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  • 1
    Electronic Resource
    Electronic Resource
    Relationships between catecholamine or 3-methoxy 4-hydroxy phenylglycol changes and the mental performance under submaximal exercise in man (1987)
    Springer
    Psychopharmacology 93 (1987), S. 188-192 
    Details
    ISSN: 1432-2072
    Keywords: Catecholamines ; Conjugated MHPG ; Submaximal exercise ; Mental activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Eleven young students were tested to determine the relationship between the improvement of mental performances observed under prolonged submaximal work and central or peripheral catecholamine changes. The subjects pedaled a bicycle ergometer for 1 h at a work load individually calculated to approximate 75% of maximal oxygen uptake. The mental test, consisting of 1-h sessions of time-limited word tests and arithmetical calculations, required a high degree of concentration (vigilance and short-term memory). Catecholamines [epinephrine (E), norepinephrine (NE), dopamine (DA)], metanephrine (MN), normetanephrine (NMN) and the glucuronide conjugate of 3-methoxy 4-hydroxyphenylglycol (MHPG) were assayed in urine to assess peripheral activity: E and MN as indexes of adrenomedullary secretion, NE, NMN and MHPG glucuronide as markers of NE metabolism in sympathetic nerves. Urinary MHPG sulfate was determined as a possible marker of central noradrenergic metabolism. When compared to the effect of single tests, the combination of prolonged submaximal work and mental task induced significant increases in MHPG sulfate and E+MN excretions. Both these increases were correlated each to one another and also correlated to the number of discriminated words. Altogether, the present data show that prolonged submaximal work under mental load activates catecholamine systems and suggest that a relationship exists between adrenomedullary activation and the improvement of mental performance. Based on literature data, the possible modulatory role of peripheral E on mental processes and central noradrenergic activity is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00179932
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  • 2
    Electronic Resource
    Electronic Resource
    A systems model of training responses and its relationship to hormonal responses in elite weight-lifters (1990)
    Springer
    European journal of applied physiology 61 (1990), S. 48-54 
    Details
    ISSN: 1439-6327
    Keywords: Strength training ; Systems model ; Fatigue ; Fitness ; Serum hormonesw
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A systems model, providing an estimation of fatigue and fitness levels was applied to a 1-year training period of six elite weight-lifters. The model parameters were individually determined by fitting the predicted performance (calculated as the difference between fitness and fatigue) to the actual one. The purpose of this study was to validate the systems model by comparing the estimated levels of fatigue and fitness with biological parameters external to the model calculation. The predicted and the actual performances were significantly correlated in each subject. The calculated fitness and fatigue levels were related to serum testosterone concentration, testosterone: cortisol and testosterone: sex hormone binding globulin ratios. The best results were obtained by the comparison between fitness and testosterone levels, which varied in parallel in each subject. In two subjects this correlation was significant (r=0.91, P〈0.05, and r=0.92, P〈0.01). The fitness changes calculated in each subject between the 15th and the 51st weeks of training were significantly correlated with the changes in serum testosterone concentration measured in the same period (r=0.99, P〈0.001). For the whole group testosterone and fitness variations were also significantly intercorrelated (r=0.73, P〈0.001). Correlations, less homogeneous and less significant, were calculated also for other hormones and ratios. These results suggest that (1) the relationships between training and performance can be described by the systems model, (2) the estimated index of fitness has a physiological meaning. The fatigue index remains to be clarified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236693
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Hormonal adaptations and modelled responses in elite weightlifters during 6 weeks of training (1992)
    Springer
    European journal of applied physiology 64 (1992), S. 381-386 
    Details
    ISSN: 1439-6327
    Keywords: Strength training ; Systems model ; Fatigue ; Fitness ; Serum hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The concentrations of serum testosterone, sex-hormone-binding-globulin (SHBG) and luteinizing hormone (LH) were examined throughout 1-year of training in six elite weightlifters. A systems model, providing an estimation of fatigue and fitness, was applied to records of training volume and performance levels in clean and jerk. The analysis focused on a 6-week training period during which blood samples were taken at 2-week intervals. A 4-week period of intensive training (period I) could be distinguished from the following 2-week period of reduced training (period II). During period I, decreases in serum testosterone (P〈0.05) and increases in serum LH concentrations (P〈0.01) were observed; a significant correlation (r=0.90,P〈0.05) was also observed between the changes in serum LH concentration and in estimated fitness. The magnitude of LH response was not related to the change in serum androgens. On the other hand, the change in testosterone: SHBG ratio during period II was significantly correlated (r=0.97,P〈0.01) to the LH variations during period I. These finding suggested that the LH response indicated that the decrease in testosterone concentration was not primarily due to a dysfunction of the hypothalamic-pituitary system control, and that the fatigue/fitness status of an athlete could have influenced the LH response to the decreased testosterone concentration. The negative effect of training on hormonal balance could have been amplified by its influence on the hypothalamic-pituitary axis. A decrease in physiological stress would thus have been necessary for the completion of the effect of LH release on androgenic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00636228
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Catecholamines and metabolic responses to submaximal exercise in untrained men and women (1983)
    Springer
    European journal of applied physiology 50 (1983), S. 393-404 
    Details
    ISSN: 1439-6327
    Keywords: Exercise ; Catecholamines ; Blood borne substrates ; Sex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of exercise on blood borne substrates in relation to plasma catecholamine (CA) levels has been studied in untrained subjects (eight men and eight women). Subjects pedalled a bicycle ergometer for 20 min at a workload approximating to 80% maximal aerobic power. During exercise women reacted similarly to men except that their weight loss and hematocrit were significantly lower. At the end of the bicycling test, plasma dopamine (DA), norepinephrine (NE) and epinephrine (E) concentrations increased similarly in both groups. There was no significant difference in blood energy substrates between men and women except that the plasma free fatty acid (FFA) level was significantly higher in the female. When fitness levels were similar, the previously reported sex-related difference in response to exercise seemed to disappear. The lack of correlation between blood borne substrates variations and CA changes raised the question whether other hormonal factors combined with CA could play a role in the mobilization of energy substrates during exercise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423245
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    Paper (German National Licenses)
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