Circadian Rhythms, Acute Exercise, And Blood Pressure In People With Type 2 Diabetes And Overweight/Obesity

PURPOSE: Circadian rhythm fluctuations offer a unique opportunity to explore how exercise can model key cardiovascular outcomes, such as blood pressure (BP). However, it is still unclear how the time of the day affects BP before and immediately after exercise. This investigation aims to determine the acute effects of exercise on BP outcomes when performed at different periods of the day (morning period (MP), afternoon period (AP), and evening period (EP)) in patients with type 2 diabetes mellitus (T2DM) and on a matched control group. METHODS: This investigation used a randomized crossover trial design with three 2-week blocks of supervised exercise (i.e., MP, AP, and EP) using high-intensity interval training (6 sessions each block), with a 2-week washout period between blocks. A total of 8 patients with T2DM and 8 matched controls with overweight/obesity were assessed for brachial systolic (SBP) and diastolic (DBP) BP before each exercise session and 1 min and 3 min after. The pre-, 1 min, 3 min BP measures were used to calculate changes. Generalized linear mixed models were used. RESULTS: After adjusting for sex, age, and treatment order, the T2DM group had no significant between-group changes for SBP (MP*AP: β = -1.27, p = 0.218; MP*EP: β = -1.66, p = 0.113; EP*AP: β = 0.39, p = 0.710) and DBP before the exercise (MP*AP: β = 0.24, p = 0.766; MP*EP: β = -0.18, p = 0.832; EP*AP: β = 0.42, p = 0.614); further, no SBP changes at 1 min (MP*AP: β = 0.41, p = 0.795; MP*EP: β = 0.62, p = 0.698; EP*AP: β = -0.21, p = 0.895) and at 3 min (MP*AP: β = 0.12, p = 0.926; MP*EP: β = 1.66, p = 0.195; EP*AP: β = -1.54, p = 0.219), as well as DBP changes at 1 min (MP*AP: β = 0.14, p = 0.896; MP*EP: β = 0.01, p = 0.990; EP*AP: β = 0.13, p = 0.908) and at 3 min (MP*AP: β = -0.27, p = 0.781; MP*EP: β = 0.12, p = 0.901; EP*AP: β = -0.39, p = 0.692) were observed. Similar results were found for the matched control group for all the outcomes. For each block and groups, no within group changes were observed from baseline to follow-up (p > 0.05). CONCLUSION: Our findings suggest that exercise timing does not impact BP values before and immediately after an exercise session in patients with T2DM and on those with overweight/obesity. Future studies should address the acute effects of exercise on BP at different times of the day on other periods such as those during the night. Supported by: This study was funded by the Fundação para a Ciência e Tecnologia (2022.08130. PTDC). The funder has no role in the study in terms of the design, data collection, management, analysis, and interpretation.