Relative use of fat and carbohydrate as metabolic fuels depends on exercise intensity.

<p>Fractional usage of carbohydrate (plasma glucose plus muscle glycogen, blue filled curve, ) and fat (plasma free fatty acids plus muscle triglycerides, red filled curve, ) are shown as functions of relative exercise intensity, . (Based on the work of Romijn and colleagues: Points plotted correspond to data points from the 1993 study <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1000960#pcbi.1000960-Romijn1" target="_blank">[24]</a>, and corresponding error bars are computed as described in the <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1000960#s4" target="_blank">Methods</a> section.)