Browsing by Autor "R. Favier"

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Adaptive changes in cardiac myosin heavy chain and creatine kinase isozymic profiles in rats native of altitude
(Wiley, 2005) A. Letout; M. Solares‐Espinoza; P. Mateo; Nathalie Koulmann; Lahoucine Bahi; B. Serrurier; R. Favier; Renée Ventura‐Clapier; Xavier Bigard
This study demonstrates that rats native and living at altitude for several generations present some features relevant to genetic selection to altitude.
Body fluid homeostasis and cardiovascular adjustments during submaximal exercise: influence of chewing coca leaves
(Springer Science+Business Media, 1997) Hilde Spielvogel; Armando Rodríguez; B. Semporé; Esperanza Cáceres; J. M. Cottet-Émard; Laurent Guillon; R. Favier
Coca chewing for exercise: hormonal and metabolic responses of nonhabitual chewers
(American Physiological Society, 1996) R. Favier; Esperanza Cáceres; Laurent Guillon; B. Semporé; Michel Sauvain; H. Koubi; Hilde Spielvogel
To determine the effects of acute coca use on the hormonal and metabolic responses to exercise, 12 healthy nonhabitual coca users were submitted twice to steady-state exercise (approximately 75% maximal O2 uptake). On one occasion, they were asked to chew 15 g of coca leaves 1 h before exercise, whereas on the other occasion, exercise was performed after 1 h of chewing a sugar-free chewing gum. Plasma epinephrine, norepinephrine, insulin, glucagon, and metabolites (glucose, lactate, glycerol, and free fatty acids) were determined at rest before and after coca chewing and during the 5th, 15th, 30th, and 60th min of exercise. Simultaneously to these determinations, cardiorespiratory variables (heart rate, mean arterial blood pressure, oxygen uptake, and respiratory gas exchange ratio) were also measured. At rest, coca chewing had no effect on plasma hormonal and metabolic levels except for a significantly reduced insulin concentration. During exercise, the oxygen uptake, heart rate, and respiratory gas exchange ratio were significantly increased in the coca-chewing trial compared with the control (gum-chewing) test. The exercise-induced drop in plasma glucose and insulin was prevented by prior coca chewing. These results contrast with previous data obtained in chronic coca users who display during prolonged submaximal exercise an exaggerated plasma sympathetic response, an enhanced availability and utilization of fat (R. Favier, E. Caceres, H. Koubi, B. Sempore, M. Sauvain, and H. Spielvogel. J. Appl. Physiol. 80: 650-655, 1996). We conclude that, whereas coca chewing might affect glucose homeostasis during exercise, none of the physiological data provided by this study would suggest that acute coca chewing in nonhabitual users could enhance tolerance to exercise.
Differential effects of ventilatory stimulation by sex hormones and almitrine on hypoxic erythrocytosis
(Springer Science+Business Media, 1997) R. Favier; Hilde Spielvogel; Esperanza Cáceres; Armando Rodríguez; B. Semporé; J. M. Pequignot; Jean-Marc Péquignot
Dopaminergic metabolism in carotid bodies and high-altitude acclimatization in female rats
(American Physiological Society, 2002) Vincent Joseph; Jorge Soliz; Ruddy Soria; Jacqueline Pequignot; R. Favier; Hilde Spielvogel; Jean Marc Pequignot
We tested the hypothesis that ovarian steroids stimulate breathing through a dopaminergic mechanism in the carotid bodies. In ovariectomized female rats raised at sea level, domperidone, a peripheral D2-receptor antagonist, increased ventilation in normoxia (minute ventilation = +55%) and acute hypoxia (+32%). This effect disappeared after 10 daily injections of ovarian steroids (progesterone + estradiol). At high altitude (3,600 m, Bolivian Institute for High-Altitude Biology-IBBA, La Paz, Bolivia), neutered females had higher carotid body tyrosine hydroxylase activity (the rate-limiting enzyme for catecholamine synthesis: +129%) and dopamine utilization (+150%), lower minute ventilation (-30%) and hypoxic ventilatory response (-57%), and higher hematocrit (+18%) and Hb concentration (+21%) than intact female rats. Consistent signs of arterial pulmonary hypertension (right ventricular hypertrophy) also appeared in ovariectomized females. None of these parameters was affected by gonadectomy in males. Our results show that ovarian steroids stimulate breathing by lowering a peripheral dopaminergic inhibitory drive. This process may partially explain the deacclimatization of postmenopausal women at high altitude.
