This project is designed to determine the minimal dose of physical activity necessary to improve cardiovascular (CV) health. More specifically, this 4-year investigation will evaluate and aerobically train 500 healthy men and women, 30-65 years of age. Both the minimal and optimal intensity and frequency of exercise necessary to elicit significant improvements in cardiovascular health will be determined. The plans also include assessment of the effect of specific doses of exercise on the reduction in systolic and diastolic blood pressure and increase in HDL-cholesterol (primary outcomes), in addition to changes in levels of physical activity, aerobic fitness (VO2 max), body composition (% fat and waist-to-hip ratio), triglycerides, and LDL-cholesterol (secondary outcomes). Psychological variables (depression, anxiety, anger, and perceived stress) and health-related quality of life will also be evaluated, and the important issue of adherence to exercise will be examined with respect to the effect of dose of exercise. Subjects will be randomized into one of 5 groups in a 2x2 factorial design plus a usual care control group (n=100 in each of 5 groups). Subjects will train at a moderate (45-55%) or high (65-75% of maximum heart rate reserve) intensity, and at a frequency of 3-4 or 5-7 days/wk (viz., Group 1, 65-75% @ 5-7 d/wk; Group 2, 65-75% @ 3-4 d/wk; Group 3, 45-55% @ 5-7 d/wk; Group 4, 45-55% @ 3-4 d/wk; and, Group 5, usual care control). Controls will receive advice from a physician to increase their physical activity. The subjects in Groups 1-4 will participate in an exercise intervention using walking as the mode of training for a total of 24 months. A lifestyle model of physical activity will be used, in that subjects can accumulate exercise minutes during the day in 10-min increments or more continuously (for a total duration of 30 min/day), and training will be conducted where it is most convenient for the subject (i.e. at home, work or some combination thereof). Tests will occur at baseline (0), 12, and 24 months of the intervention. The application posits that Groups 1-4 will show a significant reduction in systolic and diastolic blood pressure and an increase in HDL-cholesterol compared to the usual care control group. It further suggests that there will be significant main effects for both frequency and intensity, with the higher levels of each producing greater improvement on the major outcome variables compared to the lower levels of each dose. The study is also planned to determine the minimal dose response to exercise necessary to elicit significant improvement in cardiovascular and behavioral health factors. Finally, the project includes examination of the effects of age and level of initial test values on outcome variables to determine if their interactions affect the results of the intervention. The results from the proposed study will provide important data regarding the dose of exercise required to improve CV health, as described both by the NIH Consensus Conference on Physical Activity and CV Health and by the recent Report of the Surgeon General.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL058873-02
Application #
2910656
Study Section
Epidemiology and Disease Control Subcommittee 2 (EDC)
Project Start
1998-05-01
Project End
2002-04-30
Budget Start
1999-05-01
Budget End
2000-04-30
Support Year
2
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Florida
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
073130411
City
Gainesville
State
FL
Country
United States
Zip Code
32611
Anton, Stephen D; Duncan, Glenn E; Limacher, Marian C et al. (2011) How much walking is needed to improve cardiorespiratory fitness? An examination of the 2008 Physical Activity Guidelines for Americans. Res Q Exerc Sport 82:365-70
Duncan, Glen E; Anton, Stephen D; Sydeman, Sumner J et al. (2005) Prescribing exercise at varied levels of intensity and frequency: a randomized trial. Arch Intern Med 165:2362-9
Duncan, Glen E; Perri, Michael G; Anton, Stephen D et al. (2004) Effects of exercise on emerging and traditional cardiovascular risk factors. Prev Med 39:894-902
Newton Jr, Robert L; Perri, Michael G (2004) A randomized pilot trial of exercise promotion in sedentary African-American adults. Ethn Dis 14:548-57
Duncan, Glen E; Anton, Stephen D; Newton Jr, Robert L et al. (2003) Comparison of perceived health to physiological measures of health in Black and White women. Prev Med 36:624-8
Duncan, Glen E; Perri, Michael G; Theriaque, Douglas W et al. (2003) Exercise training, without weight loss, increases insulin sensitivity and postheparin plasma lipase activity in previously sedentary adults. Diabetes Care 26:557-62
Perri, Michael G; Anton, Stephen D; Durning, Patricia E et al. (2002) Adherence to exercise prescriptions: effects of prescribing moderate versus higher levels of intensity and frequency. Health Psychol 21:452-8
Duncan, G E; Sydeman, S J; Perri, M G et al. (2001) Can sedentary adults accurately recall the intensity of their physical activity? Prev Med 33:18-26