The study – published in the Journal of Applied Physiology – examined blood parameters for iron and vitamin status were studied along with objective measures of physical fitness in over a thousand healthy male and female European adolescents.
Led by Luis Gracia-Marco of the University of Zaragoza, Spain, the researchers found that blood levels of various micronutrients – including iron, vitamin D, and beta-carotene – are closely connected with performance on a physical fitness test.
The authors’ note that studies connecting micronutrients with physical fitness in any population has been ‘controversial’ and ‘limited’. This is especially true for adolescents, a group that's often difficult to gather information on. But the new findings, they say, are one of the first to find connections between micronutrients and physical fitness in this age group.
The team said their findings were promising though did not prove causality. As a result they said further research is needed: "The associations between physical fitness and iron or vitamin status observed in this cross-sectional study in adolescents should be followed up by a study specifically designed to evaluate causal relationships."
Nutrition and fitness
Several studies have shown that adolescents' intake of important nutrients, as well as their performance on standard physical fitness tests, has fallen in recent years
The authors noted that because nutrition and fitness are tightly intertwined - for example, iron forms part of hemoglobin, which carries oxygen to muscles, and antioxidants such as vitamin C aid in rebuilding damage after intense training - these two findings could be related.
As a result, they used data from 1089 adolescents (aged between 12.5 and 17.5 years) that took part in a large-scale, long-term research project known as the Healthy Lifestyle in Europe by Nutrition in Adolescents Cross-Sectional Study (the HELENA study).
Gracia-Marco and his team searched for correlations between physical fitness scores and blood levels of various micronutrients, including haemoglobin (indicative of iron intake),retinol, vitamin C, beta-carotene, alpha-tocopherol, vitamin B6, plasma folate, and vitamin D - as measured by 25(OH)D blood plasma levels.
The researchers found that adolescents' blood levels of the various micronutrients are correlated with performance in certain physical fitness tests.
For cardiorespiratory fitness, concentrations of haemoglobin, retinol, and vitamin C in males and beta-carotene and vitamin D (25(OH)D) in females was associated with maximal oxygen consumption (VO2max).
Whilst for muscular fitness, concentrations of haemoglobin, beta-carotene, retinol, and alpha-tocopherol in males and beta-carotene and vitamin D in females were associated with performing better on a standing long jump test.
Source: Journal of Applied Physiology
Published online ahead of print, doi: 10.1152/japplphysiol.01492.2011
“Iron and vitamin status biomarkers and its association with physical fitness in adolescents. The HELENA study.”
Authors: Luis Gracia-Marco, Jara Valtueña, Francisco B. Ortega, Faustino R. Perez-Lopez, German Vicente-Rodriguez, et al