Effect of intermittent hypoxia on muscle and cerebral oxygenation during a 20-km time trial in elite athletes: a preliminary report.
The effects of intermittent hypoxic exposure (IHE) on cerebral and muscle oxygenation, arterial oxygen saturation (SaO2), and respiratory gas exchange during a 20-km cycle time trial (20TT) were examined (n=9) in a placebo-controlled randomized design. IHE (7:3 min hypoxia to normoxia) involved 90-min sessions for 10 days, with SaO2 clamped at ~80%. Prior to, and 2 days after the intervention, a 20TT was performed. During the final minute of the 20TT, in the IHE group only, muscle oxyhemoglobin (oxy-Hb) was elevated (mean+/-95% confidence interval 1.3+/-1.2 ΔmicroM, p=0.04), whereas cerebral oxy-Hb was reduced (-1.9%+/-1.0%, p<0.01) post intervention compared with baseline. The 20TT performance was unchanged between groups (p=0.7). In the IHE group, SaO2 was higher (1.0+/-0.7Δ%, p=0.006) and end-tidal PCO2 was lower (-1.2+/-0.1 mm Hg, p=0.01) during the final stage of the 20TT post intervention compared with baseline. In summary, reductions in muscle oxy-Hb and systemic SaO2 occurring at exercise intensities close to maximal at the end of a 20TT were offset by IHE, although this was not translated into improved performance.
Hamlin
Michael J
MJ
Department of Social Science, Parks, Recreation, Tourism, and Sport, Environment Society and Design Division, P.O. Box 84, Lincoln University, Canterbury 7647, New Zealand. mike.hamlin@lincoln.ac.nz
Marshall
Helen C
HC
Hellemans
John
J
Ainslie
Philip N
PN
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D019344:Lactic Acid / Q000097:blood; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism* / Q000503:physiopathology; D010100:Oxygen / Q000097:blood*; D010108:Oxyhemoglobins / Q000378:metabolism; D010313:Partial Pressure; D010807:Physical Endurance; D010865:Pilot Projects; D015990:Placebo Effect; D011659:Pulmonary Gas Exchange; D012039:Regional Blood Flow; D016037:Single-Blind Method; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D055815:Young Adult
D015415:Biomarkers; D001786:Blood Glucose; D010108:Oxyhemoglobins; D002245:Carbon Dioxide; D019344:Lactic Acid; D010100:Oxygen