Work at high altitude and oxidative stress: antioxidant nutrients

Askew, E. W.

doi:10.1016/s0300-483x(02)00385-2

Cited by 211 publications

(149 citation statements)

References 43 publications

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“…In mitochondria, the lower oxygen molecule available to accept electrons from oxidative phosphorylation enhances reducing equivalents and resulting in reduction of molecular oxygen to anion superoxide (Kehrer and Lund, 1994;Mohanraj et al, 1998). Moreover, as our blood samplings were performed after the hypoxic exposure, the reoxygenation of hypoxic tissue may have enhanced the O 2 flux in the mitochondria and the subsequent free radical production, as described after ischemia reperfusion (Askew, 2002).…”

Section: Effects Of Maximal Exercise Under Normobaric Hypoxia and Normentioning

confidence: 99%

“…Additionally, in hypoxia, the reduction of mitochondria potential redox owing to an accumulation of reducing equivalent which cannot be transferred to oxygen by cytochrome oxidase (Kehrer and Lund, 1994) also enhances ROS production. Finally, after the return in normoxia, the hypoxia/reoxygenation cycle similar to ischemia/reperfusion in flooding the anoxic tissue with oxygen, can exacerbate free radical generation (Askew, 2002).…”

Section: Kàmentioning

confidence: 99%

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Effects of exercise and training in hypoxia on antioxidant/pro-oxidant balance

Pialoux¹,

Mounier²,

Ponsot

et al. 2006

Eur J Clin Nutr

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Objective: The aim was to investigate the effects of acute exercise under hypoxic condition and the repetition of such exercise in a 'living low-training high' training on the antioxidant/prooxidant balance. Design: Randomized, repeated measures design. Setting: Faculté de Médecine, Clermont-Ferrand, France. Subjects: Fourteen runners were randomly divided into two groups. A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training. Intervention: A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training. The first hypoxic group (HG, n ¼ 8) carried out these sessions under hypoxia (3000 m simulated altitude) and the second normoxic group (NG, n ¼ 6) in normoxia. In control period, the runners were submitted to two incremental cycling tests performed in normoxia and under hypoxia (simulated altitude of 3000 m). Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA) and lipid oxidizability, ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants (a-tocopherol and b-carotene) normalized for triacyglycerols and cholesterol were measured before and after the two incremental tests and at rest before and after training. Results: No significant changes of MDA and AOPP level were observed after normoxic exercise, whereas hypoxic exercise induced a 56% rise of MDA and a 44% rise of AOPP. Plasma level of MDA and arterial oxygen hemoglobin desaturations after the acute both exercises were highly correlated (r ¼ 0.73). a-Tocopherol normalized for cholesterol and triacyglycerols increased only after hypoxic exercise (10-12%, Po0.01). After training, FRAP resting values (À21%, Po0.05) and a-tocopherol/ triacyglycerols ratio (À24%, Po0.05) were diminished for HG, whereas NG values remained unchanged. Conclusions: Intense exercise and hypoxia exposure may have a cumulative effect on oxidative stress. As a consequence, the repetition of such exercise characterizing the 'living low-training high' model has weakened the antioxidant capacities of the athletes. Sponsorship: International Olympic Committee and the Direction Régionale de la Jeunesse et des Sports de la Région Auvergne.

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Section: Effects Of Maximal Exercise Under Normobaric Hypoxia and Normentioning

confidence: 99%

Section: Kàmentioning

confidence: 99%

Effects of exercise and training in hypoxia on antioxidant/pro-oxidant balance

Pialoux¹,

Mounier²,

Ponsot

et al. 2006

Eur J Clin Nutr

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“…On the other hand, acute physical work per se is a contributor to oxidative stress where mitochondria represent the major source of free radicals (Bailey et al 2001;Bailey et al 2004;Sen 1995). Apart from excercise, additional stressors increase oxidative stress at altitude, such as exposure to ultra violet light, lack of dietary antioxidants, cold climate, increased xanthine oxidase activation and catecholamine production, as well as increased reductive stress and generation of free radicals through anoxia/reoxygenation (Askew 2002 (Horvath et al 2005). In addition, maintenance of redox state depends on the efficiency of antioxidant defense systems and the amount of ROS generated.…”

Section: Introductionmentioning

confidence: 99%

Moderate altitude but not additional endurance training increases markers of oxidative stress in exhaled breath condensate

et al. 2009

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Oxidative stress occurs at altitude, and physical exertion might enhance this stress. In the present study, we investigated the combined effects of exercise and moderate altitude on redox balance in ten endurance exercising biathletes, and five sedentary volunteers during a 6 week stay at 2800 m. As a marker for oxidative stress, hydrogen peroxide (H 2 O 2 ) was analyzed by the biosensor measuring system Ecocheck TM , and 8-iso prostaglandin F2α (8-iso PGF2α) was determined by enzyme immunoassay in exhaled breath condensate (EBC). To determine the whole blood antioxidative capacity, we measured reduced glutathione (GSH) enzymatically using Ellman's reagent. Exercising athletes and sedentary volunteers showed increased levels of oxidative markers at moderate altitude, contrary to our expectations, there was no difference between both groups. Therefore, all subjects' data were pooled to examine the oxidative stress response exclusively due to altitude exposure. H 2 O 2 levels increased at altitude and remained elevated for 3 days after returning to sea level (p ≤ 0.05). On the other hand, 8-iso PGF2α levels showed a tendency to increase at altitude, but declined immediately after returning to sea level (p ≤ 0.001).Hypoxic exposure during the first day at altitude resulted in elevated GSH levels (p ≤ 0.05), that decreased during prolonged sojourn at altitude (p ≤ 0.001). In conclusion, a stay at moderate altitude for up to 6 weeks increases markers of oxidative stress in EBC independent of additional endurance training. Notably, this oxidative stress is still detectable 3 days upon return to sea level.

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“…Por otro lado, se conoce también que vivir en la altura conlleva a un incrementado estado de generación de ROS y de consumo de antioxidantes 40 . En el campo de la preeclampsia, existen varios trabajos, incluidos los nuestros [41][42][43][44][45] , en los que se señala una incrementada generación de ROS y consumo de antioxidantes en muestras de mujeres con preeclampsia.…”

Section: A R T í C U L Ounclassified