Exhaled nitric oxide concentration in the period of 60 min after submaximal exercise in the cold

Abstract

Background: Fractional expired nitric oxide (FENO ) is decreased after exercise. The effect of exercise in the cold upon FENO is unknown.

Purpose: To examine changes in FENO after a short, high intensive exercise test in a cold and in a temperate environment.

Methods: Twenty healthy well-trained subjects (eight females) aged 18-28 years performed an 8-min exercise test at 18°C (SD = 1.0) and -10°C (SD = 1.2) ambient temperature. The tests were performed in a climate chamber in random order. The workload corresponded to 90-95% of peak heart rate (HRpeak ) during the last 4 min. FENO was measured offline. Exhaled gas was sampled in Mylar(®) bags using a collector kit with a flow restrictor and analysed within 2 h. FENO was measured before exercise and repeatedly during the first hour after. ANOVA for repeated measures was used to compare differences in FENO after exercise between environments.

Results: There was no difference in baseline FENO . A significant difference in FENO between environments was found after warm-up and from 20 to 30 min after exercise, with FENO being lower after exercise in the cold (P<0.05). The maximal reduction in FENO was seen 5 min after exercise and was not different between environments.

Conclusion: Recovery of FENO was slower after exercising in -10°C compared with 18°C.

Keywords: cold environment; exercise; exhaled nitric oxide; temperate environment.