title: Improved running economy and increased hemoglobin mass in elite runners after extended moderate altitude exposure.
abstract: There is conflicting evidence whether hypoxia improves running economy (RE), maximal O(2) uptake (V(O)(2max)), haemoglobin mass (Hb(mass)) and performance, and what total accumulated dose is necessary for effective adaptation. The aim of this study was to determine the effect of an extended hypoxic exposure on these physiological and performance measures. Nine elite middle distance runners were randomly assigned to a live high-train low simulated altitude group (ALT) and spent 46+/-8 nights (mean+/-S.D.) at 2860+/-41m. A matched control group (CON, n=9) lived and trained near sea level ( approximately 600m). ALT decreased submaximal V(O)(2) (Lmin(-1)) (-3.2%, 90% confidence intervals, -1.0% to -5.2%, p=0.02), increased Hb(mass) (4.9%, 2.3-7.6%, p=0.01), decreased submaximal heart rate (-3.1%, -1.8% to -4.4%, p=0.00) and had a trivial increase in V(O)(2max) (1.5%, -1.6 to 4.8; p=0.41) compared with CON. There was a trivial correlation between change in Hb(mass) and change in V(O)(2max) (r=0.04, p=0.93). Hypoxic exposure of approximately 400h was sufficient to improve Hb(mass), a response not observed with shorter exposures. Although total O(2) carrying capacity was improved, the mechanism(s) to explain the lack of proportionate increase in V(O)(2max) were not identified.
authors: Department of Physiology, Australian Institute of Sport, Australia. philo.saunders@ausport.gov.au
authors: P U
authors: PU
authors: Saunders
authors: R D
authors: RD
authors: Telford
authors: D B
authors: DB
authors: Pyne
authors: A G
authors: AG
authors: Hahn
authors: C J
authors: CJ
authors: Gore
mesh_terms: D000531:Altitude; D001315:Australia; D001696:Biomechanical Phenomena; D006339:Heart Rate / Q000502:physiology; D006454:Hemoglobins / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000503:physiopathology*; D019344:Lactic Acid / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D012123:Pulmonary Ventilation / Q000502:physiology*; D012420:Running / Q000502:physiology*
chemical_list: D006454:Hemoglobins; D019344:Lactic Acid