Effects of coca chewing on hormonal and metabolic responses during prolonged submaximal exercise
(American Physiological Society, 1996) R. Favier; Esperanza Cáceres; H. Koubi; B. Semporé; Michel Sauvain; Hilde Spielvogel
The effects of coca chewing on prolonged submaximal exercise responses were investigated in chronic coca chewers and compared with a group of nonchewers. At rest, coca chewing during a 1-h period was followed by a significant increase in blood glucose, free fatty acid, and norepinephrine concentrations and a significant reduction in insulin plasma level. During prolonged (1-h) submaximal (65-70% peak O2 uptake) exercise, chewers displayed a significantly greater adrenergic activation (as evidenced by a higher level of plasma epinephrine) and an increased use of fat (as evidenced by a lower respiratory exchange ratio). The gradual increase in oxygen uptake (O2 drift) commonly observed during prolonged exercise was blunted in coca chewers. This blunting in O2 drift is not related to coca-induced changes in ventilatory or lactate responses to exercise but could possible be related to an enhanced glucose utilization by chewers during the late phase of exercise. The present results provide experimental evidence of the physiological effects of coca chewing that could explain the better ability of coca users to sustain strenuous work for an extended period of time.
Effects of Coca Chewing on Maximal and Submaximal Exercise Performance
(Portland Press, 1994) Hilde Spielvogel; Esperanza Cáceres; B. Semporé; H. Koubi; Michel Sauvain; R. Favier
Conference Abstract| January 01 1994 Effects of Coca Chewing on Maximal and Submaximal Exercise Performance H Spielvogel; H Spielvogel 1 Instituto Boliviano de Biologia de Altura-La Paz-Bolivia Search for other works by this author on: This Site PubMed Google Scholar E Caceres; E Caceres 1 Instituto Boliviano de Biologia de Altura-La Paz-Bolivia Search for other works by this author on: This Site PubMed Google Scholar B Sempore; B Sempore 2 Laboratoire de Physiologie, Université Claude Bernard-Lyon-France Search for other works by this author on: This Site PubMed Google Scholar H Koubi; H Koubi 2 Laboratoire de Physiologie, Université Claude Bernard-Lyon-France Search for other works by this author on: This Site PubMed Google Scholar M Sauvain; M Sauvain 1 Instituto Boliviano de Biologia de Altura-La Paz-Bolivia Search for other works by this author on: This Site PubMed Google Scholar R Favier R Favier 1 Instituto Boliviano de Biologia de Altura-La Paz-Bolivia Search for other works by this author on: This Site PubMed Google Scholar Author and article information Publisher: Portland Press Ltd Online ISSN: 1470-8736 Print ISSN: 0143-5221 © 1994 The Biochemical Society and the Medical Research Society1994 Clin Sci (Lond) (1994) 87 (s1): 113. https://doi.org/10.1042/cs087s113 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn Email Cite Icon Cite Get Permissions Citation H Spielvogel, E Caceres, B Sempore, H Koubi, M Sauvain, R Favier; Effects of Coca Chewing on Maximal and Submaximal Exercise Performance. Clin Sci (Lond) 1 January 1994; 87 (s1): 113. doi: https://doi.org/10.1042/cs087s113 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsClinical Science Search Advanced Search This content is only available as a PDF. © 1994 The Biochemical Society and the Medical Research Society1994 Article PDF first page preview Close Modal You do not currently have access to this content.
