Lower body muscle tensing is an effective countermeasure to initial orthostatic hypotension induced cerebral hypo‐perfusion upon standing from a squatted position

PURPOSE to examine the effects of 5 s of lower body muscle tensing (LBMT) after rising from squat on middle cerebral artery blood velocity (MCABV) following a squat‐to‐stand protocol. METHODS Healthy subject (n =8; 24.4 ±1.9 yrs) performed a squat‐to‐stand protocol. Upon standing participants performed either no manoeuvre (Control) or LBMT which was held for 5 s. MCABV (cm/s; surrogate for cerebral perfusion) was measured with transcranial Doppler ultrasound (TCD), mean arterial pressure (MAP) via finger photoplethysmography. Cerebral blood pressure (CBP) was calculated by measuring the hydrostatic column from the heart (MAP) to the TCD probe. Cerebral vascular conductance (CVC) was calculated from MCABV and CBP. RESULTS Data are mean ±SD. The drop in MAP upon rising from squat was −15.8 ±3.9 mmHg in Control vs. −6.02 ±10.5 mmHg in LBMT, p < 0.05. This represented a 62% attenuation of hypotension via LBMT. MCABV decreased by −11.8 ±3.07 cm/s in Control vs. −3.72 ±4.48 cm/s in LBMT, P <0.05, which represents a 68% attenuation of cerebral hypo‐perfusion. CONCLUSIONS LBMT for the first 5 s upon rising from squat is an effective countermeasure for minimizing cerebral hypo‐perfusion. NSERC .