Heightened Exercise-Induced Oxidative Stress at Simulated Moderate Level Altitude vs. Sea Level in Trained Cyclists

Abstract

Page 1 of 9 However, these responses have not been monitored in endurance-trained cyclists at altitudes typically experienced while training. Endurance trained males (n = 12; mean (± SD) age: 28 ± 4 years, V O2max 63.7 ± 5.3 ml/kg/min) undertook two 75-min exercise trials at 70% relative V O2max; once in normoxia and once in hypobaric hypoxia, equivalent to 2000m above sea level (hypoxia). Blood samples were collected before, immediately after and 2 h postexercise to assess plasma parameters of oxidative stress (protein carbonylation (PC), thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC) and catalase activity (CAT)). Participants cycled at 10.5% lower power output in hypoxia vs. normoxia, with no differences in heart rate, blood lactate or rating of perceived exertion observed. PC increased and decreased immediately after exercise in hypoxia and normoxia respectively (nmol/mg/protein: Normoxia-0.3 ± 0.1, Hypoxia + 0.4 ± 0.1; both p < .05). CAT increased immediately postexercise in both trials, with the magnitude of change greater in hypoxia (nmol/min/ml: Normoxia + 12.0 ± 5.0, Hypoxia + 27.7 ± 4.8; both p < .05). CAT was elevated above baseline values at 2 h postexercise in Hypoxia only (Normoxia + 0.2 ± 2.4, Hypoxia + 18.4 ± 5.2; p < .05). No differences were observed in the changes in TBARS and TAC between hypoxia and normoxia. Trained male cyclists demonstrated a differential pattern/ timecourse of changes in markers of oxidative stress following submaximal exercise under hypoxic vs. normoxic conditions.

Thirty Minutes of Hypobaric Hypoxia Provokes Alterations of Immune Response, Haemostasis, and Metabolism Proteins in Human Serum

“…In the present study, expression of CAT was decreased after hypobaric hypoxia. Wadley et al also found changes in the expression of CAT in the serum in cyclists at altitude but an up-regulation and not a down-regulation [ 27 ]. This is in congruency to the results of Krzeszowlak et al who also found increased CAT activity after a nine-day exposure to high-altitude conditions [ 26 ].…”

Nutrition and Altitude: Strategies to Enhance Adaptation, Improve Performance and Maintain Health: A Narrative Review

“…The excessive overproduction of RONS, in excess of the endogenous antioxidant defense systems, can cause damage to lipids, proteins and DNA which may impair cell and immune function, resulting in delayed post-exercise recovery [74]. Both acute [75, 76] and chronic exposure to hypoxia [72, 77, 78] augments oxidative stress in well-trained athletes, while reduced antioxidant capacity may persist for up to 2 weeks following altitude training [79]. Interestingly, normobaric hypoxia appears to produce a larger increase in oxidative stress than hypobaric hypoxia [80], while a recent study in a team sport setting showed no impact of intermittent hypoxia on biomarkers of oxidative stress [81].…”

Inflammation, Peripheral Signals and Redox Homeostasis in Athletes Who Practice Different Sports

“…McGinnis et al [50] simulated altitude in an environmental chamber and they found an increase in LPE after cycling at 60% at an altitude of 3000 m in comparison to 975 m of altitude. Recently, Wadley et al [51] evaluated the independent effect on OS of acute exercise and hypoxic exposure comparing two different training habits: sea level and 2000 m above sea level. At the same exercise intensity and immediately post-exercise, at high level, there is an increase in plasma CA activity and total protein carbonylation (PC) content in comparison to sea level and the authors reported a decrease in PC when the exercise was performed in normoxia.…”