Health Issues of Chronic Energy Deficit in Female Athletes

geekyjock76

Edit: I intended to post this here, but did so first in the General Weight Loss board...Oh well, here it is where it belongs....

There are many female athletes here with goals to reduce body fat percentage either for cosmetic reasons or to enhance athletic performance. However, many studies reveal that a large proportion of female athletes chronically have low energy availability - so much so they experience - or are at risks of - a number of health concerns. Unfortunately, some of these health issues remain hidden either due athletes or medical professionals not noticing signs and connecting the proverbial dots.

I present an essay which cites numerous studies regarding the various health concerns commonly associated with female athletes who chronically maintain energy deficits. The essay itself is quite lengthy, and although I'll quote a few notable excerpts, I highly recommend that all active females read all subheadings in their entirety.

Overview

One discovery has been that chronic energy deficit in the female athlete can cause musculoskeletal and reproductive dysfunction. Despite previous theories on the causes of menstrual dysfunction and the increased risk of stress fractures in the female athlete, studies have shown that the primary mechanism of menstrual disturbance in the female athlete is low energy availability.

Energy expenditure
The appetite of an athlete is not a reliable indicator of either energy balance or specific macronutrient requirements, because no biologic imperative to match intake to expenditure appears to exist.[8] Hunger is actually suppressed for a brief period after a single episode of exercise at greater than 60% maximal oxygen consumption, or VO2max.[9]

Food deprivation increases hunger, but the same low energy availability, when caused by energy expenditure from exercise, does not increase appetite.[10] In one study, a 20% increase in energy expenditure during 40 weeks of marathon training did not result in an increase in energy intake.[11, 12]

Other factors
Another factor in chronic energy deficiency in athletes is that body weight is not a reliable indicator of either energy or macronutrient balance. Because fat stores are associated with less body water than are protein and glycogen stores, the weight gain resulting from an increase in protein or glycogen stores more than counterbalances the weight loss resulting from the equivalent energy reduction in fat stores that occurs in low energy availability.

Patient History

Nutritional history
Importantly, gather information about nutritional intake and eating patterns. The components of each athlete's diet are important in terms of the quantity of protein, carbohydrate, vitamins, and minerals consumed. Also important are the effect of training on an athlete's diet and the modification of the athlete's diet in times of increased training.

Musculoskeletal history
With the increase in risk of stress fractures in females with chronic energy deficit, a careful review of past and current musculoskeletal injuries in the female athlete should be conducted, with a focus on all stress fractures.Any injury that results in loss of training or competition time should be considered major.

Menstrual history
Other than fracture, the most likely manifestation of severe, chronic low energy availability in the female athlete is menstrual disturbance. Because many women do not volunteer information concerning menstrual disturbances, it should be specifically sought during all routine and sick visits by female athletes.

A complete menstrual history should be obtained. This includes the age at menarche, average length of menses, average time between menstrual periods, variations during times of increased training, and number of cycles per year. The possibility of pregnancy should be excluded in the case of amenorrhea. The patient's personal and family history of reproductive disorders, such as premature ovarian failure, should be discussed.

Endocrine/metabolic history
A history of and the risk for any endocrine abnormalities should be explored. Any personal and family history of thyroid disorders, pituitary disorders, and diabetes should be sought. Any family history of bone disease should be elicited.

Psychosocial history
Eating patterns should be discussed, and the Eating Disorder Inventory (EDI) may be used to screen for current and past disordered eating patterns. As with all patients, alcohol, tobacco, and drug use, as well as social support, depression, anxiety, and a history of abuse, should be determined.

Performance history
During sustained energy deficiency, an athlete's strength, power, and vertical jump all decline by approximately 20%.[14] The athlete should be questioned as to whether she has noticed any change in strength or performance.

Medication history
All medications, dietary supplements, and herbal agents should be reviewed. Particular attention should be paid to medications, such as corticosteroids and anticonvulsants, that could affect bone health. The use of oral contraceptives should be elicited separately because patients often do not consider this a medication.

Physical Examinations

For patients with menstrual irregularities, the physical examination should screen for pathologies that could cause metabolic and hormonal abnormalities. Particular attention should be paid to the parotid glands (for evidence of hypertrophy, as in bulimia), visual-field testing for pituitary adenoma, muscle strength, and the epidermis.

Skin findings might include evidence of hirsutism, vitiligo, or increased pigmentation of the palmar creases in adrenal insufficiency; easy bruising or stria in Cushing syndrome; warm, moist skin in hyperthyroidism; or any lanugo in anorexia.

