The venomotor response to static muscular exercise

The venous blood pressure response to static muscular exercise was studied in seven young normal subjects by the occluded-limb technique. A slight pressure increase was obtained during the first seconds of the contraction period. Then the pressure response subsided, and the control level was reached after 1/2-1 1/2 min despite sustained contraction. The response was of the same type as that elicited by a voluntary deep breath, but usually of lesser magnitude. It seems to differ from the response to dynamic muscular exercise, suggesting that a continuous stiffening of the capacitance vessels, to maintain a high venous response, is not needed to the same extent during static muscular exercise. In previous studies a similar pressure increase has been obtained during short-lasting static muscular exercise. The present study shows that this pressure increase is confined to the initial part of the contraction period. Observations made after administration of phenoxybenzamine and atropine indicate that the venomotor response is mediated through sympathetic adrenergic nerves.