Effects of a brief Valsalva manoeuvre on hemodynamic response to strength exercises.

Strength training is a recommended measure against loss of strength and muscle mass because of age- or illness-induced inactivity. Strength exercises may impose heavy cardiovascular load by increasing heart rate and blood pressure. To increase strength efficiently, a heavy load has to be applied; this, however, leads to a spontaneous Valsalva manoeuvre, which additionally raises blood pressure. Avoidance of this manoeuvre is recommended. If the additional rise in arterial blood pressure caused by Valsalva manoeuvre is smaller than intrathoracic or intracranial pressures during this manoeuvre, Valsalva manoeuvre may actually protect arteries located in the thorax and in the brain by diminishing transmural pressure acting across these vessels. Effect of controlled breathing or brief Valsalva manoeuvre on arterial pressure at rest and during knee extension against 15-repetition maximum resistance was evaluated. In 12 healthy young men blood pressure was measured continuously and non-invasively, knee angle, speed of respiratory air or mouth pressure (MP) were continuously registered. Each combination of respiratory and exercise manoeuvres was repeated six times, for every of last three repetitions peak and trough systolic and diastolic pressure were determined. Strength exercises elevated peak pressures more than trough pressures, systolic more than diastolic. Valsalva manoeuvre increased only peak systolic and peak diastolic pressure. This increase was in average lesser than MP, thus rendering an argument in favour of protective role of brief Valsalva manoeuvre because of decline in transmural pressure acting on thoracic and possibly cerebral arteries. However, there was strong individual variability, and in few instances, arterial pressure increased because of brief Valsalva manoeuvre more than MP; thus in some subjects, the manoeuvre might enhance transmural pressure acting on thorax arteries.