Since an injured athlete cannot compete or even practice, injury reduction is the most important benefit of a well designed and executed strength program. Sprinting has a high incidence of hamstring strains, even with elite sprinters. Both Usain Bolt and Andre De Grasse have sustained hamstring strains in world competition. But, athletes are not helpless victims to this trend.

Research shows having a high eccentric strength in the hamstrings reduces strains. Studies also show that flexible hamstrings reduce injury risk in sprinters. Since recovery time from a sprint-induced hamstring strain is an average of 16 weeks to return to pre-injury level of performance, injury prevention is key. One important factor to injury prevention, is conducting screens.

These three tests will help identify whether your athlete is at risk for a hamstring strain when sprinting.

1. The Klatt Test:

Originally developed by Physical Therapist Doris Klatt and modified by Charles Poliquin, this test identifies muscle imbalances within the lower extremities and the core. It is performed by hopping off a box and observing how the torso, hips, and knees adapt to the jump.

Performing the test:

  • Take off your shoes and socks.
  • Stand on a box about 8”H. If injured, use a lower box.
  • Stand on one leg and keep eyes forward at all times.
  • Extend non-testing leg 25-30 degrees forward.
  • Extend arms 90 degrees to torso and overlap hands for balance.
  • Hop off and attempt to stick the landing.
  • If you stuck the landing, you can raise the height by 2”.
  • You only get one attempt per leg.
  • Test until you find 2 imbalances. Whichever you find first is the weakest link.
  • You can increase the height 3 more times at 2” intervals.

Interpreting the results:

If you hopped forwards when conducting this test, you have weak hamstrings. To correct this, perform a higher ratio of hamstring-dominant exercises to quadriceps-dominant exercises. The muscle imbalances you may see are:

  • Knee Buckling In: Weak Vastus Medialis Oblique and / or a Weak Glute Medius
  • Hopping Forwards: Weak Hamstrings
  • Hopping In: Weak Groin
  • Hopping Lateral: Weak Hip Abductors
  • Heel In: Weak Hip Internal Rotators
  • Heel Spin Out: Weak Hip External Rotators
  • Excessive Bend from Hip: Weak Glute or Low Back
  • Wobble to Side: Weak Quadratus Lumborum

2. Straight Leg Raise (SLR) for Assessing Hamstring Flexibility

Although research has not found a link to increased stride length and hamstring flexibility, elite sprinters are known to have very flexible hamstrings.  The transfer of this flexibility is reduced hamstring strain when sprinting. Therefore, assessing your athlete’s flexibility is very important.

Performing the test:

  • Lie supine on a table with ankles relaxed and knees locked. Gently press both legs down into the table to fixate pelvis.
  • Keeping knees locked, raise one leg as high as possible. Remember to keep pelvis fixed.  
  • Use a goniometer to measure the angle of the femur relative to the table.

Interpreting the results:

Optimal range of motion for the SLR for the average population is 80-90 degrees of hip flexion. If you are lower than 80-90 degrees, you have a high risk of hamstring strain when sprinting. At HPT, we want our sprinters to be at 100 degrees or higher. Also, an imbalance of 10 percent or more between legs significantly increases risk for injury. If you are not scoring 100 degrees or higher, or have an imbalance between sides, you need to stretch the hamstrings. Start doing PNF stretching or Active Isolated Stretching a minimum of three times per week. 

3. Single Leg Triple Jump

Sprinting is a high velocity, horizontal force-based activity. Research shows the primary drivers of this force are the hamstrings.

The single leg triple jump is an awesome assessment, as it is also a high-velocity, horizontally-based exercise powered primarily by the hamstrings. Performing this test will help you determine an imbalance in your hamstrings.

Performing the test:

  • Stand on one leg behind a line.
  • Lean over from the hips and use a double arm swing to initiate your jump.
  • Jump three times and stick the landing for at least 1 second.
  • Mark your landing.
  • Test the other leg.
  • Test two more times and average the results

Interpreting the results:

To score the test, take the average distance of the weaker side and divide by the average distance of the stronger side. Multiply by 100. This will give you the Limb Symmetry Index (LSI). The goal is to have an LSI of 90% or higher, meaning you should have no more than 10% difference between legs.  A score of more than 10% between sides puts you at risk for a hamstring strain. Some normative data has been proposed as well. Shoot for your athletes scoring within the below norms.