Rates Of Muscle Glycogen Resynthesis 72 Hours After Eccentric Exercise

INTRODUCTION: Numerous studies have examined the rates of muscle glycogen resynthesis after concentric exercise. Although muscle glycogen concentrations are significantly reduced 24-72 hours after eccentric exercise, little is known about the rates of muscle glycogen resynthesis after eccentric exercise. PURPOSE: To determine the rates of muscle glycogen resynthesis 72 hours after eccentric exercise. METHODS: A total of 9 participants performed eccentric contractions with one leg (ECC) while the contralateral leg performed concentric contractions (CON). Seventy-two hours later, participants cycled at 65% VO2peak for 1 h to deplete muscle glycogen concentrations. Participants then consumed 0.4 g CHO . h -1 . kg BW -1 . 15 min -1 for the next 4 hours (482 ± 25.7 g CHO . h -1). Muscle biopsies were obtained from the vastus lateralis of the CON and ECC legs before and after the 4 h carbohydrate feeding period to determine the rates of muscle glycogen resynthesis. Blood samples were also collected every 30 min during the 4 h feeding period and analyzed for blood glucose and blood insulin concentrations. A one-way ANOVA was used to compare ECC and CON legs. RESULTS: Data is expressed as mean ± SEM. Muscle glycogen concentrations 72 hours after ECC contractions were ~ 22% lower than the CON leg (118.7 ± 7.0 vs. 152.4 ± 9.6 μmol . g wet weight -1, p < 0.05). However, post-exercise muscle glycogen concentrations were similar between ECC and CON legs (51.6 ± 5.4 vs. 61.0 ± 8.7 μmol . g wet weight -1). The rates of muscle glycogen synthesis during the 4 h feeding period were similar between ECC and CON legs (10.5 ± 1.2 vs 7.4 ± 1.2 μmol . g wet weight -1 . h -1). Areas under the response curves for blood glucose and insulin concentrations were 1654.2 ± 9.8 mM . L -1 . 240 min -1 and 15,199.6 ± 204.3 μU . L -1 . 240 min -1, respectively. Additionally, an ANCOVA revealed initial muscle glycogen concentrations significantly influenced subsequent rates of muscle glycogen synthesis (p < 0.05). CONCLUSION: The rates of muscle glycogen resynthesis 72 hours after ECC or CON exercise were similar. In addition, the rates of muscle glycogen resynthesis were influenced by initial muscle glycogen concentrations.