Diagnostic Studies

Urinary ketones
Because body weight alone is not a good indicator of body composition and energy availability, a noninvasive biomarker that reflects these variables should be identified. Until a better biomarker of body composition and energy availability is established, the measurement of urinary ketones might be the best indicator of sustained carbohydrate deficiency, because ketones are not present in urine when carbohydrates are available.

A baseline urinary acetoacetate measurement should be conducted by a trainer or team physician. Monthly measurements of urinary acetoacetate in times of increased training in normally menstruating athletes could be performed by the athlete herself or by the athletic trainer. The goal should be a complete absence of urinary ketones before and after a meal as well as before and after training.

Other tests
Testosterone, LH, FSH, estradiol, and prolactin tests are second-line options if a patient's reproductive function is not restored with a trial of increased energy intake or if the findings on physical examination and the patient's history suggest other causes of amenorrhea. If the patient has signs of hyperandrogenism (hirsutism), testosterone tests can help to assess for androgen excess.[17]

An FSH level of approximately 40 mIU/mL indicates ovarian insufficiency. If a repeat value in 1 month confirms this finding and if the patient has experienced at least 4 months of amenorrhea, premature ovarian failure is confirmed. If the FSH level is 20-40 mIU/mL in a patient with disordered menses, the diagnosis is overt ovarian insufficiency, also known as prodromal premature ovarian failure.

Menstrual Cycles in Athletes and Nonathletes

On average, menarche appears to occur at a later age in athletes. Generally, girls in the United States tend to get their first menstrual period between ages 12 and 13 years. For female athletes, however, studies have found an average age of 13.6 years in track and field athletes,[21] 14.2 years in Olympic volleyball candidates,[22] 14 years in elite figure skaters, 12.9 years in elite Alpine racers, 13.4 years in competitive swimmers,[23] and 15.6 years in elite gymnasts.[24]

Large-scale studies have yet to be performed using the same 3-month definition of amenorrhea to directly compare data from female college athletes with that from general college-age women. Smaller studies of athletes using the same 3-month definition of amenorrhea have shown a prevalence as high as 44% in dancers and 65% in long-distance runners.[27]

The incidence of luteal suppression and anovulation is high in regularly menstruating recreational and competitive athletes. Approximately 78% of regularly menstruating female runners have luteal suppression or anovulation in at least 1 month out of 3.[28]

Amenorrhea

The prevalence of amenorrhea strongly depends on how amenorrhea is defined. When the definition requires more months without menstrual periods, lower prevalence rates are reported. Studies of the general population have specified 3 months, because menstrual cycles longer than 90 days are extremely rare, even in the first and last decades of reproductive life. In large epidemiologic studies of college-age women in which amenorrhea was defined as no menstrual cycles for 3 consecutive months, prevalence rates of 2-5% have been reported.[33, 34, 35]

If no evidence suggests musculoskeletal injury (eg, stress fracture) in an amenorrheic or oligomenorrheic patient, discontinuing or decreasing physical activity is not necessary to restore menstrual function. Animal studies have shown that an increase in energy intake is sufficient to restore menstrual function.[15] Future studies on refeeding in amenorrheic females are needed to confirm that this is the safest and most effective treatment.

Different menstrual disorders can be symptoms of the same medical condition, and the same menstrual disorder can be a symptom of various conditions. Since the discovery in the late 20th century of progressive skeletal demineralization in amenorrheic athletes, most research has focused on amenorrhea in athletes. For inferential reasons, amenorrheic athletes have been compared with athletes who have highly regular menstrual cycles and with equally regular sedentary women. This research has identified undernutrition as the primary cause—and indeed the only demonstrated cause—of amenorrhea and luteal suppression in athletes.

Oral Contraceptives in Athletes

Studies have not shown that oral contraceptives have a major impact on performance, but several studies on monophasic and triphasic low-dose oral contraceptives have found a decrease in maximal oxygen consumption (VO2max) in females from all athletic backgrounds after more than 1 month's use of these drugs. Athletes should be educated regarding this effect.[38, 39] Because these same studies have shown a reversal of this effect within 1 month of the cessation of oral contraceptives, women who choose to take an oral contraceptive should be counseled that the decrease in VO2max is likely reversible.

