Strenuous exercise in warm environment is associated with improved microvascular function in sickle cell trait

Sickle cell trait is characterized by the presence of both normal and abnormal haemoglobin in red blood cells. The rate of exertional collapse is increased in athletes and military recruits who carry the trait, particularly in stressful environmental conditions. The aim of the present study was to investigate microvascular function and its determinants in response to intense exercise at control and warm environmental temperatures in carriers (AS) and non-carriers (AA) of sickle cell trait.

Nine AS and 11 AA, all healthy physically active young men, randomly participated in four experimental sessions (rest at 21 °C and 31 °C and cycling at 21 °C and 31 °C). All participants performed three exercises bouts as follows: 18-min submaximal exercise; an incremental test to exhaustion; and three 30-s sprints spaced with 20-s resting intervals.

Skin Blood Flow (SkBF) was similar at rest between AA and AS. SkBF for all participants was higher at 31 °C than 21 °C. It was significantly higher in the AS group compared to the AA group immediately after exercise, regardless of the environmental conditions. No significant differences in hemorheological parameters, muscle damage or cardiac injury biomarkers were observed between the two groups. Our data also suggest higher oxidative stress for the AS group, with high superoxide dismutase (P = 0.044 main group effect).

A specific profile is identified in the AS population, with increased microvascular reactivity after maximal exercise in stressful environment and slight pro-/antioxidant imbalance.