An Exercise-based Rehabilitation Program for a Recreational Long-distance Runner With Long-standing Groin Pain

A 38-year-old male recreational runner reported pain in his right groin (adductor and lower abdomen area). The mean pain level reported was 2 in a numeric pain rating scale (NPRS) of 0-10, which occasionally increased to 3. Aggravating exercises included straight abdominal sit-ups, sliding hip exercise, and hip adductor squeeze at 45 degrees. In addition, symptoms were provoked by laughing and sexual intercourse. The initial onset of pain was nine years before the athlete contacted the research team seeking assistance (2017). Pain was resolved after two years (2019) of systematic resistance training, but reappeared five years later. The athlete did not report any specific mechanism of the initial injury, but described an insidious pain presented during an intense running period. Although the athlete had a number of physiotherapy sessions within the last year, including electrotherapeutic modalities (TENS, radiofrequency therapy) and massage, there was no improvement of the pain in the groin area. His weekly training schedule during the month before the clinical examination included one running session (10 km), one upper limb resistance training session, and one groin-specific resistance training session. The athlete reported no previous musculoskeletal injuries, while no radiological examination had been performed.

The program will comprise two distinct phases. Phase A will consist of a baseline monitoring period, during which the athlete will exclusively perform adductor strength testing without any exercise intervention. This phase will serve to establish a stable baseline strength level before the athlete starts the rehabilitation program. Transition to Phase B will be determined by the strength variance between sessions; if there is a difference of ≤ 10% across the first three sessions for each leg, the athlete will move to Phase B at the fourth week. Otherwise, further testing sessions will be needed before the athlete starts the program, provided that a difference of ≤ 10% is achieved across three consecutive testing sessions.

In phase B, the athlete will perform a pain-guided progressive rehabilitation program which comprises three distinct components: anterior chain, posterior chain, and functional training. Anterior chain includes exercises relevant to the groin (adductor muscles, hip flexor muscles, and trunk muscles), posterior chain exercises targeting muscle groups not related to the injured area (hip extensor and abductor muscles, knee extensor and flexor muscles, and ankle plantar flexor muscles), and functional exercises related to the sport (hopping and jumping and linear running). The athlete will be allowed to choose between a number of exercises for each muscle group included in anterior and posterior chain components. Weekly training frequency will vary between 3 to 6 sessions, including 3 anterior chain sessions, 2-3 posterior chain sessions, and 2-3 functional training sessions, depending on the athlete's availability. Once specific return to sport criteria are fulfilled (Appendix II), Phase B will be completed.

During the rehabilitation period, the athlete will not be allowed to participate in any other form of training outside the predefined protocol. Additional upper limb exercises and any therapeutic options will be allowed after discussion with the research team, provided they do not interfere with the rehabilitation protocol implementation.

Exercise progression

Anterior chain exercise progression will be determined by the pain level, while no pain will be allowed during posterior chain exercises. In exercises where pain is present, a "pain-controlled repetition maximum" (PRM) approach will be followed. The athlete will perform each set until failure keeping pain at 2/10. If pain is more than 2, the athlete will have to reduce the load. If pain is less than 2, the athlete will have to increase the load. If the athlete experiences pain \> 2/10 longer than 24 hours after training, he will be advised to return to the previous training level until pain returns to normal. In exercises where pain is absent, a repetition maximum (RM) approach will be followed, during which the athlete will perform 8-10 repetitions keeping 3 repetitions in reserve (RIR) in each set.

The rehabilitation protocol will be performed as an unsupervised intervention, reflecting pragmatic clinical scenarios where recreational athletes lack access to clinical supervision due to financial or other constraints. However, adherence, exercise execution, or any difficulties during rehabilitation will be addressed during weekly meetings with the physiotherapist performing strength testing. During these meetings, the physiotherapist will ensure that exercises are executed with proper form and any queries by the athlete are answered. In addition, prior to initiation of the rehabilitation the athlete will be provided with documents including detailed exercise descriptions, ensuring understanding and proper execution.

• Hip-related quality of life [Срок оценки: Hip-related quality of life will be evaluated baseline and at the end of the rehabilitation. The estimated time for the intervention completion is 12 weeks.]
• Athlete's recovery perception [Срок оценки: Subjective overall recovery perception will be evaluated on a weekly basis. Although the overall duration of the intervention cannot be defined due to the criteria-based nature of the progression, the estimated time for completion is 12 weeks.]