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  • 1
    ISSN: 1432-2013
    Keywords: Training ; Normoxia ; Muscle ; Morphometry ; Mitochondria ; Capillaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1439-6327
    Keywords: Training ; Exercise ; Plasma AVP ; Renin activity ; Aldosterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of endurance-training on hematocrit, plasma vasopressin, renin activity, and aldosterone changes at rest and at the end of an exercise performed until exhaustion at a given and constant relative work-load (87% of maximal oxygen uptake) has been studied in four untrained subjects submitted to a 5-month training. At the end of this period, maximal oxygen uptake increased of 15.2% (p〈0.01). Hematocrit at rest slightly rose after training, and if exercise constantly induced increases in hematocrit before (p〈0.001) and after training (p〈0.005), the per cent increase after training was lower than before (p〈0.05). Comparison between the importance of weight loss and hematocrit variation showed that when untrained subjects become trained the variation of hematocrit after exercise becomes smaller while weight loss is more important (p〈0.01). Plasma renin activity (PRA), aldosterone (Aldo) and vasopressin (AVP) levels, compared to control values, displayed a significant increase after exercise before as well as after training. Control values remained unchanged after training for aldosterone and AVP, but were significantly lower (p〈0.05) for PRA. This latter observation could be explained by the change in blood volume induced by exercise.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 59 (1990), S. 399-404 
    ISSN: 1439-6327
    Keywords: Anthropometry ; Buoyancy ; Drag ; Performance ; Swimming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The passive drag (Dp) of 218 competitive swimmers was studied and related to their performance level. To study this relationship, specific attention was given to anthropometric and joint laxity (JL) variations. The Dp was measured at 1.40 m·s−1, using a mechanical winch and a strain gauge with a load cell connected to a strain bridge. Swimmers were towed in a prone position holding their breath after a maximal inspiration. Buoyancy was evaluated by the hydrostatic lift (HL), i.e. the maximal weight just necessary to maintain the swimmer in a balanced position under the water after a maximal inspiration. The JL was assessed by a standard scoring system. The Dp was related mainly to the surface area (SA) (r=0.73 and 0.53;P〈0.01, for males and females respectively). For a given SA, Dp was inversely related to the performance level. The JL explained 7% of the variability of Dp. On average, Dp measured, after a maximal expiration, increases of about 22% SD 3% (P〈0.01). This increase was related to individual vital capacities (r=0.86,P〈0.01). As Dp was mainly related to SA and HL, it is suggested that the body exerts a large pressure effect on the water. The contribution to performance might be related to the gliding phase of swimming.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 63 (1991), S. 12-16 
    ISSN: 1439-6327
    Keywords: Anthropometric size ; Energy cost ; Buoyancy ; Performance ; Swimming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this study was to examine the relationship between the energy cost of swimming per unit distance (CS) at different velocities (ν) and performance level, body size and swimming technique in women. A total of 58 females swimmers were studied. Three performance levels (A, B, C) were determined, ranging from the slower (A) to the faster (B, C). At level C and at 1.1 m·s−1, Cs,1.1 was reduced by 7% when directly compared to level B. The Cs,1.1 was reduced by 10% when calculated per unit of height (h) and by 37% when calculated per unit ofh and hydrostatic lift (HL). For the whole group of swimmers, the equation regression was Cs, 1.1 = 0.27h −2.38 HL−7.5 (r=0.53,P〈0.01). To evaluate the specific influence of arm length two groups of long- and short-armed swimmers were selected among swimmers of similarh and performance. The Cs was significantly higher (P〈0.05) by 12%, SD 2.2%, for short-armed than for long-armed swimmers. To evaluate the influence of different types of swimming technique, two other groups of similar performance and anthropometric characteristics were selected. The Cs was significantly higher (P〈0.05) by 12%, SD 4.5% for swimmers using for preference their legs rather than their arms. The Cs of the sprinters was 15.7%, SD 2% higher than that of the long-distance swimmers. For all groups, CS increased withv on average by 8% to 11% every 0.1 m · s−1. These findings showed that Cs variations of these women were close to those previously demonstrated for men. The Cs depends on performance level, body size, buoyancy, swimming technique and ν.
    Type of Medium: Electronic Resource
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