title: Impaired oxygen uptake kinetics in the first high-level athlete with Hb Hope: a case study.
abstract: Hemoglobin (Hb) Hope is a beta-globin chain variant with reduced oxygen (O₂) affinity, known to induce anemia. This usually leads to limitations in O₂uptake (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), VO(2max) and gas exchange threshold (GET) within normal ranges for healthy females. Constant WR testing at 90% of GET showed that kinetics of pulmonary VO₂included the presence of a slow component. This was in disagreement with the data on VO₂kinetics 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 O₂delivery 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.
authors.affiliation: EA 2992 Dynamics of Cardiovascular Incoherencies, Montpellier 1 University, Montpellier, France - daniel.legallais@univ-montp1.fr.
authors.forename: I
authors.initials: I
authors.lastname: Touhami
authors.forename: D
authors.initials: D
authors.lastname: Le Gallais
authors.forename: S
authors.initials: S
authors.lastname: Perrey
authors.forename: A
authors.initials: A
authors.lastname: Bibi
authors.forename: D
authors.initials: D
authors.lastname: Koubaa
authors.forename: R
authors.initials: R
authors.lastname: Mankai
authors.forename: Z
authors.initials: Z
authors.lastname: Bartagi
authors.forename: T
authors.initials: T
authors.lastname: Messaoud
authors.forename: S
authors.initials: S
authors.lastname: Fattoum
mesh_terms: D000328:Adult; D056352:Athletes; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D006453:Hemoglobinopathies / Q000097:blood* / Q000503:physiopathology; D006455:Hemoglobins, Abnormal / Q000378:metabolism*; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology
chemical_list: D006455:Hemoglobins, Abnormal; C038623:hemoglobin Hope; D010100:Oxygen