ORIGINAL ARTICLE
Effects of the ‘live high–train low’ method on
prooxidant/antioxidant balance on elite athletes
V Pialoux
1, R Mounier
1, E Rock
2, A Mazur
2, L Schmitt
3, J-P Richalet
4, P Robach
5, J Brugniaux
4,
J Coudert
1and N Fellmann
11Laboratoire de Biologie des Activite´s Physiques et Sportives, Faculte´ de Me´decine, Universite´ d’Auvergne, Clermont-Ferrand, France; 2Equipe Stress Me´tabolique et Micronutriments, Unite´ de Nutrition Humaine UMR 1019, INRA, Saint Gene`s Champanelle, France; 3Centre National de Ski Nordique, ID Jacobeys, Pre´manon, France;4Laboratoire Re´ponses cellulaires et fonctionnelles a` l’hypoxie, Universite´ Paris 13, Bobigny, France and5Ecole Nationale de Ski et d’Alpinisme, Chamonix, France
Background/Objectives: We previously demonstrated that acute exposure to hypoxia (3 h at 3000 m) increased oxidative stress markers. Thus, by using the ‘living high–training low’ (LHTL) method, we further hypothesized that intermittent hypoxia associated with endurance training alters the prooxidant/antioxidant balance.
Subjects/Methods: Twelve elite athletes from the Athletic French Federation were subjected to 18-day endurance training. They were divided into two groups: one group (control group) trained at 1200 m and lived in hypoxia (2500–3000 m simulated altitude) and the second group trained and lived at 1200 m. The subjects performed an acute hypoxic test (10 min at 4800 m) before and immediately after the training. Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA), ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants normalized for triacylglycerols, and cholesterol and retinol were measured before and after the 4800 m tests.
Results: After the training, MDA and AOPP concentrations were decreased in response to the 4800 m test only for the control group. Eighteen days of LHTL induced a significant decrease of all antioxidant markers (FRAP, P ¼ 0.01; a-tocopherol, P ¼ 0.04; b-carotene, P ¼ 0.01 and lycopene, P ¼ 0.02) for the runners. This imbalance between antioxidant and prooxidant might result from insufficient intakes in vitamins A and E.
Conclusions: The LHTL model characterized by the association of aerobic exercises and intermittent resting hypoxia exposures decreased the antioxidant status whereas the normoxic endurance training induced preconditioning mechanisms in response to the 4800 m test.
European Journal of Clinical Nutrition (2009) 63, 756–762; doi:10.1038/ejcn.2008.30; published online 9 April 2008
Keywords: intermittent hypoxia; endurance training; oxidized lipids; AOPP; FRAP; a-tocopherol
Introduction
Since the 1970s, altitude training is frequently used by endurance athletes to improve their sea-level performance (Levine and Stray-Gundersen, 1997; Stray-Gundersen et al., 2001). Nevertheless, scientific studies showed conflicting results probably due to the complex adaptation of training load in hypoxia (Levine, 2002). The ‘living high–training low’ (LHTL) model purposed by Levine et al. (1991) reduces
the deleterious effects of altitude exposure during training caused by reduced exercise intensity. Indeed, LHTL is characterized by a continuous exposure to hypoxia during resting periods and by physical training sessions in normoxia.
Nowadays, it is clearly demonstrated that an acute physical exercise increases reactive oxygen species (ROS; Ji, 1996) and subsequent oxidative stress markers in the biological tissues (Vollaard et al., 2005). The positive correlation between the leakage of electrons in the mito-chondrial matrix from the II and III complexes and the oxygen flux is the most well-known hypothesis for explaining the ROS over generation during exercise (Sen, 2001). Additionally, other phenomena such as the activation of the enzymes nicotinamide adenine
Received 25 April 2007; revised 12 February 2008; accepted 28 February 2008; published online 9 April 2008
Correspondence: Dr N Fellmann, Laboratoire de Physiologie-Biologie du Sport, Faculte´ de Me´decine, 28 place Henri Dunant, Clermont-Ferrand 63000, France.
E-mail: pialouxvincent@yahoo.fr
dinucleotide phosphate oxidase and xanthine oxidase (Askew, 2002) could be also responsible for this ROS over production.
