Influences of normobaric hypoxia training on metabolic risk markers in human subjects.
OBJECTIVE
Endurance exercise and hypoxia regulate pathways that are crucial to glucose and lipid metabolism. We hypothesized that training under hypoxia results in similar or even greater metabolic improvement compared with exercise under normoxia at a lower workload.


METHODS
We randomly assigned 20 healthy men to single blind training under hypoxia (FiO2 = 15%) or normoxia (FiO2 = 21%). Subjects trained thrice weekly for 60 min over a 4-wk period at a heart rate measured at 3 mmol x L(-1) lactate during pretraining exercise testing. Before and after the training period, we determined body composition, venous blood parameters, oral glucose tolerance, and blood pressure. Furthermore, we assessed oxygen uptake (VO2), lactate, and respiratory quotient, and heart rate (HR) during incremental exercise testing, both in hypoxia and in normoxia. Training workload was 1.39 +/- 0.2 W x kg(-1) in the hypoxia and 1.67 +/- 0.15 W x kg(-1) in the normoxia group (P< 0.001) with an identical training heart rate in both groups.


RESULTS
Exercise capacity improved similarly with both interventions. With hypoxia training, body fat content, triglycerides, HOMA-Index, fasting insulin (P < 0.05), and area under the curve for insulin (P < 0.01) during the oral glucose tolerance test improved more than with the training in normoxia. We did not observe major changes in adipokine measurements.


CONCLUSIONS
Endurance training in hypoxia over a 4-wk period elicits a similar or even better response in terms of cardiovascular and metabolic risk factors than endurance exercise in normoxia. The fact that workload and, therefore, mechanic strain can be reduced in hypoxia could be particularly beneficial in obese patients and in patients with orthopedic conditions.
Franz Volhard Clinical Research Center, Medical Faculty of the Charité, Berlin, Germany.
Sven
S
Haufe
Susanne
S
Wiesner
Stefan
S
Engeli
Friedrich C
FC
Luft
Jens
J
Jordan
D000222:Adaptation, Physiological / Q000502:physiology; D054392:Adipokines / Q000032:analysis; D000328:Adult; D005951:Glucose Tolerance Test; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D008660:Metabolism / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology; D012307:Risk Factors; D016037:Single-Blind Method; D055815:Young Adult
D054392:Adipokines; D010100:Oxygen