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The main focus of this thesis was to establish the effects of a novel method of undertaking isometric exercise training on resting arterial blood pressure in middle aged (45-60 years) males and to further determine whether isometric exercise training could generate concomitant adaptations in local or systemic vasculature function and structure. This novel method allowed exercise intensities to be set at a relative proportion of peak electromyographic activity (%EMGpeat). which provides a more accurate means of determining isometric exercise intensity than the traditional use of%MVC. Methods: Prior to the start of the experimental sIDdies preliminary tests were undertaken to determine the reliability of the equipment and measures used to determine the main dependant variables, including resting blood pressure using a non-invasive blood pressure monitor and vascular diameter, blood flow and velocity, using a Doppler ultrasound. During all three srudies participants completed either a unilateral or bilateral leg incremental isometric test during which heart rate, blood pressure and EMG were recorded. During the final study, resting heart rate, blood pressure and vascular measures were taken at pre, mid and post 8 weeks of isometric exercise training. Results: The linear relationship betvleen %EMG and heart rate reported in the initial study was not consistently evident in all subjects which further established the bilateral protocol as the preferred method for determining such relationships. The data from the second study involving bilateral leg isometric exercise indicated that these relationships in middle aged participants were linear in all cases, for both habitually active and sedentary individuals, showing that this method of prescribing isometric exercise intensity could be used in this age group. From the training data it is evident that following 8 weeks of bilateral isometric exercise training heart rate, SBP and mean arterial pressure (MAP) was significantly reduced in the higher (85%T) training group with concomitant local vascular adaptations. However, no significant change in resting blood press~e or vascular adaptations was evident in the lower (70%T) intensity group. These data has not been reported previously. Discussion: These results are in agreement with the majority of the previous research which have used isometric exercise training as an intervention for lowering arterial blood pressure. Furthermore, the findings lend support to the research evidence that" systeniic vascular adaptations are not responsible for the observed reductions in resting blood pressure foHowing isometric exercise training. Furthennore, the absence of changes in the 70%T group suggest the possibility of an exercise intensity threshold below which the exercise intensity is insufficient to stimulate cardiovascular adaptations.