Decrease in accelerometer assessed physical activity during the first-year post-myocardial infarction: a prospective cohort study

To elucidate physical activity in the first year after myocardial infarction (MI), and to explore differences in various subgroups, delineated by age, participation in exercise-based cardiac rehabilitation (exCR), or restrictions due to the covid-19 pandemic. Secondly, to explore associations between changes in physical activity variables with blood pressure and lipid levels. A longitudinal study in 2017-2023. Physical activity variables were assessed <i>via</i> accelerometers at two- and twelve months post-MI. The intensity was divided into, sedentary, light, moderate, and vigorous-intensity physical activity, according to established cut-offs. Blood pressure and lipids were measured by standardized procedures at the same time points. There were 178 patients included at baseline, 81% male, mean age of 64 (9 SD) years. Patients spent 72% of their time sedentary, followed by light (19%), moderate (8%), and vigorous physical activity (1%). Patients included during covid-19 restrictions and younger patients had a higher level of moderate-intensity physical activity compared to patients included during non-pandemic restrictions and older patients. At 12-month follow-up, patients overall increased time (1%) in sedentary behavior (<i>p</i> = 0.03) and decreased time (0.6%) in moderate-intensity physical activity (<i>p</i> = 0.04), regardless of participation in exCR or age. There was a positive association between the change in mean physical activity intensity and HDL-cholesterol (<i>p</i> = 0.047). Participants had a low fraction of time in moderate-to-vigorous-intensity physical activity two months post-MI, which deteriorated during the first year. This emphasizes the need for improved implementation of evidence-based interventions to support and motivate patients to perform regular physical activity.