Preventive measures for the critical postexercise period in sickle cell trait and disease.

The immediate postexercise/physical activity period is critical for sickle cell trait (SCT) carriers and disease (SCD) patients. Exercise-related blood acidosis is known to trigger the cascade of HbS deoxygenation and polymerization, leading to red blood cell sickling and subsequent complications. Unfortunately, two facts worsen exercise-related blood acidosis during the initial postexercise period: First, blood lactate and H+ concentrations continue to increase for several minutes after exercise completion, exacerbating blood acidosis. Second, blood lactate concentration remains elevated and pH altered for 20-45 min during inactivity after intense exercise, keeping acid/base balance disturbed for a long period after exercise. Therefore, the risk of complications (including vasoocclusive crises and even sudden death) persists and even worsens several minutes after intense exercise completion in SCT carriers or SCD patients. Light physical activity following intense exercise (namely, active recovery) may, by accelerating lactate removal and acid/base balance restoration, reduce the risk of complications. Scientific evidence suggests that light exercise at or below the first lactate threshold is an appropriate strategy.