What could an increase in systolic blood pressure and decrease in diastolic mean?

Question

Sorry if this is a really simple question but my academic background is in completely different sciences. I recently made a computer game for an experiment that was related to anxiety and relaxation. One of the ways that I measured for success was to record participants blood pressure before and after they played the game.

There was a slight increase in systolic BP after playing the game, but not by a statistically significant amount. However the data shows a decrease in diastolic BP that is statistically significant. I've been trying to figure out why this might have happened but can't seem to find any answers. My brief overview of search engines and journals only seem to relate these changes to certain types of exercise. Which doesn't help as the participants of the experiment were asked to remain seated for 20 minutes by the time the second BP recording was made. Just wondering if anyone has any information in relation to relaxation techniques that might result in this pattern?

If it helps heart rate has mostly uniform throughout the experiment.

Answer 1

First, a couple of considerations

• Heart rate (HR) is lower when seating, and even lower when lying. I assume that participants were seated when the first measure was taken.
• Cardiac output is not constant during the day. Depending on the moment, some factors such as digestion have an impact in Cardiac output, so take that into account when carrying out the experiments.

Normal walking may cause that blood pressure pattern. I think that you should not consider the increase in systolic pressure if it is not significant, as something as simple as crossing your legs when seated can increase your systolic pressure and normally diastolic pressure provides more information for physicians. Relaxation techniques usually decrease heart rate, which can affect the blood pressure. However, the point in this case seems to be that HR remains constant. I suppose that Mean Arterial Pressure $(MAP)$ has decreased.

If we part from:

$\textit{MAP} = (CO \cdot SVR) + CVP$ where $CO$ is cardiac output, $SVR$ is systemic vascular resistance and $CVP$ central venous pressure.

$CVP$ is usually depreciable. $CO$ is defined by $SV \cdot HR$, where $SV$ is the stroke volume. Then, if the HR is constant, only $SV$ or $SVR$ could have changed. Maybe the heart is pulsating more vigorously, or a vasodilation is decreasing $SVR$. I find the latter more likely. However, I don´t know why the smooth muscle could be relaxing. Make sure that heart rate is not changing and consider your sample size. I hope it helps, at least to focus you search on cardiac regulation. It is difficult to conclude anything without seeing the data but I tried to answer from my limited knowledge since I am not specialized in cardiac physiology.