LONG-TERM EFFECTS OF VARYING INTENSITIES AND FORMATS OF PHYSICAL-ACTIVITY ON PARTICIPATION RATES, FITNESS, AND LIPOPROTEINS IN MEN AND WOMEN AGED 50 TO 65 YEARS

Background Although exercise parameters such as intensity and format h ave been shown to influence exercise participation rates and physiolog ical outcomes in the short term, few data are available evaluating the ir longer-term effects. The study objective was to determine the 2-yea r effects of differing intensities and formats of endurance exercise o n exercise participation rates, fitness, and plasma HDL cholesterol le vels among healthy older adults. Methods and Results Higher-intensity, group-based exercise training; higher-intensity, home-based exercise; and lower-intensity, home-based exercise were compared in a 2-year ra ndomized trial. Participants were 149 men and 120 postmenopausal women 50 to 65 years of age who were sedentary and free of cardiovascular d isease. Recruitment was achieved through a random digit-dial community telephone survey and media promotion. All exercise occurred in commun ity settings. For higher-intensity exercise training, three 40-minute endurance training sessions per week were prescribed at 73% to 88% of peak treadmill heart rate. For lower-intensity exercise, five 30-minut e endurance training sessions per week were prescribed at 60% to 73% o f peak treadmill heart rate. Treadmill exercise performance, lipoprote in levels and other heart disease risk factors, and exercise adherence were evaluated at baseline and across the 2-year period. Treadmill ex ercise test performance improved for all three training conditions dur ing year 1 and was successfully maintained during year 2, particularly for subjects in the higher-intensity, home-based condition. Subjects in that condition also showed the greatest year 2 exercise adherence r ates (P<.003). Although no significant increases in HDL cholesterol we re observed during year 1, by the end of year 2 subjects in the two ho me-based training conditions showed small but significant HDL choleste rol increases over baseline (P<.01). The increases were particularly p ronounced for subjects in the lower-intensity condition, whose exercis e prescription required more frequent exercise sessions per week. For all exercise conditions, increases in HDL cholesterol were associated with decreases in waist-to-hip ratio in both men and women (P<.04). Co nclusions While older adults can benefit from initiating a regular reg imen of moderate-intensity exercise in terms of improved fitness level s and small improvements in HDL cholesterol levels, the time frame nee ded to achieve HDL cholesterol change (2 years) may be longer than tha t reported previously for younger populations. Frequency of participat ion may be particularly important for achieving such changes. Supervis ed home-based exercise regimens represent a safe, attractive alternati ve for achieving sustained participation.