Exhaled nitric oxide after high-intensity exercise at 2800 m altitude.
BACKGROUND
Nitric oxide (NO) concentration in exhaled gas is a marker of some inflammatory processes in the lung, and endogenous NO plays a role in the physiological responses to exercise and altitude. The aim of this study was to compare changes in exhaled NO concentration 5-60 mins after high-intensity exercise at 2800 m and at 180 m altitude.


METHODS
Twenty trained healthy volunteers (12 men), aged 19-28 years, were included in this open, crossover study. Subjects performed two exercise tests at different altitudes, 2800 m and 180 m, in a randomized order. The fraction of NO in exhaled gas (FE(NO)) was measured 5 mins before and 5-60 mins after 8 mins of running on a treadmill at a heart rate (HR) of 90% of peak HR. Peak HR was assessed during a pretest at 180 m. Ambient temperature was 20.1°C (SD = 1.2) and relative humidity 40.2% (SD = 3.2). FE(NO) measurements were corrected for altitude gas density effects and converted to partial pressure of NO (PE(NOcorr)).


RESULTS
PE(NOcorr) was reduced from 1.47 (1.21, 1.73) millipascal (mPa) at baseline to 1.11 (0.87, 1.34) mPa 5 mins after exercise at 2800 m and from 1.54 (1.24, 1.84) to 1.04 (0.87, 1.22) mPa 5 mins after exercise at 180 m. There was no difference in PE(NOcorr) between exercise at 2800 m and 180 m, and PE(NOcorr) was normalized within 20 mins.


CONCLUSIONS
Exercise at 2800 m induces a similar acute reduction in exhaled nitric oxide concentration as compared with 180 m in healthy subjects.
Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
Julie
J
Stang
Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
Veslemøy
V
Bråten
Institute of Medicine, University of Bergen, Bergen, Norway.
Cecilie
C
Caspersen
Institute of Medicine, University of Bergen, Bergen, Norway.|Department of Occupational Medicine, Haukeland University Hospital, Bergen, Norway.
Einar
E
Thorsen
Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
Trine
T
Stensrud
D000328:Adult; D000531:Altitude; D001944:Breath Tests / Q000379:methods; D015444:Exercise / Q000502:physiology*; D045853:Exhalation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D010807:Physical Endurance / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
D009569:Nitric Oxide
airway inflammation; altitude; athletes; endurance sports; exercise; ventilation