Maximum-Speed Single-Leg Bridge Test for Concentric Functional Assessment and Exercise in an Athlete with Recurrent Hamstring Strain Injuries: A Case Report.

Introduction: The high recurrence rate of hamstring strain injuries (HSI) suggests that using only muscle strength and flexibility differences between the injured and uninjured sides may be insufficient. Recurrences are frequent during high-speed movements; however, no assessment method currently exists to evaluate high-speed functional performance. This case report aimed to highlight the use of the Maximum-Speed Single-Leg Bridge Test (MS-SLBT) in a rugby player with a fourth recurrence of HSI to identify functional impairments that are not detectable with conventional assessments, and to demonstrate that these impairments can be improved by utilizing the test as an intervention. Case Description: A 21-year-old university rugby player with a history of three prior HSI experienced a fourth recurrence in the semitendinosus. Magnetic resonance imaging (MRI) confirmed a Grade I injury, and ultrasound images showed scarring and tenderness of the muscle fibers. At one month post-injury, the subject reported no pain during hamstring stretching, isometric or eccentric contractions, or sprinting. The subject was unable to complete the MS-SLBT because of severe pain and fear. After two months, the pain during the test decreased, but the buttock-raising speed and height remained limited. The subject then performed the MS-SLBT exercise as a daily intervention for two months and the effects of training and detraining were evaluated. Outcome: After the intervention, there was a 76% improvement in buttock-raising speed, 84% improvement in height, 34% increase in isometric knee flexor torque, and 97% increase in flexibility. These improvements were maintained even after a 1.5 month of detraining period. Ultrasound images showed reduced muscle fiber irregularities, improved centralization of muscle contractions, and increased contraction speed. Discussion: The MS-SLBT is effective in identifying residual functional impairments in athletes who meet conventional return-to-play criteria after HSI. Furthermore, MS-SLBT may serve as an effective intervention to improve these functional deficits within one month. Level of Evidence: 5.