PubMed · 10693911
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S M Haffner. 2000. Oxidative stress: introduction.. https://doi.org/10.1016/s0026-0495(00)80076-1
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Physical activity enhances insulin action in obese/overweight individuals. However, the exercise prescription required for the optimal enhancement is not known. The purpose of this study was to test the hypothesis that exercise training consisting of vigorous-intensity activity would enhance insulin sensitivity more substantially than moderate-intensity activity. Sedentary, overweight/obese subjects (n = 154) were randomly assigned to either control or an exercise group for 6 mo: 1) low-volume/moderate-intensity group [ approximately 12 miles walking/wk at 40-55% peak O2 consumption (Vo2 peak)], 2) low-volume/high-intensity group ( approximately 12 miles jogging/wk at 65-80% Vo2 peak), and 3) high-volume/high-intensity group ( approximately 20 miles jogging/wk at 65-80% Vo2 peak). Training volume (miles/wk) was achieved by exercising approximately 115 min/wk (low-volume/high-intensity group) or approximately 170 min/wk (low-volume/moderate-intensity and high-volume/high-intensity groups). Insulin action was measured with an insulin sensitivity index (SI) from an intravenous glucose tolerance test. In the control group, there was a decrement (P < 0.05) in SI. In contrast, all the exercise groups significantly (P < 0.05) increased SI; the relative increment in the low-volume/moderate-intensity and high-volume/high-intensity groups ( approximately 85%) were greater than in the low-volume/high-intensity group ( approximately 40%). In conclusion, physical activity encompassing a wide range of intensity and volume minimizes the insulin resistance that develops with a sedentary lifestyle. However, an exercise prescription that incorporated approximately 170 min of exercise/wk improved insulin sensitivity more substantially than a program utilizing approximately 115 min of exercise/wk, regardless of exercise intensity and volume. Total exercise duration should thus be considered when designing training programs with the intent of improving insulin action.
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OBJECTIVE: To investigate the plasma insulin levels and insulin sensitivity in the offspring of parents with family hypertensive history in Tibetan population. METHODS: Tibetan hypertensive pedigrees and normotensive pedigrees based on a door-to-door cross section study performed from 1997 to 1998 in stable communities in the ruban district of Lhasa city were set up, 47 offsprings from hypertensive pedigrees (group I) and 21 offsprings from normotensive pedigrees (group II) were enrolled into this study. Plasma insulin levels using by radioimmunoassay and insulin sensitivity with the formulae insulin sensitivity = 1/(fasting plasma glucose x fasting plasma insulin) were compared between two groups. RESULTS: There were no statistically significant differences in fasting blood glucose levels between group I and group II. But fasting plasma insulin level was 10.20 +/- 6.95 m IU/L in group I and 6.56 +/- 2.81 m IU/L in group II, respectively, and there were statistically significant differences between these two groups. The insulin sensitivity index in group I was significantly lower than that in group II (0.036 +/- 0.024 and 0.046 +/- 0.022, respectively). CONCLUSION: Offspring of Tibetan hypertensive pedigrees were observed to be hyperinsulinemia and reduced insulin sensitivity. These metabolic abnormalities may be associated with hypertension and dyslipidemia in adulthood.