Correlation of the physiologic parameters of a continuous ramp versus an incremental James exercise protocol in normal children

Until recently, all clinically available exercise protocols involved steady-state or incremental increases in work load.1 In these protocols, the subject exercises against a predetermined and unchanging work load or exercises with the work load increasing in a continuous stepwise fashion. These protocols were designed so that the subject would be at or near steady state when physiologic parameters were measured. This was especially important in the past when only a limited number of points by Douglas bag collection of respiratory gases were obtainable to assess the patient's physiology. Today, with the use of computer systems interfaced to rapid gas analyzers, this limitation in the number of data points collected no longer exists. However, the small number of work loads assessed and the size of the step increments limit these protocols. These limitations are especially significant in small children or children with moderate to severe exercise intolerance. By starting at zero watts (unloaded pedalling) and continuously increasing the work load in small increments, a ramp protocol alleviates these problems. The ramp protocol, however, introduces a new problem. The patient is never at a steady state when physiologic parameters are measured. To assess the effects of a non-steady-state exercise protocol on physiologic parameters, we compared the responses of normal children to both a continuously increasing non-steady-state ramp protocol and the standard incremental “steady state” James2–4 protocol.