The Prevalence of Iron Deficient Anemia among New Infantry Recruits and Its Effect on Physical Fitness.

Background: Oxygen carrying capacity is clearly an important factor in physical fitness. There is limited information regarding the optimal hemoglobin level and iron stores status for physical activity and most studies followed relatively few participants. This information is usually on people participating in different sports of variable intensities, and it is difficult to predict how hemoglobin level might affect sports level in the general population.

Object: To assess hemoglobin and iron stores levels at induction and their impact on physical fitness.

Methods: 363 new infantry recruits were asked to participate in the study. Prior to recruitment all subjects were provided with a written, itemized protocol for a self-administered training regimen. Blood samples for hemoglobin, iron, ferritin, transferrin, folic acid and soluble transferrin receptor were taken from recruits that consented. A detailed medical and nutritional history was noted. Recruits performed the Wingate field fitness test including a 2Km. run. Recruits were grouped by the hemoglobin levels as pronounced anemia (<12 g/dl), intermediate anemia (<13g/dl), mild anemia (<14 g/dl) or normal (>14 g/dl).

Results: Laboratory information was available for 358 recruits, 333 of which also completed the Wingate test. Mean hemoglobin was 13.8 ± 1.0 g/dl (SD). 11.7% 37% and 4.5% of the recruits had lower levels that 14,13 and 12 g/dl, respectively. Mean ferritin was 57 ± 34 ng/ml (SD) with 15% of the recruits under the 25ng/ml norm. Mean folic acid level was 6.1 ±2.1 ng/ml (SD) with 7.9% of recruits under 3.7ng/ml. On multivariate analysis, pre-induction training improved running scores (P<0.001). Intermediate pre-induction hemoglobin level (12–14 g/dl) was associated with significantly better 2 km. running time (530sec ± 69) than both the lower hemoglobin group (570sec ± 77) and even the higher hemoglobin group (552sec ± 86, P<0.05). Smoking and poultry consumption were not associated with running scores or anemia.

Discussion: The subjects in this study are normal healthy young men, not sportsmen by acceptable criteria. The only pre-selection is that they volunteered and were found fit for the infantry. The high rate of abnormal hemoglobin and ferritin values in this population is most likely the result of “sports anemia” due to the intense physical training regimen adopted prior to their recruitment.

The improvement of running results with higher hemoglobin than 12 g/dl is certainly in line with previous work. The anemia may be partly encountered to physiologic dilutional pseudoanemia caused by plasma volume expansion reactive to physical activity. The decline of running result with lower hemoglobin, less than 12g/dl, can be explained with depleted iron stores. Depletion of iron stores could be also a result of strenuous exercise with recurrent events of bowel ischemia during exercise and occult blood loss, or poor diet as this group had also lower levels of folic acid. The decrease in running ability with increased hemoglobin above 14 g/dl is surprising and will need further evaluation.