International Congress on Physical Activity and Public Health Australian Conference of Science and Medicine in Sport National Sports Injury Prevention Conference (Be Active 2012), 4th (Sydney, Australia, 31-Oct-2012 – 03-Nov-2012)
High blood pressure (BP) during exercise has been shown to increase the risk of developing hypertension later in life with BP during exercise rather than casual post exercise BP strongly related to mortality and morbidity from myocardial infarction. However few studies have examined the BP response of obese women with high resting BP during sub-maximum treadmill exercise. Twelve obese (BMI ≥30 kg·m2) and twelve untrained normal weight (BMI ≤24.9 kg·m2) women aged 18 to 50 years completed a maximal oxygen consumption (VO2max) test and three days later completed a
sub-maximal aerobic test at a fixed load of 4.5 km/hr, and four relative intensities at 30%, 40%, 50% and 60% of VO2max. Each stage was three minutes in duration with BP recorded by manual auscultation after two and a half minutes of each stage. Body composition was evaluated using dual-energy x-ray absorptiometry (DEXA). Body mass, percentage body fat and resting BP were significantly (p less than 0.001) higher in obese (104.4±18.4 kg, 51.2±2.5% and 132/80 mmHg respectively) compared to normal weight (60.9±7.8 kg, 17.6±5.7% and 110/70 mmHg respectively) women. Maximal oxygen consumption was significantly (p less than 0.001) lower in obese (23.8±3.7 ml·kg·min-1) compared to normal weight (38.3±7.2 ml·kg·min-1) women. At each sub-maximal exercise stage the systolic and diastolic BP of the obese women were significantly (p less than 0.001) higher than the normal weight women. During the relative sub-maximal exercise intensities the change in BP from resting values for the obese women (20±3%) was significantly (p less than 0.001) greater at 60% of VO2max compared to the normal weight women (16±4%). At the absolute load of 4.5 km/hr the change in BP from resting values for the obese women (15±4%) was significantly (p less than 0.001) greater compared to the normal weight women (2±2%). Our results show that obese women with high resting BP have greater increases in BP during moderately high exercise intensities than normal weight women. Furthermore obese women have greater increases in BP at the same absolute exercise intensity as normal weight women. Large changes in exercise BP have been associated with increases in arterial stiffness and associated cardiovascular diseases. Additionally clinicians and health practitioners need to prescribe different exercise intensities and loads for obese women to avoid excessively high BP during sub-maximal aerobic exercise.
