Modern Hamstring Injury Prevention: A Holistic Approach

Gone are the days when a single factor is touted as the holy grail of hamstring injury prevention. Hamstring injuries are multifactorial, meaning strength coaches must take a broad approach to injury prevention.

The only thing worse than a hammy pull is more than one. Unfortunately, hamstring injuries are notorious for being consistent problems, with a recurrence rate as high as 63%.¹ A single hamstring injury can spell doom for an athletic career, robbing an athlete of training and game time both now and in the future.

The only thing worse than a hammy pull is more than one. Unfortunately, hamstring injuries are notorious for being consistent problems, with a recurrence rate as high as 63%, says @KD_KyleDavey. Share on X

A recent paper by Lahti et al. describes a unique, individualized approach to hamstring injury prevention that can be implemented at the team level.² I believe the intervention was underway when the COVID-19 pandemic struck and unfortunately ended the study, so the group instead published the protocol with intention to complete it when the pandemic ceases.

The intervention looks promising, covering many topics including mobility, sprint mechanics, and strength, among others. It will be exciting to see the completed project and understand how effective the protocol is.

In the meantime, we’re left with the approach the intervention takes, the two novel assessments the authors put forth, and the thoughts the paper provokes.

Screening and Intervening: the Exercise is the Rehab and the Rehab is the Exercise

One striking aspect of the Lahti et al. paper is how the intervention addresses the players deemed at-risk for hamstring injury. What should those athletes do?

The same as the athletes who are not at-risk. Just more of it.

The protocol calls for all athletes to receive a healthy dose of range of motion, strength, lumbopelvic control, and sprint work, but those who meet the criteria get a double dose compared to those who don’t.

This underscores the necessity for well-balanced, well-planned training. There is no magic bullet or fancy exercise that vaccinates against hamstring pulls. Instead, there are basic foundational qualities and competencies that should be practiced, maintained, and improved upon throughout the training year. Rather than waiting for a red flag to pop up, strength coaches can nip these issues in the bud by training these qualities before they become problems.

Asymmetrical Presentation Calls for Asymmetrical Loading

Asymmetries in force production are thought to be contributing factors to hamstring injury.^3,4 At least one study has directly linked eccentric hamstring strength with risk of hamstring injury.⁵ The authors tested glute hip extensor and hamstring strength in elite sprinters and followed up with them over a one-year period. Each of the six hamstring injuries observed happened in the weaker hamstring. Thus, symmetrical force production capabilities appear protective against injury.

As mentioned above, the protocol in the Lahti et al. paper calls for several aspects of performance to be assessed. If asymmetries were present in strength or range-of-motion (ROM), athletes performed extra work on the lagging leg. There was not a magical intervention to “correct” asymmetry; rather, all athletes perform strength and mobility work, and athletes with asymmetries simply do more of it.

All athletes perform strength and mobility work, and athletes with asymmetries simply do more of it, says @KD_KyleDavey. Share on X

Misdiagnosing asymmetry and mistakenly programming more work on one side could actually cause asymmetry, and valid and reliable measurements are critical. The old pull-into-my-hand, this-side-feels-weaker muscle test isn’t going to cut it as a valid measurement and probably won’t be convincing when trying to persuade an athlete why they should perform three sets of single-leg deadlifts on one leg and only one set on the other.

Isokinetic dynamometry or another valid, reliable assessment that clearly and objectively shows force production capability is the best way to get athlete buy-in, to be fully informed as a practitioner, and to prescribe efficacious training interventions.

The Jurdan Test

How much ROM is necessary to reduce the risk of hamstring injury? This question is not currently answered, but we can safely assume that possessing enough mobility to enter archetypal maximum velocity positions allows an athlete to effectively reach said positions and is therefore protective against hamstring injury. A little extra ROM to add wiggle room and ensure the athlete isn’t hitting end range with each stride is also probably a good thing.

The authors of the Lahti paper introduce the Jurdan test, a novel sprint-specific mobility assessment named after its originator Jurdan Mendiguchia. The test places the athlete in an artificial toe-off sprint position, which becomes clear when you rotate the picture 90°, and assesses swing leg hamstring range of motion and stance leg hip extensibility in relationship to maximum sprint mechanics.

