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Guido Ferretti - One of the best experts on this subject based on the ideXlab platform.
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effect of respiratory muscle training on maximum aerobic power in Normoxia and hypoxia
Respiratory Physiology & Neurobiology, 2010Co-Authors: Fabio Esposito, Eloisa Limonta, G Alberti, Arsenio Veicsteinas, Guido FerrettiAbstract:To assess the effects of respiratory muscle training (RMT) on maximum oxygen uptake (VO2max) in Normoxia and hypoxia, 9 healthy males (age 24 +/- 4 years; stature 1.75 +/- 0.08 m; body mass 72 +/- 9 kg; mean +/- SD) performed on different days maximal incremental tests on a cycle ergometer in Normoxia and normobaric hypoxia (FIO2=0.11), before and after 8 weeks of RMT (5 days/week). During each test, gas exchange variables were measured breath-by-breath by a metabolimeter. After RMT, no changes in cardiorespiratory and metabolic variables were detected at maximal exercise in Normoxia. On the contrary, in hypoxia expired and alveolar ventilation (V(E(and V(A), respectively) at maximal exercise were significantly higher than pre-training condition (+12 and +13%, respectively; P < 0.05). Accordingly, alveolar O2 partial pressure (PAO2) after RMT significantly increased by approximately 10%. Nevertheless, arterial PO2 and VO2max did not change with respect to pre-training condition. In conclusion, RMT improved respiratory function but did not have any effect on VO2max, neither under normoxic nor hypoxic condition. In hypoxia, the significant increase in V(E) and V(A) at maximum exercise after training lead to higher alveolar but not arterial PO2 values, revealing an increased A-a gradient. This result, according to the theoretical models of VO2max limitation, seems to contradict the lack of VO2max increase in hypoxia, suggesting a possible role of increased ventilation-perfusion mismatch.
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Maximal exercise performance in chronic hypoxia and acute Normoxia in high-altitude natives
Journal of Applied Physiology, 1995Co-Authors: R. Favier, Dominique Desplanches, Hilde Spielvogel, Guido Ferretti, Bengt Kayser, Hans HoppelerAbstract: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)
André Geyssant - One of the best experts on this subject based on the ideXlab platform.
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Effects of training in Normoxia and normobaric hypoxia on human muscle ultrastructure.
Pflügers Archiv: European Journal of Physiology, 1993Co-Authors: Dominique Desplanches, Hans Hoppeler, M. T. Linossier, Christian Denis, H. Claassen, D. Dormois, Jean-rené Lacour, André GeyssantAbstract:The adaptive response of skeletal muscle to training in Normoxia and in severe normobaric hypoxia was studied. The first group of five male subjects trained for 3 weeks on a bicycle (2 h/day, 6 days/week) in Normoxia (Control training, Con T). A second group of five subjects trained in an ambient FIO2 decreasing progressively from 12.7% to a final level of 10.0% (hypoxic training, Hyp T). Fourteen months later, these subjects trained in Normoxia at the same absolute power (normoxic training, Nor T). Peak oxygen consumption (\(\dot V\)O2 max) was measured in normoxic and hypoxic conditions. Biopsies from the vastus lateralis muscle were analysed for fibre size, capillary and ultrastructural composition. Nor T had no effect on muscle tissue or \(\dot V\)O2 max. Con T increased volume density of total mitochondria and lipids by 36 and 135% respectively (P
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effects of training in Normoxia and normobaric hypoxia on human muscle ultrastructure
Pflügers Archiv: European Journal of Physiology, 1993Co-Authors: Dominique Desplanches, Hans Hoppeler, M. T. Linossier, Christian Denis, H. Claassen, D. Dormois, Jean-rené Lacour, André GeyssantAbstract:The adaptive response of skeletal muscle to training in Normoxia and in severe normobaric hypoxia was studied. The first group of five male subjects trained for 3 weeks on a bicycle (2 h/day, 6 days/week) in Normoxia (Control training, Con T). A second group of five subjects trained in an ambient FIO2 decreasing progressively from 12.7% to a final level of 10.0% (hypoxic training, Hyp T). Fourteen months later, these subjects trained in Normoxia at the same absolute power (normoxic training, Nor T). Peak oxygen consumption ( $$\dot V$$ O2 max) was measured in normoxic and hypoxic conditions. Biopsies from the vastus lateralis muscle were analysed for fibre size, capillary and ultrastructural composition. Nor T had no effect on muscle tissue or $$\dot V$$ O2 max. Con T increased volume density of total mitochondria and lipids by 36 and 135% respectively (P<0.05). Hyp T induced a 10% increase (P<0.05) in peak $$\dot V$$ O2 max measured in hypoxia. Mean fibre cross-sectional area, interfibrillar mitochondrial volume density and capillary-to-fibre ratio were increased (P<0.05) by 10, 42 and 13% respectively in the Hyp T group. These results suggest that training at the same relative workload in Normoxia and hypoxia have similar, but not identical, effects on muscle tissue. If training in Normoxia is carried out at the same absolute workload as in severe hypoxia, no significant effects are observed.
