Reversal of Lower Limb Venous and Lymphatic Pooling by Passive Non-Invasive Calf Muscle Pump Stimulation

Our preliminary data indicate that exogenous plantar micromechanical stimulation at 45 Hz applied at the plantar surface can prevent tachycardia and blood pressure depression associated with immobility, consistent with improvement in venous and lymphatic fluid return delivered by increased calf muscle activity. In this study, instantaneous beat-to-beat systolic blood pressure of thirty four healthy adult women participants (n=34; age range: 35-78 years) were assessed non-invasively using servo-controlled infra-red finger arterial plethysmography, for 30 minutes in the supine position, followed by 30 minutes in the seated position without plantar stimulation, and lastly for 30 minutes in the seated position with the application of a 45 Hz plantar stimulus (50 mum, p-p). Thirty minutes of supine rest resulted in an average increase of 15 mmHg in systolic pressure. During the 30 minutes of upright sitting regimen, two distinct sub-populations were observed. One group (n=18; "hypotensives") experienced a depression of approximately 15 mmHg in systolic pressure, while the other group (n=16; "normotensives and hypertensives") experienced an elevation in the systolic pressure by approximately 8 mmHg. The subsequent 30 minute application of plantar stimulus reversed the pressure drop in hypotensives and elevated the systolic pressure by approximately 20 mmHg in all the subjects. Plantar-based exogenous micromechanical vibration may be an effective approach for reversal of blood pressure depression associated with the physical stress of immobility over a long term, consistent with enhanced venous and lymphatic fluid return delivered via improved calf muscle contractility