Age-specific Resistance-type Exercise Training Improves Performance Without Altering Strain-injury Susceptibility

Abstract

PURPOSE: Two tenets of exercise programming/training are injury prevention and performance enhancement. The purpose of this study was to determine whether a validated model of resistance-type exercise training (RTET) utilizing stretch-shortening contractions (SSCs) could alter susceptibility to the mechanical induction of skeletal muscle strain injury with aging. METHODS: F344xBN rats’ dorsiflexor muscles were SSC RTET in vivo for 1 month on a custom-built isokinetic rodent dynamometer utilizing age-specific RTET protocols. Performance for dorsiflexor muscles were analyzed temporally, and immediately following skeletal muscle strain injury. ANOVA was used for statistical analysis; α was set at p < 0.05. RESULTS: Rodents receiving no SSC RTET prior to injury had significant static (-48.6% and -54.5%, respectively) and dynamic (-40.9% and -49.8%, respectively) peak force deficits. Age-specific, SSC RTET improved muscle performance in young and old rodents by 15% and 18%, respectively (p < 0.05). Interestingly, young and old rodents undergoing SSC RTET still incurred significant static (-48.8% and -55.7%, respectively) and dynamic (-47.5% and -48.7%, respectively) peak force deficits, which were similar deficits compared to untrained rodents. CONCLUSIONS: Although age-specific SSC RTET increases skeletal muscle adaptation, these results suggest that skeletal muscle strain induction susceptibility is unaltered following SSC RTET, irrespective of age.