered by the analysis.

When considering hamstring injuries it is interesting to note the specific nature of the injury. The hamstrings are made up of the bicep femoris, the semimembranosus and the semitenindosus. Nearly all hamstring injuries involve only the bicep femoris, most specifically at the tendinous attachment to the ischial tuberosity. (2) In the most severe of injuries the tendon is actually avulsed form the ischium. (2)

Hamstring injuries frequently happen during running and jumping activities, typically during either the late swing or early stance phase of the gait cycle. (3) During late swing the hamstrings are eccentrically contracting to slow the rapid forward movement of the thigh and leg.

The hamstrings must instantly change at foot strike to a maximal concentric contraction to accelerate the hip into extension. (3) Figure 1 (below) illustrates an athlete throughout the late swing and early stance phase while this transition is happening. If the athlete lacks adequate eccentric-concentric coupling a hamstring injury is a likely result.

Figure 1 - Late swing and early stance phase of
The gait cycle while running

A look at figure 2 (below) clearly shows the overlapping nature of the posterior musculature of the lower extremity. The glute medias and glute maximus have distal attachments that reach past the proximal attachments of the bicep femoris, semimebranosus and semitendinosus.

Similarly, the distal attachments of the hamstrings reach past the proximal attachments of the gastrocnemius and soleus. It is this overlapping structure that leads to the concept of a kinetic chain when discussing the function of these muscles.

Figure 2 - Posterior view of the lower extremity musculature
Courtesy of eMedTool tm 3D Anatomical Slides
Accessible at

It has been proposed that analyzing specific movements can indicate where in the kinetic chain dysfunction is occurring. (4) This knowledge can than be applied in the design of a program to optimize movement efficiency and thus prevent injury. The most common and simplest test for kinetic chain assessment is the overhead squat test.

This test allows us to examine how an athlete's feet, knees, hips and lumbar spine interact to create movement. The specific nature of motion at these joints can aid in the detection of muscle length and strength imbalances that may predispose an athlete to injury.

Performance of the overhead squat test is rather simple; the athlete simply holds a light bar overhead and performs a squat as deeply as he or she can. During this performance the clinician needs to observe each joint along the kinetic chain. (5) To illustrate the use of this test I offer a brief case study. A female athlete with a history of previous hamstring injuries presents to the clinic. As part of her evaluation I perform the overhead squat test.

In the anterior view it is I observe that her feet are maintaining an arch and are not externally rotating. Moving up the chain her knees are observed to be in abduction. This implies that the glute medias, piriformis and bicep femoris are shortened and the hip adductors and hamstrings are weak. (5) Moving to the hips and lumbar spine it is observed that the lumbar spine is excessively flexing. This implies hamstring tightness, weak hip flexors and poor trunk control (5).

From this analysis of the overhead squat a corrective exercise program can de designed. Emphasis for this athlete would be on static stretching to lengthen the glute medias, piriformis and hamstrings. Strengthening exercises would need to focus on the hamstrings, hip adductors and hip flexors.

Sidebar 1 is the program that was implemented for this particular athlete. Once the athlete is able to perform the overhead squat test without significant deviations it is time to move into an integrated training program to address core stability, flexibility, strength and eccentric-concentric coupling.

Sample Program

Sidebar 1 - Corrective Exercise Program for an athlete demonstrating knee abduction and lumbar flexion during the overhead squat test.

Self-Myofascial Release with foam rollers (30 seconds to 1 minute each)

Static Stretching (hold 20-30 seconds, repeat each stretch 2-3 times) Strengthening (2-3 sets of 10 reps)
  • Straight Leg Raises in 4 planes - View
  • Bridging - View
  • Single Leg Squats - View


  1. Agre JC. Hamstring Injuries. Proposed aetiological factors prevention, treatment. Sports Med. 1985; 2(1):21-33.
  2. Koulouris G, Connell D. Evaluation of the hamstring complex following acute injury. Skeletal Radiol. 2003; 32(10):582-9
  3. Smith LK, Weiss EL, Lehmkuhl, LD. Brunstrom's clinical kinesiology 5th ed. 1996; FA David Company.
  4. Clark, M. Integrated training and rehabilitation: the future. 2003 1st Annual Symposium on Functional Training and Rehabilitation; Boston, MA.
  5. Clark, M. Education-Solutions-Tools. 2003 1st Annual Symposium on Functional Training and Rehabilitation; Boston, MA.

About The Author

Eric Wheeler, MSPT, MPE, CSCS

Eric is a staff physical therapist at Cape Cod Rehabilitation, an out-patient orthopedic and sports physical therapy clinic with offices in Mashpee, Hyannis and Osterville, Massachusetts. He is also the sports medicine consultant to the Cape Cod Crusaders of the PDL soccer league.

A graduate of Springfield College he holds Masters Degrees in Physical Therapy and Physical Education, is a Certified Strength and Conditioning Specialist (NSCA) and a member of the National Academy of Sports Medicine. He can be reached at

Note: This is part two, click here for part one.