Brothers, M. D., Nelson, J. L., Doan, B. K., Zupan, M. F., Prommer, N., Ryan, B., & Byrnes, W. C. (2010). Hematological acclimatization and de-acclimatization of former sea level residents exposed chronically (46 weeks) to moderate altitude. Presentation 1040 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

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"Rapid loss in total hemoglobin mass as a result of neocytolysis has been documented in astronauts as well as high altitude mountain climbers upon return to lower altitudes. Whether similar hematological changes occur when moderate altitude residents return to sea level is unknown."

This study examined total hemoglobin mass adaptations to moderate altitude following three weeks at sea-level after acclimatizing to the U.S. Air Force Academy environment (~2210 m). Freshman cadets (M = 33; F = 17; 8 originally from moderate altitude and 50 from sea-level environments) were assessed for total hemoglobin mass within 72 hours of in-processing at the USAFA. Assessments continued four to seven weeks thereafter and just prior to the three week winter break. A final testing occurred upon return from the sea-level experience. Ss were randomly assigned to either a placebo group (cornstarch) or a low-dose iron supplement group (100 mg ferrous sulfate), with doses taken daily throughout the study.

Sea-level cadetsí total hemoglobin mass increased significantly over time with the iron cohort peaking at week 15, the placebo cohort peaking at week 28. There was no significant change among the originally moderate altitude cadets. Significant loss of total hemoglobin mass was observed upon return to sea-level during the three-week winter break:

Implication. A significant 40+% loss of total hemoglobin mass gained during moderate-altitude adaptation occurred among Ss who returned to sea-level for three weeks, suggesting the occurrence of neocytolysis.

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