The aim of the present investigation was to evaluate the influence of the physical fitness of a cardiopulmonary resuscitation (CPR) provider on the performance of and physiologic response to CPR. To this end, comparisons were made of sedentary and physically active subjects in terms of CPR performance and physiologic variables. Two study groups were established: group P (n=14), composed of sedentary, professional CPR rescuers (mean [+/-SD]; age, 34+/-6 years; VO2max, 32.5+/-5.5 mL/kg/min), and group Ex (n=14), composed of physically active, nonexperienced subjects (age, 34+/-6 years; VO2max, 44.5+/-8.5 mL/kg/min). Each subject was required to perform an 18-min CPR session, which involved manual external cardiac compressions (ECCs) on an electronic teaching mannequin following accepted standard CPR guidelines. Subjects' gas exchange parameters and heart rates (HRs) were monitored throughout the trial. Variables indicating the adequacy of the ECCs (ECC depth and the percentage of incorrect compressions and hand placements) also were determined. Overall CPR performance was similar in both groups. The indicators of ECC adequacy fell within accepted limits (ie, an ECC depth between 38 and 51 mm). However, fatigue prevented four subjects from group P from completing the trial. In contrast, the physiologic responses to CPR differed between groups. The indicators of the intensity of effort during the trial, such as HR or percentage of maximum oxygen uptake (VO2max) were higher in group P subjects than group Ex subjects, respectively (HRs at the end of the trial, 139+/-22 vs 115+/-17 beats/min, p < 0.01; percentage of VO2max after 12 min of CPR, 46.7+/-9.7% vs 37.2+/-10.4%, p < 0.05). These results suggest that a certain level of physical fitness may be beneficial to CPR providers to ensure the adequacy of chest compressions performed during relatively long periods of cardiac arrest.