The research: Twelve recreationally trained cyclists were studied by University of Nebraska at Omaha researchers as they cycled in both outdoor and indoor settings. The cyclists were told to exert the same perceived effort (a measure of intensity based on a scale) for both the indoor laboratory effort and the outdoor 40 km trials. The result: when outdoors, cyclists exerted more power and had higher heart rates than when they were indoors, despite similar environmental conditions and exertion. What it means: Cycling indoors may distort a person’s perception of how hard they’re working when compared to outdoor riding, says one of the study’s authors Dustin R. Slivka, PhD. “Our research indicates that when riding at the same perceived intensity, you are actually producing around 25% less power indoors compared to an outdoor session.”  The bottom line: Kick it up a notch or two when cycling indoors if you want to burn the same calories, says Dr. Slivka. How much harder depends on your fitness level and how you perceive exercise (how tough it feels for you). “Just know that it isn’t just you that feels it’s so hard to reach your target power or heart rate when riding indoors,” he says.  More from Prevention: Cycling Is Better For You Than Running