What do our hamstrings do? A hamstring never gets a moment's rest during the gait cycle. It is constantly modulating its length, both concentrically and more importantly eccentrically. It is “ecconcentrically” constantly at work. It does not simply contract and relax in an antagonist/protagonist relationship. In fact, it is working in concert with most of our other muscle groups to harness the most important driving forces of movement: gravity, ground reaction and momentum. Even the quads group are closely associated synergists rather than antagonists when considering control of the hip and knee within a complete gait cycle:
- The hamstrings decelerate the tibia as it travels into knee extension before heel strike.
- As the heel/foot engages the ground, the hamstrings eccentrically decelerate the tibia as momentum crashes it forwards and over the ankle.
- Gary Gray described the lateral and medial insertions into the sides of the tibia as a pair of “riding reins.” They control and modulate tibial motion in all three planes, especially at this stage decelerating pronatory tibial internal rotation. This control is modulated according to directional demand and velocity.
- Also at this stage in the gait cycle, they are working to decelerate anterior pelvic rotation... absorbing and controlling momentum and ground force “shock.”
- They are now loaded and lengthened and have harnessed and modulated momentum and gravity. During the initial sprint acceleration phase, they can now contribute to drawing the leg underneath the trunk, complimenting the momentum, driving back into true hip extension. During “cutting” directional changes, they can behave like complimentary adductors as they assist femoral control.
- Keeping “hold” of the ischial tuberosity, they have the important task of contributing to lumbo-pelvic stability and keeping the pelvis from collapsing into anterior shear and frontal plane tilt. This helps the powerful hip flexors to be lengthened and loaded, ready to fire the leg forward at toe off.
- At this point, it is the hip flexors that fire the femur up and through with the weight of the lower leg breaking the knee into flexion and the hamstrings only contributing to this in terms of timing, control and minimal tibial “lift.”
- The hamstrings can only achieve this process if all of the other muscle groups and “slings” are efficiently contributing to this “kinetic chain.”
- In function, the hamstrings never work in isolation, and we now recognize that they significantly “team up” with the other muscle groups of the posterior longitudinal “chain.”
- In function, they must perform this process in all three planes of motion, at different velocities, when fatigued and when other contributors are potentially weak or dysfunctional.
- They must achieve this in every “body shape” possible. In dynamic activity and sport, if your body can make a shape or move, at some stage it will make that shape or move... and your hamstrings have to be prepared.
The Contributors to Hamstring Dysfunction
Poor three dimensional pelvic girdle control:
- Poor pelvic girdle control with anterior shear and hyper-lordosis often seen.
- Behavioural “lengthening” of the hamstrings, poor posture.
- Lack of pelvis preloading into neutral/posterior tilt, causing lack of eccentric feed into hamstring function.
- Tight hip flexors, tight lats, weak glutes and poor abdominal control, setting the hamstring up for failure.
Inefficient core stability:
- Similar factors seen to above.
- Hamstrings and abdominals work as force couple to damp huge sagittal plane ground reaction forces at the pelvis, especially at heel strike and absorption phase. Imbalances are common.
Faulty three dimensional femoral control:
- The correct degree of total limb pronation and internal rotation on force absorption leads to a correct eccentric pre-load. Hamstring deceleration of this load is disturbed by tight hip flexors and hip ext rotators, creating total limb “turn out” as the leg is “held off” from this pronation action.
- However, glute and hip ext rotator weakness may allow the femur to slide into excessive internal rotation and adduction, creating an over loaded or mal-timed hamstring pre-load.
- Once the foot is in weight bearing, the two heads of the gastrocnemius provide transverse plane control of the femur from below. Prior calf injury and both weakness and tightness can allow or even facilitate faulty femoral “torsion,” eventually asking the hamstrings to contribute more than their fair share.
Inappropriate Training and Rehabilitation Techniques
- Open and closed chain confusion. At heel strike, the foot becomes closed chain. The hamstrings have been pre-loaded, lengthened, proprioreceptively “charged” and excited. Are our exercises reflecting this process? Is our rehab? Are our feet even on the ground?
- Poor exercise selection. At no stage in function does the hamstring perform as it does in a hamstring curl machine, unless you are in a hamstring curl machine!!! This sort of activity is non-integrated isolation in an un-functional position, performed with a reversed concentric/eccentric relationship, in a bio-mechanically disadvantageous inner range position, proprioreceptively sparse, open and closed chain “confused” and offers the hamstring no opportunity to express itself in all three planes. Poor training, and even worse rehab! At no point in real time function does the hamstring perform as an isolated knee flexor on a fixed femur.
