The aim of this study was to assess the effect of a daily intake of
copper supplements on negative
copper balance during prolonged exposure to
hypokinesia (decreased number of kilometers per day). During
hypokinesia (HK), negative
copper balance is shown by increased, not by decreased, serum
copper concentration, as it happens in other situations. Studies were done during a 30-d prehypokinetic period and a 364-d hypokinetic period. Forty male trained volunteers aged 22-26 yr with a peak
oxygen uptake of 66.4 mL/min/kg and with an average of 13.7 km/d running distance were chosen as subjects. They were equally divided into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SACS and SHKS groups took 0.09 mg
copper carbonate/kg
body weight daily. The SHKS and UHKS groups were maintained under an average running distance of 1.7 km/d, whereas the SACS and UACS groups did not experience any modifications in their normal training routines. During the 30-d prehypokinetic period and the 346-d hypokinetic period, urinary excretion of
copper,
calcium, and
magnesium and serum concentrations of
copper,
calcium, and
magnesium were measured.
Copper loss in feces and
copper balance was also determined. In both UHKS and SHKS groups, urinary excretion of
copper,
calcium, and
magnesium and concentrations of
copper,
magnesium, and
calcium in serum increased significantly when compared with the SACS and UACS groups. Loss of
copper in feces was also increased significantly in the SHKS and UHKS groups when compared with the UACS and SACS groups. Throughout the study, the
copper balance was negative in the SHKS and UHKS groups, whereas in the SACS and UACS groups, the
copper balance was positive. It was concluded that a daily intake of
copper supplements cannot be used to prevent
copper deficiency shown by increased
copper concentration.
Copper supplements also failed to prevent negative
copper balance and
copper losses in feces and urine in endurance-trained subjects during prolonged exposure to HK.