Early versus delayed lengthening exercises for acute hamstring injury in male athletes: a randomised controlled clinical trial

Key Points

1. Hamstring rehabilitation programs that include lengthening exercises reduce time to return to sport and lower reinjury rates, but the optimal point in rehabilitation to introduce these exercises was not known.
2. In this study, 90 males with acute hamstrings strain injuries were randomized into two groups: an early lengthening group and a delayed lengthening group.
3. There was no statistically significant difference in time to return to sport or reinjury rates between groups.

BACKGROUND & OBJECTIVE

Hamstring strains are a burdensome injury in terms of time loss, cost and performance impairments. As such, high-quality rehabilitation is crucial to return athletes back to full performance as quickly and safely as possible with minimized risk of reinjury.

Two recent studies showed that rehabilitation programs which included exercises that lengthened the hamstrings reduced time to return to sport and lowered reinjury rates (1,2). However, the optimal point in rehabilitation to introduce these exercises had not been studied. The purpose of this study was to compare return to sport and reinjury rates in two groups, one that performed lengthening exercises early in rehabilitation and one that performed them later on (delayed).

Hamstring strains are a burdensome injury in terms of time loss, cost and performance impairments.

Lengthening exercises can safely be introduced at the start or midpoint of hamstring rehabilitation, with a potentially slight advantage in time to return to sport for early lengthening.

METHODS

• Over a 4.5-year period, 90 males between the ages of 18 and 36 (median = 26) with acute hamstring strain injuries (grade 1 or 2 confirmed by MRI) participated in a randomized controlled trial (RCT).

• Both the early and delayed lengthening groups rehabilitated 3-5 days/week using six-phase standardized, criteria-based rehabilitation programs. The only difference in the group’s programs was the timing of three hamstring lengthening exercises: the “extender”, the “diver”, and the “slider” (see the video for these exercises).

HAMSTRING LENGTHENING EXERCISES

• The early lengthening group performed these exercises beginning in their first session (median = 5 days post-injury). The delayed group introduced the lengthening exercises in the third phase of the program (once they could run at 70% of their self-rated maximal speed), which was a median of 16 days post-injury.

• The primary outcome of the study was the number of days between injury and return to sport (i.e. unrestricted training or competition). The secondary outcome was reinjury rate during the first year after return to sport.

RESULTS

• There were no statistically significant differences between the early and delayed lengthening groups in time to return to sport or reinjuries (see Table 1).

• Participants returned to sport a median of 27 days post-injury (interquartile range = 17-39).

• 19% of the participants reinjured their hamstring within one year.

• Overall, participants attended a median of 77% of the recommended rehabilitation sessions.

LIMITATIONS

• All participants in this study were male, and the majority were professional footballers. Care should be taken in extrapolating the present findings to females, other sports, and other levels of play.

• While dropouts are unavoidable, this study was limited by a high dropout rate (19%), which could be considered a threat to its validity. This high dropout rate may have affected the researchers’ ability to find a statistically significant between-group difference in time to return to sport.

CLINICAL IMPLICATIONS

Sports medicine practitioners and researchers are always looking for ways to return athletes to sport faster with minimized risk of reinjury. One popular approach is more aggressive rehabilitation protocols. For example, a recent RCT of hamstring rehabilitation compared a group that was allowed to work up to a 4/10 pain rating with a group that had to remain pain-free (3). The study found no difference in return-to-sport clearance time or reinjuries between groups.

Similarly, in the present study (in which both groups rehabilitated pain-free) there were no statistically significant differences between groups in time to return to sport or reinjuries. These null findings are not altogether surprising given the similarity of the two groups: the only difference was the timing of the three lengthening exercises.

On one hand, the lack of a statistically significant reduction in time to return to sport in the early lengthening group could be perceived as discouraging. On the other hand, the study does show that early lengthening is safe and non-inferior to delayed lengthening. Moreover, the median between-group difference of 8 days – which favored the early lengthening group – could mean an extra match played. The researchers considered this difference to be clinically relevant.

In conclusion, lengthening exercises can safely be introduced at the start or midpoint of hamstring rehabilitation (with a potentially slight advantage in time to return to sport for early lengthening). To make the decision, physiotherapists may rely on their own clinical expertise and intuition in conjunction with patient preference.

+STUDY REFERENCE

Vermeulen R, Whiteley R, van der Made A, van Dyk N, Almusa E, Geertsema C, Targett S, Farooq A, Bahr R, Tol J, Wangensteen A (2022) Early versus delayed lengthening exercises for acute hamstring injury in male athletes: A randomised controlled clinical trial. British Journal of Sports Medicine, Epub ahead of print.

SUPPORTING REFERENCE

1. Askling CM, Tengvar M, Thorstensson A. Acute hamstring injuries in Swedish elite football: a prospective randomised controlled clinical trial comparing two rehabilitation protocols. Br J Sports Med 2013;47:953–9.
2. Askling, C. M., Tengvar, M., Tarassova, O., & Thorstensson, A. (2014). Acute hamstring injuries in Swedish elite sprinters and jumpers: A prospective randomised controlled clinical trial comparing two rehabilitation protocols. British Journal of Sports Medicine, 48(7), 532–539.
3. Hickey, J. T., Timmins, R. G., Maniar, N., Rio, E., Hickey, P. F., Pitcher, C. A., Williams, M. D., & Opar, D. A. (2020). Pain-free versus pain-threshold rehabilitation following acute hamstring strain injury: A randomized controlled trial. Journal of Orthopaedic & Sports Physical Therapy, 50(2), 91–103.