On other hand, periods of hypoxia could also cause an oxidative stress (Joanny et al., 2001; Bailey et al., 2001a; Wing et al., 2003). We previously demonstrated (unpublished data) that a 3-h exposure to hypoxia, at rest, at a simulated altitude of 3000 m induced an increase in oxidized lipids (malondialdehydes, MDA) and in advanced oxidation pro-teins products (AOPP) in elite endurance athletes known to have strong enzymatic antioxidant defenses (Robertson et al., 1991; Urso and Clarkson, 2003). Indeed, during hypoxia, ROS generation would be increased by mito-chondrial dysfunction causing an excessive leakage of electrons from the respiratory chain (Kehrer and Lund, 1994), by an enhancement of catecholamine production and by phospholipase A2 activation (Askew, 2002).
Consequently, the association of physical exercise and hypoxia exposure during LHTL training might induce an imbalance between prooxidant and antioxidant. Previous works show that the oxidative stress was accentuated during a training course at moderate altitude (Vasankari et al., 1997; Chao et al., 1999; Subudhi et al., 2004). Additionally, we previously described a weakening of antioxidant markers in plasma after a ‘living low–training high’ model (Pialoux et al., 2006). We concluded that the increase of prooxidant molecule production during such training led to an antioxidant consumption, which outmatched the anti-oxidant intake.
Therefore, the main goal of this study was to determine whether an LHTL model (using a normobaric hypoxia simulating an altitude of 2500–3000 m) modifies the anti-oxidant/prooxidant balance on the elite endurance athletes. To investigate the underlying mechanisms of this pheno-menon, we examined, after the LHTL training, exactly the same acute hypoxia test reported in our first article. We hypothesized that this type of training characterized by repeated aerobic exercise sessions and resting moderate hypoxia periods LHTL could weaken the resting antioxidant status and increase the values of oxidative stress markers (lipids and proteins derived) in response to the acute hypoxic test. The second aim was to determine whether the antioxidant intake was sufficient when compared with recommended values for this population.
We have tested elite endurance runners subjected to 18 days of LHTL.
Materials and methods
Subjects
The study was approved by the Necker Hospital Ethics Committee (Paris, France). After a complete medical examination and an echocardiography, written informed consent was obtained from all the subjects. All subjects were
low-altitude residents and were not acclimatized to altitude prior to the study.
Twelve elite middle-distance male runners were recruited from the national team of the French Athletic Federation. Means (s.e.m.) for age, height and body mass were 23.9 years (4.8), 177.2 cm (4.4) and 63.3 kg (3.2), respectively.
The subjects were divided into two groups of six subjects matched according to their maximal oxygen uptake (VO
2-max): a group subjected to LHTL (HG) and a control group (CG) subjected to a ‘living low–training low’ model, that is which undertook the same training as HG in normoxia without exposure to hypoxia during the resting periods. All runners participated either in International (World and European cups) trials.
Experimental design
Testing procedure and training sessions of the two studies were led in the Centre National de ski Nordique in Pre´manon (France) during the aerobic preparation period of athlete’s prior to the competitive season.
The subjects were subjected to 18-day period of supervised aerobic training with (HG) or without (CG) hypoxia exposure. The evaluation were conducted before (pre-train-ing period, PRE) and the first day after (post-train(pre-train-ing period, POST) the training period cessation (Figure 1).
Pre-training and post-training period. During these periods echocardiography, blood samplings, performance tests (VO
2-max and field trials) and hypoxia tolerance test (4800 m test) were carried out.
Training period
Runners. HG runners trained during 18 days (1 h per day) at the low altitude of Pre´manon (1200 m) spend resting and sleeping periods (14 h per day) in a hypoxic chamber at a simulated altitude of 2500 m for 6 nights and of 3000 m for
18 training days 3,000m 2,500m
1,200m
PRE POST
Control group Acute hypoxic tests
3 days 3 days
Hypoxic group Performance tests
Figure 1 Experimental design. PRE, pre-training period; POST,
post-training period. The black bars represent resting and sleeping periods in hypoxia for hypoxic group subjected to living high– training low. The open bars represent resting and sleeping periods in normoxia for control group and training sessions for the both groups.
the 12 subsequent nights. CG runners followed the same training program as HG runners and lived at the altitude of 1200 m. Complete protocol of the running session was described elsewhere (Brugniaux et al., 2006a).
