Metabolic responses to exercise after carbohydrate loads in healthy men and women.
OBJECTIVE
This study aimed to investigate gender differences in i) pancreatic insulin secretory (beta-cell sensitivity) and whole body insulin sensitivity responses to an intravenous carbohydrate (CHO) load, and (ii) metabolic responses to exercise after both intravenous and oral CHO loads.


METHODS
Seven untrained healthy men and seven age-, body mass-, and VO2max-matched women performed two trials. In one trial they cycled for 60 min at 50% VO2max, starting 60 min after ingestion of a carbohydrate-rich meal (ME trial). In the other trial, subjects were infused with 20% dextrose solution to maintain blood glucose concentration at approximately 8 mmol x L(-1) for 60 min (INF trial), then the infusion rate was maintained constant during the following 60 min while exercising at 50% VO2max.


RESULTS
There was no gender effect on beta-cell sensitivity (serum insulin: 161 +/- 37 and 159 +/- 28 pmol x L(-1) for men and women, respectively) and whole body insulin sensitivity (155 +/- 24 and 135 +/- 29 mg x KgFFM(-1) x min(-1) per pmol x L(-1) x 100 for men and women, respectively). This may explain the similarity in glycemic, substrate oxidation and other metabolic responses to exercise after both intravenous and oral CHO loads in men and women.


CONCLUSIONS
These results suggest that moderate exercise performed in the postprandial state presents a similar challenge to the ability of healthy, untrained men and women to perform exercise without a substantial decline in plasma glucose concentration below fasting values.
Leelayuwat
Naruemon
N
Centre for Integrated Biology and Medicine, Institute of Clinical Research, University of Nottingham Medical School, Nottingham, United Kingdom.
Tsintzas
Kostas
K
Patel
Kishor
K
Macdonald
Ian A
IA
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D001944:Breath Tests; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D010101:Oxygen Consumption; D019518:Postprandial Period; D012737:Sex Factors
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D007328:Insulin