Low Energy Availability and Reproduction

Female athletes can be chronically energy deficient.[15] With the exception of cross-country skiers, female endurance athletes consume approximately 70% as much energy and carbohydrates (controlled for body weight) as male athletes.[41] Biochemical markers in female athletes indicate a mobilization of fat stores, slowing of the metabolic rate, and a decline in glucose utilization, with more extreme abnormalities in amenorrheic athletes and less extreme abnormalities in regularly menstruating athletes.[15]

Studies in humans and monkeys have shown that this chronic energy deficiency causes reproductive disturbances in many female athletes. In 1998, Loucks and colleagues demonstrated that the stress of exercise did not suppress LH pulse frequency, because the disruption of LH pulsatility in exercising women could be prevented with dietary supplementation. On the other hand, low energy availability, caused either by an increase in exercise energy expenditure or by dietary energy restriction alone, did disrupt LH pulsatility.[42] This low-energy state also suppressed levels of triiodothyronine (T3), insulin, insulinlike growth factor–1, and leptin and raised levels of growth hormone and cortisol in a pattern similar to those seen in amenorrhea and luteal suppression with eumenorrhea.[42]

Curiously, LH pulsatility is less disrupted in women who exercise than in women whose energy availability is reduced by exactly the same amount because of dietary restriction. This is surprising, because no one had previously suggested that exercise might be protective against menstrual disorders. On closer examination, working muscle in energy-deprived women who exercised reduced its glucose utilization, so that substantially more carbohydrate was available to the brain. This finding strengthens the hypothesis that reproductive function in women specifically depends on brain glucose availability.[15]

The dose-response relationship between energy availability and LH pulsatility has also been investigated. LH pulsatility was found to have been disrupted below a threshold of energy availability of approximately 30 kcal/kg of lean body mass (LBM) per day. The dose-dependent effects on LH pulsatility most closely resembled the metabolic substrates glucose and beta-hydroxybutyrate and the metabolic hormones cortisol and growth hormone. These findings support the reported hypothesis that "reproductive function reflects the availability of metabolic fuels, especially glucose, which may be signaled in part by activation of the adrenal axis."[15]

Low Energy Availability and Bone Health

The principal role of estrogen, through its action on osteoblasts and its indirect effect on osteoclasts, is to prevent bone resorption.[46] In the past, some have theorized that the decreased bone densities observed in females with anorexia nervosa and in amenorrheic athletes was due solely to chronic hypoestrogenism. However, estrogen replacement in these individuals does not fully reverse the decrease in bone density.[47, 48, 49, 50, 51, 52] This finding prompted researchers to investigate chronic undernutrition as an estrogen-independent mechanism for decreased bone mineral density in these patients.

The effects of low energy availability on bone health are evident even in normally menstruating sedentary women. In a landmark study, Ihle and Loucks demonstrated for the first time that bone formation is impaired within 5 days of the onset of low energy availability. At levels of energy deficit milder than that in bone resorption and at extreme energy restriction (10 kcal/kg LBM/day), increased bone resorption becomes uncoupled from decreased bone formation.[53]

The findings of the study are applicable to female athletes, because normally menstruating athletes have reported energy availabilities of approximately 30 kcal/kg LBM/day, and amenorrheic athletes have reported energy availabilities of approximately 16 kcal/kg LBM/day.[54]

Peak bone mass is a significant predictor of risk for the development of osteoporosis.[46] The decrease in bone formation and increase in resorption (uncoupling) that occurs in a severe, chronic energy-deficient state is dangerous at any age. Because approximately 50% of peak bone mass is achieved in adolescence and is completed in most women by the end of the second decade,[56, 57] the consequence of suppressing bone formation in adolescence can be disastrous.

Nutritional Counseling

Because appetite is not a reliable means of determining the energy needs of the female athlete and because exercise appears to suppress appetite, nutritional counseling is important for normally menstruating athletes and for athletes with menstrual disturbances.

Athletes need to eat by discipline, not by appetite. Studies have shown that a threshold of 20-30 kcal/kg LBM/day is needed for reproductive function and bone health, and a diet comfortably greater than 30 kcal/kg LBM/day is recommended.

Counseling should focus on how a patient's diet can provide close to 45 kcal/kg LBM/day in order for the patient to maintain reproductive and skeletal health. A balanced, nutrient-rich sample diet of 45 kcal/kg LBM/day tailored to individual weight or a general sample diet for weights of 55, 60, 65, and 70 kg on either a poster in the training room or a handout would be helpful. In addition, an estimation of the energy expenditure during a typical daily training regimen and the replacement of this expenditure are important.

Athletes should be counseled that, if they underconsume, they are actually slowing their metabolic rate and that an increase in energy intake helps to restore their metabolic rate, prevent deleterious effects on reproductive and skeletal health, and even improve performance. Therefore, if the athlete's weight increases while her metabolic rate is adjusting, at least part of it is likely due to an increase in LBM, which even further improves performance.

For athletes with menstrual disturbances, energy intake should be even more closely monitored to ensure that it approximates 45 kcal/kg LBM/day along with the replacement of energy used during exercise. While intake is increased over a period of 1-2 weeks, electrolytes and hematocrit values should be monitored at least once a week during the transition.

http://emedicine.medscape.com/article/312312-overview#a1