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The Journal of Sports Medicine and Physical Fitness 2015 May;55(5):544-8


lingua: Inglese

Impaired oxygen uptake kinetics in the first high-level athlete with Hb Hope: a case study

Touhami I. 1, 4, Le Gallais D. 1, Perrey S. 2, Bibi A. 3, Koubaa D. 4, Mankai R. 4, Bartagi Z. 4, Messaoud T. 3, Fattoum S. 3

1 EA 2992 Dynamics of Cardiovascular Incoherencies, Montpellier 1 University, Montpellier, France; 2 EA 2991 and Biochemical Laboratory, Children’s Hospital, Tunis, Tunisia; 3 Molecular Biology and Movement To Health (M2H), Euromov Montpellier 1 University, Montpellier, France; 4 National Centre of Sports Sciences and Medicine, Tunis, Tunisia


Hemoglobin (Hb) Hope is a beta-globin chain variant with reduced oxygen (O2) affinity, known to induce anemia. This usually leads to limitations in O2 uptake (VO2) and exercise tolerance. We studied the case of a high-level female athlete with Hb Hope. She had been selected for cross-country races from 13 yrs onward, then was a national junior champion in 400-m race, and finally failed to win any cross-country races as an adult. Hematological analysis revealed normal red blood cell indices and Hb level (12.3 g.dL-1). Incremental exercise showed peak work rate (WR), VO2max and gas exchange threshold (GET) within normal ranges for healthy females. Constant WR testing at 90% of GET showed that kinetics of pulmonary VO2 included the presence of a slow component. This was in disagreement with the data on VO2 kinetics response to exercise intensities below GET. Phase 2 parameters, time constant (τ2, 31 s), time delay (TD2, 39 s), amplitude (A2, 780 ml.min-1), and gain in VO2 (ΔVO2 .ΔWR-1, 9.2 ml.min-1.W-1) were within normal ranges. Phase 3 showed a slow component similar to that reported in severe exercise. The absence of anemia and the normality of phase 2 suggested normal O2 delivery and oxidative metabolism in exercising muscles. In contrast, phase 3 suggested poor aerobic capacity and limited exercise tolerance. However, the lack of symptoms during testing also suggested that the slow component was due to the specific recruitment of fast-twitch fibers in this former champion athlete with Hb Hope in races requiring mainly anaerobic metabolism.

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