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Acta Physiol Scand. 2004 Jul;181(3):289-95.

Arterial blood pressure and carotid baroreflex function during arm and combined arm and leg exercise in humans.

Author information

1
Department of Anaesthesia, The Copenhagen Muscle Research Centre, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark.

Abstract

AIM:

During arm cranking (A) blood pressure is higher than during combined arm and leg exercise (A + L), while the carotid baroreflex (CBR) is suggested to reset to control a higher blood pressure in direct relation to work intensity and the engaged muscle mass.

METHOD:

This study evaluated the function of the CBR by using neck pressure and neck suction during upright A, L and A + L in 12 subjects and, in order to evaluate a potential influence of the central blood volume on the CBR, also during supine A in five subjects. Exercise intensities for A and L were planned to elicit a heart rate response of c. 100 and 120 beats min(-1), respectively, in the upright position and both workloads were maintained during A + L and supine A.

RESULTS:

The CBR operating point, corresponding to the pre-stimulus blood pressure, was 88 +/- 6 mmHg (mean +/- SE) at rest. During upright A, L and A + L and supine A it increased to 109 +/- 9, 95 +/- 7, 103 +/- 7 and 104 +/- 4 mmHg, respectively, and it was thus higher during upright A than during A + L and supine A (P < 0.05). In addition, the CBR threshold and saturation pressures, corresponding to the minimum and maximum carotid sinus pressure, respectively, were higher during upright A than during supine A, A + L, L and at rest (P < 0.05) with no significant change in the maximal reflex gain.

CONCLUSION:

These findings demonstrate that during combined arm and leg and exercise in the upright position the CBR resets to a lower blood pressure than during arm cranking likely because the central blood volume is enhanced by the muscle pump of the legs.

[Indexed for MEDLINE]

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