METABOLITE AND HORMONAL RESPONSE IN SMOKERS DURING REST AND SUSTAINEDEXERCISE

To evaluate the effects of acute and chronic smoking on blood glucose homeostasis, concentrations of metabolites, and hormonal responses at rest and during submaximal exercise, seven male smokers and seven simi lar nonsmokers were studied after an overnight fast. Nonsmokers (NS) a nd chronic smokers, abstaining from smoking (CS), were tested during r est and 60 min of cycle ergometry exercise at 49.7 +/- 0.8% of VO(2)pe ak. Smokers were restudied after acutely smoking (AS) two cigarettes p rior to rest and one prior to exercise. Blood glucose levels were simi lar among NS, CS, and AS at all times. Lactate levels were elevated in AS compared with NS during exercise (2.32 +/- 0.22 mM vs 1.81 +/- 0.1 1; P < 0.05), with no differences in alanine. Free fatty acid levels w ere initially lower at rest in CS (0.45 +/- 0.04 mM) than in either AS (0.77 +/- 0.11) or NS (0.64 +/- 0.06; P < 0.05), but no other differe nces were found. During exercise, CS had lower glycerol levels (0.31 /- 0.02 mM) than either AS (0.38 +/- 0.02) or NS (0.41 +/- 0.02; P < 0 .05). Nevertheless, respiratory exchange ratio values were not signifi cantly different during steady-state rest or exercise; and insulin, gl ucagon, and norepinephrine levels were also similar. Smokers effective ly maintained normal blood glucose levels with only minor changes in s ome metabolite and hormone concentrations during rest and sustained ex ercise.