Physical Exercise and Erythrocyte Deformability: A Narrative Review of Mechanisms and Physiological Adaptations

The aim of the present review was to summarize the effects of physical exercise of varying intensity, duration, and frequency on the key biological and biomechanical factors that determine erythrocyte deformability. Erythrocyte deformability is a multifactorial property influenced by mechanical, biochemical, metabolic, and hemodynamic mechanisms activated during exercise, including membrane rheology, osmotic balance, hemoglobin concentration, intracellular Ca2+ homeostasis, ATP availability and release, nitric oxide (NO) signaling, oxidative stress, erythrocyte age, and temperature. Current evidence indicates that the effect of physical exercise on erythrocyte deformability is bidirectional. Moderate and well-adapted exercise generally improves membrane properties, microcirculatory blood flow, and oxygen delivery, whereas exhaustive or prolonged exercise may induce oxidative and structural damage and transiently reduce deformability. NO-dependent vasodilation and ATP release from erythrocytes appear to have central regulatory roles in optimizing microvascular perfusion during exercise. Osmotic changes, lactate accumulation, intracellular Ca2+ concentration, dehydration, and temperature are critical physiological modulators of erythrocyte mechanics. Because each athlete may exhibit an individual erythrocyte deformation profile shaped by biological, hemorheological, physiological, and training-related factors, individualized training loads and regular monitoring of hemorheological indicators are recommended. Such an approach may contribute to the development of hemorheological fitness and improved exercise performance. Overall, erythrocyte deformability should be regarded as a complex, multifactorial hemorheological parameter shaped by the dynamic interaction of cellular, metabolic, physiological, and environmental determinants. Consequently, its response to physical exercise is highly individual and context-dependent, reflecting not only the characteristics of the exercise stimulus but also each individual’s underlying biological and hemorheological profile.