The effects of treadmill running on aging laryngeal muscle structure.

OBJECTIVES/HYPOTHESIS Age-related changes in laryngeal muscle structure and function may contribute to deficits in voice and swallowing observed in elderly people. We hypothesized that treadmill running, an exercise that increases respiratory drive to upper airway muscles, would induce changes in thyroarytenoid muscle myosin heavy chain (MHC) isoforms that are consistent with a fast-to-slow transformation in muscle fiber type. STUDY DESIGN Randomized parallel group controlled trial. METHODS Fifteen young adult and 14 old Fischer 344/Brown Norway rats received either treadmill running or no exercise (5 days/week/8 weeks). Myosin heavy chain isoform composition in the thyroarytenoid muscle was examined at the end of 8 weeks. RESULTS Significant age and treatment effects were found. The young adult group had the greatest proportion of superfast-contracting MHCIIL isoform. The treadmill running group had the lowest proportion of MHCIIL and the greatest proportion of MHCIIx isoforms. CONCLUSION Thyroarytenoid muscle structure was affected both by age and treadmill running in a fast-to-slow transition that is characteristic of exercise manipulations in other skeletal muscles. LEVEL OF EVIDENCE NA. Laryngoscope, 126:672-677, 2016.