Dominique Desplanches - One of the best experts on this subject based on the ideXlab platform.
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Hormonal and metabolic adjustments during exercise in hypoxia or Normoxia in highland natives
Journal of Applied Physiology, 1996Co-Authors: R. Favier, Dominique Desplanches, Hans-heinrich Hoppeler, Esperanza Caceres, A. Grunenfelder, H. Koubi, Michele Leuenberger, B. Sempore, L. Tuscher, Hilde SpielvogelAbstract: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.
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Maximal exercise performance in chronic hypoxia and acute Normoxia in high-altitude natives
Journal of Applied Physiology, 1995Co-Authors: R. Favier, Dominique Desplanches, Hilde Spielvogel, Guido Ferretti, Bengt Kayser, Hans HoppelerAbstract: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)
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Effects of training in Normoxia and normobaric hypoxia on human muscle ultrastructure.
Pflügers Archiv: European Journal of Physiology, 1993Co-Authors: Dominique Desplanches, Hans Hoppeler, M. T. Linossier, Christian Denis, H. Claassen, D. Dormois, Jean-rené Lacour, André GeyssantAbstract:The adaptive response of skeletal muscle to training in Normoxia and in severe normobaric hypoxia was studied. The first group of five male subjects trained for 3 weeks on a bicycle (2 h/day, 6 days/week) in Normoxia (Control training, Con T). A second group of five subjects trained in an ambient FIO2 decreasing progressively from 12.7% to a final level of 10.0% (hypoxic training, Hyp T). Fourteen months later, these subjects trained in Normoxia at the same absolute power (normoxic training, Nor T). Peak oxygen consumption (\(\dot V\)O2 max) was measured in normoxic and hypoxic conditions. Biopsies from the vastus lateralis muscle were analysed for fibre size, capillary and ultrastructural composition. Nor T had no effect on muscle tissue or \(\dot V\)O2 max. Con T increased volume density of total mitochondria and lipids by 36 and 135% respectively (P
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effects of training in Normoxia and normobaric hypoxia on human muscle ultrastructure
Pflügers Archiv: European Journal of Physiology, 1993Co-Authors: Dominique Desplanches, Hans Hoppeler, M. T. Linossier, Christian Denis, H. Claassen, D. Dormois, Jean-rené Lacour, André GeyssantAbstract:The adaptive response of skeletal muscle to training in Normoxia and in severe normobaric hypoxia was studied. The first group of five male subjects trained for 3 weeks on a bicycle (2 h/day, 6 days/week) in Normoxia (Control training, Con T). A second group of five subjects trained in an ambient FIO2 decreasing progressively from 12.7% to a final level of 10.0% (hypoxic training, Hyp T). Fourteen months later, these subjects trained in Normoxia at the same absolute power (normoxic training, Nor T). Peak oxygen consumption ( $$\dot V$$ O2 max) was measured in normoxic and hypoxic conditions. Biopsies from the vastus lateralis muscle were analysed for fibre size, capillary and ultrastructural composition. Nor T had no effect on muscle tissue or $$\dot V$$ O2 max. Con T increased volume density of total mitochondria and lipids by 36 and 135% respectively (P<0.05). Hyp T induced a 10% increase (P<0.05) in peak $$\dot V$$ O2 max measured in hypoxia. Mean fibre cross-sectional area, interfibrillar mitochondrial volume density and capillary-to-fibre ratio were increased (P<0.05) by 10, 42 and 13% respectively in the Hyp T group. These results suggest that training at the same relative workload in Normoxia and hypoxia have similar, but not identical, effects on muscle tissue. If training in Normoxia is carried out at the same absolute workload as in severe hypoxia, no significant effects are observed.
John P. O’hara - One of the best experts on this subject based on the ideXlab platform.
