title: Effects of nicotinic acid on respiratory exchange ratio and substrate levels during exercise.
abstract: The purpose of this study was to investigate the effects of pharmacologic treatment with nicotinic acid (NA) (3 g NA.d-1) on fuel utilization during exercise and on total and HDL-cholesterol levels of trained runners. Eight experienced male runners performed four 30-min submaximal treadmill runs (SUB) at approximately 60% of aerobic capacity: the first served as the control condition, whereas SUBs 2, 3, and 4 were conducted at the onset, midpoint, and conclusion of the 3-wk NA treatment period. A 1-g NA dose was ingested 1 h prior to SUBs 2-4, which were conducted in the morning following a 12-h fast. The respiratory exchange ratio (RER) was significantly higher during SUBs 2, 3, and 4 (0.919 +/- 0.009, 0.898 +/- 0.007, and 0.896 +/- 0.009, respectively) than during SUB1 (0.871 +/- 0.008); and the RER during SUB2 was also significantly higher than that during SUB3 and SUB4 (P < 0.001). Serum free fatty acid (FFA) and glycerol levels were significantly lower during SUBs 2, 3, and 4 as compared with SUB1 (P < 0.001). Total cholesterol showed a significant decrease (from 195.3 +/- 9.2 to 174.5 +/- 9.2 mg.dl-1) and HDL cholesterol showed a significant elevation (from 56.2 +/- 2.9 to 63.0 +/- 3.9 mg.dl-1) during the NA treatment period (P < 0.05). The RER, FFA, and glycerol data demonstrate a persistent inhibition of fat utilization during submaximal exercise due to NA treatment. The 3-wk NA treatment period also proved to be sufficient to effect changes in total and HDL-cholesterol levels of these runners.
authors.affiliation: Department of Exercise and Sport Science, Oregon State University, Corvallis 97331.
authors.forename: E M
authors.initials: EM
authors.lastname: Heath
authors.forename: A R
authors.initials: AR
authors.lastname: Wilcox
authors.forename: C M
authors.initials: CM
authors.lastname: Quinn
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D050260:Carbohydrate Metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002784:Cholesterol / Q000097:blood*; D008076:Cholesterol, HDL / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005990:Glycerol / Q000097:blood; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007773:Lactates / Q000097:blood; D008297:Male; D009525:Niacin / Q000008:administration & dosage / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000187:drug effects / Q000502:physiology; D015657:Respiratory Transport / Q000187:drug effects* / Q000502:physiology; D012420:Running / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D008076:Cholesterol, HDL; D005230:Fatty Acids, Nonesterified; D007773:Lactates; D002245:Carbon Dioxide; D009525:Niacin; D002784:Cholesterol; D005990:Glycerol