The effects of an acute bout of strenuous aerobic exercise on plasma, erythrocyte, urinary and dietary values for selected trace minerals
Edgren, Kimberly K.
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Nineteen competitive cyclists participated in a week-long study to determine if prolonged, intense aerobic exercise produced a significant change in plasma, erythrocyte, and/or urine values for zinc(Zn) and copper(Cu). Subjects pedaled a cycle ergometer for 1 hour at 80% anaerobic threshold, after which, resistance was incrementally increased by 20 watts/minute until voluntary exhaustion. Six blood collections were drawn: preexercise, post-exercise and 2-, 24-, 72-, and 120-hours post-exercise, respectively. Five 24-hour urine collections were taken: one day pre-exercise, the exercise day, and 1-, 2-,and 4-days post-exercise, respectively. Results were significant (p<O.OS) for: plasma-Zn, erythrocyte-Zn, plasma-Cu, and erythrocyte-Cu changes, respectively, over the study period; post-exercise plasma-Zn increased over all other blood draws; pre-exercise erythrocyte-Zn and erythrocyte-Cu higher than each subsequent blood draw; and postexercise plasma-Cu higher than prior or subsequent blood draws, respectively. Results suggest that Zn and Cu status cannot be maintained in plasma and erythrocytes when athletes consume self-selected unsupplemented diets.