Increased carbohydrate oxidation after ingesting carbohydrate with added protein.
OBJECTIVE
To examine the metabolic impact of including protein in a postexercise carbohydrate supplement when ingested between two bouts of prolonged running performed within the same day.


METHODS
Six healthy men participated in two trials separated by 14 d, each involving a 90-min treadmill run at 70% VO2max followed by 4 h of recovery and a subsequent 60-min run at the same intensity. At 30-min intervals during recovery, participants ingested either a solution containing 0.8 g.kg(-1)h(-1) of carbohydrate (CHO) or the same solution plus an additional 0.3 g.kg(-1)h(-1) of whey protein isolate (CHO-PRO). Muscle biopsies were obtained from the vastus lateralis at the beginning and end of the recovery period, with a third muscle biopsy taken following the second treadmill run.


RESULTS
Despite higher insulinemic responses to the CHO-PRO solution than to the CHO solution (P < 0.05), rates of muscle glycogen resynthesis during recovery were not different between treatments (CHO = 12.3 +/- 2.2 and CHO-PRO = 12.1 +/- 2.7 mmol glucosyl units per kilogram of dry mass per hour). Furthermore, there were no differences between treatments in muscle glycogen degradation during subsequent exercise (CHO = 2.2 +/- 0.3 and CHO-PRO = 2.0 +/- 0.1 mmol glucosyl units per kilogram of dry mass per minute). In contrast, whole-body carbohydrate oxidation during the second run was significantly greater with the CHO-PRO treatment than with the CHO treatment (48.4 +/- 2.2 and 41.7 +/- 2.6 mg.kg(-1)min(-1), respectively; P < 0.01).


CONCLUSIONS
These data show that the inclusion of protein in a carbohydrate-recovery supplement can increase the oxidation of extramuscular carbohydrate sources during subsequent exercise without altering the rate of muscle glycogen degradation.
Betts
James A
JA
Sport and Exercise Science, University of Bath, Bath, United Kingdom. J.Betts@bath.ac.uk
Williams
Clyde
C
Boobis
Les
L
Tsintzas
Kostas
K
D000328:Adult; D001784:Blood Gas Analysis; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000008:administration & dosage; D004311:Double-Blind Method; D005080:Exercise Test; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D011506:Proteins / Q000008:administration & dosage / Q000378:metabolism*; D012420:Running / Q000502:physiology*; D018709:Statistics, Nonparametric; D013997:Time Factors; D016482:Urinalysis
D002241:Carbohydrates; D011506:Proteins; D006003:Glycogen