No abstract

The purposes of the study were to compare insulin responses after rest and exercise of two different intensities and equal total energy expenditure and to examine these responses in normoglycemic women. Twenty-four untrained women (age 23.4 +/- 0.9 yr) completed three randomly assigned treatments over the course of a 3- to 4-wk period: rest, 40% maximal oxygen consumption x 87 min (Low), and 70% maximal oxygen consumption x 50 min (High). Total energy expenditure was 1,821 +/- 61 and 1,692 +/- 59 kJ, heart rate was 119 +/- 2 and 163 +/- 2 beats/min, and oxygen consumption was 17.1 and 27.2 ml.kg-1.min-1 for Low and High, respectively. Fifteen to 17 h posttreatment and 12 h postprandial, each subject drank a 75-g glucose solution (oral glucose tolerance test). Blood samples were drawn before and at 30, 60, 90, 120, and 150 min after ingestion and were analyzed for glucose and insulin. Glucose areas and responses at the same time points across treatments were similar. Area under the insulin curve was significantly lower (P < 0.05) after High (51,864 +/- 3,780 pM x min) compared with rest (61,009 +/- 4,425 pM x min), but Low (59,191 +/- 5,307 pM x min) was not different from either rest or High. The insulin level at the 120-min time point was significantly (P < 0.01) lower after High (290.8 pM) compared with rest (391.7 pM). On the basis of these results, exercise-related changes in insulin responses are more dependent on exercise intensity than on energy expenditure in untrained women.

The purpose of this investigation was to determine the independent and combined effects of aerobic exercise and omega-3 fatty acid (n-3fa) supplementation on lipid and lipoproteins. Sedentary, normoglycemic, nonsmoking men (n = 11) were assigned to perform rest and exercise before and during n-3fa supplementation. Exercise consisted of 3 consecutive days of treadmill walking at 65% maximum O(2) consumption for 60 min. Supplementation consisted of 42 days of 4.55 g/day of n-3fa. A two-way factorial ANOVA with repeated measures revealed significant reductions in total cholesterol (P = 0.001, -9.2%) and triglyceride (P = 0.007, -32.4%) concentrations postexercise. In addition, exercise increased LDL peak particle size (P = 0.001) from 26.2 to 26.4 nm, but not HDL size. The n-3fa supplementation resulted in a significant shift in the distribution of HDL-cholesterol (HDL-C) carried by HDL(2b+2a) (P = 0.001, 14.2%) and HDL(3a+3b) (P = 0.001, -22.8%), despite no significant changes in lipid and lipoprotein-cholesterol concentrations. The majority of the shift in HDL-C was noted in HDL(2b) (P = 0.001, 20.9%) and HDL(3a) (P < 0.001, -31.0%) particles. There were no combined effects of exercise and n-3fa supplementation on lipids and lipoproteins. Three consecutive days of aerobic exercise reduced triglyceride and total cholesterol concentrations with a concomitant increase in LDL peak particle size. In contrast, n-3fa supplementation shifted HDL-C from HDL(3) particles to HDL(2) particles, despite no significant changes in HDL(2)-C and HDL(3)-C concentrations. Exercise and n-3fa supplementation do not synergistically improve serum lipids and lipoproteins, but rather independently affect the metabolism of lipids and lipoproteins.

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The purpose of the study was to determine the efficacy of a low-volume, moderate-intensity bout of resistance exercise (RE) on glucose, insulin, and C-peptide responses during an oral glucose tolerance test (OGTT) in untrained women compared with a bout of high-volume RE of the same intensity. Ten women (age 30.1 ± 9.0 years) were assessed for body composition, maximal oxygen uptake, and 1-repetition maximum (1RM) before completing 3 treatments administered in random order: 1 set of 10 REs (RE1), 3 sets of 10 REs (RE3), and no exercise (C). Twenty-four hours after completing each treatment, an OGTT was performed after an overnight fast. Glucose area under the curve response to an OGTT was reduced after both RE1 (900 ± 113 mmol·L(-1)·min(-1), p = 0.056) and RE3 (827.9 ± 116.3, p = 0.01) compared with C (960.8 ± 152.7 mmol·L(-1)·min(-1)). Additionally, fasting glucose was significantly reduced after RE3 (4.48 ± 0.45 vs. 4.90 ± 0.44 mmol·L(-1), p = 0.01). Insulin sensitivity (IS), as determined from the Cederholm IS index, was improved after RE1 (10.8%) and after RE3 (26.1%). The reductions in insulin and C-peptide areas after RE1 and RE3 were not significantly different from those in the C treatment. In conclusion, greater benefits in glucose regulation appear to occur after higher volumes of RE. However, observed reductions in glucose, insulin, C-peptide areas after RE1 suggest that individuals who may not well tolerate high-volume RE protocols may still benefit from low-volume RE at moderate intensity (65% 1RM).