Hypoxic rooms. Normobaric poikilocapnic hypoxia in the rooms was obtained through an oxygen extraction system (OBS, Husøysund, Norway). For safety reasons, air composi-tion (O2and CO2) of each hypoxic room was continuously
monitored by O2 and CO2 analyzers (OBS) as well as
nocturnal arterial oxygen saturation of each athlete by finger pulse oximetry (NPB-290, Nellcor Puritan Bennett, Pleasanton, CA, USA).
Hypoxia tolerance test. Hypoxia tolerance test (4800 m test), presented in Figure 2 and described in details in Brugniaux et al. (2006b), was carried out the morning after the breakfast, 3 days before and the first day after the training cessation. Briefly, this test is composed of four successive of 5-min stages on cycle ergometer (stage 1, normoxia at rest; stage 2, hypoxia at rest; stage 3, hypoxia at 30% of VO2max
and stage 4, normoxia at 30% of VO2max).
Performance tests. The subjects performed two aerobic performance tests (VO2max and a field test) the second
and the third days after the training. Complete description of performance tests was published elsewhere (Brugniaux et al., 2006a).
Measurements
Intake. The intake of vitamins E and A (retinol þ b-carotene) and percentage of energy intake of carbohydrates, lipids and proteins were determined from the dietary recording using GENI software (MICRO-6, Villers-le`s-Nancy, France) with French (Regal) and German (Souci) tables for food composi-tion. The diet was evaluated during the training period by
the estimation of food and beverage intake. The subjects had to record in their notebooks food intake as precisely as possible. All these data were validated using a specific picture book for the estimation of quantities (Le Moulenc et al., 1996).
Biochemical analysis. Blood was collected in sitting position from an antecubital vein in three 5 ml EDTA tubes for biochemical (plasma) and hematological (total blood) analyses in PRE and POST before and after the 4800 m test in sitting position.
We measured:
(1) Oxidative stress markers: plasma-oxidized lipids measured as MDA and plasma AOPP
(2) Antioxidant markers: plasma ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants (a-tocopherol, b-carotene and lycopene)
(3) Blood lipids: plasma triacylglycerols (TGs) and total cholesterol (CH)
(4) Hemoglobin concentration ([Hb]), hematocrit (Ht) and red-cell volume.
The complete description of biochemical and hemato-logical analyses was described in Pialoux et al. (2006).
Statistics
Statistical analyses were performed using Statview software (5.0, SAS Institute Inc., Cary, NC, USA). The values were expressed as means (s.e.m.) or percentage. A three-way repeated-measures analysis of variance (ANOVA) was used (two groups, CG and HG; two times, before and after the training; two conditions, rest and 4800 m test) followed by Tukey’s post hoc test.
Results
Effect of LHTL (PRE vs POST)
Runners trained 20 h for 18 days. Training data were not significantly different between CH and HG. Complete results concerning training data, hematology and performance were published elsewhere (Brugniaux et al., 2006a).
Biochemical responses
Plasma AOPP. The endurance training increased resting plasma AOPP concentration (PRE vs POST) for both groups ( þ 87%; Po0.001 for CG and þ 104%; P ¼ 0.002 for HG) (Tables 1 and 2).
In PRE, 4800 m test induced an AOPP rise in both groups ( þ 7%, P ¼ 0.03 for HG and þ 33%; P ¼ 0.01 for CG) whereas in POST, only HG increased plasma AOPP concentration after the same test ( þ 81%; P ¼ 0.01) (Figure 3).
Plasma MDA. As for AOPP concentration, the endurance training increased the resting plasma MDA (PRE vs POST) for
Rest Hypoxia Exercise Blood withdrawal
1,200m 4,800m 1,200m 30% VO2 max . 30% VO2 max . Exercise 5 min Stage IV Stage III Stage II Stage I 5 min 5 min 5 min Rest
Figure 2 Short-time 4800 m test procedure. Stage I, resting period
in normoxia; stage II, resting period in hypoxia (FiO2¼ 0.115); stage
III, exercise (30% of VO2max) under hypoxia and stage IV, exercise
(30% of VO2max) in normoxia.
both groups ( þ 28%; P ¼ 0.02 for CG and þ 62%; P ¼ 0.002 for HG). This increase was significantly higher in HG than in CG (P ¼ 0.02). Only before training, the 4800 m test induced a significant increase in both groups ( þ 4%; P ¼ 0.04 for HG and þ 4%; P ¼ 0.04 for CG) (Tables 1 and 2).
