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Comparison of the Effects of Morning Versus Evening Walking on Plasma Nitric Oxide(NO) and Endothelin-1(ET-1) Levels in Healthy Middle-Aged Men
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M Sepehri Manesh1   , M Fathi2 , R Rezaei1 |
1- Department of Physical Education and Sports Sciences, Lorestan University, Khorramabad, Iran.
2- Department of Physical Education and Sports Sciences, Lorestan University, Khorramabad, Iran. , fathi.m@lu.ac.ir |
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Abstract: (1714 Views) |
Background & aim: Endothelial function is a critical biomarker of cardiovascular health, regulated by the production and release of vasoactive mediators such as nitric oxide (NO) and endothelin-1 (ET-1). While physical activity is an effective strategy to prevent endothelial dysfunction, the optimal timing of exercise concerning circadian rhythms remains a subject of interest. This study aimed to compare the effects of morning and evening walking on plasma levels of NO and ET-1 in healthy middle-aged men.
Methods: In this quasi-experimental study conducted in 2025, 40 healthy men (aged 50–60 years) were randomly assigned to either a morning exercise group (n=20) or an evening exercise group (n=20). The participants engaged in a 12-week walking program, consisting of three sessions per week at an intensity of 65% to 70% of their maximum heart rate. Venous blood samples were collected at baseline and 48 hours after the final training session to measure plasma NO and ET-1 levels. Data were analyzed using SPSS software, employing dependent t-tests for within-group comparisons and Analysis of Covariance (ANCOVA) for between-group differences.
Results: Following the 12-week intervention, plasma NO levels increased significantly in both the morning and evening exercise groups (increases of 0.9 pg/mL and 1.06 pg/mL, respectively; P<0.01); however, no significant difference was observed between the two groups (P>0.05). Conversely, plasma ET-1 levels decreased significantly in both groups (decreases of 1 pg/mL in the morning and 1.26 pg/mL in the evening; P< 0.01). Notably, the reduction in ET-1 was significantly greater in the evening group compared to the morning group (P<0.05).
Conclusion: Twelve weeks of moderate-intensity walking improves endothelial function in middle-aged men by increasing the vasodilator NO and decreasing the vasoconstrictor ET-1. While both exercise timings were beneficial, evening walking appears to be more effective in reducing ET-1 levels, potentially offering greater cardiovascular benefits related to vascular tone regulation.
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| Keywords: Aerobic Exercise, Walking, Nitric Oxide, Endothelin-1, Circadian Rhythm, Endothelial Function. |
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Full-Text [PDF 813 kb]
(72 Downloads)
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Type of Study: Research |
Subject:
Sport Physiology
Received: 2025/09/17 | Accepted: 2025/12/23 | Published: 2026/02/3
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