Abstract
Urinary and/or serum concentrations of electrolytes (sodium, potassium, calcium, magnesium),
hormones (aldosterone, cortisol, catecholamines), and metabolic parameters (lactate,
glucose, free fatty acids) were determined during different volleyball matches.
While [Na+]s was slightly increased - not exceeding the hemoconcentration effect - [K+]s, [Mg2+]s, and [Ca2+]s were diminished after the matches. Due to a lowered glomerular filtration rate
(GFR), urinary excretion of water, sodium, and potassium was decreased. In addition,
the tubular resorption and secretion of fluid and electrolytes was influenced by different
hormones leading to a lowered [Na+]u and an increase of [K+]u after exercise.
Low concentrations of lactate (2.54±1.21 mmol/l) during and after the matches and
an increase of [FFA]s indicate that energy during the short exercise periods (9 s)
is mainly supplied by a breakdown of creatine phosphate, while aerobic pathways restore
the energy sources during the resting periods (12 s).
Serum concentrations of aldosterone and cortisol as well as the excretion of adrenaline
are enhanced on the same scale as after endurance sports. The excretion of noradrenaline
corresponds to values during exercise of high intensity.
Key words
volleyball - electrolytes - urinary excretion - hormones - energy supply
