Effect of acute normobaric hypoxia on the ventilatory threshold.
OBJECTIVE
This study investigated the response of the ventilatory threshold (VT) to acute normobaric hypoxia and compared the agreement between software-based algorithms which use automatic detection to identify the VT. Results were used to examine whether the VT can be used as a physiological parameter to prescribe and monitor exercise intensity in hypoxic exercise training programs.


METHODS
Fourteen untrained individuals (7 women, 7 men; age 22 ± 2 years, [Formula: see text]O2peak 46 ± 7 mL kg(-1) min(-1)) completed five identical graded exercise tests (randomized order) on a cycle ergometer to measure VT at sea-level (SL) and in response to four normobaric hypoxic conditions (FIO2: 0.185, 0.165, 0.142, 0.125) equivalent to 1,000, 2,000, 3,000 and 4,000 m. Data were analyzed using a one-way analysis of variance (ANOVA) with repeated measures.


RESULTS
The VT was similar across all conditions (SL = 1.98 ± 0.46, 1,000 m = 2.03 ± 0.61, 2,000 m = 2.27 ± 0.62, 3,000 m = 1.84 ± 0.50, 4,000 m = 2.29 ± 0.58 L min(-1)) for all algorithms used despite a reduction in arterial oxygen saturation at 3,000 (P ≤ 0.01) and 4,000 m (P ≤ 0.01) compared with SL values.


CONCLUSIONS
The VT appears to be a suitable physiological parameter for exercise prescription in normobaric hypoxia up to an altitude of 4,000 m.
Department of Sport and Exercise Sciences, University of Chichester, College Lane, Chichester, West Sussex, PO19 6PE, UK.
Carla A
CA
Gallagher
Mark E T
ME
Willems
Mark P
MP
Lewis
Stephen D
SD
Myers
D000531:Altitude; D015444:Exercise; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010101:Oxygen Consumption; D012123:Pulmonary Ventilation; D055815:Young Adult