CLOCK and brain ischemia: The most frequently used keyword was “exercise therapy,” followed by “stroke,” “rehabilitation,” “peripheral artery disease,” and “intermittent claudication.” All keywords were classified into 6 clusters (#0 cerebral ischemia, #1 coronary artery disease, #2 peripheral artery disease, #3 elderly patient, #4 endothelial function, #5 clock genes) and identified by a timeline in CiteSpace, as shown in Figure 8C. The figure showed the top 10 keywords with the most vigorous citation bursts.