Effects of coca chewing on metabolic and hormonal changes during graded incremental exercise to maximum
(American Physiological Society, 1996) Hilde Spielvogel; Esperanza Cáceres; H. Koubi; B. Semporé; Michel Sauvain; R. Favier
We examined the effects of 1 h of coca chewing on metabolic and hormonal responses during incremental exercise to exhaustion in traditional coca chewers (C; n = 8), and the results were compared with a group of nonchewers (n = 13). For 1 h, C chewed approximately 12 g of coca leaves that resulted in the apparition of cocaine in blood that reached 72 +/- 9 ng/ml. In resting conditions, even though sympathoadrenergic activity (as assessed by norepinephrine and epinephrine plasma levels) was similar in both groups, C displayed a higher level of plasma free fatty acids. Oxygen uptake measured at exhaustion and delta work efficiency during exercise were similar in both groups. During the incremental exercise, C displayed a significantly lower arterial oxygen saturation that cannot be explained by a reduced ventilatory response after coca chewing. In fact, even at maximal exercise, both ventilatory output and ventilatory equivalent were higher in C compared with nonchewers. It is concluded that the beneficial effects of coca chewing on exercise tolerance reported frequently by traditional coca users is not related to either an improved maximal exercise capacity or an increased work efficiency. However, during incremental exercise, coca chewing appeared to result in an increased free fatty acid availability that could be beneficial for prolonged submaximal exercise.
Endurance Training at High Altitude: Effects of Inhalation of a Normoxic Gas Mixture during Exercise
(Portland Press, 1994) R. Favier; Hilde Spielvogel; D. Desplanches; Guido Ferretti; Bengt Kayser; Stan L. Lindstedt; Hans Hoppeler
Conference Abstract| January 01 1994 Endurance Training at High Altitude: Effects of Inhalation of a Normoxic Gas Mixture during Exercise R Favier; R Favier 1 Instituto Boliviano de Biologia de Altura-La Paz-Bolivia Search for other works by this author on: This Site PubMed Google Scholar H Spielvogel; H Spielvogel 1 Instituto Boliviano de Biologia de Altura-La Paz-Bolivia Search for other works by this author on: This Site PubMed Google Scholar D Desplanches; D Desplanches 2 Laboratoire de Physiologie, Université Claude Bernard-Lyon-France Search for other works by this author on: This Site PubMed Google Scholar G Ferretti; G Ferretti 3 Laboratoire de Physiologie, Centre médical Universitaire-Genève-Switzerland Search for other works by this author on: This Site PubMed Google Scholar B Kayser; B Kayser 3 Laboratoire de Physiologie, Centre médical Universitaire-Genève-Switzerland Search for other works by this author on: This Site PubMed Google Scholar S Lindstedt; S Lindstedt 4 Biology Department, Northern Arizona University-Flagstaff-USA Search for other works by this author on: This Site PubMed Google Scholar H Hoppeler H Hoppeler 5 Anatomisches Institut, Universität Bern-Bern-Switzerland Search for other works by this author on: This Site PubMed Google Scholar Clin Sci (Lond) (1994) 87 (s1): 17–18. https://doi.org/10.1042/cs087s017a Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Cite Icon Cite Get Permissions Citation R Favier, H Spielvogel, D Desplanches, G Ferretti, B Kayser, S Lindstedt, H Hoppeler; Endurance Training at High Altitude: Effects of Inhalation of a Normoxic Gas Mixture during Exercise. Clin Sci (Lond) 1 January 1994; 87 (s1): 17–18. doi: https://doi.org/10.1042/cs087s017a Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsClinical Science Search Advanced Search This content is only available as a PDF. © 1994 The Biochemical Society and the Medical Research Society1994 Article PDF first page preview Close Modal You do not currently have access to this content.
