Comparison of free range and graded exercise testing

Previous studies with athletes have demonstrated greater physiologic responses during free range (FR) compared with graded (GXT) exercise testing. Since the sensitivity of clinical exercise testing depends upon the magnitude of physiologic responses, we sought to determine whether FR might provoke greater responses than GXT in nonathletic individuals and patients. Healthy, physically active nonathletes and clinically stable CHD patients (N = 12) performed GXT on cycle ergometer (15 W + 15 W.min-1) and FR (minimal time for 75 kJ task) on a cycle ergometer. A starting power output was recommended for FR, but the patients were free to pedal at their own rates. During FR, VO2max (36.5 +/- 10.1 vs 34.1 +/- 9.4 mL.min-1.kg-1), HRmax (156 +/- 25 vs 144 +/- 27 beats.min-1), double product (31.4 +/- 4.9 vs 29.1 +/- 5.9) and VEmax (111 +/- 26 vs 94 +/- 17 L.min-1) were all significantly greater than during cycle GXT. The mean peak power output during GXT (180 +/- 45 W) was not significantly different than the mean power output during FR (204 +/- 45 W). During FR, successive "0.5 mile laps" (approximately 12.5 kJ) were accomplished at power outputs of 217 +/- 45, 217 +/- 52, 192 +/- 60, 194 +/- 65, 199 +/- 63, and 207 +/- 63 W. No patient experienced angina or ECG changes during either FR or GXT. The patients uniformly reported that FR felt like "hurrying" in the real world. Some patients had to make large reductions in their power output in mid ride to allow recovery from a too aggressive start, much as they would in the real world. We conclude that FR exercise provides a clinically useful method of exercise testing that is not only more like real world exercise patterns but also provokes greater physiologic responses than are achievable during conventional GXT.