The operating point of the carotid baroreflex (CBR) resets during exercise in direct relation to the intensity and the recruited muscle mass (Norton et al. 1999). However, during arm cranking (A) blood pressure is higher than during combined arm and leg exercise (A+L) (Volianitis & Secher, 2002). This study evaluated the carotid baroreflex (CBR) function during leg cycling (L), A, and A+L.

CBR stimulus-response relationships were compared in 12 volunteers by using the neck pressure-neck suction technique during dynamic exercise. Exercise intensities for A and L were chosen to elicit a heart rate response of ~100 and ~120 b.p.m., respectively. A+L was performed with the combination of the same absolute workloads used in the A and L trials. Comparisons across exercise conditions were made with one-way ANOVA with repeated measures and Student-Newman-Keuls t test. Significance was accepted at P < 0.05.

The position of the operating point (the prestimulus blood pressure) of the carotid-vasomotor reflex at rest was 87.9 ± 5.6 mmHg (mean ± S.E.M.) and during L, A+L and A it was 91.4 ± 6.9, 103.1 ± 7.2 and 109.4 ± 9.3 mmHg, respectively (P < 0.05). The threshold and saturation pressures of the reflex during A were >A+L, >L and >than at rest (P < 0.05) with no significant change in the maximal reflex gain.

These findings suggest the CBR during combined arm and leg exercise resets lower than during arm cranking alone.

S.V. was supported by a Marie Curie Fellowship of the European Community programme Improving Human Potential under contract number HPMF-CT-2000-00526.