The effect of isometric exercise training on arterial stiffness: a randomised crossover controlled study

Isometric exercise training (IET) is an effective intervention for the management of resting blood pressure (BP). However, the effects of IET on arterial stiffness remain largely unknown. Eighteen unmedicated physically inactive participants were recruited. Participants were randomly allocated in a cross-over design to 4-weeks of home-based wall squat IET and control period, separated by a 3-week washout period. Continuous beat-to-beat haemodynamics, including early and late systolic (sBP 1 and sBP 2, respectively) and diastolic blood pressure (dBP) were recorded for a period of 5-minutes and waveforms were extracted and analysed to acquire the augmentation index (AIx) as a measure of arterial stiffness. sBP 1 (-7.7±12.8 mmHg, p=0.024), sBP 2 (-5.9±9.9 mmHg, p=0.042) and dBP (-4.4±7.2mmHg, p=0.037) all significantly decreased following IET compared to the control period. Importantly, there was a significant reduction in AIx following IET (-6.6±14.5%, p=0.02) compared to the control period. There were also adjacent significant reductions in total peripheral resistance (-140.7±65.8 dyne·s·cm-5, p=0.042) and pulse pressure (-3.8±4.2, p=0.003) compared to the control period. This study demonstrates an improvement in arterial stiffness following a short-term IET intervention. These findings have important clinical implications regarding cardiovascular risk. Mechanistically, these results suggest that reductions in resting BP following IET are induced via favourable vascular adaptations, although the intricate details of such adaptations are not yet clear.