Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
©Journal of Sports Science and Medicine (2020) 19, 282 - 288

Research article
Acute Maltodextrin Supplementation During Resistance Exercise
Dylan T. Wilburn, Steven B. Machek, Thomas D. Cardaci, Paul S. Hwang, Darryn S. Willoughby 
Author Information
Exercise and Biochemical Nutrition Laboratory, Department of Health, Human Performance, and Recreation, Baylor University, Baylor University, Waco, TX USA

Darryn S. Willoughby
‚úČ Ph.D. Department of Health, Human Performance, and Recreation, Baylor University, 1312 South 5 Street, Waco, TX 76798, USA
Publish Date
Received: 17-12-2019
Accepted: 02-02-2020
Published (online): 01-05-2020
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Most of the research investigating the ergogenic enhancing mechanisms of carbohydrate have been conducted using aerobic based exercise. Therefore, the purpose of this study was to investigate the effects of pre-exercise maltodextrin ingestion on resistance exercise performance, serum insulin, epinephrine, glucose, and muscle glycogen concentrations. In a double blind, cross over, repeated measures design, participants completed four sets to failure at 70% of 1-RM with 45s rest on the angled leg press with or without pre-exercise maltodextrin (2g/kg) after a 3hr fast. Serum glucose, epinephrine, and insulin were assessed at baseline, 30 min post-ingestion, immediately after, and 1hr post-exercise with or without carbohydrate supplementation. Muscle glycogen was assessed from biopsy specimens sampled from the vastus lateralis before supplementation, immediately after exercise, and 1hr post exercise under both conditions. There was no main effect of supplement on resistance exercise performance (p = 0.18). Muscle glycogen concentration decreased across time for both groups (p < 0.001). There was an interaction in serum glucose decreasing more during exercise in the carbohydrate condition (p = 0.026). An interaction occurred showing insulin decreased during exercise in the carbohydrate condition (p = 0.003). Also, there was a main effect of insulin being elevated with carbohydrate consumption (p = 0.027). Epinephrine was decreased across all time points after carbohydrate ingestion (p = 0.023). Carbohydrate supplementation before resistance exercise did not improve leg press performance to fatigue despite increased metabolic substrate availability. These results indicate that pre-exercise dietary carbohydrate will be utilized preferentially during exercise due to decreased epinephrine, decreased serum glucose, and increased insulin concentrations. However, the increases in glycolytic substrate availability will not increase exercise performance or glycogen content following 1hr of recovery.

Key words: Skeletal muscle, anaerobic exercise, hormones, glycogen

           Key Points
  • Pre-exercise carbohydrate intake does not alter brief resistance exercise performance to fatigue when one is already consuming adequate dietary carbohydrate.
  • The carbohydrate timing decreased in epinephrine while increasing insulin leading to higher dietary glucose utilization but not glycogen sparing during the brief exercise bout.
  • Carbohydrate supplementation did not accelerate glycogen recovery within 1hr recovery.
  • Longer time frames may be necessary to see glycogen concentration return to baseline (2-3hr).
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