Acute Responses and Chronic Adaptations of the Arterial System to Resistance Exercise

Resistance training is rarely prescribed to enhance cardiovascular function; in fact, suggestions have been made that long-term resistance training may lead to chronic augmentations in carotid arterial stiffness and consequently, an increased risk of cardiovascular disease. This has led some to conclude that resistance exercise may have negative effects on vascular health. Despite this, there is substantial evidence supporting favourable effects of resistance exercise on both physiological and psychosocial well-being. Given the debate around the effects of resistance exercise, the main aim of this thesis was to comprehensively assess the true impact of resistance training on the carotid artery, whilst also advancing our understanding of the acute responses and chronic adaptations of major peripheral arteries (brachial and femoral) to resistance training. The findings provide evidence that exercise-induced remodelling in arterial diameter is a localised phenomenon. Furthermore, during acute resistance exercise, transient changes in the mechanical behaviour of the carotid arterial wall occur in healthy, but untrained men. These include reductions in circumferential deformation (strain) and the rate of deformation of the carotid arterial wall during systole (systolic strain rate). Conversely, immediately post-exercise, both strain and systolic strain rate are augmented above baseline levels. The rate of deformation of the carotid arterial wall during diastole (diastolic strain rate) is also augmented immediately post-exercise, but this is only observed in resistance trained men. Collectively, the findings of this thesis suggest that long-term resistance training may produce health-related benefits to the arterial system, as evidenced by the greater diastolic strain rate observed in resistance trained men. An enhanced diastolic strain rate in the carotid artery likely represents a superior ability to buffer the elevations in flow and pressure associated with resistance exercise, serving as a protective mechanism to prevent rupture of the arterial wall at supra-systolic pressures, and helping to deliver a less pulsatile flow downstream. Enhanced diastolic function associated with long-term resistance training may therefore reflect an important index of improved health, and compliment the cardiovascular adaptations associated with endurance-based exercise, although further research is still required.