Blood volume: importance and adaptations to exercise training, environmental stresses, and trauma/sickness

Abstract

This paper reviews the influence of several perturbations (physical exercise, heat stress, terrestrial altitude, microgravity, and trauma/sickness) on adaptations of blood volume (BV), erythrocyte volume (EV), and plasma volume (PV). Exercise training can induce BV expansion: PV expansion usually occurs immediately, but EV expansion takes weeks. EV and PV expansion contribute to aerobic power improvements associated with exercise training. Repeated heat exposure induces PV expansion but does not alter EV. PV expansion does not improve thermoregulation, but EV expansion improves thermoregulation during exercise in the heat. Dehydration decreases PV (and increases plasma tonicity) which elevates heat strain and reduces exercise performance. High altitude exposure causes rapid (hours) plasma loss. During initial weeks at altitude, EV is unaffected, but a gradual expansion occurs with extended acclimatization. BV adjustments contribute, but are not key, to altitude acclimatization. Microgravity decreases PV and EV which contribute to orthostatic intolerance and decreased exercise capacity in astronauts. PV decreases may result from lower set points for total body water and central venous pressure, while EV decreases may result from increased erythrocyte destruction. Trauma, renal disease, and chronic diseases cause anemia from hemorrhage and immune activation which suppresses erythropoiesis. The re-establishment of EV is associated with healing, improved life quality, and exercise capabilities for these injured/sick persons.

The prevalence of low hemoglobin values among new infantry recruits and nonlinear relationship between hemoglobin concentration and physical fitness

“…This results from two mechanisms: iron deficiency (nutritional or from increased exercise related loss) and hemodilution. In the majority of the athletes the relative hemoglobin decline is explained by plasma volume expansion [7,8,[18][19][20]. This phenomenon is characteristic during the first 3-5 days of increased exercise intensity and the hemoglobin level usually returns to baseline levels within 3-5 days after exercise cessation [17].…”

Comparison of Selected Morphological, Rheological and Biochemical Parameters of Winter Swimmers' Blood at the End of One Winter Swimming Season and at the Beginning of Another

“…The magnitude of Hct change seems to depend on exercise intensity during training sessions and the type of exercise (strength vs. endurance; for review see HU & LIN, 2012). A few weeks after the training intervention a new steady state had established, and Hct had returned to pre-training values (SAWKA et al 2000).…”

Contribuição dos grandes vasos arteriais na adaptação cardiovascular a ortostase

“…Additionally, the gravitational stress can be aggravated by the level of physical activity, environmental temperature, and drug use and by several physiopathological processes, all capable of augmenting the disparity between the vascular volumetric capacity and blood fl ow volume [18][19][20] .…”