Erythrocyte sickling during exercise and thermal stress

Clin J Sport Med. 2004 Nov;14(6):354-6. doi: 10.1097/00042752-200411000-00005.

Abstract

Objective: To examine effects of exercise in the heat and fluid intake on erythrocyte sickling and neutrophil activation in carriers of sickle cell trait (HbAS).

Design, setting, and participants: Six African American men (2 HbAS; 42% HbS, 4 HbAA; 20.7 +/- 0.8 years; 87.4 +/- 9.6 kg) participated in 2 randomized sessions (separate days) each consisting of 45 minutes of brisk walking (treadmill) in a hot (33 degrees C) environment.

Intervention: Subjects consumed no fluids or fluid for 3 hours prior to (ad libitum) and during (1.02 L) testing.

Main outcome measurements: Core temperature, heart rate, and perceived exertion were measured. Forearm venous blood was analyzed for percent erythrocyte sickling and plasma myeloperoxidase.

Results: Time-averaged heart rate (126.6 +/- 5.7 vs. 146.7 +/- 5.9 bpm; P = 0.02) and core temperature (37.6 +/- 0.1 vs. 38.1 +/- 0.1 degrees C; P < 0.05) responses were lower during fluid versus no fluid, with no statistically significant difference in perceived exertion (12.3 +/- 0.5 vs. 13.6 +/- 0.4; P = 0.06). Erythrocyte sickling progressively increased (to 3.5%-5.5%) for HbAS carriers during no fluid exercise only. No sickling was detected in HbAA subjects. Plasma myeloperoxidase responses to exercise were greater (P = 0.03) in HbAS versus HbAA.

Conclusions: Fluid ingestion at a rate sufficient to offset a body weight deficit can effectively reduce erythrocyte sickling during exercise in the heat.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • African Americans / genetics*
  • Body Temperature Regulation
  • Case-Control Studies
  • Erythrocytes, Abnormal / metabolism*
  • Exercise / physiology*
  • Heart Rate
  • Heterozygote
  • Hot Temperature*
  • Humans
  • Male
  • Oxygen Consumption / physiology
  • Physical Endurance
  • Physical Exertion / physiology
  • Reference Values
  • Risk Assessment
  • Sensitivity and Specificity
  • Sickle Cell Trait / genetics*
  • Stress, Physiological