Heart DiseaseCardiovascular disease, endothelial health, and our biological rhythms. Posted on September 13, 2015September 13, 2016 by nwright This article discusses the relationship between biological rhythms such as our circadian clocks, endothelial cell activity, and cardiovascular disease. nwright Improved endothelial function is associated with a significant increase in exercise capacity. Exercise training, endothelial function, and coronary artery disease.