Abstract

Amplitude and phase response of ventilation (VE), carbon dioxide output (VCO2) and oxygen uptake (VO2) during sinusoidally varying work load for periods of 1 to 16 min were studied in six healthy men. The relationships between these parameters and aerobic capacity (VO2max, ATVO2) were also examined. The results and conclusions obtained were as follows: (1) The relationship between the period of exercise and amplitude response of VO2, VCO2 and VE was well described by first-order exponential models. However, the relationship between the period of exercise and the phase shift (phase responses of VO2, VCO2, and VE) was better described by complex models comprising a first-order exponential function and a linear equation. This can be explained by Karpmans threshold theory. (2) High negative correlations were observed between the steady-state amplitude of phase response or the time constants of amplitude response and VO2max, and ATVO2. Significantly high negative correlations for all gas exchange parameters may be more rapid in individuals with greater aerobic capacity. (3) A close relationship between the response of VCO2 and VE was demonstrated by a higher correlation coefficient than that between VO2 and VCO2 or between VO2 and VE. This can be partly, but not completely, explained by the cardiodynamic theory. Verf.-Referat