Exercise training in chronic hypoxia has no effect on ventilatory muscle function in humans
(Elsevier BV, 1998) R. Thomas; Paul C. LaStayo; Hans Hoppeler; R. Favier; Guido Ferretti; Bengt Kayser; D. Desplanches; Hilde Spielvogel; Stan L. Lindstedt
Fluid regulatory hormone response to exercise after coca-induced body fluid shifts
(American Physiological Society, 1997) R. Favier; Esperanza Cáceres; B. Semporé; J. M. Cottet-Émard; G. Gauquelin; C. Gharib; Hilde Spielvogel
To determine the effect of coca chewing on heart rate (HR), mean arterial blood pressure (MAP), and plasma volume and their relationship with the hormones regulating cardiovascular and body fluid homeostasis, 16 male volunteers were examined at rest and during 1 h of cycle exercise at approximately 75% of their peak oxygen uptake in two trials separated by 1 mo. One trial was performed after the subjects chewed a sugar-free chewing gum (Coca- trial), whereas the other was done after the subjects chewed 15 g of coca leaves (Coca+), with the order of the Coca- and Coca+ trials being randomized. Blood samples were taken at rest, before (R1) and after 1-h chewing (R2), and during the 5th, 15th, 30th, and 60th min of exercise. They were analyzed for hematocrit, hemoglobin concentration, red blood cell count, plasma proteins, and for the fluid regulatory hormones, including plasma catecholamines [norepinephrine (NE) and epinephrine], renin, arginine vasopressin, and the atrial natriuretic peptide (ANP). During the control trial (Coca-), from R1 to R2, there was no significant change in hematologic, hormonal, and cardiovascular status except for a small increase in plasma NE. In contrast, it can be calculated that coca chewing at rest induced a significant hemoconcentration (-3.8 +/- 1. 3% in blood and -7.0 +/- 0.7% in plasma volume), increased NE and MAP, and reduced plasma ANP. Chewing coca before exercise reduced the body fluid shifts but enhanced HR response during exercise. These effects were not accompanied by changes in NE, epinephrine, renin, and arginine vasopressin plasma levels. In contrast, plasma ANP response to exercise was lower during the Coca+ trial, suggesting that central cardiac filling was reduced by coca use. It is likely that the reduction in body fluid volumes is a major contributing factor to the higher HR at any given time of exercise after coca chewing.
Funktionelle und strukturelle Anpassungen an ein Dauerleistungstraining ober- oder unterhalb der 4 mM/l-Laktatschwelle
(1997) M. Leuenberger; Andi Grünenfelder; Hans Hoppeler; R. Favier; D. Desplanches; Hilde Spielvogel; Stan L. Lindstedt; Guido Ferretti; Bengt Kayser
Gender differentiation of the chemoreflex during growth at high altitude: functional and neurochemical studies
(American Physiological Society, 2000) Vincent Joseph; Jorge Soliz; J. M. Pequignot; B. Semporé; J. M. Cottet-Émard; Y. Dalmaz; R. Favier; Hilde Spielvogel; J. M. Pequignot
The effect of chronic hypoxia on gender differences in physiology and neurochemistry of chemosensory pathways was studied in prepubertal and adult rats living at sea level (SL; Lyon, France) or at high altitude (HA; La Paz, Bolivia, 3,600 m). HA adult rats had higher hematocrit (Ht%), Hb concentration, resting ventilatory rate (Ve(100)), and higher tyrosine hydroxylase (TH) activity in carotid bodies (CB) than SL animals. At HA and SL, adult females had lower Ht% (46.0 +/- 0.8 vs. 50.4 +/- 0.6% at HA, P < 0.05 and 43.8 +/- 0.9 vs. 47.1 +/- 0.8% at SL, P < 0.05) and Hb (16.1 +/- 0.3 vs. 17.7 +/- 0.2 g/dl at HA, P < 0.05 and 14.5 +/- 0.3 vs. 15.6 +/- 0.1 g/dl at SL, P < 0.05) than males. Females had higher Ve(100) [170 +/- 19 vs. 109 +/- 7 ml. min(-1). 100 g(-1) at HA, P < 0.05 and 50 +/- 3 vs. 40 +/- 2 ml. min(-1). 100 g(-1) at SL, not significant (NS)] and lower CB-TH activity (1.40 +/- 0.2 vs. 3.87 +/- 0.6 pmol/20 min at HA, P < 0.05 and 0.52 +/- 0.1 vs. 0.68 +/- 0.1 pmol/20 min at SL; NS) than males at HA only. The onset of hypoxic ventilatory response during development was delayed at HA. Prepubertal HA females had higher Ve(100) than males (2 wk old, +47%) and higher CB-TH activity (3 wk old, +51%). Medullary noradrenergic groups were sex dimorphic during development at SL. Rats raised at HA had a drop of TH activity between the second and the third postnatal week in all medullary groups. In conclusion, our data support the hypothesis that the CB is the major site for sexual differentiation of the ventilatory control. Ventilatory differences appeared before puberty, and the animals bred at HA had profound alterations in the developmental process of the chemoreflex and its neural pathways. Some of these alterations are under dependence of the sex of the animal, and there is an important interaction between gender and the hypoxic environmental condition during the developmental period.
