DERUISSEAU, K. C., L. M. ROBERTS, M. R. KUSHNICK, A. M. EVANS, K. AUSTIN, and E. M. HAYMES. Iron Status of Young Males and Females Performing Weight-Training Exercise. Med. Sci. Sports Exerc., Vol. 36, No. 2, pp. 241–248, 2004.
Purpose: To determine the effect of weight training on measures of iron status in young males and females.
Methods: Forty (27 female, 13 male) non-weight-trained college age subjects participated in a 12-wk weight-training program conducted 3 d·wk−1. Blood samples and food diaries were obtained pretraining and at 4-wk intervals. Blood was analyzed for hemoglobin, hematocrit, serum iron (SI), total iron binding capacity (TIBC), transferrin saturation (TS), serum ferritin (SF), soluble transferrin receptor (sTfR), and creatine kinase (CK). Subjects were grouped by SF level (FL, females ≤ 20 μg·L−1; FN, females > 20 μg·L−1; ML, males ≤ 45 μg·L−1; MN, males ≥ 50 μg·L−1) to determine the impact of initial iron status on measured responses.
Results: Weight training increased strength and fat-free mass and decreased levels of percent body fat. Hemoglobin concentration declined after 12 wk of training (13.7 ± 1.6 vs 13.2 ± 1.7 g·dL−1), independent of gender or initial iron status. Only the MN group experienced a decline in SF level after 8 wk of training (129.7 ± 77.9 vs 102.0 ± 57.8 μg·L−1). No significant changes were observed for hematocrit, SI, TIBC, TS, sTfR, or CK measures. Total iron intake, but not heme or bioavailable iron intakes, declined at the 12th week of training compared with baseline (13.4 ± 6.5 vs 10.7 ± 4.8 mg·d−1) and was not significantly correlated with hematological or iron status measures.
Conclusions: Hemoglobin concentration declines without alterations in SI, TIBC, TS, or sTfR after 12 wk of weight training. The SF level of males with adequate iron status is lowered with weight training but not among females or males with low iron status.
Traditionally, studies examining the effect of exercise on measures of iron status have focused on endurance athletes. However, weight training has become an important part of exercise programs among both competitive and recreational athletes. This form of training may adversely affect measures of iron status. Damage to red blood cells incurred as a result of mechanical and oxidative stresses may lead to increased intravascular hemolysis and iron turnover (15,22). An increased level of fat-free mass (FFM) may increase tissue iron demand and result in elevated soluble transferrin receptor (sTfR) levels (19). Additionally, exercise-induced muscle damage may be associated with an acute phase inflammatory response. Indices of iron status including serum iron (SI), serum ferritin (SF), total iron binding capacity (TIBC), and transferrin saturation (TS) are affected by inflammation (11).
Limited data suggest that an alteration in iron status can occur among young individuals participating in weight-training exercise. Young males have experienced impaired measures of iron transport and storage (13,22) and lower hemoglobin levels (22) after 6–8 wk of weight training. A preliminary investigation involving young females has reported an improved iron status following twelve weeks of aerobic-resistance exercise (14). Therefore, the main purpose of this investigation was to further examine the relationship between weight-training exercise and measures of iron status during a program of progressive weight training involving young males and females. In addition, a second purpose was to assess the effect of exercise induced muscle damage on SF levels.
Individuals with initially low iron status were hypothesized to experience a decline in the levels of hemoglobin, SI, TS, and elevations in sTfR as a result of the weight-training program. Individuals with initially adequate iron stores were expected to experience decreased SF levels with no change in hemoglobin or measures of iron transport.
Department of Nutrition, Food, and Exercise Sciences, Florida State University, Tallahassee, FL
Address for correspondence: Emily M. Haymes, Department of Nutrition, Food, and Exercise Sciences, 436 Sandels Building, Florida State University, Tallahassee FL 32306-1493; E-mail: email@example.com.
Submitted for publication November 2002.
Accepted for publication October 2003.