Muscle cytokine mRNA changes after 2.5 h of cycling: influence of carbohydrate.
OBJECTIVE
To study the effect of carbohydrate compared to placebo ingestion on plasma cytokines and muscle cytokine mRNA following 2.5 h of intensive cycling in 15 trained cyclists.


METHODS
Fifteen trained cyclists cycled for 2.5 h at 60% Wmax on two occasions while receiving 4 mL.kg.15 min carbohydrate (6%) (CHO) or placebo (PLA) beverages in a randomized, counterbalanced design. Blood and vastus lateralis muscle biopsy samples were collected before and after exercise and 12 h postexercise and compared to samples taken from five cyclists who rested in the lab during the exercise sessions. Blood cell counts were determined, and plasma was analyzed for interleukin (IL)-6, IL-10, IL-1 receptor antagonist (ra), IL-8, cortisol, epinephrine, glucose, and insulin. Muscle was analyzed for glycogen content and relative gene expression of four cytokines, IL-6, IL-8, tumor necrosis factor (TNF) alpha, and IL-1beta, using real-time quantitative reverse transcriptase polymerase chain reaction.


RESULTS
Plasma glucose and insulin were higher, and epinephrine, cortisol, IL-6, IL-10, and IL-1ra, but not IL-8, were significantly lower postexercise in CHO versus PLA. Muscle glycogen content decreased 68% immediately postexercise and the pattern of change did not differ between CHO and PLA. Muscle IL-6, IL-8, TNF-alpha, but not IL-1beta mRNA increased immediately postexercise compared to controls, with no differences between CHO and PLA.


CONCLUSIONS
CHO compared to PLA beverage ingestion attenuated the increase in plasma cortisol, epinephrine, IL-6, IL-10, and IL-1ra, but not muscle IL-6, IL-8, and TNF-alpha mRNA in athletes cycling 2.5 h at 60% Wmax.
Nieman
David C
DC
Department of Health, Leisure, and Exercise Science, Fischer Hamilton/Nycom Biochemistry Laboratory, Appalachian State University, Boone, NC 28608, USA. niemandc@appstate.edu
Davis
J Mark
JM
Henson
Dru A
DA
Gross
Sarah J
SJ
Dumke
Charles L
CL
Utter
Alan C
AC
Vinci
Debra M
DM
Carson
James A
JA
Brown
Adrienne
A
McAnulty
Steve R
SR
McAnulty
Lisa S
LS
Triplett
N Travis
NT
D001642:Bicycling; D001772:Blood Cell Count; D016207:Cytokines / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D002149:Energy Intake; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D018482:Muscle, Skeletal / Q000378:metabolism*; D009657:North Carolina; D010919:Placebos; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D016207:Cytokines; D004040:Dietary Carbohydrates; D007328:Insulin; D010919:Placebos; D012333:RNA, Messenger; D006003:Glycogen; D006854:Hydrocortisone