Dynamic Movement Screening Choices and the Link to the Hamstrings
The following table (although significantly “generalized”) lists the common regional dysfunctions to be aware of when dynamic movement screening. The individual movement screens that are most likely to reveal these dysfunctions are listed. It is not within the scope of this article to describe movement screening technique, selection and interpretation. The reader is encouraged to review other PTN articles and courses related to screening.
||Dynamic Functional Screening Test Choices
|Lat Dorsi Thoracic Kyphosis
||Postural shortening Over-training
||Squat to overhead/stick raise Postural wall hold Frontal plane overhead reach
||Postural shortening, over-active in “abs” training, “turned out” in functional sport demand
||Posterior lunge with overhead In-line lunge Pelvic angle in squat Control of int. rot. in single leg stance Postural wall hold
||Reciprocal inhibition De-conditioned deep stabilisers…medius, minimus Poor 3D pelvis control Demanding more of an over worked hamstring
||Squat pelvic control Lunge...control of int. rot and effective adduction deceleration. Chair/hurdle step-over Anterior balance reach control
||Overactive dominant short external rotators or “tightness-weakness” Functionally weak internal rotators
||Double and single leg standing wall touch rotation In-line lunge control Single leg stance balance reach...lower and upper limb reaches esp. transverse plane
||Dominant resistance training leads to recip. inhib. of hamstrings Synergistic imbalance
||Posterior lunge Split stance squat with arms overhead
|Abdominals Core stabilisers Thoracic hypo-mobility
||Poor stability Poor 3D pelvis control
||3D lunge control Chair/hurdle step-over Deep lunge pelvic position Lunge control with 3D arm drives Postural wall hold and rotation
|Calf (also reduced structural ankle dorsi-flexion)
||Short, overactive Poor training technique Trauma/degenerative impingement
||Squat Posterior lunge and in-line lunge Single leg stance reach tests and squat/dip range
||Short, overactive, femoral “turn-out” Shutting down the hamstrings transverse plane action
||Gait...loaded away from stance in frontal plane In-line lunge control Overhead frontal plane reach
|Sub-talar joint Inverters, everters
||Over pronation/supination Hypo-mobility Post trauma inhibition The mid-tarsal jt, sub-talar jt. and tibia are not decelerated by the hamstring
||Gait Single leg reach, frontal and transverse Chair/hurdle step-over Simple cross body frontal plane lunge
Findings and “targets” revealed by movement screening can be further investigated and supported if necessary by more traditional length-tension testing of muscle groups and range of movement testing of joints.
Digital Motion Capture
The practical application and interpretation of movement screening is enhanced when it is allied with digital motion capture (video analysis).
- Use slow motion observations, digital measurements and twin screen/overlay comparisons. The “digital” eye offers the potential for more refined analysis. However, even simple dysfunctions can become more apparent at slower speeds.
- Show and educate our clients about their strengths and weaknesses in their own visual movement language.
- Keep an un-equivocal visual archive for reflection, review and comparison with our clients as they progress through their programs and rehab.
Above, screen captures from a typical motion capture application. Figure 1 shows a simple split screen comparison of two very different squat screen presentations. Figure 2 shows how measurement tools and drawing overlay tools can offer a more “quantifiable” option to the essentially qualitative practice of movement screening.
Rehab, corrective and performance training professionals are moving towards incorporating “movement education,” in its many guises, into their practice. Visual analysis and perhaps more importantly visual training and feedback helps to clarify and focus this process for both the practitioner and the client. For example, our hamstring injury sufferers focus is often, understandably, on the site of pain and discomfort and not on their potential weak links and postural distortions that have contributed to the hamstring's demise. A simple motion capture analysis and discussion can help a client appreciate, feel and of course see how he truly moves and help him value the broader picture when it comes to tackling movement dysfunction.
Acting Upon Your Findings
- Always thoroughly and purposefully “clean up” any regional dysfunctions that are contributing to the hamstring's demise. Attend to these weak links, and then the hamstring will have a chance to “express” its true and effective function.
- Establish a good foundation of unloaded fundamental movement patterns (i.e., squat, lunge, etc.).
- Both stretch and strengthen the hamstring in three planes.
- Primarily strengthen with the affected foot on the ground. Decelerate the tibia and decelerate the trunk as it drives over the hip. 3D lunges, multi-level lunges and low reach lunges emphasize trunk lowering eccentrically and exploding back into trunk extension concentrically. Seek out “hip dominant” patterns.
- Open chain eccentrics must be performed in functional positions.
- Core control and general flexibility must be maintained.
- In exercise selection terms, position to expose the hamstring and then re-position to integrate, especially in terms of adding gluteal contribution. Isolate only with a view towards integration.
- Use single leg stance and stork stance balances and trunk drives. Facilitate hamstring control of the trunk as well as the leg.
- Increase the speed and then increase the loads. Dumbbells, elastic resistance and weight vests are potentially more useful than isokinetic installations!
- Progress to total body dynamic patterns including squats, jumps, split squat, split jumps.
- Integrate dynamic balance training.
- Progress into sport specific dynamic drills, ballistics and pliometrics.
Selectively re-screen at all times, even during individual sessions. Continue to act upon any dysfunction in motion before it becomes established. We are still tempted to talk in terms of individual muscles. However, the real consequences of isolated hamstring problems are a dysfunction in motion. Integrating movement screening and motion analysis into our work helps us to shift our emphasis towards understanding and dealing with movement dysfunction.
- Clark, Mike. Integrated Training Series, 2002
- Cook, Gray. Athletic Body in Balance, Human Kinetics, 2003
- Gray, Gary. Lower Extremity Functional Profile, Wynn Marketing, 1995
- Gray, Gary. Functional Digest Series, 2008
- National Academy of Sports Medicine, Integrated Anatomy for the New Millennium, 2000
- Shirley Sarhmann, Diagnosis and treatment of movement impairment syndromes. St. Louis: Mosby.