In brief, the mechanisms that cause stiff arteries (atheroma) may be the same mechanisms that cause stiff backs and pain. If that were the case, you’d expect people who have a long history of back pain to more frequently have heart disease. Turns out they do! In case you just want to go to the sources first (to confirm I’m not a raving lunatic) and then read my longer article afterwards, here are the research links below..
Is Chronic Low Back Pain Associated with the Prevalence of Coronary Heart Disease when Genetic Susceptibility Is Considered? A Co-Twin Control Study of Spanish Twins: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4865187/