RESUMEN
BACKGROUND: A conventional treadmill provides manually controlled constant speed during exercise. A fast interactive automatic speed control treadmill (FAST), which is highly sensitive to the position of the user on the belt and spontaneously adjusts its speed accordingly, was evaluated in terms of energy expenditure (EE) during exercise. METHODS: A total of 43 subjects were recruited and assigned to one of three exercise intensity groups-low (LIG; 40-50% of VO2max), moderate (MIG; 55-65% of VO2max), and high (HIG; 70-80% of VO2max). During the first test (Test-1), each subject performed an exercise bout on the FAST while spontaneously changing their locomotion speed within their assigned range of intensity. The average speed in Test-1 was calculated and applied to the second test (Test-2), in which the subjects exercised at a constant belt speed and matched the total travel distance of Test-1. During the tests, the oxygen uptake (VO2), heart rate (HR), respiratory quotient (RQ), oxygen pulse (OP), and EE of each subject were measured. RESULTS: The average VO2 in Test-1 was higher than that in Test-2 for both the LIG (22.95+/-2.55 vs. 21.72+/-2.90 ml/kg/min) and MIG (31.17+/-3.75 vs. 29.73+/-4.86 mL/kg/min) (P<.05) subjects. The EE in Test-1 was higher than that in Test-2 for both the LIG (7.09+/-1.67 vs. 6.71+/-1.73 kcal/min) and MIG (9.79+/-2.62 vs. 9.32+/-2.71 kcal/min) (P<.05) subjects. The HR, RQ, and OP in the LIG and the MIG were similar. There was no difference between Test-1 and Test-2 in any of the metabolic parameters for the HIG subjects. CONCLUSIONS: The results indicated that, low- to moderate-intensity treadmill exercise at varying speeds required higher energy expenditure than that at a constant speed. Thus, a treadmill with a spontaneous speed variation function may be an effective exercise modality that increases energy expenditure.