Hormonal and metabolic adjustments during exercise in hypoxia or normoxia in highland natives
(American Physiological Society, 1996) R. Favier; D. Desplanches; Hans Hoppeler; Esperanza Cáceres; A. Grünenfelder; H. Koubi; M. Leuenberger; B. Semporé; L. Tüscher; Hilde Spielvogel
In sea-level natives, exposure to hypoxia for a few weeks is characterized by an increased dependence on blood glucose and a decreased reliance on lactate for energy metabolism during exercise. These metabolic adjustments have been attributed to behavioral changes in the sympathoadrenergic and pancreatic systems. The aim of this study was to test the hypothesis of a reduced sympathoadrenergic activation and subsequent metabolic changes when high-altitude natives are acutely exposed to normoxia. Young Andean natives performed incremental exercise to exhaustion during hypoxia (arterial PO2 55.1 +/- 1.1 Torr) or during acute normoxia (arterial PO2 78.7 +/- 1.7 Torr). As a whole, oxygen uptake was increased in normoxia compared with hypoxia during graded exercise. This finding is not related to a decrease in anaerobic metabolism but rather is interpreted as a consequence of a shift in substrate utilization during exercise (increased contribution of fat as assessed by a reduction in the respiratory exchange ratio). These metabolic changes are not accompanied by modifications of glucoregulatory hormones (catecholamines, insulin, and glucagon). In particular, the exercise-induced catecholamine secretion was similar in chronic hypoxia and acute normoxia. As a consequence, blood lactate accumulation during incremental exercise was similar in both conditions. It is concluded that high-altitude natives do not display any sign of a greater sympathoadrenergic activation during chronic hypoxia and that the exercise-induced hormonal changes remained unaffected by acute inhalation of a normoxic gas mixture.
Influence of gender and endogenous sex steroids on catecholaminergic structures involved in physiological adaptation to hypoxia
(Springer Science+Business Media, 1997) J. M. Pequignot; Hilde Spielvogel; Esperanza Cáceres; Armando Rodríguez; B. Semporé; J. M. Pequignot; R. Favier
Lactate and epinephrine during exercise in altitude natives
(American Physiological Society, 1996) Bengt Kayser; R. Favier; Guido Ferretti; D. Desplanches; Hilde Spielvogel; H. Koubi; B. Semporé; Hans Hoppeler
We tested the hypothesis that the reported low blood lactate accumulation ([La]) during exercise in altitude-native humans is refractory to hypoxianormoxia transitions by investigating whether acute changes in inspired O2 fraction (FIo2) affect the [La] vs. power output (W) relationship or, alternatively, as reported for lowlanders, whether changes in [La] vs. W on changes in FIo2 are related to changes in blood epinephrine concentration ([Epi]). Altitude natives [n = 8, age 24 +/- 1 (SE) yr, body mass 62 +/- 3 kg, height 167 +/- 2 cm] in La Paz, Bolivia (3,600 m) performed incremental exercise with two legs and one leg in chronic hypoxia and acute normoxia (AN). Submaximal one- and two-leg O2 uptake (Vo2) vs. W relationships were not altered by FIo2. AN increased two-leg peak Vo2 by 10% and peak W by 7%. AN paradoxically decreased one-leg peak Vo2 by 7%, whereas peak W remained the same. The [La] vs. W relationships were similar to those reported in unacclimatized lowlanders. There was a shift to the right on AN, and maximum [La] was reduced by 7 and 8% for one- and two-leg exercises, respectively. [Epi] and [La] were tightly related (mean r = 0.81) independently of FIo2. Thus normoxia attenuated the increment in both [La] and [Epi] as a function of W, whereas the correlation between [La] and [Epi] was unaffected. These data suggest loose linkage of glycolysis to oxidative phosphorylation under influence from [Epi]. In conclusion, high-altitude natives appear to be not fundamentally different from lowlanders with regard to the effect of acute changes in FIo2 on [La] during exercise.
