Noninvasive polygraphic tracings obtained at rest and during isometric hand-grip exercise were analysed in 67 healthy subjects. The purpose of the study was to determine the response of noninvasive polygraphic parameters to isometric exercise. During the third minute of sustained squeezing of a balloon dynamometer (30% of maximal voluntary contraction) a significant increase occurred in heart rate (+16.8 +/- 10.7 beats/min) an increase in both systolic and diastolic blood pressure (+3.4 +/- 1.6 kPa and 2.6 +/- 1.7 kPa respectively), increase in apexcardiographic index 100.a/D (+14.5 +/- 15.0% "D" amplitude), decrease of diastolic amplitude time index square root 2-c/(2-0) X (a/D) (-20.1 +/- 26.5), shortening of pulse transmission time (-0.006 +/- 0.005 s) and prolongation of cardiac cycle length corrected for left ventricular ejection time (+0.011 +/- 0.010 s) discussed. All these changes were statistically significant.