Erythrocyte sickling during exercise and thermal stress.
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).


METHODS
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.


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


METHODS
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.
Bergeron
Michael F
MF
Department of Physical Therapy, Medical College of Georgia, Augusta, GA 30912-0800, USA. mbergero@mcg.edu
Cannon
Joseph G
JG
Hall
Elaina L
EL
Kutlar
Abdullah
A
D000328:Adult; D001741:Black or African American / Q000235:genetics*; D001833:Body Temperature Regulation; D016022:Case-Control Studies; D004913:Erythrocytes, Abnormal / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate; D006579:Heterozygote; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance; D005082:Physical Exertion / Q000502:physiology; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012805:Sickle Cell Trait / Q000235:genetics*; D013312:Stress, Physiological