title: Year-to-year variability in haemoglobin mass response to two altitude training camps.
abstract: OBJECTIVE
  To quantify the year-to-year variability of altitude-induced changes in haemoglobin mass (Hb(mass)) in elite team-sport athletes.
  
  
  METHODS
  12 Australian-Footballers completed a 19-day (ALT1) and 18-day (ALT2) moderate altitude (∼2100 m), training camp separated by 12 months. An additional 20 participants completed only one of the two training camps (ALT1 additional n=9, ALT2 additional n=11). Total Hb(mass) was assessed using carbon monoxide rebreathing before (PRE), after (POST₁) and 4 weeks after each camp. The typical error of Hb(mass) for the pooled data of all 32 participants was 2.6%. A contemporary statistics analysis was used with the smallest worthwhile change set to 2% for Hb(mass).
  
  
  RESULTS
  POST₁ Hb(mass) was very likely increased in ALT1 (3.6 ± 1.6%, n=19; mean ± ∼90 CL) as well as ALT2 (4.4 ± 1.3%, n=23) with an individual responsiveness of 1.3% and 2.2%, respectively. There was a small correlation between ALT1 and ALT2 (R=0.21, p=0.59) for a change in Hb(mass), but a moderately inverse relationship between the change in Hb(mass) and initial relative Hb(mass) (g/kg (R=-0.51, p=0.04)).
  
  
  CONCLUSIONS
  Two preseason moderate altitude camps 1 year apart yielded a similar (4%) mean increase in Hb(mass) of elite footballers, with an individual responsiveness of approximately half the group mean effect, indicating that most players gained benefit. Nevertheless, the same individuals generally did not change their Hb(mass) consistently from year to year. Thus, a 'responder' or 'non-responder' to altitude for Hb(mass) does not appear to be a fixed trait.
authors.affiliation: Sport Science Department, Collingwood Football Club, , Melbourne, Victoria, Australia.
authors.forename: Blake D
authors.initials: BD
authors.lastname: McLean
authors.forename: David
authors.initials: D
authors.lastname: Buttifant
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Gore
authors.forename: Kevin
authors.initials: K
authors.lastname: White
authors.forename: Justin
authors.initials: J
authors.lastname: Kemp
mesh_terms: D000531:Altitude; D001315:Australia; D015992:Body Mass Index; D004921:Erythropoietin / Q000378:metabolism; D005538:Football / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D055070:Resistance Training; D012156:Reticulocytes / Q000502:physiology; D013997:Time Factors
chemical_list: D006454:Hemoglobins; D004921:Erythropoietin
keywords: Altitude; Elite performance; Exercise; Physiology