Abstract
There is considerable debate on the effects of endurance stress on concentrations of trace minerals and as to whether athletes, who restrict calories to maintain low body weights, could comprise their trace mineral levels. In a prospective study, the effect of running a marathon course on whole blood levels of chromium, cobalt, nickel, and molybdenum was evaluated. Blood samples of 13 test runners (2 females, 11 males) were obtained twice before, immediately after, and 1 week after running a marathon. The analyses of the concentrations in whole blood were performed using graphite tube atom absorption spectrometry (GFAAS). The chromium level of the samples ranged between 1.3 ng/g and 19.3 ng/g. Mean chromium concentrations were elevated before and immediately after the marathon (4.3–7.4 ng/g) and decreased to an average of 2.7 ng/g after the marathon course. The difference between chromium concentrations obtained immediately after and 1 week after the marathon course was significant. Levels of chromium exhibited a high variability; however, the percentage of concentrations below the detection limit was 0%. Similarly, owing to different individual response to strenuous exercise, concentrations of nickel, molybdenum, and cobalt were highly variable, exceeding normal limits by 47.3%, 25.1%, and 4.6%, respectively. Mean concentrations of nickel, cobalt, and molybdenum ranged from 4.3–22.7 ng/g (Ni), 0.16–2.2 ng/g (Co), and 0.2–0.7 ng/g (Mo); the difference was not significant at any time. The current study was able to show that running a marathon course does not lead to significant changes in the whole blood levels of cobalt, nickel and molybdenum. Chromium levels, however, were significantly decreased immediately after the marathon course, a finding that corresponds well with previous observations of increased mobilization of chromium from body stores and subsequently elevated serum levels. J. Trace Elem. Exp. Med. 15:201–209, 2002. © 2002 Wiley‐Liss, Inc.