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Substrate oxidation and the influence of breakfast in normobaric hypoxia and Normoxia
European Journal of Applied Physiology, 2019Co-Authors: Alex Griffiths, Kevin Deighton, Oliver M. Shannon, Jamie Matu, Roderick King, John P. O’haraAbstract:Purpose Previous research has reported inconsistent effects of hypoxia on substrate oxidation, which may be due to differences in methodological design, such as pre-exercise nutritional status and exercise intensity. This study investigated the effect of breakfast consumption on substrate oxidation at varying exercise intensities in normobaric hypoxia compared with Normoxia. Methods Twelve participants rested and exercised once after breakfast consumption and once after omission in normobaric hypoxia (4300 m: F_iO_2 ~ 11.7%) and Normoxia. Exercise consisted of walking for 20 min at 40%, 50% and 60% of altitude-specific $$\dot{\text{V}}$$ V ˙ O_2max at 10–15% gradient with a 10 kg backpack. Indirect calorimetry was used to calculate carbohydrate and fat oxidation. Results The relative contribution of carbohydrate oxidation to energy expenditure was significantly reduced in hypoxia compared with Normoxia during exercise after breakfast omission at 40% (22.4 ± 17.5% vs. 38.5 ± 15.5%, p = 0.03) and 60% $$\dot{\text{V}}$$ V ˙ O_2max (35.4 ± 12.4 vs. 50.1 ± 17.6%, p = 0.03), with a trend observed at 50% $$\dot{\text{V}}$$ V ˙ O_2max (23.6 ± 17.9% vs. 38.1 ± 17.0%, p = 0.07). The relative contribution of carbohydrate oxidation to energy expenditure was not significantly different in hypoxia compared with Normoxia during exercise after breakfast consumption at 40% (42.4 ± 15.7% vs. 48.5 ± 13.3%, p = 0.99), 50% (43.1 ± 11.7% vs. 47.1 ± 14.0%, p = 0.99) and 60% $$\dot{\text{V}}$$ V ˙ O_2max (54.6 ± 17.8% vs. 55.1 ± 15.0%, p = 0.99). Conclusions Relative carbohydrate oxidation was significantly reduced in hypoxia compared with Normoxia during exercise after breakfast omission but not during exercise after breakfast consumption. This response remained consistent with increasing exercise intensities. These findings may explain some of the disparity in the literature.
Hans Hoppeler - One of the best experts on this subject based on the ideXlab platform.
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Maximal exercise performance in chronic hypoxia and acute Normoxia in high-altitude natives
Journal of Applied Physiology, 1995Co-Authors: R. Favier, Dominique Desplanches, Hilde Spielvogel, Guido Ferretti, Bengt Kayser, Hans HoppelerAbstract: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)
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Effects of training in Normoxia and normobaric hypoxia on human muscle ultrastructure.
Pflügers Archiv: European Journal of Physiology, 1993Co-Authors: Dominique Desplanches, Hans Hoppeler, M. T. Linossier, Christian Denis, H. Claassen, D. Dormois, Jean-rené Lacour, André GeyssantAbstract:The adaptive response of skeletal muscle to training in Normoxia and in severe normobaric hypoxia was studied. The first group of five male subjects trained for 3 weeks on a bicycle (2 h/day, 6 days/week) in Normoxia (Control training, Con T). A second group of five subjects trained in an ambient FIO2 decreasing progressively from 12.7% to a final level of 10.0% (hypoxic training, Hyp T). Fourteen months later, these subjects trained in Normoxia at the same absolute power (normoxic training, Nor T). Peak oxygen consumption (\(\dot V\)O2 max) was measured in normoxic and hypoxic conditions. Biopsies from the vastus lateralis muscle were analysed for fibre size, capillary and ultrastructural composition. Nor T had no effect on muscle tissue or \(\dot V\)O2 max. Con T increased volume density of total mitochondria and lipids by 36 and 135% respectively (P
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effects of training in Normoxia and normobaric hypoxia on human muscle ultrastructure
Pflügers Archiv: European Journal of Physiology, 1993Co-Authors: Dominique Desplanches, Hans Hoppeler, M. T. Linossier, Christian Denis, H. Claassen, D. Dormois, Jean-rené Lacour, André GeyssantAbstract:The adaptive response of skeletal muscle to training in Normoxia and in severe normobaric hypoxia was studied. The first group of five male subjects trained for 3 weeks on a bicycle (2 h/day, 6 days/week) in Normoxia (Control training, Con T). A second group of five subjects trained in an ambient FIO2 decreasing progressively from 12.7% to a final level of 10.0% (hypoxic training, Hyp T). Fourteen months later, these subjects trained in Normoxia at the same absolute power (normoxic training, Nor T). Peak oxygen consumption ( $$\dot V$$ O2 max) was measured in normoxic and hypoxic conditions. Biopsies from the vastus lateralis muscle were analysed for fibre size, capillary and ultrastructural composition. Nor T had no effect on muscle tissue or $$\dot V$$ O2 max. Con T increased volume density of total mitochondria and lipids by 36 and 135% respectively (P<0.05). Hyp T induced a 10% increase (P<0.05) in peak $$\dot V$$ O2 max measured in hypoxia. Mean fibre cross-sectional area, interfibrillar mitochondrial volume density and capillary-to-fibre ratio were increased (P<0.05) by 10, 42 and 13% respectively in the Hyp T group. These results suggest that training at the same relative workload in Normoxia and hypoxia have similar, but not identical, effects on muscle tissue. If training in Normoxia is carried out at the same absolute workload as in severe hypoxia, no significant effects are observed.