For the start position of the test, the athlete lies supine on a table with a posterior pelvic tilt, their bottom leg hanging passively off the table, and their top leg femur set plumb vertical. From there, the athlete extends their top leg knee as far as possible while keeping their lower back visibly flat and pressed into the table.

Appropriate scores do not yet exist, as this test is brand new, but there are obvious implications: if an athlete cannot extend the knee to achieve a desirable strike position then their hamstring mobility is a liability, may increase injury risk, and should be addressed.

Moreover, without adequate ROM at the knee or hip, affordances are limited and athletes will never reach the desired maximum velocity kinematics, leaving you frustrated as a coach and the athlete slower than they should or could be. Perhaps this is one cause of chronic backside kinematics: the ROM at the hip or knee simply isn’t available for the athlete to perform ideal frontside mechanics.

Be aware when scoring the test that the same score may be achieved via two movement strategies. For instance, a shin angle of 60° – (-10°) hip extension yields a score of 70°, but so does a shin angle of 73° – 3° of hip flexion. The latter circumstance occurs if an athlete cannot enter hip extension.

The Kick-back Method

If you’re reading this article, I don’t need to convince you that sprint mechanics matter.

Lahti et al. present a novel method to quantify frontside versus backside mechanics: the kick-back score.

Although there is not a definitive answer at this point, the hypothesis is that backside mechanics increase risk of hamstring injury more than frontside mechanics. The kick-back score provides an objective method to track progress in technical improvements and allows coaches to separate athletes into groups of frontside and backside dominant for training purposes.

Exposure to High Speeds

Track and field sprinters usually sprint at maximum velocity weekly, but team sport athletes do not always reach maximum velocity regularly. Malone et al.⁶ found a U-shaped relationship between high-speed sprint volume and hamstring injury risk. Not enough exposure to high-speed sprinting increased the likelihood of hamstring injury, but so did too much. There appears to be a sweet spot in the middle that is protective.

Not enough exposure to high-speed sprinting increased the likelihood of hamstring injury, but so did too much. There appears to be a sweet spot in the middle that is protective, says @KD_KyleDavey. Share on X

This seems to make sense both on an intuitive and a physiologic level. Mama always said too much of a good thing can be a bad thing, and sprinting itself is eccentric exercise for the hamstring group, which will be discussed in greater detail later in this article.

The only problem? We don’t have a handbook to tell us exactly how to program high-speed programming to prevent injuries. How much is too much? How much is too little?

The authors of the Malone et al. paper do highlight two important factors: athletes with high chronic training loads are at reduced risk, and players who experience “large weekly changes” in high-speed sprint exposures are at higher risk. In other words, iron forges iron, and consistent high-speed sprinting forms a robustness against hamstring injury, while doing very little followed by a ton of it increases risk.

Iron forges iron, and consistent high-speed sprinting forms a robustness against hamstring injury, while doing very little followed by a ton of it increases risk, says @KD_KyleDavey. Share on X

Classify Strength Training by Joint Angle

It is well-known that strength training adaptations are joint-angle specific and some exercises strengthen a particular ROM of a movement more than others. This is why the general rule of thumb is to train through a full range of motion, so athletes experience strength gains in the largest ROM possible.

Lahti et al. separate hip extension training into three categories: 0-60° (extended position), 60-90° (mid-range), and 90-110° (deep). Below are a few exercises they name for each:

• 0-60°: hip thrust, glute bridge, back extension
• 60-90°: deadlift, trap bar deadlift, high sled push, high step up
• 90-110°: split squat and split squat variations, RDL, low sled push

What is the value in categorizing exercise as such? Perhaps exercises are most transferrable at specific joint-angles.

For instance, in the initial steps of an acceleration—whether out of blocks or from a two-point stance—the knee and hip travel through a greater range of motion during ground contact than in upright mechanics, terminating in complete or near-complete hip extension for at least the first few steps. Thus, all three categories of exercises are applicable, as the hip moves through all three ranges of motion. If strength training neglects any of these ROM categories, improvements in acceleration may be compromised.

