This article is a continuation of my post on December 3, Hamstring Injuries: Frequency, re-injury, and length of recovery.
Return to play following a hamstring or lower extremity strain may be one of the more difficult decisions a medical staff makes. Often the athlete is progressed through the rehabilitation process to tolerance. Every few days he/she is able to sustain increased workload to the point that they are running "sprints" at approximately 90 percent; they have resumed some practice; have begun cutting or functional drills; and have "full strength" when their hamstring muscle is tested by the physician or athletic trainer (while they are lying on a table).
The player often feels good and being an elite competitive athlete wants to return to play ASAP to help his team. Testing at this point is functional as lying on a table is much different than playing a dynamic sport like football. The tests often consists of:
1) returning to full straight ahead speed;
2) returning to full speed with changes of direction and cutting;
3) having normal explosive power.
Sprinting at full speed for rehabilitation may be somewhat controversial as some people would suggest "saving it for the game," but if a speed athlete cannot run at full speed in a controlled environment without pain, they will likely have difficulty doing it in a game. When adrenaline is rushing in the game, instincts will kick in and they will try to run at full speed; if the injury is not sufficiently healed, re-injury will likely occur.
Estimating speed in practice is difficult as injured athletes often do not realize how fast they truly are and often overestimate the speed they are running. A 40-yard dash time in football (or home to first time in baseball) can be compared from pre-season to current to get a percentage of their full speed.
Being able to change directions is important in nearly every sport. Two tests used are the Lower Extremity Functional Test (LEFT) and the T-Test. Both tests require change of direction, forward and backward sprinting, and lateral or side to side movements. In an ideal world, these tests are performed prior to the season for comparison; otherwise they can be compared to "norms" although these are much less accurate than a pre-season time.
The last important test is a HOP test. It is performed as single leg Hop: the player jumps as far as possible and holds his landing; as well as a triple jump (with 1 leg), 3 consecutive jumps and the total distance is calculated.1 This test can be modified many ways (jumping sideways, time, etc.), but should be compared ideally to pre-season values or should be within 95% of the non-injured leg.
Return to play after a lower extremity muscle strain is difficult and determining when that can occur is a combination of art and science. Using objective measurements assist in that decision, but those tests are limited as no test can truly simulate the speed and quickness of an NFL game.
1) Hamilton RT, Shultz SJ, Schmitz RJ, Perrin DH. Triple-hop distance as a valid predictor of lower limb strength and power. J Athl Train. 2008;43(2):144-51.