Gender Differences in Postexercise Hypotension

Abstract

The role of postexercise hypotension (PEH) is potentially significant in designing first line strategies against hypertension. Gender differences in the magnitude and pattern of PEH may be influenced by the phases of oral contraception (OC) use. PURPOSE: To examine central and peripheral haemodynamics regulating PEH following moderate-intensity exercise in moderately active normotensive males and females. The impact of OC phase upon potential gender differences was examined by investigating females in two phases of OC use. METHODS: We studied 8 females (age: 21±1 yr) during the consumption and withdrawal phases of OC use and 8 males (age: 21±0.7 yr) on 2 separate occasions. Central and peripheral haemodynamics were recorded via echocardiography and venous occlusion plethysmography before and for 45 min following 30 min of cycle ergometry at 80% of the lactate threshold. RESULTS: Postexercise haemodynamics did not differ with OC phase (P > 0.05). Significant PEH was observed in all subjects (P < 0.05), with the magnitude of the nadir in all blood pressure variables being significantly greater (P < 0.05) in females compared to males (11±7 vs 4±1, 11±6 vs 5±1, 9±5 vs 4±1 for systolic, diastolic and mean arterial blood pressure, respectively), whilst no interactions between gender and phase of OC use were reported (P > 0.05). Cardiac output (CO) and heart rate (HR) increased transiently postexercise and displayed gender by time interactions (P < 0.05), with a greater initial rise in CO in males than in females (31% vs 20 %) due to a larger increase in HR (26 % vs 5 %). Ejection fraction in females initially increased by 6% compared to rest, whilst in males it remained below baseline values for 40 min of recovery revealing a gender by time interaction (P < 0.05). Postexercise calf blood fow was greater in males than females (2.9±1.0 mL·100 mL-1·min-1 vs 2.0±0.9 mL·100 mL-1·min-1; P < 0.05), as a result of a significantly lower (P < 0.05) mean calf vascular resistance in males (46±21 units vs 34±12 units in females). No gender by time interactions were reported (P > 0.05). CONCLUSION: The magnitude of postexercise hypotension is greater in females receiving oral contraceptives compared to males. There were distinct gender differences in the cardiovascular mechanisms underpinning PEH but these were not influenced by the phase of OC use.