Tell us more about yourself and the author team.
I am a passionate exercise physiologist! I work as an Associate professor (Docent) in Experimental clinical physiology at Linköping University in Linköping, Sweden, and a medical doctor (MD) in Clinical Physiology at Linköping university hospital. I try to keep a rather wide approach in my research, studying patients, healthy subjects, and athletes, which gives me a chance to elucidate the whole spectrum of how the cardiovascular and respiratory systems adapt to exercise and training. And I really enjoy collaborations – across research fields and across the world.
In this particular study, I got the chance to work with an amazing team of U.S. researchers (Drs Jonatan Myers, Ross Arena, Leonard Kaminski and Ahmad Sabbahi), who fortunately were interested in the same research questions as myself. I met and worked with Dr Myers during my post-doc at Stanford University in 2018-19. He has outstanding experience in exercise physiology and several large datasets suitable to test research hypotheses. This is one of the large advantages and upsides of being a researcher – the chance to collaborate with all these great persons interested in the same things as yourself!
What is the story behind your study?
One of the topics I studied during my post-doc was the systolic blood pressure response to exercise. That was a question raised at my own clinic before I left for post-doc, and digging into the literature, I found several controversies and unanswered questions, which triggered my “academic nerve”. One of the longstanding questions is whether a high systolic blood pressure during exercise testing is negative for prognosis and how ‘dangerous´ a low or inadequate systolic blood pressure response is. We know that blood pressure during exercise is influenced by several factors, for example, age, sex, hypertension and what workload you reach.However, this has often been neglected previously, contributing to some of the controversy and conflicting results.
We hypothesized that using normative standards in interpreting the systolic blood pressure would offer a way to study the association with prognosis, similar to what we do for exercise capacity. Thus, we aimed to apply recent reference standards for systolic blood pressure during exercise, derived from the large U.S. FRIEND-initiative, and determine the impact on prognosis.
In your own words, what did you find?
We found that low systolic blood pressure, at least the failure to increase the systolic blood pressure from the baseline value, was associated with increased mortality during a long follow-up period. This was robust to adjustment for known confounders as age, sex, systolic blood pressure at rest, exercise capacity and cardiovascular risk factors. In contrast, a high systolic blood pressure (or a large increase) was not associated with a worse outcome. The traditional cutoff value defining an exaggerated systolic blood pressure response to exercise (210 mmHg in males) did not associate with prognosis.
What was the main challenge you faced in your study?
Working with large datasets is always associated with massive work concerning database management, quality control of data, and many decisions on who to include and exclude from analysis to maximize the integrity and validity of the dataset. Fortunately, I worked with the same dataset previously, knew the database structure, and had close contacts with Dr Myers, who knows the database in detail.
If there is one take-home message from your study, what would that be?
The most important take-home message I would say is that clinicians need to interpret the systolic blood pressure response not only as exaggerated or not-exaggerated. Much of the prognostic information seems to lie in the lower end of the spectrum, not at the “top”.