Plasma FRAP. Eighteen days of LHTL induced a decrease in resting antioxidant power (HG, 20%; P ¼ 0.01) whereas FRAP values were not altered by the normoxic training. Moreover, FRAP was significantly lower (P ¼ 0.04) in HG than in CG after the training whereas we did not find any differences before the training (Figure 4).
Regardless the training model (normoxia vs LHTL) and the period (PRE vs POST), FRAP was not significantly modified by the 4800 m test (Tables 1 and 2).
Lipids-soluble antioxidants. As for FRAP, 18 days of LHTL induced a decrease in resting a-tocopherol (HG runners, 18%; P ¼ 0.04), a-tocopherol/triacylglycerols (TG) ratio (26%; P ¼ 0.005) and a-tocopherol/CH ratio (35%; P¼ 0.02) whereas these values were not altered by the normoxic training (Figure 4). On the contrary, regardless the training model (normoxia vs LHTL) and the period (PRE vs POST), a-tocopherol/TG and a-tocopherol/CH ratios were not significantly modified by 4800 m test (Tables 1 and 2).
As for a-tocopherol, its resting lycopene (37%; P ¼ 0.01) and b-carotene (15%; P¼ 0.03) concentrations only decreased for HG runners after LHTL training.
Retinol. As expected, plasma retinol concentrations were not modified regardless the conditions and the groups (Tables 1 and 2).
Table 1 Effects of ‘living low–training low’ regimen in runners (CG) on MDA, selected lipids-soluble non-enzymatic antioxidant markers, TG and CH at
rest and after the 4800 m test
ANOVA CG runners
PRE POST
Rest 4800 m test Rest 4800 m test
Mean s.e.m. Mean s.e.m. Mean s.e.m. Mean s.e.m.
MDA (mmol/l) Po0.05 1.67 0.04 1.73* 0.04 2.71w 0.08 2.18 0.19
CH (mmol/l) Po0.05 4.14 0.22 4.55* 0.14 4.61w 0.17 5.46w 0.59 TG (mmol/l) Po0.05 1.02 0.11 1.12 0.05 0.94 0.15 1.43* 0.29 a-Tocopherol/TG (mmol/mol TG) NS 23.4 3.1 21.3 4.2 28.7 4.2 21.1 3.4 a-Tocopherol/CH (mmol/mol CH) NS 5.49 0.60 5.23 0.64 6.23 0.54 5.06 0.66 Retinol (mmol/l) NS 0.51 0.04 0.55 0.06 0.53 0.05 0.54 0.02 Lycopene (mmol/l) NS 0.27 0.04 0.25 0.03 0.31 0.09 0.27 0.03 b-Carotene (mmol/l) NS 0.43 0.06 0.50* 0.03 0.38 0.13 0.40 0.07
Abbreviations: ANOVA, analysis of variance; CH, cholesterol; MDA, malondialdehydes; NS, not significant; TG, triacylglycerols. Values are means (s.e.m.) for six runners. Significance of differences: *Po0.05 vs rest, andw
Po0.05 vs PRE.
Table 2 Effects ‘living high–training low’ regimen in runners (HG) on MDA, selected lipids-soluble non-enzymatic antioxidant markers, TG and CH at
rest and after the 4800 m test
ANOVA HG runners
PRE POST
Rest 4800 m test Rest 4800 m test
Mean s.e.m. Mean s.e.m. Mean s.e.m. Mean s.e.m.
MDA (mmol/l) Po0.05 1.70 0.07 1.77* 0.07 2.17w 0.21 2.14 0.21
CH (mmol/l) Po0.05 4.76 0.19 5.11* 0.14 5.96w 0.57 5.36 0.63
TG (mmol/l) Po0.01 0.67 0.09 0.80 0.09 1.24ww 0.20 1.44 0.21
a-Tocopherol/TG (mmol/mol TG) Po0.01 33.8 8.0 33.8 4.8 25.1ww 5.0 22.2 4.4
a-Tocopherol/CH (mmol/mol CH) Po0.05 5.32 0.44 5.00 0.32 3.45w 0.54 5.00 0.44
Retinol (mmol/l) NS 0.47 0.05 0.53 0.04 0.56 0.05 0.53 0.06
Lycopene (mmol/l) Po0.05 0.38# 0.03 0.35 0.03 0.24w# 0.02 0.25 0.02
b-Carotene (mmol/l) Po0.05 0.53 0.04 0.59* 0.03 0.45w 0.05 0.56 0.10
Abbreviations: ANOVA, analysis of variance; CH, cholesterol; MDA, malondialdehydes; NS, not significant; TG, triacylglycerols. Values are means (s.e.m.) for six runners. Significance of differences: *Po0.05 vs rest,w
Po0.05 andww
Po0.01 vs PRE and#Po0.05 vs CG corresponding values (see
Table 3).
