Keep Hypertension “Outdoor” from your Cardiovascular Health

INTRODUCTION: Hypertension is the primary risk factor for global mortality. Physical activity (PA) has been established as an effective treatment for hypertension, leading to reductions in Systolic BP (sBP), a response known as Post-Exercise Hypotension (PEH). Although gym-based exercise is the most common form of PA, there has been a growing trend towards outdoor activities. Considering the limited research on its benefits, this study aims to compare the sBP response and the PEH following indoor (laboratory) and outdoor activities. METHODS: 11 subjects (age:24.3±1.1 years; BMI: 23.5±2.6 kg/m2) completed an outdoor activities on a selected hike and participated in a laboratory-based treadmill test, incorporating both uphill and downhill walking. During the laboratory test, subjects self-selected their speed to replicate their pace from the outdoor activities. The initial 2-min stage was set at 0% grade. The grade then increased by 2% at each 2-min stage during the uphill phase until subjects reached 95% of their estimated maximum heart rate (HRmax) or volitional fatigue, followed by a decrease of 2% at each 2-min stage during the downhill phase until it returned to 0% grade. During both sessions, sBP was measured 15-min before (PRE) and 30-min after (POST). Means (M) and standard deviations of PRE and POST sBP, along with PEH (difference between PRE and POST sBP measurements), were determined. Repeated measures mixed models assessed the effects on sBP, treating subjects as a random effect and measurement times (PRE and POST) as fixed effects. Paired t-tests compared PEH be-tween field and laboratory settings, with statistical significance set at p<0.05. RESULTS: Significant reductions were observed in the field session (length: ~3800m, max slope: 19%, M slope: 5.3%, M duration: 41:86min, M HRmax: 84%) between PRE (127.8 ± 7.8 mmHg) and POST (110.2 ± 8.6 mmHg) sBP measurements, resulting in a PEH of 17.6±6.7mmHg (p<0.001), and in the laboratory session (length: ~2800m, max slope: 25%, M slope: 8.1%, M duration: 40:00min, M HRmax: 92%) between PRE (124.5±8.6mmHg) and POST (106.1±6.4mmHg) sBP measurements, resulting in a PEH of 18.4±10.7mmHg (p<0.001). No significant (p=0.80) differences in PEH (M difference: 0.9 ± 11.3 mmHg) were found between the sessions. CONCLUSION: Our findings align with the existing literature, confirming the positive effect of PA on reducing BP. These results suggest that the beneficial effects of PA on sBP could be replicated, and potentially even enhanced, by exercising in outdoor environments. This enhancement is linked to subjects achieving a lower internal load during outdoor activities, suggesting a stronger cardiovascular protective effect, even with similar exercise characteristics. Outdoor activities replicate traditional PA benefits and provide a potentially more sustainable and beneficial approach to improving overall health by reducing cardiovascular stress.