Hemodynamic responses to handgrip exercise in persons with and without Down syndrome when matched for heart rate responses

Abstract

Individuals with Down syndrome (DS) have altered autonomic function and hemodynamic responses to certain physiological stressors. However, these data are generally reported as group means. It is not known if there is a subgroup of individuals with DS that have similar responses to a non-DS group.PURPOSE: To compare hemodynamic responses to isometric exercise between persons with and without DS when matched for HR changes to that stressor.METHODS: Persons with and without DS (n=9/grp; 27 yrs) were matched for HR responses during a 2-min isometric handgrip task (peak HG HR-baseline HR) that was performed at 30% of maximal voluntary contraction. Hemodynamics were determined using finger beat-to-beat photoplethysmography and included: systolic blood pressure (SBP), diastolic BP (DBP), mean arterial pressure (MAP), cardiac output (Qi) and stroke volume indexed (SVi) to body surface area, as well as total peripheral resistance (TPR).RESULTS: Both groups responded similarly to the handgrip task, with time effects observed for Qi and SBP (*p<0.05). Individuals with DS had lower overall SBP (p<0.05).CONCLUSIONS: Hemodynamic responses to an isometric task are similar between persons with DS and non-DS individuals when they exhibit a normal HR response to an isometric exercise task. This suggests that autonomic dysregulation may not be prevalent in allpersons with DS.