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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 69 (1994), S. 550-556 
    ISSN: 1439-6327
    Keywords: Muscle ; Metabolism ; Enzymes ; Buffer value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The degree to which the y-intercept (Y-int) of the linear regression of maximal work output on exercise duration represented anaerobic capacity was determined in ten well-trained male cyclists [peak oxygen uptake ( $$\dot V{\text{O}}_{{\text{2peak}}} $$ = 69.8 (SD 4.2) ml · kg −1 · min −1). Each cyclist performed three exhausting cycle sessions on separate occasions; the mean exercise durations were 312, 243 and 141 s for the low (approximately 104% $$\dot V{\text{O}}_{{\text{2peak}}} $$ , medium (approximately 108% $$\dot V{\text{O}}_{{\text{2peak}}} $$ and high (approximately 113% $$\dot V{\text{O}}_{{\text{2peak}}} $$ intensities respectively, and Y-int (kilojoules; joules per kilogram was derived from the regression of work output on exercise duration. The muscle anaerobic adenosine 5′-triphosphate (ATP) yield (ΣATP) and anaerobic capacity (AC) were estimated from changes in metabolites in the vastus lateralis muscle and blood lactate concentration during the high intensity cycling session. The activities of glycogen phosphorylase, phosphofructokinase and citrate synthase, as well as muscle buffer value (in vitro β) were also determined. The Y-int (kilojoules) was positively correlated (P≤0.05) with AC (r=0.73), ΣATP (r=0.70) and in vitro β (r=0.71); similar correlations (P≤0.05) were observed for Y-int (joules per kilogram). The Y-int was not correlated (P〉0.05) with any enzyme activity. When the Y-int was transformed into oxygen equivalents [litres of oxygen equivalent (1 O2 Eq)] it was, on average, 0.92 1 O2 Eq lower than AC (P≤0.05); however, an alternative method of establishing the work-duration regression yielded a mean Y-int which was only 0.19 1 O2 Eq less than AC (P≥0.05). These findings support the validity of Y-int as a work estimate of anaerobic capacity in well-trained cyclists.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 54 (1985), S. 436-441 
    ISSN: 1439-6327
    Keywords: Swimming ; Biochemical changes ; Exercise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We set out to demonstrate whether changes in plasma volume, haematocrit and some important blood constituents occurred after swimming 100 m and 800 m, as well as monitoring the duration of these changes. We measured exercise-induced changes in concentration of plasma constituents in eight subjects, and determined the expected effects of haemoconcentration on these constituents. We also investigated the different biochemical responses occurring after maximal exercise (100 m), as compared to submaximal exercise (800 m). The haematocrit increased significantly after the 100 m swim and to a lesser extent after the 800-m swim, returning to basal levels within 30 min. The plasma volume decreased by 16% on completion of the 100 m and by 8% on completion of the 800 m. The blood lactate concentration increased 15-fold and 10-fold after the 100-m and 800-m swims respectively. The plasma potassium concentration increased significantly immediately on completion of the 100-m swim, then decreased significantly at 2 1/2 and 5 min post-exercise, returning to near-basal values at 30 min. The potassium concentration measured after the 800-m event did not differ significantly from basal levels, however the measured concentrations were significantly lower than the concentrations expected on the basis of haemoconcentration. The plasma sodium concentrations measured after both 100-m and 800-m swims were significantly increased. However, calculations correcting for haemoconcentration showed significant losses in toal circulating sodium. Our study demonstrates marked changes in plasma volume and certain blood constituents after maximal intensity swimming, and less marked changes after submaximal exercise. We also demonstrated the importance of taking the effects of haemoconcentration into account when evaluating changes in concentration of plasma constituents.
    Type of Medium: Electronic Resource
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