Effects of a multivitamin and iron supplement on running performance in Gambian children.

Forty boys and girls between 11 and 14.5 years with evidence of subclinical vitamin deficiencies were allocated to two groups to receive, twice weekly, either a placebo or a multivitamin and iron supplement. Prior to supplementation and on two subsequent occasions about 5 weeks apart, the children performed an exercise regimen on a treadmill during which expired air was collected and heart rate monitored. The supplement resulted in marked improvements in riboflavin and vitamin C status and checked the decline in iron stores seen in the unsupplemented children. During the study the running performance of unsupplemented children deteriorated, and markedly so in a subgroup with initially poor nutrient status. The vitamin and iron supplement prevented this deterioration so as to produce a significant reduction in the energy cost of treadmill running in the more malnourished subgroup, relative to the changes seen in children receiving no supplement.