Vitamins A and E intake. The daily intake values are presented in Table 3.
Vitamins A and E intake represented respectively 76 and 53% of recommended daily allowance (RDA).
The percentage of lipids for the runners was lower (21%) and the percentage of carbohydrates was higher (59%) than RDA.
Discussion
As we hypothesized, intense normoxic training associated with resting exposures to hypoxia during a long period (18 days) worsened the antioxidant capacities of the runners.
By mobilizing the antioxidant defenses to neutralize ROS overgeneration during normoxic training sessions and periods spent under hypoxia, the runners subjected to 18 days of LHTL may have decreased their resting antioxidant capacities as illustrated by the decrease in FRAP, a-tocopherol, lycopene and b-carotene. On the contrary, the same training without hypoxia exposure had no effect on the antioxidant capacities. These results suggest that a running training associated with hypoxia exposure was too severe for main-taining plasma antioxidant status.
In this context, the post-training a-tocopherol values of HG runners, 35% under the normal range (31 mmol/l; Hercberg et al., 2004), were similar to the serum smoker’s values (20 mmol/l) known to be pathological (Kharb et al., 2001).
Physical exercise and hypoxia exposure are able to increase ROS. We previously found in the same individual athletes before training that a 3-h exposure to the simulated altitude of 3000 m at rest induced an increase in plasma oxidative stress markers and a transient decrease in non-enzymatic antioxidant values (FRAP and, a-tocopherol/TG ratio; unpublished data).
Moreover, the oxidative stress induced by physical exercise is well described in the literature (Vollaard et al., 2005). The increase of oxygen flux occurring in mitochondria can lead to an overproduction of superoxide anion (O2
K ) and 0 100 200 300 400 500 †† ††
**
CG HG ††**
*
†† AOPP (micromol/l) POST 4,800m POST at rest PRE 4,800m PRE at restFigure 3 Effects of ‘living high–training low’ (HG) and ‘living low–
training low’ (CG) regimen in swimmers and runners on plasma advanced oxidation protein products (AOPP), at rest and after the 4800 m test. Values are means (s.e.m.) for CG (n ¼ 6) and HG (n ¼ 6). Significance of differences: *Po0 05 and **Po0 01 vs rest,
w
Po0 05 andww
Po0 01 vs pre-training period (PRE).
CG HG 400 500 600 700 800 900 1000 FRAP (millimol/l) PRE POST † 15 17 19 21 23 25 27 29 α -tocopherol (micromol/l) PRE POST †
Figure 4 Effects of ‘living high–training low’ (HG) and ‘living low–
training low’ (CG) regimen on plasma ferric-reducing antioxidant power (FRAP) and a-tocopherol, at rest. Values are means (s.e.m.) for
CG (n ¼ 6) and HG (n ¼ 6). Significance of differences:wPo0.05 vs
pre-training period (PRE).
Table 3 Daily vitamins A and E intakes and percentage of lipids and
carbohydrates in the energy contribution of swimmers and runners
Training period RDA CNI
HG (n ¼ 6) CG (n ¼ 6)
Mean s.e.m. Mean s.e.m.
Vitamin A (RE per day) 457 30 489 30 600 200
Vitamin E (mg per day) 6.2* 0.3 6.5* 0.2 12 12
Lipids (%) 21* 2 20* 2 30 —
Carbohydrates (%) 59 3 61 4 50 —
Abbreviations: CNI, complementary nutritional intakes; RDA, recommended daily allowances; RE, retinol.
Values are means (s.e.m.). RE, RDA and CNI (ASSFA, 2003). RDA is calculated on the basis of a daily energetic expenditure of 9196 kJ per day. CNI have to be added to RDA for each 4800 kJ per day spent above 9196 kJ per day. Significance of differences: *Po0.05 vs RDA.
oxygen-derived intermediates (Sen, 1995). Although Clarkson and Thompson (2000) and Miyazaki et al. (2001) showed that endurance training improved the antioxidant enzymatic response, the excess of ROS produced during oxidative stress periods may partially deplete the antioxidant pool. We recently reported in highly trained runners a decrease in antioxidant parameters after repetition of oxidative stimuli (intense hypoxic exercises) during 6 weeks (Pialoux et al., 2006).
