title: High-intensity kayak performance after adaptation to intermittent hypoxia.
abstract: BACKGROUND
  Live-high train-low altitude training produces worthwhile gains in performance for endurance athletes, but the benefits of adaptation to various forms of artificial altitude are less clear.
  
  
  OBJECTIVE
  To quantify the effects of intermittent hypoxic exposure on kayak performance.
  
  
  METHODS
  In a crossover design with a 6-week washout, we randomized 10 subelite male sprint kayak paddlers to hypoxia or control groups for 3 weeks (5 days/week) of intermittent hypoxic exposure using a nitrogen-filtration device. Each day's exposure consisted of alternately breathing hypoxic and ambient air for 5 minutes each over 1 hour. Performance tests were an incremental step test to estimate peak power, maximal oxygen uptake, exercise economy, and lactate threshold; a 500-m time trial; and 5 x 100-m sprints. All tests were performed on a wind-braked kayak ergometer 7 and 3 days pretreatment and 3 and 10 days posttreatment. Hemoglobin concentration was measured at 1 day pretreatment, 5 and 10 days during treatment, and 3 days after treatment.
  
  
  RESULTS
  Relative to control, at 3 days posttreatment the hypoxia group showed the following increases: peak power 6.8% (90% confidence limits, + or - 5.2%), mean repeat sprint power 8.3% (+ or - 6.7%), and hemoglobin concentration 3.6% (+ or - 3.2%). Changes in lactate threshold, mean 500-m power, maximal oxygen uptake, and exercise economy were unclear. Large effects for peak power and mean sprint speed were still present 10 days posthypoxia.
  
  
  CONCLUSIONS
  These effects of intermittent hypoxic exposure should enhance performance in kayak racing. The effects might be mediated via changes in oxygen transport.
authors.affiliation: Sport and Recreation Dept, AUT University, Private Bag 92006, Auckland, Auckland 1020 New Zealand.
authors.forename: Darrell L
authors.initials: DL
authors.lastname: Bonetti
authors.forename: Will G
authors.initials: WG
authors.lastname: Hopkins
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Kilding
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D054874:Athletic Performance; D015415:Biomarkers / Q000097:blood; D018592:Cross-Over Studies; D005080:Exercise Test; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology*; D010101:Oxygen Consumption; D010807:Physical Endurance; D012767:Ships; D013647:Task Performance and Analysis; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D006454:Hemoglobins; D019344:Lactic Acid