The Impact Of Exercise On Derived Central Measures Obtained From The Sphygmocor Device

Abstract

PURPOSE: To investigate whether measures derived from the SphygmoCor device and its associated transfer function are influenced by exercise-induced alterations in vascular tone. To do this, measurements were taken from either the exercised or the contra-lateral non-exercised limb, during repeated and identical incremental hand-grip protocols. METHODS: Eight male subjects performed 3, 3-minute bouts of handgrip exercise, on two occasions. The exercise intensities were set at: 3kg and 5kg, with a final 1.5kg bout performed during cuff ischaemia (1.5Isch). Blood pressure waveforms were recorded from the radial artery of either the exercised or non-exercised limb using applanation tonometry (SphygmoCor) during a 90 s rest period immediately after each exercise bout. Central blood pressures and augmentation indices, an index of arterial stiffness, were derived using the peripheral waveform and the inbuilt SphygmoCor transfer function (TF). RESULTS: Augmentation index (AIx) was consistently ∼10% higher in the exercised arm during all trials compared to the non-exercised lim. Similarly, there was a consistent and significant difference (∼3 mmHg; P<0.05) between exercised and non-exercised arms for the derived central systolic and mean arterial blood pressures. CONCLUSION: Despite similar central haemodynamic responses to the identical bouts of exercise, AI and well as central systolic and mean arterial blood pressures derived from applanation tonometry at the peripheral radial artery were statistically different when assessed at the exercising arm versus the non-exercising arm. Changes in vascular tone with exercise may modify the intrinsic characteristics of the vessel wall and could compromise the assumptions underlying transfer functions used to derive central measures using applanation tonometry.