In this context, an antioxidant supplementation during intense training could maintain physiological antioxidant values and limit ROS damages induced by physical exercise (Schroder et al., 2000; Goldfarb et al., 2005; Morillas-Ruiz et al., 2006). However, the efficiency of antioxidant on the cellular protection against ROS has not yet been fully established. Indeed, oxidative stress induced by 14 days at high altitude was not diminished, as well at rest as after submaximal exercise, after 3 weeks of antioxidant supple-mentation (Subudhi et al., 2004). Nevertheless, in demon-strating that antioxidant supplementation was effective only if it is combined with endurance training, the results of Marsh et al. (2006) may explain these controversial reports.
Although we failed to find correlation between vitamin intake and plasma antioxidant, we speculate that the increase in demand of antioxidant during LHTL caused by the repetitions of normoxic exercise and moderate hypoxia exposure could reduce the antioxidant pool if the non-enzymatic antioxidant dietary does not match their utiliza-tion (Sen, 2001).
The intake in selected lipid-soluble antioxidant like vitamins A (sum of retinol and b-carotene) and E for our subjects was not enough when compared to the recom-mended allowances and definitely insufficient if we con-sidered from the dietary recording that our subjects daily spent more energy than 2200 kcal (Table 3) (ASSFA, 2003). The deficit in vitamins A and E could be explained by the intake of lipids (the most suppliers in lipid-soluble vitamins) that were lower than those recommended (Table 3) and by the lack of supplementation in antioxidants. Indeed, the strategy of a lipid reduction in the diet during the aerobic preparation periods to lose fat mass is frequently used by elite endurance runners (Burke et al., 2003).
Additionally, the resting oxidative stress values seem to confirm the antioxidant status levels. Indeed, after training the HG strongly increased both markers ( þ 104% for AOPP and þ 62% for MDA). These resting oxidative stress increases were already reported by Chao et al. (1999) in trained US marines subjected to moderate altitude (approximately 3000 m) during strenuous work. Moreover, both AOPP and MDA concentrations measured after training were close to those reported for chronic renal failure or hemodialysis patients (Witko-Sarsat et al., 1996; Mezzano et al., 2001). On the contrary, the swimmers exhibited post-training values similar to healthy subjects (Mezzano et al., 2001).
As for their antioxidant status levels, HG increased their values of oxidative stress in response to acute hypoxia stress (4800 m test) after the training (Table 2). This result
corroborates those of Palazzetti et al. (2003) who observed higher values in MDA following a normoxic maximal exercise after an overloaded training period. Because of the antioxidant status decrease, the HG runners were less efficient to neutralize the excess of ROS produced during the 4800 m test.
In the control group, post-training plasma oxidative damages (MDA and AOPP) were not affected in response to 4800 m test whereas they increased in pre-training. Improve-ment of antioxidant defenses and decrease in oxidative stress are usually observed after endurance training performed at sea level (Ohno et al., 1988; Robertson et al., 1991; Di Massimo et al., 2004). Although the subjects were highly trained athletes, the runners significantly increased their daily training volume during the intervention ( þ 45%) compared to their usual training (Brugniaux et al., 2006a). In this context, Miyazaki et al. (2001) reported that the decreased in plasma MDA in response to exhausting exercise after 12-week endurance training was mainly explained by antioxidant enzyme activity increase.
Furthermore, these results could also be assimilated to the mechanism of preconditioning to hypoxia observed in rats by Chen et al. (2003). They demonstrated that chronic exposure to high altitude (5500 m, 15 h a day during 4 weeks) attenuated the renal response to free radicals in rats subjected to oxidative stress and concluded that this adaptation was due to higher superoxide dismutase activity. In this context, the ROS overproduced in hypoxia seem to improve the antioxidant gene expression to limit its subsequent cellular damages (Das and Maulik, 2006).
In conclusion, the repetition of aerobic training sessions in normoxia associated with resting exposure to hypoxia was responsible for a decrease in antioxidant in the plasma probably enhanced by too low intakes of lipid-soluble antioxidants. Nevertheless, the reduction of the stimulus load (that is, lower duration of the training and/or lack of additional hypoxia exposure) allowed maintaining the plasma antioxidant status at the baseline level.
