Comparison of cardiovascular responses between upright and recumbent cycle ergometers in healthy young volunteers performing low-intensity exercise: assessment of reliability of the oxygen uptake calculated by using the ACSM metabolic equation.

OBJECTIVES: To clarify (1) differences in cardiovascular response during low-intensity exercise in the upright versus the recumbent position, and (2) whether the oxygen uptake (V o 2 ) calculated by the American College of Sports Medicine (ACSM) metabolic equation reflects the actual V o 2 at low-intensity testing.
DESIGN: Repeated-measures comparison study.
SETTING: University research laboratory. PARTICIPANTS: Thirty-one healthy, young volunteers (age, 23+/-2y).
INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Blood pressure, rate pressure product (RPP), V o 2 , oxygen pulse, carbon dioxide output (V co 2 ), and ventilatory equivalent (V e ) were measured during graded exercise testing using upright and recumbent cycle ergometers. The estimated V o 2 was calculated by using the ACSM metabolic equation.
RESULTS: Systolic blood pressure, RPP, V o 2 , oxygen pulse, V co 2 , and V e at 15 or 30W were significantly higher in the recumbent position than in the upright one ( P <.05), however, no significant differences were observed at 50 and 70W. The estimated V o 2 during exercise was significantly higher than the actual one, at every level of intensity, from 15 to 70W ( P <.05).
CONCLUSIONS: Cardiovascular responses should be carefully monitored even during low-intensity exercise using a recumbent cycle ergometer. The V o 2 estimated using the ACSM metabolic equation did not reflect the actual V o 2 during low-intensity exercise at 70W or less.