Objectively Measured Aerobic and Resistance Exercise and Cardiovascular Disease Risk Factor Response

Abstract

PURPOSE: To examine the effects of objectively measured weekly exercise weight (EW) lifted and exercise heart beats (EHB) during exercise training on changes in cardiovascular disease (CVD) risk factors. METHODS: We randomized 31 pre-to-stage 1 hypertensive (not on medication), overweight/obese, and sedentary non-smokers (58±8 years) into an aerobic training (AT) only (n=16) or a resistance training (RT) only (n=15) 8 week exercise intervention. Participants exercised 3 days/week for 60 min/session. An innovative exercise training system and software (TechnoGym) captured EW lifted and EHB automatically each session. Total weekly EW lifted was calculated as the sum of weight x repetitions x sets for each exercise, averaged over 8 weeks, then divided by body weight (lbs). Total weekly EHB were calculated by the sum of exercise heart rate x min/session/week, with resting heart rate x minutes of exercise subtracted. We measured peripheral and central blood pressure (BP), % body fat, cardiorespiratory fitness, bench and leg press 1 repetition maximum (1RM), and blood lipids at baseline and 8-weeks. Individual CVD risk factors were standardized as sex specific z-scores for each participant and the mean was used to establish an overall clustered CVD risk score. Data was analyzed using Pearson correlation and linear mixed models adjusting for age, sex, and average daily steps. RESULTS: The average weekly EW and EHB were 220±68 lbs and 7004±1419 beats, respectively. Regression analysis showed a reduction in overall CVD risk score by -0.25 (p = 0.06) per 100 lbs lifted relative to body weight with RT and -0.1 (p=0.16) per 1000 beats with AT. With RT, we found strong correlations between total EW and changes in peripheral systolic (r=-0.45, p=0.09) and diastolic BP (r=-0.59, p=0.02), central systolic (r=-0.47, p=0.08) and diastolic BP (r=-0.53, p=0.04), and leg press 1RM (r=0.62, p=0.01). With AT, strong correlations with total EHB were noted with change in triglyceride levels (r=-0.50, p=0.049). CONCLUSIONS: In individuals at high risk of developing CVD, increased total EW lifted and EHB are associated with improved overall CVD risk, especially peripheral and central BP with greater EW lifted, and triglyceride levels for additional EHB. Supported by Iowa State University College of Human Sciences seed grant.