Similarly, archetypal front side maximum velocity mechanics call for a relatively high swing leg knee at toe-off, with the thigh at roughly 90°. Perhaps exercises in the deep and mid-range categories are most appropriate for building the base of strength needed to achieve high angular velocity of the thigh as the foot travels downwards to initiate ground contact.

Further, hamstring exercises are sub-categorized into “knee over hip” movements and “hip over knee” movements. “Hip over knee” describes movement in which the hip extends with a relatively fixed knee angle. Romanian deadlifts, straight leg cable pulls, and isometrics in an extended hip position fit into this category. These exercises seem to mimic the hip extensors driving the foot down towards the ground during swing phase.

In “Knee over hip” movements, knee flexion is the driver of the work. Nordic hamstring curls (eccentric knee flexion) and hamstring sliders fall in this category. These exercises seem to contribute most to preventing the knee from extending open during the swing phase so the foot is in position to be effectively driven towards the ground.

Lumbopelvic Control

Tilting the pelvis anteriorly lengthens the hamstrings and encourages backside sprint mechanics. Lumbopelvic control—in this context, the ability to maintain a neutral pelvis while sprinting—is thought to be a key kinematic protector of hamstring injury. Higher relative activity of glute and trunk musculature (the muscle groups that prevent anterior pelvic tilt) during flight phase has been negatively associated with hamstring injury risk.⁷

Video 1. Pelvic tilts. Pelvic anterior / posterior tilts are a basic motor control exercise. Without conscious control of the pelvis independent of the lumbar spine, pelvic control cannot be expected at all. This drill serves as an introduction to lumbopelvic training and awareness.

Whether anterior pelvic tilt is the result of a motor control or a strength deficit, lumbopelvic exercises provide the context and physiologic requirements to maintain a neutral pelvis while sprinting.

We’re essentially talking about strengthening the hollow body position: ribs depressed and pelvis neutral or in a slight posterior tilt.

I group lumbopelvic control into four basic categories:

• Basic motor control
• Static isometric strength
• Dynamic isometric strength
• Competition movements (like sprinting)

In my experience, many athletes (especially youth athletes) lack the awareness to move the pelvis independent from the lumbar spine. They need to be taught how to tilt anteriorly and posteriorly as opposed to leaning forwards and back. Basic motor control competency is often the starting point of training.

Video 2. The deadbug teaches lumbopelvic disassociation and strengthens the trunk musculature that prevents anterior pelvic tilt while sprinting. Athletes begin on their back, posteriorly tilt the hips and depress the rib cage, and then flatten the lower back against the ground. This position is held as the knees and arms are put into the air. For bonus points, exhale forcefully as if blowing up a balloon while actively depressing the ribs.

Below are a few examples of exercises in each category.

• Basic motor control: pelvic anterior / posterior and lateral tilts
• Static strength: hollow body holds, deadbug, planks, side planks
• Dynamic strength: overhead step ups, overhead A-skips, stir the pot, marching deadbug, split squats
• Competitive movement: sprinting

Video 3. Overhead step-ups act to strengthen hip extensor musculature while promoting a lumbopelvic position appropriate to upright sprinting.

Video 4. The overhead A-skip challenges the coordinative abilities necessary to maintain a neutral pelvis while sprinting.

Any exercise can be a lumbopelvic control exercise if the goal and focus is directed there. Plyos like skips, hops, split jumps, and single leg bounding could be considered advanced dynamic strength exercises, so long as the athlete is encouraged to maintain a healthy relationship between the pelvis and lumbar spine.

Video 5. The marching deadbug is a progression to the standard deadbug. The key is to hold the position while the legs are moving. That is, do not allow the pelvis to tilt or the ribs to rise while marching. To make this drill more challenging, reach the heel further from the body.

Video 6. The hollow body hold is another advanced version of the deadbug. Maintain a posterior pelvic tilt and depressed rib cage while assuming a V-shaped posture. Hold it steady.
Any exercise can be a lumbopelvic control exercise if the goal and focus is directed there, says @KD_KyleDavey. Share on X

Eccentric Strength

I would be remiss to not mention the Nordic hamstring curl. It is not going to single-handedly prevent all hamstring injuries, as was perhaps once thought, but the data is clear that when added to a well-rounded strength and conditioning program it does have a preventative effect.^8-11

It is not entirely clear why this is, and skeptics are quick to point out that the exercise does not visually appear to have much transfer to sport (it doesn’t look functional). While it does not resemble a sport-specific movement, it does replicate the eccentric demands placed on the hamstring musculature during the swing phase of sprinting. Further, eccentric exercise is known to induce sarcomerogenesis, the lengthening of fascicles, which allows for greater force to be produced at longer muscles lengths.