Further studies are required to investigate whether an antioxidant supplementation could balance antioxidant status in athletes subjected to intense and prolonged training associated with hypoxia.
Acknowledgements
We thank the subjects for their contribution. We also thank Clark Ellice for reviewing the paper. This study was funded by the International Olympic Committee, the Ministe`re des sports franc¸ais and the Direction Re´gionale de la Jeunesse et des Sports de la Re´gion Auvergne.
References
Askew EW (2002). Work at high altitude and oxidative stress: antioxidant nutrients. Toxicology 180, 107–119.
ASSFA (2003). Comple´ments et supple´ments pour le sportif.In: Martin A (ed). Apports nutritionnels conseille´s pour la population franc¸aise, 3rd edn. Tec et Doc: Paris. pp 380–382.
Bailey DM, Davies B, Young IS, Hullin DA, Seddon PS (2001a). A potential role for free radical-mediated skeletal muscle soreness in the pathophysiology of acute mountain sickness. Aviat Space Environ Med 72, 513–521.
Brugniaux JV, Schmitt L, Robach P, Jeanvoine H, Zimmermann H, Nicolet G et al. (2006b). Living high–training low: tolerance and acclimatization in elite endurance athletes. Eur J Appl Physiol 96, 66–77.
Brugniaux JV, Schmitt L, Robach P, Nicolet G, Fouillot JP, Moutereau S et al. (2006a). Eighteen days of ‘living high, training low’ stimulate erythropoiesis and enhance aerobic performance in elite middle-distance runners. J Appl Physiol 100, 203–211.
Burke LM, Slater G, Broad EM, Haukka J, Modulon S, Hopkins WG (2003). Eating patterns and meal frequency of elite Australian athletes. Int J Sport Nutr Exerc Metab 13, 521–538.
Chao WH, Askew EW, Roberts DE, Wood SM, Perkins JB (1999). Oxidative stress in humans during work at moderate altitude. J Nutr 129, 2009–2012.
Chen CF, Tsai SY, Ma MC, Wu MS (2003). Hypoxic preconditioning enhances renal superoxide dismutase levels in rats. J Physiol 552, 561–569.
Clarkson PM, Thompson HS (2000). Antioxidants: what role do they play in physical activity and health? Am J Clin Nutr 72, 637–646. Das DK, Maulik N (2006). Cardiac genomic response following
preconditioning stimulus. Cardiovasc Res 70, 254–263.
Di Massimo C, Scarpelli P, Penco M, Tozzi-Ciancarelli MG (2004). Possible involvement of plasma antioxidant defences in training-associated decrease of platelet responsiveness in humans. Eur J Appl Physiol 91, 406–412.
Goldfarb AH, Bloomer RJ, McKenzie MJ (2005). Combined antiox-idant treatment effects on blood oxidative stress after eccentric exercise. Med Sci Sports Exerc 37, 234–239.
Hercberg S, Galan P, Preziosi P, Bertrais S, Mennen L, Malvy D et al. (2004). The SU.VI.MAX Study: a randomized, placebo-controlled trial of the health effects of antioxidant vitamins and minerals. Arch Intern Med 164, 2335–2342.
Ji LL (1996). Exercise, oxidative stress, and antioxidants. Am J Sports Med 24, 20–24.
Joanny P, Steinberg J, Robach P, Richalet JP, Gortan C, Gardette B et al. (2001). Operation Everest III (Comex’97). The effect of simulated sever hypobaric hypoxia on lipid peroxidation and antioxidant defence systems in human blood at rest and after maximal exercise. Resuscitation 49, 307–314.
Kharb S, Singh V, Ghalaut PS, Sharma A, Singh GP (2001). Plasma lipid peroxidation and vitamin E levels in smokers. Indian J Med Sci 55, 309–312.
Kehrer JP, Lund LG (1994). Cellular reducing equivalents and oxidative stress. Free Radic Biol Med 17, 65–75.
Le Moulenc N, Deheeger M, Preziosi P, Monterio P, Valeix P, Rolland-Cachera MF et al. (1996). Validation du manuel photo utilise´ dans l’enqueˆte alimentaire SU.VI.MAX. Cah Nutr Diet 3, 158–164. Levine BD (2002). Intermittent hypoxic training: fact and fancy. High
Alt Med Biol 3, 177–193.
