Endurance running trial in tropical environment: A blood rheological study

Abstract

Purpose: The aim of this study was to clarify whether exercising in a tropical climate induces blood rheology alterations despite ad libitum hydration.Methods: Hematological, biochemical and hemorheological changes were investigated in young healthy adults (N = 9 men, 20.7 ± 0.8 yrs) after a 10-km race in hot and humid conditions. Subjects' maximal aerobic abilities were tested using a maximal ramp exercise. Blood was sampled at rest (T R ), at the end of the race (T Ex ), and after 24 hours of recovery (T 24 ). Ad libitum hydration was allowed during the race. Blood viscosity (b), red blood cell deformability (EI), aggregation (AI) and disaggregation shear rate (␥) were measured.Results: Hematocrit, hemoglobin and plasma concentration of chlorine, sodium and potassium did not change in response to exercise. No functional consequence was observed on RBC deformability since EI remained unchanged. Percentages of echinocytes, schizocytes and stomatocytes remained in the subclinical range at all times. AI, ␥ and b did not present change.Conclusion: Running exercise in tropical climate with ad libitum hydration does not alter the main rheological properties of blood.

Eryptosis and hemorheological responses to maximal exercise in athletes: Comparison between running and cycling

“…While this finding could seem surprising, it is in agreement with previous studies showing no change in blood viscosity after a marathon 12 or a 10-km running competition performed in the hot and wet environment. 13 Blood viscosity is also strongly affected by the RBC rheological properties, with a rise in RBC deformability and a decrease in RBC aggregation resulting in a decrease in blood viscosity. 3,28,29 Indeed, the increase in RBC deformability and the lack of change in RBC aggregation observed during the running test have probably limited the rise in blood viscosity caused by the change in hematocrit.…”

“…7 These works reported an increase in blood viscosity at the end of the exercise mainly in relation with the rise in hematocrit, 8 subsequent to water loss, fluid shift, and the release of spleen trapped RBC 9,10 In contrast and surprisingly, previous studies conducted on running exercises, such as a marathon or a 10-km running competition, did not find any change in blood viscosity. [11][12][13] Authors hypothesized that this lack of change could be due to the absence of hematocrit variations presumably explained by RBC foot strike hemolysis during running. 7,11,12 In addition, while most of the cycling studies have been performed in standardized laboratory conditions where water intake was not allowed, most of the running studies were performed in outdoor environment with allowed hydration.…”

“…This difference could also explain the diverging hemorheological responses between cycling and running exercise. 13 Yet, the major divergences observed between cycling and running impact on blood rheology could be attributed to difference in RBC deformability and aggregation, 2 RBC rheological properties affecting blood viscosity. 3 Several factors may modulate RBC rheological parameters, such as lactate anion 14 and oxidative stress.…”

Exercise hemorheology: Classical data, recent findings and unresolved issues

“…Cycling exercise usually increases blood viscosity by 15-20% [11][12], due to an increase in plasma viscosity (+5-10%) and hematocrit (+10-15%). In contrast, prolonged running exercise performed in an outdoor environment does not alter blood viscosity or hematocrit [38,60,84]. Senay and Pivarnik [73] proposed that blood and plasma volumes are usually well maintained during such exercise, unless athletes lose a considerable amount of water (around 4-5% of total body weight).…”

“…In addition, the footstrike hemolysis that occurs during running has been suggested to be responsible for the lack of change in the hemorheological profile observed in these studies. The most rigid RBCs could be destroyed during foostrike hemolysis, and the typical rise in hematocrit could be partially blunted [82,84]. Further studies investigating the effects of cycling and running exercise on blood rheology in the same population (e.g., triathletes) may assist with definitively addressing this issue.…”