Moderate altitude but not additional endurance training increases
oxidative stress in man
Abstract
The effects of moderate altitude and exercise on redox balance were investigated in ten endurance exercising biathletes and five sedentary volunteers during a 6 week training camp at 2800 m. As marker for oxidative stress, hydrogen peroxide (H2O2) was analyzed by the biosensor measuring system EcocheckTM and 8- iso prostaglandin F2α (8-iso PGF2a) was measured by enzyme immunoassay in exhaled breath condensate. To determine the whole blood antioxidative capacity, we measured reduced glutathione (GSH) by the enzymatic method using Ellman's reagent. Exercising athletes and sedentary volunteers showed increased levels of oxidative markers at moderate altitude, however, there were no differences between the groups. Therefore, subject's data were pooled to examine the oxidative stress response due to exposure to altitude only. H2O2 significantly increased at altitude and continued to be elevated 3
days after returning to sea level (71 ± 41 to 142 ± 65, 153 ± 83 nmol/l respectively; p ≤ 0.05). 8-iso PGF2a showed a tendency to increased levels during the sojourn at altitude and was significantly decreased immediately after returning to sea level (2.81 ± 0.75 to 3.51 ± 1.53, 1.87 ± 0.51 pg/ml respectively p = 0.05). Hypoxic exposure during the first 24 h at altitude resulted in a significantly increase in GSH levels (4.62 ± 0.87 to 5.40 ± 0.82 µmol/g Hb, p = 0.05), while GSH significantly decreased at altitude. In conclusion, moderate altitude increases oxidative stress independent of additional endurance training. Of note, oxidative stress is still detectable 3 days upon return to sea level.
