B-48 Free Communication/Slide - Exercise in Special Populations: MAY 28, 2008 3:15 PM - 4:45 PM ROOM: 116
PURPOSE: Iron overload as a result of hereditary hemochromatosis (HH) may impair the response to aerobic exercise secondary to altered cardiovascular and skeletal muscle function. The purpose of the present study is to assess the impact of phlebotomy on aerobic exercise performance in asymptomatic subjects with HH.
METHODS: Seventeen asymptomatic newly diagnosed HH subjects (12 male/5 female, mean age: 48.7 ± 11.1 years) underwent laboratory assessments for iron, transferrin, ferritin, hemoglobin (Hgb) and mean corpuscular volume (MCV) before and after six months of phlebotomy. Maximal oxygen consumption (VO2Max), peak respiratory exchange ratio (RER) and the oxygen uptake efficiency slope (OUES; VO2 = a log10VE + b, units: L/min) were determined from exercise testing.
RESULTS: Differences in the variables of a priori interest prior to and following phlebotomy are presented in Table 1. Ferritin, iron and Hgb were significantly reduced while transferrin and OUES were significantly higher following six months of phlebotomy.
CONCLUSION: The OUES, an index of aerobic exercise performance, is a reflection of pulmonary, cardiovascular, and skeletal muscle function during exercise. Thus, phlebotomy therapy appears to enhance aerobic exercise performance through one or more of these systems in asymptomatic newly diagnosed HH subjects. The improvement of transferrin level by phlebotomy may be also involved in this process through improving muscle mitochondrial function. Interestingly, VO2Max, the most commonly assessed exercise variable, was unaltered after phlebotomy, thus, the OUES may be a more sensitive marker in this instance.