Maximal exercise performance in chronic hypoxia and acute normoxia in high-altitude natives
(American Physiological Society, 1995) R. Favier; Hilde Spielvogel; D. Desplanches; G. Ferretti; Bengt Kayser; Hans Hoppeler
Maximal O2 uptake (VO2max) was determined on a bicycle ergometer in chronic hypoxia (CH) and during acute exposure to normoxia (AN) in 50 healthy young men who were born and had lived at 3,600 m altitude (La Paz, Bolivia). VO2max was significantly improved (approximately 8%) by AN. However, the difference in VO2max measured in CH and AN (delta VO2max) was lower than that reported in sea-level natives (SN) who exercised in chronic normoxia and acute hypoxia. It is shown that high-altitude natives (HN) and SN have a similar VO2max in normoxia, but highlanders can attain a greater VO2max when O2 availability is reduced by altitude exposure. In addition, in HN, the higher the subject's VO2max in hypoxia, the smaller his delta VO2max. These results contrast with the data obtained in 14 lowlanders acclimatized to high altitude who showed that their delta VO2max was positively related to their VO2max in hypoxia, as previously reported in SN who exercised in acute hypoxia (A. J. Young, A. Cymerman, and R. L. Burse. Eur. J. Appl. Physiol. Occup. Physiol. 54: 12-15, 1985). Furthermore, arterial O2 saturation of HN behaved differently from acclimatized lowland natives, inasmuch as it fell less during exercise both in CH and AN. HN with high aerobic capacity display a lower exercise ventilation and a reduced arterial saturation, which could explain their inability to improve VO2max with normoxia.(ABSTRACT TRUNCATED AT 250 WORDS)
Maximal Exercise Performance in Chronic Hypoxia and Acute Normoxia in High-Altitude Natives
(Portland Press, 1994) R. Favier; Hilde Spielvogel; D. Desplanches; Guido Ferretti; Bengt Kayser; Stan L. Lindstedt; Hans Hoppeler
Conference Abstract| January 01 1994 Maximal Exercise Performance in Chronic Hypoxia and Acute Normoxia in High-Altitude Natives R Favier; R Favier 1 Instituto Boliviano de Biologia de Altura-La Paz-Bolivia Search for other works by this author on: This Site PubMed Google Scholar H Spielvogel; H Spielvogel 1 Instituto Boliviano de Biologia de Altura-La Paz-Bolivia Search for other works by this author on: This Site PubMed Google Scholar D Desplanches; D Desplanches 2 Laboratoire de Physiologie, Université Claude Bernard-Lyon-France Search for other works by this author on: This Site PubMed Google Scholar G Ferretti; G Ferretti 3 Laboratoire de Physiologie, Centre médical Universitaire-Genève-Switzerland Search for other works by this author on: This Site PubMed Google Scholar B Kayser; B Kayser 3 Laboratoire de Physiologie, Centre médical Universitaire-Genève-Switzerland Search for other works by this author on: This Site PubMed Google Scholar S Lindstedt; S Lindstedt 4 Biology Department, Northern Arizona University-Flagstaff-USA Search for other works by this author on: This Site PubMed Google Scholar H Hoppeler H Hoppeler 5 Anatomisches Institut, Universität Bern-Bern-Switzerland Search for other works by this author on: This Site PubMed Google Scholar Clin Sci (Lond) (1994) 87 (s1): 46–47. https://doi.org/10.1042/cs087s046a Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Cite Icon Cite Get Permissions Citation R Favier, H Spielvogel, D Desplanches, G Ferretti, B Kayser, S Lindstedt, H Hoppeler; Maximal Exercise Performance in Chronic Hypoxia and Acute Normoxia in High-Altitude Natives. Clin Sci (Lond) 1 January 1994; 87 (s1): 46–47. doi: https://doi.org/10.1042/cs087s046a Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsClinical Science Search Advanced Search This content is only available as a PDF. © 1994 The Biochemical Society and the Medical Research Society1994 Article PDF first page preview Close Modal You do not currently have access to this content.
