LAUSR

The regulation of mean arterial pressure (MAP) during exercise has important physiological and clinical implications. Kinetics analysis on numerous physiological variables following the transition from unloaded-to-loaded exercise has revealed important information regarding their control. Surprisingly, the dynamic response of MAP during this transition remains to be quantified. Therefore, ten healthy participants (5/5 M/F, 24±3 years) completed repeated transitions from unloaded to moderate- and heavy-intensity dynamic single-leg knee-extensor exercise to investigate the on-kinetics of MAP. Following the transition to loaded exercise, MAP increased in a first-order dynamic manner, subsequent to a time delay (moderate:23±10; heavy:19±9 s, P>0.05) at a speed (tau, moderate:59±30; heavy:66±19 s, P>0.05) which did not differ between intensities, but the MAP amplitude was doubled during heavy-intensity exercise (moderate:12±5; heavy:24±8 mmHg, p<0.001). The reproducibility (coefficient of variation (CV)) during heavy-intensity for unloaded baseline, amplitude, and mean response time, when assessed as individual transitions were 7±1, 18±2, and 25±4%, respectively. Averaging two transitions improved the CVs to 4±1, 8±2, and 13±3%, respectively. Preliminary findings supporting the clinical relevance of evaluating MAP kinetics in middle-aged hypertensive (n=5) and, age-matched, normotensive (n=5) participants revealed an exaggerated MAP response in both older groups (P<0.05), but the MAP response was slowed only for the patients with hypertension (P<0.05). It is concluded that kinetics modeling of MAP is practical for heavy-intensity knee-extensor exercise and may provide insight into cardiovascular health and the effect of aging.