Female athletes are notoriously susceptible to more exercise-induced health consequences in relation to their male counterparts, simply by virtue of their genetic anatomy and physiology. The three most common and worrisome disorders include iron deficiency anemia, amenorrhea, and stress fractures, each of which will be covered in depth below. Extra precautions need to be taken when undergoing a heavy training load in order to avoid these potentially debilitating disorders.
Iron Deficiency
Anemia is defined as an insufficient amount of healthy red blood cells in circulation, and it is frequently associated with iron-deficiency (1). A potential source of the anemia may be blood loss from the gastrointestinal and urinary tract after intense exercise, a result of transient ischemia from the vasoconstriction of splanchnic (GI) and renal vessels during exercise (2).The maximum amount of oxygen that can be carried in the blood is determined by the amount of the oxygen-carrying protein, hemoglobin, present in the blood. Iron is an essential component of hemoglobin, and so an iron deficiency places a greater demand on the cardiovascular system as a result of the reduced oxygen carrying capacity. Athletes are more at risk for iron-deficiency than the general population, with female endurance athletes being in the greatest danger (3). Common symptoms include fatigue, irritability, moodiness, headaches, and impaired concentration, potentially worsening to lightheadedness upon standing, pica (non-food cravings, such as ice), brittle nails, sore tongue, and shortness of breath (1). Iron-supplementation with ferrous sulfate is highly recommended for female endurance athletes and correction of this deficiency can lead to enhanced performance and health status.
Amenorrhea
Amenorrhea is a disorder of absent menstruation in females, characterized by three or more consecutive missed cycles (4). High-risk lifestyle factors include low body weight (>10% under normal), excessive exercise, and stress (4). A higher incidence of amenorrhea is found in female athletes than in the general population, due to the fact that strenuous activity causes metabolic alterations in the endocrine system, leading to severe hormonal disturbances (5). Exercise-induced amenorrhea leads to an impaired menstrual cycle due to decreased follicle-stimulating hormone (FSH) and luteinizing hormone (LH); a lack of these two disrupts the hypothalamic center in the brain, which is responsible for hormone signaling, specifically lowering estrogen levels (5). Estrogen is a key player in the development and maintenance of the body’s immune system, and so depleting this hormone leads to increased susceptibility to infections such as those of the upper respiratory tract (5). If no intervention precedes, predisposed infertility and progression to refractory amenorrhea (second-grade) with decreased bone density (osteoporosis) are likely to occur (5).
Stress Fractures
A stress fracture occurs when the body is unable to absorb the shock of impact on some surface, typically due to overuse and fatiguing muscles. Both iron-deficiency anemia and amenorrhea have been linked to secondary decreased bone mineral density and thus stress fractures, after early signals and symptoms have been ignored (2). IL-6 is an inflammatory mediator in the body that responds to intensive exercise stress (2). When IL-6 upregulates, it induces osteoclast activity, or the breakdown of bone minerals with the intent to rebuild. However, IL-6 also activates hepcidin, a small molecule that promotes iron deficiency (2). Iron-deficient bone cannot rebuild itself properly, leaving the athlete in a state of weakened bone mineral density and vulnerable to stress fractures if the deficiency is not overcome. Animal studies have also shown that iron deficiency impairs the bone resorption (rebuilding) process (6) and the root of the issue may be nothing more than an insufficiently iron-supplemented diet (2). Other studies have found a correlation between menstrual irregularities and the incidence of stress fractures in female athletes (2). A large majority of stress fractures occur in the lower leg and take a minimum of six to eight weeks to heal, creating a major setback in a competitive athlete’s training regimen regardless of the sport.
Training volume and intensity may need to be modified to give the athlete’s body a chance to recuperate and strengthen itself naturally. Both of these exercise variables create significant stress on the various systems of the body, temporarily depressing its natural functions to focus attention on the presented stressor. Coaches and parents alike should be aware of the presenting symptoms common to these three health issues in particular, for both the well-being and athletic longevity of all female competitors.
References
- Brittenham GM. Disorders of iron homeostasis: iron deficiency and overload. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, Pa: Elsevier Saunders; 2012: Ch 34.
- Yanovich, R, Merkel, D, Israeli, E, Evans, RK, Erlich, T, and Moran, DS. Anemia, iron deficiency, and stress fractures in female combatants during 16 months. Journal of Strength & Conditioning Research 25:12 (2011). Pgs 3412-3421.
- Hinrichs, T, Franke, J, Voss, S, Bloch, W, Schänzer, W, and Platen, P. Total hemoglobin mass, iron status, and endurance capacity in elite field hockey players. Journal of Strength & Conditioning Research 24:3 (2010). Pgs 629-638.
- Shimizu, K, Suzuki, N, Nakamura, M, Aizawa, K, Imai, T, Suzuki, S, Eda, N, Hanaoka, Y, Nakao, K, Suzuki, N, Mesaki, N, Kono, I, and Akama, T. Mucosal immune function comparison between amenorrheic and eumenorrheic distance runners. Journal of Strength & Conditioning Research 26:5 (2012) Pgs 1402-06.
- DeCherney AH, et al. Current Diagnosis & Treatment Obstetrics & Gynecology.11th ed. New York, N.Y.: The McGraw-Hill Companies (2013), Web.
- Katsumata, S, Katsumata-Tsuboi, R, Uehara, M, and Suzuki, K. Severe iron deficiency decreases both bone formation and bone resorption in rats. Journal of Nutrition 139 (2009). Pgs 238-243.
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