Muscle tissue adaptations of high-altitude natives to training in chronic hypoxia or acute normoxia
(American Physiological Society, 1996) D. Desplanches; Hans Hoppeler; L. Tüscher; M. H. Mayet; Hilde Spielvogel; G. Ferretti; Bengt Kayser; M. Leuenberger; A. Grünenfelder; R. Favier
Twenty healthy high-altitude natives, residents of La Paz, Bolivia (3,600 m), participated in 6 wk of endurance exercise training on bicycle ergometers, 5 times/wk, 30 min/session, as previously described in normoxia-trained sea-level natives (H. Hoppeler, H. Howald, K. E. Conley, S. L. Lindstedt, H. Claassen, P. Vock, and E. R. Weibel. J. Appl. Physiol. 59: 320-327, 1985). A first group of 10 subjects was trained in chronic hypoxia (HT; barometric pressure = 500 mmHg; inspired O2 fraction = 0.209); a second group of 10 subjects was trained in acute normoxia (NT; barometric pressure = 500 mmHg; inspired O2 fraction = 0.314). The workloads were adjusted to approximately 70% of peak O2 consumption (VO2peak) measured either in hypoxia for the HT group or in normoxia for the NT group. VO2peak determination and biopsies of the vastus lateralis muscle were taken before and after the training program. VO2peak in the HT group was increased (14%) in a way similar to that in NT sea-level natives with the same protocol. Moreover, VO2peak in the NT group was not further increased by additional O2 delivery during the training session. HT or NT induced similar increases in muscle capillary-to-fiber ratio (26%) and capillary density (19%) as well as in the volume density of total mitochondria and citrate synthase activity (45%). It is concluded that high-altitude natives have a reduced capillarity and muscle tissue oxidative capacity; however, their training response is similar to that of sea-level residents, independent of whether training is carried out in hypobaric hypoxia or hypobaric normoxia.
Training in hypoxia vs. training in normoxia in high-altitude natives
(American Physiological Society, 1995) R. Favier; Hilde Spielvogel; D. Desplanches; G. Ferretti; Bengt Kayser; A. Grünenfelder; M. Leuenberger; L. Tüscher; Esperanza Cáceres; Hans Hoppeler
To determine the interactions between endurance training and hypoxia on maximal exercise performance, we performed a study on sedentary high-altitude natives who were trained in normoxia at the same relative (n = 10) or at the same absolute (n = 10) intensity of work as hypoxia-trained subjects (n = 10). The training-induced improvement of maximal oxygen uptake (VO2max) in hypoxia-trained subjects was similar to that obtained in normoxia-trained sea-level natives submitted to the same training protocol (H. Hoppeler, H. Howald, K. Conley, S. L. Lindstedt, H. Claassen, P. Vock, and E. W. Weibel. J. Appl. Physiol. 59: 320-327, 1985). Training at the same absolute work intensity in the presence of increased oxygen delivery failed to provide a further increase in VO2max. VO2max was not improved to a greater extent by simultaneously increasing absolute work intensity and O2 delivery during the training sessions. In addition, training in normoxia is accompanied by an increased blood lactate accumulation during maximal exercise, leading to greater drops in arterial pH, bicarbonate concentration, and base excess. We conclude that, in high-altitude natives, 1) training at altitude does not provide any advantage over training at sea level for maximal aerobic capacity, whether assessed in chronic hypoxia or in acute normoxia; 2) VO2max improvement with training cannot be further enhanced by increasing O2 availability alone or in combination with an increased work intensity during the exercising sessions; and 3) training in normoxia in these subjects results in a reduced buffer capacity.