Jan 29, 2015Iron Deficiencies During Training
Although often overlooked, iron plays an important role in exercise. It is required for the formation of hemoglobin and myoglobin, which are oxygen-binding proteins. However, there are conflicting views about the effects of iron deficiency on athletic performance.
By Heather Barnhill & Dr. Christopher Mohr
Heather Barnhill, MS, is a freelance writer and editor in the health and fitness field. Christopher Mohr, PhD, RD, is the owner of Louisville, Ky.-based Mohr Results, Inc., which provides nutrition and training consultations for individuals and corporations. He can be reached through his Web site: www.MohrResults.com.
We do know that training can cause significant fluctuations in iron status. But we do not know whether dietary or supplementary iron intake affects iron status and performance in a significant way.
That’s why a team of researchers decided to study iron status in 24 healthy, collegiate female swimmers over a 16-week training period. The researchers also wanted to determine the effects of training on body composition and dietary intake.
The subjects were responsible for their own meals and were provided a daily multivitamin-mineral supplement containing 18 mg of iron, the recommended daily allowance for female athletes. They were also given counseling by a registered dietitian, who gave them advice on how to best meet their energy and specific nutrient needs.
The training took place six days a week, two hours per day. Swim workouts occurred every day, with dryland training (of resistance, strength, and flexibility exercises) three of the six days. In the pool, the athletes covered 6,400 to 10,000 meters per day.
The researchers analyzed blood samples for various biochemical indices of iron status before and after the 16-week period. Total lean body mass was measured using a DEXA scanner. Energy intake was also measured to ascertain if the swimmers were consuming adequate energy sources to meet their demands. Finally, swim time and stroke length were used to determine if iron status affected performance.
The study found a decrease in body fat mass and an increase in lean body mass over the 16-week training period. It also indicated that energy intake did not meet energy demand. Dietary quality did improve over the course of the study, perhaps due to the nutritional counseling. All those findings were typical and expected.
What they were looking for most, however, was a decrease in iron among the participants. Although the swimmers were ingesting at least 18 mg of iron daily, the researchers expected to find that training would diminish those stores and the athletes would have iron deficiencies.
What they found, instead, was that iron status improved. It did not improve enough to be considered statistically significant, but there were slight increases in hemoglobin and hematocrit. The results did not fit the hypothesis that female athletes are at-risk of developing sports anemia caused by training. The researchers also found that a change in iron status did not correlate with a change in performance in their subjects.
The researchers then concluded the increase in iron stores may have been due to the improved dietary intake during the training period. They noted that the athletes increased their vitamin C intake, which increases iron absorption. They found that improving dietary intakes of iron and vitamin C and taking supplements with iron may prevent the anticipated decline in iron status associated with training.
While more research is clearly needed concerning iron and its impact on sports performance, it is well known that a nutritionally sound eating plan is crucial for peak performance. Iron rich food sources include: eggs, lean meats, legumes, whole grains, and green leafy vegetables. And for those who eat only non-meat sources of iron, which are not absorbed as well as meat sources, consuming vitamin C with meals enhances absorption.
Study Specs: “Body Composition, Dietary Intake, and Iron Status of Female Collegiate Swimmers and Divers,” appeared in the June 2006 issue of The International Journal of Sport Nutrition and Exercise Metabolism, and was authored by H. Petersen, C. Peterson, M. Reddy, K. Hanson, J. Swain, R. Sharp, and D. Alekel. The journal can be found on the Web at: www.humankinetics.com/IJSNEM/journalabout.cfm..