Given that hamstring injuries are thought to occur at lengthened positions, the ability to generate (or withstand) high forces in lengthened positions has a strong physiologic rationale as protective against hamstring injuries.

The beauty with Nordics is that they don’t take much. As little as two or three sets of five reps two-to-three times per week will decrease the likelihood of hamstring injury.

Triceps Surae Strength

A history of ankle sprains have been linked to increased risk of hamstring injury.¹² It is not clear whether the ankle sprain itself makes the hamstring group more vulnerable or if both injuries are manifestations of the same underlying causal factor(s).

Video 7. Split stance heel raise iso holds: The hardest easy-looking exercise you’ll ever do. Prop the ball of your foot up, assume a split stance so that the thigh is parallel to the floor and the shin is vertical, and raise your heel as high as possible. Hold for 30s on each side.

Strengthening the triceps surae group may be protective of ankle injury and can certainly have performance benefits. Concentric, eccentric, and isometric exercises are all beneficial, but isometrics are of particular relevance to sprint performance. Lahti et al. outline isometric holds at 90°, 110°, and “high plantar flexion,” presumably instructing athletes to raise the heel as high as possible.

Video 8. Split stance heel raises: Same setup and the split stance heel raise iso holds, but with a 1-1-1-tempo. Raise the heel as high as possible, and control it on the way down.

Further, isolating the soleus is of interest. The gastrocnemius is a highly active plantar flexor when the knee is extended, as in standing calf raises, and the soleus is less of a contributor in this position. The gastroc produces less force when the knee is flexed, making the soleus the heavy hitter in this position. Isometric holds and calf raises from a flexed knee position, like a split stance, are great ways to build soleus strength and improve fortitude against ankle and hamstring injury.

Aerobic Health

Aerobic health has also been linked with decreased risk of hamstring injury.⁶ Why might this be?

Fatigue changes things. Mental processes like decision-making and mechanics are modified by fatigue. This is evident to anyone who has ever trained or played hard.

Greater aerobic fitness delays the onset of fatigue, which delays injurious alterations to kinematic and decision-making processes. Less game time in fatigued conditions means less time spent in the danger zone of injury. Likewise, lower absolute fatigue during intense gameplay also reduces risk.

Less game time in fatigued conditions means less time spent in the danger zone of injury. Likewise, lower absolute fatigue during intense gameplay also reduces risk, says @KD_KyleDavey. Share on X

Developing “cardio” in athletes who play sports predominated by anaerobic processes is often criticized. However, understanding that athletes who are in “better shape” are less likely to get hurt certainly warrants aerobic training during the offseason.

Team Programming: the Percentile Approach

It would be nice if absolute values existed for the several risk factors discussed in this article. But they don’t.

To accommodate for this, one can take the percentile approach. This is particularly useful when working with a large group of athletes, like a team, but can also be applied to individual athletes once enough data points have been collected.

The method is simple: measure everybody and split them up into thirds or quartiles and prescribe individualized programs from there. For instance, say you’re measuring hamstring strength with a dynamometer or ROM with an active straight leg raise. You can predetermine that the bottom quartile—the weakest and least flexible athletes—will get more strength and mobility work than the others.

If you don’t have a whole team available to test, begin testing your athletes one-by-one and eventually you will have a database you can use for a ranking system.

While not a perfect system, it does provides an avenue to identify the top and bottom performers within a group and program from there.

Putting it all Together: Programming for Hamstring Injury Prevention

If hamstring injuries were simple, this article would have one subheader. Needless to say, there’s a lot to consider when programming with the intent of preventing hamstring injury.

Recognizing every athlete, sport, and time of year will look different, throwing out a sample calendar with a daily training gameplan will be of little use to you.

