Ever wonder which gives you a better cardio workout—a treadmill or an elliptical machine? The difference in health benefits between the two is minimal, says Thomas Altena, professor of nutrition sciences at the University of Missouri at Columbia. He conducted a study to find out if the treadmill or elliptical was more effective in terms of physiological responses. Eighteen males completed separate workouts on a treadmill and an elliptical machine. During the two sessions, the subjects exercised at the same intensity with regard to oxygen consumed and calories burned. For each workout, Altena measured oxygen retained, lactic acid, heart rate and perceived exertion. After researching if the treadmill or elliptical provided a better cardio workout, he concluded that while there were some differences, such as in maximal-effort intensity, these were minimal.