The effect of vitamin and mineral supplementation was studied over 7 to 8 months of training and competition in 82 athletes from four sports: basketball, gymnastics, rowing, and swimming. Matched subgroups were formed and a double-blind design used, with subgroups being given either the supplementation or a placebo. All athletes were monitored to ensure that the recommended daily intakes (RDI) of vitamins and minerals were provided by diet alone. Sport-specific and some common tests of strength as well as aerobic and anaerobic fitness were performed. Coaches' assessment of improvement was also obtained. The only significant effect of supplementation was observed in the female basketball players, in which the supplementation was associated with increased body weight, skinfold sum, and jumping ability. A significant increase in skinfold sum was also demonstrated over the whole group as a result of supplementation. In general, however, this study provided little evidence of any effect of supplementation to athletic performance for athletes consuming the dietary RDIs.
Richard D. Telford, Edward A. Catchpole, Vicki Deakin, Allan G. Hahn and Ashley W. Plank
Richard D. Telford, Edward A. Catchpole, Vicki Deakin, Alan C. McLeay and Ashley W. Plank
Blood indicators of eight vitamins (
Richard D. Telford, Christopher J. Bunney, Edward A. Catchpole, Wendy R. Catchpole, Vicki Deakin, Bon Gray, Allan G. Hahn and Deborah A. Kerr
This investigation aimed to determine whether the physical work capacity of nonanemic athletes could be improved when plasma ferritin concentrations of below 30 nglml were raised at least 15 ng/ml. The experimental group consisted of 15 training athletes, each of whose plasma ferritin concentration was less than 30 ng/ml (mean and SD of 19.8 ±8.4 nglml). In a control group of 16, each was measured with a plasma ferritin concentration of more than 40 ng/ml (mean and SD of 83.3 ±37.6 ngfml). All participated in submaximal and maximal tests for aerobic and anaerobic power. Following iron supplementation, plasma fenitin concentration in each experimental subject increased by at least 15 nglml to more than 30 ng/ml, to a new mean of 46.3 ±15.5 ng/ml. The performance measures were also repeated, but no significant overall effects were associated with the increased plasma ferritin concentrations. These data provide no sound evidence that physical work capacity of athletes is enhanced when plasma ferritin concentrations of around 20 ng/ml are increased by at least 15 ng/ml.