CONTINUOUS MEASUREMENT OF BLOOD-PRESSURE, HEART-RATE AND LEFT-VENTRICULAR PERFORMANCE DURING AND AFTER ISOMETRIC-EXERCISE IN HEAD-OUT WATERIMMERSION

Experiments were performed to determine the changes in blood pressure (BP)? heart rate (HR) and left ventricular function during and after i sometric knee extension during thermoneutral(35 degrees C) head-out wa ter immersion (HWI) or in air. Seven healthy male subjects mean age 24 (SD 3) years kept their knees extended (60% maximal voluntary extensi on) until they reached exhaustion, The mean BP at rest was 80(SD 10) a nd 78 (SD 8)mmHg [10.7 (SD 1.33) and 10.4 (SD 1.07)kPa] in air and dur ing HWI, respectively, (NS). They increased progressively (P < 0.01) d uring contraction and reached maximal values of 148 (SD 22) and 143 (S D 26) mmHg [19.7 (SD 2.93) and 19.1 (SD 3.47) kPa] in air and in HWI, respectively, (NS). The mean HR at rest was 74 (SD 8) and 70 (SD 11) b eats . min(-1) in air and in HWI, respectively, (NS). They also increa sed progressively (P < 0.01) and reached 126 (SD 14) and 118(SD 17) be ats . min(-1) in air and in HWI, respectively, (NS). The changes in BP and HR during contraction in HWI tended to be smaller than those in a ir (NS). Left ventricular end diastolic diameters (d(d)) at rest in HW I were greater than those in air and were maintained at higher values during and after isometric contraction, In contrast, d(d) decreased du ring isometric contraction in air (P < 0.01). The change of left ventr icular systolic diameters (d(s)) in HWI was no different to those in a ir. From these findings, isometric exercise in thermoneutral HWI would seem to be characterized by a greater d(d) than in air and this could be useful for patients with deconditioning effects such as orthostati c hypotension.