Thesis
The effect of morning versus evening aerobic exercise on 24-hour ambulatory blood pressure
University of Iowa
Master of Science (MS), University of Iowa
Spring 2025
DOI: 10.25820/etd.007983
Abstract
Aerobic exercise is a well-established intervention for blood pressure (BP) management; however, the influence of exercise timing on 24-hour ambulatory blood pressure (ABP) and related cardiovascular outcomes remains unclear. This study investigates whether morning or evening aerobic exercise elicits differential effects on 24-hour ABP, including systolic and diastolic BP, mean blood pressure (MBP), and pulse pressure (PP), nocturnal dipping patterns, sleep quality, and heart rate variability (HRV) in otherwise healthy, young adults. A randomized crossover design was used in which 13 participants completed both morning and evening 45-minute aerobic exercise sessions. ABP monitoring and actigraphy were used to assess 24-hour BP patterns, sleep variables such as total sleep time, sleep onset latency, wakefulness after sleep onset, and sleep efficiency, and HRV following three conditions: baseline (control), morning exercise, and evening exercise. Repeated-measures one-way ANOVAs and mixed effects models were used to analyze outcomes. Both morning and evening exercise caused a similar magnitude of post-exercise hypertension at 1-h post-exercise. However, no statistically significant differences were observed in systolic BP, diastolic BP, MBP, or PP dipping between morning and evening exercise conditions. Heart rate dipped more following morning than evening exercise (p = 0.03). Sleep outcomes, including total sleep time and sleep efficiency, did not differ significantly across conditions (all p > 0.04). HRV analysis revealed no significant changes during the nocturnal period or during the AM surge, defined as the hour immediately following wake up. Overall, while aerobic exercise timing did not significantly affect 24-hour BP or HRV metrics in this cohort, morning exercise may increase nocturnal heart rate dipping and both morning and evening exercise elicited post-exercise hypotension observable for ~1 h. These findings suggest that timing of aerobic exercise may have subtle physiological effects that warrant further investigation in larger samples and other populations (e.g., those with hypertension or disrupted sleep) in whom optimization of non-pharmacological strategies for BP management is important.
Details
- Title: Subtitle
- The effect of morning versus evening aerobic exercise on 24-hour ambulatory blood pressure
- Creators
- Anna Zucker
- Contributors
- Nathaniel Jenkins (Advisor)Anna Stanhewicz (Committee Member)Gary Pierce (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Health and Human Physiology
- Date degree season
- Spring 2025
- DOI
- 10.25820/etd.007983
- Publisher
- University of Iowa
- Number of pages
- viii, 34 pages
- Copyright
- Copyright 2025 Anna Zucker
- Language
- English
- Date submitted
- 04/22/2025
- Description illustrations
- illustrations
- Description bibliographic
- Includes bibliographical references (page 30-34).
- Public Abstract (ETD)
Blood pressure that remains high over time, considered any value for systolic blood pressure greater than 120 mmHg and diastolic blood pressure over 80 mmHg, is a major risk factor for heart disease, chronic illnesses, and mortality. One method of blood pressure management that continues to be proven effective is aerobic exercise, defined as physical activities that require the body to use oxygen to produce energy. This study aimed to investigate whether exercising in the morning or the evening may elicit different effects on blood pressure and sleep variables in healthy, young adults.
Participants in this study completed both morning and evening exercise sessions on separate days. Participants wore monitors on their upper arms with electrocardiogram that measured blood pressure and heart rate over a 24-hour period, as well as wrist devices, similar to watches, that track sleep patterns. We compared these results to a baseline control period, during which they did not engage exercise.
We found that while overall 24-h blood pressure and sleep patterns did not change based on the time-of-day participants exercised, both morning and evening exercise lowered blood pressure immediately after exercise and there was a small difference in how their heart rate pattern evolved at night, or while asleep, after exercising in the morning. This may suggest some physiological benefits of morning exercise in young healthy adults. In summary, this research helps us better understand how to personalize exercise recommendations in order to gain the most benefit for our health. While further investigation is needed, it is still appropriate to conclude that aerobic exercise is beneficial for heart health.
- Academic Unit
- Center for Social Science Innovation; Health, Sport, and Human Physiology
- Record Identifier
- 9984831124302771
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