Relationship between Isokinetic Trunk Muscle Strength and Return to Sports Competition after Conservative Therapy in Fresh Cases of Lumbar Spondylolysis: A Retrospective Observational Study

This study aimed to clarify the relationship between isokinetic trunk muscle strength and return to sporting activities in fresh cases of lumbar spondylolysis treated with conservative therapy. Patients included a total of ten men (age: 13.5 +/- 1.7) who were instructed by their attending physicians to stop exercising and who met the eligibility criteria. Isokinetic trunk muscle strength was measured immediately after exercising for the first time (First) and one month (1M). Flexion and extension and maximum torque/body weight ratio were significantly lower First compared to 1M at all angular velocities (p < 0.05). Maximum torque generation time was significantly lower for First at 120 degrees/s and 180 degrees/s than at 1M (p < 0.05). Correlations with the number of days to return to sports competition were detected at 60 degrees/s for maximum torque generation time (p < 0.05, r = 0.65). Following conservative treatment for lumbar spondylolysis, it was considered necessary to focus on trunk flexion and extension muscle strength and contraction speed of trunk flexors at the beginning of the exercise period. It was suggested that trunk extension muscle strength in the extension range might be one of the critical factors for returning to sports.

Automated summary

This study aimed to investigate the relationship between isokinetic trunk muscle strength and return to sporting activities in patients with lumbar spondylolysis who underwent conservative therapy. The results showed that trunk muscle strength and maximum torque/body weight ratio were lower immediately after exercising compared to one month later. The time to generate maximum torque was shorter at higher angular velocities. Correlation analysis indicated that the time to return to sports competition was related to the maximum torque generation time at a speed of 60 degrees/s. These findings suggest that trunk flexion and extension muscle strength and contraction speed of trunk flexors are important for returning to sports after conservative treatment for lumbar spondylolysis. Trunk extension muscle strength in the extension range may also play a critical role.