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Chocolate Milk And Glycogen Replenishment After Endurance Exercise In Moderately Trained Males: 862: June 4 9:45 AM - 10:00 AM

Karfonta, Kirstin; Lunn, William; Colletto, Megan; Anderson, Jeff; Rodriguez, Nancy FACSM

Medicine & Science in Sports & Exercise: May 2010 - Volume 42 - Issue 5 - p 86
doi: 10.1249/01.MSS.0000385622.48600.1e
E-12 Free Communication/Slide - Carbohydrate Metabolism I: JUNE 4, 2010 8:00 AM - 10:00 AM: ROOM: 345

University of Connecticut, Storrs, CT.

(K. Karfonta, Dairy Management, Inc., Contracted Research.)

PURPOSE: The purpose of this study was to compare muscle glycogen content after consumption of either fat-free chocolate milk or an isocaloric non-protein drink after an endurance exercise bout.

METHODS: Moderately trained male runners (N=8, 23.7 ± 1.6 y, 76.0 ± 3.8 kg, BMI = 24.0 ± 0.9, body fat = 14.4 ± 2.0%, VO2peak = 53.1 ± 1.6 mL·kg-1·min-1) participated in a randomized, crossover-design study during which they consumed a eucaloric diet providing 1.5 g protein·kg-1 and approximately 6 g carbohydrate·kg-1 for two weeks. At the end of each week, subjects performed a 45-min run at 65% of VO2peak after which 16 oz. of either fat-free chocolate milk (MILK) providing 0.84 ± 3.8 g/kg of carbohydrate or a non-nitrogenous, isocaloric control beverage (CON) providing 1.2 ± 0.95 g/kg of carbohydrate was consumed. Vastus lateralis muscle biopsy and blood samples were taken for muscle glycogen and plasma glucose measurements, respectively, during the 1-h postexercise recovery period.

RESULTS: Immediate post-exercise muscle glycogen concentrations before beverage consumption were not different between MILK and CON (6.4 ± 1.1, 5.7 ±.53 g·100g-1 tissue, respectively). Glycogen concentrations were greater for MILK at 30 and 60 minutes post exercise (6.5 ± 0.9 and 6.4 ± 0.9 g·100g-1 tissue, respectively) compared to CON (5.4 ± 0.5, 5.4 ± 0.6 g·100g-1 tissue, respectively) (p<0.05). Although blood glucose concentrations before beverage consumption were not different (90 ± 3 mg/dL and 88 ± 2 mg/dL for MILK and CON, respectively), glucose concentrations were lower for MILK at 30 and 60 minutes post exercise (122 ± 4, 94 ± 5 mg/dL, respectively) than CON (141 ± 7, 113 ± 7mg/dL, respectively) (p<0.05).

CONCLUSIONS: These findings suggest that ingestion of fat-free chocolate milk following an endurance exercise bout supports glycogen replenishment to a greater extent than a non-nitrogenous, isocaloric beverage. While the benefit of carbohydrate supplementation on glycogen replenishment following endurance exercise is well-established, a mixed carbohydrate-protein beverage may provide additional advantages to muscle recovery.

Supported in part by Dairy Management, Inc.

© 2010 American College of Sports Medicine