What you can do, however, is run through the below checklist to make sure you’re hitting each of these categories once per week at an absolute minimum:

• Hip and knee ROM
• Sprint mechanics
• High-speed sprinting
• Strength training at different working angles
• Eccentric strengthening of the hamstrings
• Lumbopelvic control
• Triceps surae strength
• Aerobic development

If you don’t tick each of these items off the list as you review your training plan, it’s time to go back to the drawing board.

Hamstring injuries are nasty, recurring injuries that stifle, if not end, athletic careers. The time lost in training and gameplay can be irrecuperable.

To best protect yourself and your athletes, take a multifaceted approach and cover all your bases. Your hammies will thank you.

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References

1. De Visser, H. M., Reijman, M., Heijboer, M. P., & Bos, P. K. (2012). Risk factors of recurrent hamstring injuries: a systematic review. British Journal of sports medicine, 46(2), 124- 130.

2. Lahti, J., Mendiguchia, J., Ahtiainen, J., Anula, L., Kononen, T., Kujala, M., … & Edouard, P. (2020). Multifactorial individualised programme for hamstring muscle injury risk reduction in professional football: protocol for a prospective cohort study. BMJ Open    Sport & Exercise Medicine, 6(1), e000758.

3. Girard, O., Brocherie, F., Morin, J. B., & Millet, G. P. (2017). Lower limb mechanical asymmetry during repeated treadmill sprints. Human movement science, 52, 203-214.

4. Brown, S. R., Feldman, E. R., Cross, M. R., Helms, E. R., Marrier, B., Samozino, P., & Morin, J. B. (2017). The potential for a targeted strength-training program to decrease asymmetry and increase performance: a proof of concept in sprinting. International Journal of Sports Physiology and Performance, 12(10), 1392-1395.

5. Sugiura, Y., Saito, T., Sakuraba, K., Sakuma, K., & Suzuki, E. (2008). Strength deficits identified with concentric action of the hip extensors and eccentric action of the hamstrings predispose to hamstring injury in elite sprinters. Journal of orthopaedic & sports physical therapy, 38(8), 457-464.

6. Malone, S., Owen, A., Mendes, B., Hughes, B., Collins, K., & Gabbett, T. J. (2018). High-speed running and sprinting as an injury risk factor in soccer: Can well-developed physical qualities reduce the risk? Journal of science and medicine in sport, 21(3), 257-262.

7. Schuermans, J., Danneels, L., Van Tiggelen, D., Palmans, T., & Witvrouw, E. (2017). Proximal neuromuscular control protects against hamstring injuries in male soccer players: a prospective study with electromyography time-series analysis during maximal sprinting. The American journal of sports medicine, 45(6), 1315-1325.

8. Ishøi, L., Krommes, K., Husted, R. S., Juhl, C. B., & Thorborg, K. (2020). Diagnosis, prevention and treatment of common lower extremity muscle injuries in sport–grading the evidence: a statement paper commissioned by the Danish Society of Sports Physical Therapy (DSSF). British journal of sports medicine, 54(9), 528-537.

9. Longo, U. G., Loppini, M., Berton, A., Marinozzi, A., Maffulli, N., & Denaro, V. (2012). The FIFA 11+ program is effective in preventing injuries in elite male basketball players: a cluster randomized controlled trial. The American journal of sports medicine, 40(5), 996-1005.

10. Sugiura, Y., Sakuma, K., Sakuraba, K., & Sato, Y. (2017). Prevention of hamstring injuries in collegiate sprinters. Orthopaedic journal of sports medicine, 5(1), 2325967116681524.

11. Seagrave III, R. A., Perez, L., McQueeney, S., Toby, E. B., Key, V., & Nelson, J. D. (2014). Preventive effects of eccentric training on acute hamstring muscle injury in professional baseball. Orthopaedic journal of sports medicine, 2(6), 2325967114535351.

12. Malliaropoulos, N., Bikos, G., Meke, M., Vasileios, K., Valle, X., Lohrer, H., … & Padhiar, N. (2018). Higher frequency of hamstring injuries in elite track and field athletes who had a previous injury to the ankle-a 17 years observational cohort study. Journal of Foot and Ankle Research, 11(1), 7.