Impact of Exercise Intensity on Cardiovascular Disease in a Rat Model of Hypertension: A Systematic Review and Meta-Analysis
Authors: Crouse Natalie , Luckey Stephen , Meredith Kayla , Sethi Rohan 
Published: May 2024

Objective: Hypertension increases the risk of morbidity and mortality including stroke, myocardial infarction, and other serious complications. To prevent these events, regular exercise has been recommended as a nonpharmacological intervention for hypertensive patients, but the optimal exercise intensity, in response to the variation of the condition, remains a subject of investigation. Therefore, our study investigates the impact of exercise training on the disease progression in spontaneously hypertensive rats (SHR), a well-established rat model of hypertension. Specifically, we aim to perform a meta-analysis that measures the effects of low, moderate, and high-intensity exercise on at least one of the following cardiovascular variables: systolic blood pressure (SBP), mean arterial pressure (MAP), and resting heart rate (RHR). Hypothesis: We hypothesize that the meta-analysis findings will determine that treadmill training at low and moderate intensities will significantly improve SBP, MAP, and RHR in SHRs. We also anticipate that we will find that high intensity will produce less benefit due to its stress-inducing effects. Methods: We performed a meta-analysis adhering to the PRISMA guidelines. A systematic search for scientific studies was conducted in the CINAHL, EMBASE, SPORTDiscus, and SciFinder databases using the following key words: “spontaneously hypertensive rat,” and “exercise” yielded 900+ research articles. Subsequent selection of articles included studies that comprised of only treadmill running, more than 45 minutes of exercise per day during the training period, at least five days of training per week, and a duration of at least four weeks. Finally, eligible studies included at least one of the three cardiovascular parameters. Each study was categorized into low, moderate, or high intensity based on either treadmill speed or VO2 max, or both. Quantitative SBP, MAP, and RHR data were extracted from the included studies. Results: A total of 90 studies are included in this qualitative analysis, 9.6% of which include female rats. Preliminary data analysis evaluating means for each intensity determined that all levels of intensity significantly benefited the measured cardiovascular parameters. However, the degree of benefit was greater in the low and moderate intensities as compared to the high intensity. Conclusion: All levels of intensity exercise had a beneficial response to lowering cardiovascular parameters in SHR, however, low and moderate levels of intensity produced the greatest effects. The failure of high-intensity exercise to improve cardiovascular outcomes may suggest a role played by oxidative stress and merits further investigation. Further subgroup analysis based on sex, age, and duration of exercise will be conducted to determine if these confounding variables play role in modulating these benefits. This research was supported by the MJ Murdock charitable trust. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.