Branched-chain amino acids plus vitamin D supplementation promote increased muscle strength following lumbar surgery for lumbar spinal stenosis: a randomized trial

Abstract

Background context: Adequate nutrition is essential to address the surgical stress response and mitigate loss of muscle mass, strength, and functionality in older adults with lumbar spinal stenosis (LSS). However, it is unknown whether amino acids and/or vitamin D are beneficial in older adults following lumbar surgery for LSS.

Purpose: To evaluate whether branched-chain amino acids (BCAA) plus vitamin D supplementation could attenuate the loss of muscle mass and strength, accelerate the return of functional mobility, and improve clinical outcomes following lumbar surgery for LSS.

Study design/setting: A single-center, single-blind randomized controlled trial.

Patient sample: Eighty patients who received lumbar surgery for LSS.

Outcome measures: The primary outcome was the Zurich claudication questionnaire (ZCQ), and secondary outcomes included knee muscle strength, muscle mass measured by bioelectrical impedance analysis, gait speed and a timed up-and-go test (TUG) at 12 weeks postoperatively. Follow-up assessment was performed for the ZCQ at 52 weeks postoperatively.

Methods: Patients ingested the supplementation (BCAA group: BCAA plus vitamin D, Nonamino acid group: nonamino acid) twice daily for 3 weeks from the day after surgery, and received two hours of postoperative inpatient rehabilitation 5 times a week.

Results: No significant differences were observed in the mean changes on the ZCQ between the two groups at 12 weeks and 52 weeks. At 2 weeks postoperatively, the nonamino acid group showed significant deterioration compared with the BCAA group for strengths of knee extensor and knee flexor (p < .01). At 12 weeks, the BCAA group showed significant improvements in knee extensor strength and knee flexor strength compared with the nonamino acid group (p <.01). There were no significant differences in mean changes of muscle mass, maximum gait speed, and TUG at 12 weeks between two groups.

Conclusions: BCAA plus vitamin D supplementation did not improve LSS-related clinical outcomes after lumbar surgery for LSS, even though muscle strength increased. Future studies should focus on long-term outcomes for muscle mass and physical function, including development of sarcopenia and frailty.

Keywords: Amino acids, Branched-chain amino acids; Lumbar spinal stenosis; Muscle mass; Muscle strength; Nutrition; Physical therapy; Protein; Surgery; Vitamin D.