Effect of body position on the afterload response during sustained exercise.

Hemodynamic and cardiovascular responses were studied in 80 males (age: 30 +/- 2 years) at rest, and during separate three minute trials of upright and supine isometric deadlift exercise at 30% of maximum voluntary contraction (MVC). MVC did not differ significantly between supine and upright deadlift exercise. In comparison to values at rest, both forms of isometric exercise resulted in significant increases (p less than 0.05) in heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, oxygen uptake, oxygen pulse and double product. In the upright exercise, the values obtained for all of the physiological variables were found to be significantly higher (p less than 0.05) than in the supine exercise. These findings indicate that the upright isometric deadlift produces a higher after-load than the supine maneuver, and that this response may be a good indicator of cardiovascular functioning.