Autonomic control as a mechanism of prolonged hypotension after acute aerobic exercise in individuals with normal and elevated blood pressure: a systematic review and meta-analysis

INTRODUCTION: Altered autonomic control has been proposed as a mechanism underlying postexercise hypotension (PEH). This meta-analysis examined the effects of acute aerobic exercise on blood pressure (BP) and autonomic outflow in adults with normal or elevated BP. METHODS: A systematic search identified trials involving adults who performed aerobic exercise, with BP and autonomic measures taken before and at least 30 min after exercise. Random-effects models were used to calculate Hedge's g effect sizes. RESULTS: Sixty-five trials (118 interventions; 1248 participants) were analyzed. Individuals were relatively young (mean age 37.5 ± 5.5 years) with average BP of 122.5 ± 8.8/75.2 ± 6.6 mmHg. Aerobic exercise significantly reduced systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) ( g = -0.373 to -0.813, P < 0.05). These reductions were accompanied by increased sympathetic (g = 0.279 to 0.436, P < 0.01) and decreased parasympathetic ( g = -0.535 to -0.414, P < 0.003) activity. In individuals with normal BP, pressoric reductions were inversely related to sympathetic activity (overall BP: n = 153, slope = -0.199, P = 0.016) and positively related to parasympathetic activity (overall BP: n = 147, slope = 0.134; P = 0.046), though not all associations reached statistical significance. In those with elevated BP, the opposite pattern emerged from meta-regression: BP reductions were positively associated with sympathetic activity (SBP: n = 43, slope = 0.402, P = 0.002; overall BP: n = 153, slope = -0.199, P = 0.016) and negatively with parasympathetic activity (SBP: n = 38, slope = -0.230, P = 0.011; overall BP: n = 73, slope = -0.140, P = 0.018). CONCLUSION: These findings support autonomic control as a mechanism of prolonged PEH in individuals with elevated, but not normal BP. Aerobic exercise induced BP reductions appear linked to differing autonomic responses depending on baseline BP status.