Figure 1. Raw data traces showing arterial and venous blood velocity, mean arterial pressure, gastric (P_GA) and oesophageal (P_ES) pressure, calf force and airflow during resting conditions.

Inspiration is denoted by the shaded areas and an upward deflection in airflow; the actual force being produced by the calf under these conditions is zero (baseline force is elevated due to the elastic cord pulling the foot against a metal bar positioned to achieve 90 degree ankle dorsiflexion). Note that arterial inflow remains unaffected by the type of breathing pattern utilized by the subject. In contrast, femoral venous blood flow is augmented only observed during inspiration with ribcage breathing, whereas femoral venous return is virtually abolished for the latter half of a diaphragmatic inspiration.