Effect of exercise intensity on circulating microparticles in men and women

New Findings: What is the central question of this study? What is the effect of exercise intensity on circulating microparticle populations in young, healthy men and women? What is the main finding and its importance? Acute, moderate-intensity continuous exercise and high-intensity interval exercise altered distinct microparticle populations during and after exercise in addition to a sex-specific response in CD62E⁺ microparticles. The microparticles studied contribute to cardiovascular disease progression, regulate vascular function and facilitate new blood vessel formation. Thus, characterizing the impact of intensity on exercise-induced microparticle responses advances our understanding of potential mechanisms underlying the beneficial vascular adaptations to exercise. Abstract: Circulating microparticles (MPs) are biological vectors of information within the cardiovascular system that elicit both deleterious and beneficial effects on the vasculature. Acute exercise has been shown to alter MP concentrations, probably through a shear stress-dependent mechanism, but evidence is limited. Therefore, we investigated the effect of exercise intensity on plasma levels of CD34⁺ and CD62E⁺ MPs in young, healthy men and women. Blood samples were collected before, during and after two energy-matched bouts of acute treadmill exercise: interval exercise (10 × 1 min intervals at ∼95% of maximal oxygen uptake (Formula presented.)) and continuous exercise (65% (Formula presented.)). Continuous exercise, but not interval exercise, reduced CD62E⁺ MP concentrations in men and women by 18% immediately after exercise (from 914.5 ± 589.6 to 754.4 ± 390.5 MPs μl⁻¹; P < 0.05), suggesting that mechanisms underlying exercise-induced CD62E⁺ MP dynamics are intensity dependent. Furthermore, continuous exercise reduced CD62E⁺ MPs in women by 19% (from 1030.6 ± 688.1 to 829.9 ± 435.4 MPs μl⁻¹; P < 0.05), but not in men. Although interval exercise did not alter CD62E⁺ MPs per se, the concentrations after interval exercise were higher than those observed after continuous exercise (P < 0.05). Conversely, CD34⁺ MPs did not fluctuate in response to short-duration acute continuous or interval exercise in men or women. Our results suggest that exercise-induced MP alterations are intensity dependent and sex specific and impact MP populations differentially.