The Blood Pressure Response to Exercise: Untangling the Relationship between Fitness and Fatness

The systolic blood pressure (SBP) during prescribed exercise (ExSBP) represents cardiovascular strain during tasks of daily living and is predictive of future cardiovascular disease. Individuals with greater body mass reportedly have a greater increase in ExSBP when exercise is performed at an absolute intensity (e.g., walking 2.5 mph). It is unclear if this exaggerated response persists when exercise is performed at the same intensity relative to one’s fitness (e.g., % Lactate Treshold). PURPOSE: Determine if individuals with a high body mass index (BMI) exhibit an exaggerated ExSBP when exercise is prescribed with respect to personal fitness level. METHODS: Thus far, six adults with low (22.8±1.6 kg∙m-2) and six adults with a high (30.3 ±3.9 kg∙m-2) body mass index (BMI), matched for sex and age, have completed this study. ExSBP was measured during 5 minutes of treadmill walking at 2.5 mph, 0% grade, 2.5 mph, 12% grade and again at 80% and 120% of predetermined lactate threshold (LT). RESULTS: The ExSBP of the High BMI group did not differ from the Low BMI group at rest (120.0 ± 7 vs. 120.7 ± 5 mmHg, P=0.796), or when exercising at 2.5 mph with 0% grade (136.5 ± 15 vs. 128 ± 3 mmHg, P=0.220) or 80% LT (162.0 ± 14 vs. 152.0 ± 20 mmHg, P=0.347). However, the High BMI group did exhibit a tendency for increased ExSBP when working at higher intensities like 2.5 mph with 12% grade (176.4 ± 29 vs. 148.6 ± 19 mmHg, P=0.083) and 120% LT (194.8 ± 27 vs. 168.5 ± 19 mmHg, P=0.078). CONCLUSION: Analysis of these preliminary data highlights the need for more subject recruitment. Nevertheless, thus far individuals with a higher BMI exhibit a tendency for an exaggerated ExSBP at higher intensities of exercise, whether absolute or relative to LT. If these results hold with a greater number of subjects it indicates that the exaggerated ExSBP of people with a high BMI is not merely due to fitness level. In other words, it appears that fatness has an independent effect on ExBP from fitness.