Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article


Master of Science




Lemon, Peter W. R.


Introduction: Epidemiological evidence suggests physical inactivity can increase the likelihood of hospitalization from the SARS-COV-2 virus. Further, some data indicate a greater ratio of angiotensin 1-9 to angiotensin I helps prevent severe outcomes during infection. Moreover, related hormones can enhance potentially both physical activity and health. The purpose of this study was to determine whether plasma concentrations of angiotensin (1-9) are modified after a single exhaustive exercise bout and whether sex or chronic physical activity is associated with greater plasma concentrations.

Methods: Participants (n=14) performed a graded exercise test on a cycle ergometer. Antecubital area venipunctures were performed before, immediately following volitional fatigue, and after thirty minutes of recovery. Plasma was analyzed for angiotensin (1-9) using standard ELISA techniques.

Results: No significant changes in concentration of angiotensin (1-9) between time points or between sexes appeared. However, there was a significant correlation between quantity of weekly physical activity and concentration of angiotensin (1-9) immediately post exercise intervention. These results are likely affected by the changes in plasma volume with exercise and not from an increase in production of angiotensin (1-9).

Conclusion: There appears to be no obvious effect of a single dose of exhaustive exercise, sex, or the weekly accumulation of physical activity minutes on the circulating concentrations of angiotensin (1-9).

Summary for Lay Audience

When an individual becomes infected with COVID-19, there is a down regulation of certain hormones which are part of a messaging system that controls blood pressure via dilation or constriction of blood vessels. Further, when these hormones become downregulated, complications can arise that can result in fatality. Recent research has indicated that regular physical activity may be beneficial to preventing complications due to COVID-19. Moreover, data suggests that targeting these hormones via supplementation may have an ergogenic effect on exercise performance. The purpose of this study was to determine whether a single exhaustive bout of exercise affects the circulating concentrations of one of these hormones [angiotensin (1-9)] and whether chronic physical activity alters these conditions. Eight males and six females completed a progressive exercise test to volitional fatigue on a stationary bicycle and had blood drawn from their forearm while resting, immediately following and thirty minutes into their recovery. There were no significant differences between any timepoint or between sexes due to wide variability in the measurements. If more participants were recruited, a difference between the two sexes may be more apparent. There was a positive association with physical activity and concentrations of the target hormone immediately after the exercise test, however, these results are likely an artifact of normal blood volume changes during physical activity. Additional research is required to determine how physically active individuals exhibit a protective effect from complications due to COVID-19 or if there are any performance benefits from targeting this hormone.