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  • 1
    Electronic Resource
    Electronic Resource
    Effects of hydration state on plasma testosterone, cortisol and catecholamine concentrations before and during mild exercise at elevated temperature (1994)
    Springer
    European journal of applied physiology 69 (1994), S. 294-300 
    Details
    ISSN: 1439-6327
    Keywords: Dehydration ; Fluid intake ; Testosterone ; Cortisol ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This investigation examined the influence of pre-exercise hydration status, and water intake during low intensity exercise (5.6 km · h−1 at 5% gradient) in the heat (33° C), on plasma testosterone (TEST), cortisol (CORT), adrenaline (A), and noradrenaline (NA) concentrations at baseline (BL), pre-exercise (PRE), and immediately (IP), 24 h (24 P), and 48 h postexercise (48 P). Ten active men participated in four experimental treatments. These treatments differed in preexercise hydration status [euhydrated or hypohydrated (HY, −3.8 (SD 0.7)% body mass)] and water intake during exercise (water ad libitum or no water intake during exercise, NW). There were no significant changes in TEST, CORT, or A concentrations with time (BL, PRE, IP, 24 P, and 48 P), or among treatments. However, significant increases from BL and PRE plasma NA concentrations were observed at IP during all four treatment conditions. In addition, HY + NW resulted in significantly higher plasma NA concentrations at IP compared to all other treatments. These results suggest that moderate levels of hypohydration during prolonged, low intensity exercise in the heat do not influence plasma TEST, CORT, or A concentrations. However, plasma NA appears to respond in a sensitive manner to these hydration and exercise stresses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392033
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  • 2
    Electronic Resource
    Electronic Resource
    The effects of exercise training of different intensities on neuromuscular junction morphology (1993)
    Springer
    Journal of neurocytology 22 (1993), S. 603-615 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Little is known about the effects of exercise training on neuromuscular junction morphology in skeletal muscle. The objectives of this investigation were: 1) to determine if exercise training would elicit changes in neuromuscular junction morphology, 2) to determine if exercise training of different intensities would evoke specific changes in neuromuscular junction morphology, and 3) to determine whether changes in neuromuscular junction structure occur independently of changes in muscle fibre type and size. Twenty-four age and size matched male Sprague-Dawley rats were randomly assigned to three groups: high-intensity trained (HIT), low-intensity trained (LIT), or untrained. Neuromuscular junction morphology of the soleus muscle was determined via immunofluorescent staining. Presynaptic acetylcholine vesicles were visualized with SV-2 antibody in conjunction with fluorescein isothiocyanate labelled secondary antibody. Postsynaptic acetylcholine receptors were identified with rhodamine labelled α-bungarotoxin. Laser scanning microscopy was used to produce images of synapses, which were used to quantitate the following: total area of SV-2 and α-bungarotoxin staining, density of acetylcholine vesicles and receptors, structural complexity, and synaptic coupling. To visualize nerve terminal branching, a smaller number of neuromuscular junctions were stained with C-2 antibody, which reacts with a neurofilament epitope, in conjunction with fluorescein isothiocyanate labelled secondary antibody. Total length of branching, number of branches, average length of branches, and ratio of secondary to primary branches per neuromuscular junction were determined. Citrate synthase activity, fibre type composition and fibre cross-sectional areas of the soleus muscle were assessed to determine the presence of a training effect in that muscle. Results indicate that training did induce hypertrophy of the neuromuscular junction that was independent of muscle hypertorphy. Although the HIT and LIT groups exhibited similar hypertrophic responses of the neuromuscular junction, the HIT group displayed more dispersed synapses than the LIT group. Neither exercise training program, however, resulted in altered densities of acetylcholine vesicles or receptors, nor did training significantly change synaptic coupling. Nerve terminal branching was also affected by exercise training. Neuromuscular junctions from the HIT group demonstrated a greater total length of branching, average length per branch, and number of finer, or secondary, branches than those of the LIT group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01181487
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    Paper (German National Licenses)
    Fulltext
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