These distinct responses in SV and thigh Hb during standing PCM (versus supine PCM) could potentially provide a method for non‐invasive investigation of skeletal muscle pump function which warrants further study; in such studies, contraction intensity could be systematically varied—perhaps using real‐time EMG feedback to titrate force—and measure the resulting changes in cardiovascular measures to define the optimal ‘dose’ of PCM for preventing orthostatic intolerance. The gene discussed is GSTM1; the disease is postural orthostatic tachycardia syndrome.