O93 BRIGHT LIGHT EXPOSURE ATTENUATES BLOOD PRESSURE REDUCTION POSTEXERCISE

Background and objective: A single session of aerobic exercise lowers blood pressure (BP), known as postexercise hypotension (PEH). Bright light (BL) exposure increases BP at rest compared to dim light (DL). However, whether BL exposure can attenuate PEH remains unknown, and this hypothesis was tested in the current study. Methods: Twenty healthy men (27±5 years) underwent two experimental sessions: one under BL (5000 lux) and another under dim light (DL ≤8 lux), performed in random order. In each session, subjects executed an aerobic exercise session on a cycle ergometer for 30 min at 50-60-% heart rate (HR) reserve. BP (oscillometric) and HR (HR monitor) were measured, and rate-pressure-product (RPP) was calculated (systolic BP * HR) pre- and postexercise. Additionally, subjects wore an ambulatory BP monitor (ABPM) for 24 hours after postexercise measurements. Results: Systolic BP decreased similarly postexercise in both sessions, but its levels were higher in BL than DL throughout the experimental session (Figure 1A). Diastolic and mean BPs decreased postexercise only in DL at 30 min, while they increased in BL at 60 and 90 min (Figure 1B and 1C, respectively). HR and RPP increased in both sessions postexercise, but RPP levels were higher throughout the experimental session in BL than DL (Figure 1D and 1E, respectively) and for the first three hours of ABPM. Conclusions: In healthy adult men, BL exposure increased systolic BP and cardiac work and attenuated PEH on diastolic and mean BPs.