Background Green exercise means exercise carried out in natural environment with plants, which has been widely accepted to benefit mental well-being, but related physiological effects remain unclear.
Objective This study aims to explore the effects of green exercise on heart rate variability and blood pressure.
Methods In the current study, blood pressure, heart rate variability, potential green environment (forest or garden, etc.), and common exercise (walking or jogging, etc.) were used as key words, and relevant studies that contained randomized controlled, non-randomized controlled, and prepost controlled designs were included via Pubmed, Web of Science, Embase, Medline, Green FILE, Environment Complete, ERIC, Sport Discus, CNKI, VIP, and Wanfang databases. A systematic review using meta-analysis was performed. Measurements of heart rate variability were standard deviation of normal-normal interval (SDNN), root mean square of successive differences in adjacent NN intervals (RMSSD), short axis of Poincare diagram SD1, low frequency power (LF), high frequency power (HF), and LF/HF. Measurements of blood pressure included systolic blood pressure (SBP) and diastolic blood pressure (DBP).
Results A total of 1 138 articles were screened. After removing irrelevant and invalid studies, 22 articles were included, involving a total of 1233 subjects. Compared with non-green exercise, green exercise was associated with higher HF (SMD=-0.37; 95% CI: -0.48﹣-0.26; P < 0.001) and lower LF/HF (SMD=-0.37; 95% CI: -0.48﹣-0.26; P < 0.001), but the differences post green and non-green exercise was still unclear. In terms of blood pressure, SBP decreased after green exercise (MD=-5.25; 95% CI: -7.47﹣-3.02; P < 0.001), and the decrease was greater than that after non-green exercise (MD=-5.27; 95% CI: -8.60﹣-1.93; P < 0.01); similarly, DBP also decreased after green exercise (MD=-4.03; 95%CI: -5.63﹣-2.42; P < 0.001), and the decrease was greater than that after non-green exercise (MD=-4.60; 95%CI: -7.80﹣-1.40; P < 0.01).
Conclusion Green exercise can effectively lower SBP and DBP and show better antihypertensive performance than non-green exercise.
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