Levine BD, Stray-Gundersen J (1997). ‘Living high–training low’: effect of moderate-altitude acclimatization with low-altitude training on performance. J Appl Physiol 83, 102–112.
Levine BD, Stray-Gundersen J, Duhaime G, Schell PG, Friedman DB (1991). ‘Living high–training low’: the effect of altitude
acclima-tization/normoxic training in trained runners. Med Sci Sports Exerc 23, S25.
Marsh SA, Laursen PB, Coombes JS (2006). Effects of antioxidant supplementation and exercise training on erythrocyte antioxidant enzymes. Int J Vitam Nutr Res 76, 324–331.
Mezzano D, Pais EO, Aranda E, Panes O, Downey P, Ortiz M et al. (2001). Inflammation, not hyperhomocysteinemia, is related to oxidative stress and hemostatic and endothelial dysfunction in uremia. Kidney Int 60, 1844–1850.
Miyazaki H, Oh-ishi S, Ookawara T, Kizaki T, Toshinai K, Ha S et al. (2001). Strenuous endurance training in humans reduces oxidative stress following exhausting exercise. Eur J Appl Physiol 84, 1–6.
Morillas-Ruiz JM, Villegas Garcia JA, Lopez FJ, Vidal-Guevara ML, Zafrilla P (2006). Effects of polyphenolic antioxidants on exercise-induced oxidative stress. Clin Nutr 25, 444–453.
Ohno H, Yahata T, Sato Y, Yamamura K, Taniguchi N (1988). Physical training and fasting erythrocyte activities of free radical scaven-ging enzyme systems in sedentary men. Eur J Appl Physiol Occup Physiol 57, 173–176.
Palazzetti S, Richard MJ, Favier A, Margaritis I (2003). Overloaded training increases exercise-induced oxidative stress and damage. Can J Appl Physiol 28, 588–604.
Pialoux V, Mounier R, Ponsot E, Rock E, Mazur A, Dufour S et al. (2006). Effects of exercise and training in hypoxia on antioxidant/ prooxidant balance. Eur J Clin Nutr 60, 1345–1354.
Robertson JD, Maughan RJ, Duthie GG, Morrice PC (1991). Increased blood antioxidant systems of runners in response to training load. Clin Sci (London) 80, 611–618.
Schroder H, Navarro E, Tramullas A, Mora J, Galiano D (2000). Nutrition antioxidant status and oxidative stress in professional basketball players: effects of a three compound antioxidative supplement. Int J Sports Med 21, 146–150.
Sen CK (1995). Oxidants and antioxidants in exercise. J Appl Physiol 79, 675–686.
Sen CK (2001). Antioxidants in exercise nutrition. Sports Med 31, 891–908.
Stray-Gundersen J, Chapman RF, Levine BD (2001). ‘Living high– training low’: altitude training improves sea level performance in male and female elite runners. J Appl Physiol 91, 1113–1120. Subudhi AW, Jacobs KA, Hagobian TA, Fattor JA, Fulco CS, Muza SR
et al. (2004). Antioxidant supplementation does not attenuate oxidative stress at high altitude. Aviat Space Environ Med 75, 881–888.
Urso ML, Clarkson PM (2003). Oxidative stress, exercise, and antioxidant supplementation. Toxicology 189, 41–54.
Vasankari TJ, Kujala UM, Rusko H, Sarna S, Ahotupa M (1997). The effect of endurance exercise at moderate altitude on serum lipid peroxidation and antioxidative functions in humans. Eur J Appl Physiol Occup Physiol 75, 396–399.
Vollaard NB, Shearman JP, Cooper CE (2005). Exercise-induced oxidative stress: myths, realities and physiological relevance. Sports Med 35, 1045–1062.
Wing SL, Askew EW, Luetkemeier MJ, Ryujin DT, Kamimori GH, Grissom CK (2003). Lack of effect of Rhodiola or oxygenated water supplementation on hypoxemia and oxidative stress. Wilderness Environ Med 14, 9–16.
Witko-Sarsat V, Friedlander M, Capeille`re-Blandin C, Nguyen-Khoa T, Nguyen AT, Zingraff J et al. (1996). Advanced oxidation protein products as a novel marker of oxidative stress in uremia. Kidney Int 49, 1304–1313.
