Cardiopulmonary and gas exchange responses to acute strenuous exercise at 1,270 meters in sickle cell trait

The impact of strenuous exercise and environmental hypoxia on sickle cell trait (SCT) remains controversial. To determine if these factors induce cardiopulmonary and gas exchange abnormalities in SCT, healthy, young black male volunteers, 25 with SCT (HbAS) and 16 control subjects (HbAA), were evaluated during incremental and steady-state exercise tests using a cycle ergometer at 1,270 meters and 24°C. Peak incremental exercise values for power (242 ± 7 versus 253 ± 10 watts), oxygen consumption (3.08 ± 0.1 versus 3.26 ± 0.14 liters/minute), heart rate (188 ± 2 versus 189 ± 3 beats/minute), minute ventilation (129 ± 4.6 versus 144 ± 7.7 liters/minute), oxygen pulse (16.4 ± 0.5 versus 17.3 ± 0.8 ml/beat), and respiratory exchange ratio (1.31 ± 0.01 versus 1.33 ± 0.02) revealed no significant differences (p <0.05) between the SCT and control groups, respectively. Peak incremental exercise values for arterial oxygen tension (82 ± 1.7 versus 82 ± 2.2 mm Hg), arterial carbon dioxide tension (32 ± 0.7 versus 31 ± 0.9 mm Hg), and alveolararterial oxygen pressure differences (19 ± 1.4 versus 21 ± 1.9 mm Hg) were similar for the SCT and control groups, respectively. Steadystate exercise results corroborate incremental exercise findings. It is concluded that cardiopulmonary and gas exchange responses to a brief period of strenuous exercise performed at low altitude at 24°C in a well-characterized SCT sample of recruits were within normal limits and comparable to those of a carefully selected control sample.