Does Critical Power Influence The Blood Pressure Response To Submaximal Exercise?

BACKGROUND: Recent studies have shown that exercise blood pressure is predictive of future cardiovascular disease, which is a leading cause of death in the US. Many of these studies have not categorized exercise intensity relative to physiological thresholds (e.g. critical power) and capacities (V̇O2MAX). Critical Power (CP) which separates compensable exercise from non-compensable exercise. For many physiological factors, critical power represents an inflection point after which changes accelerate. V̇O2MAX, and its associated power during an exercise test (PMAX) represent the capacity of oxygen consumption during exercise. Therefore, differences in blood pressure response to exercise observed in previous studies may have been driven by differences in CP or PMAX. PURPOSE: To determine if there was an inflection point around CP for exercise blood pressure and if exercise intensity described by CP is more related to blood pressure response than exercise intensity described by PMAX. METHODS: 13 healthy adults (6 female and 7 male) ages 22-34 were recruited for this study. Subjects reported to the laboratory four times. Visits 1-3 involved a health history questionnaire, body composition testing, a V̇O2MAX test, and other exercise tests that were used calculate CP. On the fourth visit, subjects performed 5 bouts of 5-minute cycling exercise at 75%, 85%, 95%, 105%, and 115% of their predetermined CP in a randomized order. Blood pressure was measured at minutes 2 and 4 of each of these cycling bouts. RESULTS: Changes in SBP from baseline were linearly related to exercise intensity (%CP: r = 0.733, p < .001; %PMAX: r = .694, p < .001) with no inflection point around CP. Changes in DBP from baseline were linearly related to exercise intensity (%CP: r = 0.280, p = .01; %PMAX: r = .274, p < .012). Changes in HR from baseline were linearly related to exercise intensity (%CP: r = 0.899, p < .001; %PMAX: r = .847, p < .001). CONCLUSION: Blood pressure response to exercise is linearly related to exercise intensity measured by CP or PMAX and there is no inflection point in blood pressure at CP. Future studies investigating the blood pressure response to submaximal exercise should consider personal exercise intensity thresholds.