Expired Nitric Oxide Is Reduced After Exercise In A Cold Environment

Abstract

PURPOSE: To compare changes in FENO from before to after high intensive exercise in a normal tempered (20°C) and a cold (-10°C) environment. METHODS: Twenty healthy, well trained subjects (8 females), aged 18-28 years performed 8 minutes high intensive exercise tests in a cold and in a normal tempered environment in random order at a workload corresponding to 90 -95% of maximum heart rate (HFmax) the last four minutes. FENO was measured offline before exercise, after warm up and 5, 10, 15, 20, 30 and 60 minutes and 24 hours after exercise. Samples of expired air were collected in Mylar bags using a Collector Kit with flow restrictor and analysed within two hours in a NO chemiluminescence analyzer (EcoMedics, Duerten Switzerland). ANOVA for repeated measures (mix models) was used to calculate differences in FENO between environments. RESULTS: There was no significant difference in baseline FENO between the cold and normal environment. A significant differense in FENO between the cold and normal environment was found after warm-up 11.2 ppb (9.1, 13.3) [mean (95% confidence intervals)] and 15.4 ppb (12.6, 18.2) respectively (p<0.05) and after 20 (p<0.01), 30 and 60 minutes (p<0.05). FENO was reduced compared to baseline 5 and10 minutes (p<0.001) (p<0.01) after exercise in the normal tempered environment and after warm-up (p<0.001) and 5, 10 and 15 minutes (p<0.05) after exercise in the cold climate. Maximum reduction from baseline was 5 minutes after exercise; 30.7 % (±18.3)[mean(± SD)] in the cold environment and 28.5% (±19.0) in the normal environment. CONCLUSIONS: FENO is reduced after exercise both in normal and cold environment. A cold environment induces an initial decrease in FENO and was reduced until 60 minutes post exercise compare to normal environment.