The Female Athlete

History of Women in Sports

  • Throughout history, women have participated in sports at much lower rates than men.

  • The Modern Olympics was first held in 1896; in the inaugural year, there were no female participants. The year 1900 marked the first female participation, and women constitute 2.2% of athletes in just two of the 95 sporting events held.

  • In the United States, in 1971, high school girls constitute just 7.4% of all high school athletes; concurrently, women accounted for 14.6% of Olympic participants.

  • Title IX was passed in 1972, which stated that no person in the United States shall, on the basis of sex, be excluded from participation in, be denied the benefits of, or be subjected to discrimination under any educational program or activity receiving federal funding.

  • CDC data from 2013 showed that 48.5% of high school girls played one or more sports in the previous year compared with 59.6% of boys, indicating a statistically significant difference.

  • A prospective study evaluating activity levels throughout childhood revealed that girls had less active minutes per day than boys across all ages and that overall active minutes decreased with age. By 17 years, only 6% of girls were achieving the recommended 30 minutes of daily activity as opposed to 100% of boys.

  • From childhood to adolescence, a similar rate of decline is observed in sports participation levels. Although the rate of decline is similar between boys and girls, girls begin with overall lower levels of sports participation.

  • Sociocultural determinants that improve female sports participation include parental support (may take form of verbal support, a rule to participate in sport, or role modeling), higher socioeconomic status, higher rates of sibling sports activity, and higher parental education level.

  • Female participation in sports increased when the sport was perceived to be fun, involved friends, and had familial and school support through feedback and role modeling.

  • Females with higher intrinsic motivation participate more in sports.

Pros/Cons of Women in Sports

  • Adolescent participation in sports has short- and long-term risks and benefits over physical activity alone.

  • Studies have revealed an overall reduction in all-cause mortality and a significant reduction in cancer rates into adulthood in adolescents who were former athletes.

  • In addition, adolescent sports participation correlates with increased bone density in youngsters and in middle-aged women who previously participated in sports in comparison with those who did not.

  • High school and collegiate girls who participate in sports every day have a decreased BMI and increased cardiorespiratory fitness compared with female nonathletes.

  • Measures of mental health and well-being in terms of self-esteem, depression, and suicidality are all positively affected by sports participation in high school and college athletes. However, no apparent correlation has been observed between decreased suicidal ideation and depression levels and gender, race, or ethnicity.

  • Cognitive benefits, academic performance, and education levels have an overwhelming positive response to participation in high school and collegiate athletes.

  • The overall risk of victimization in the form of bullying, property violence, sexual abuse, rape, and violent contact is lower among female athletes than among nonathletes. These findings were consistent even with controls for race, mother’s education, age, number of relationships, and alcohol consumption.

  • Sexual behavior in female athletes is complex, but overall, most studies suggest that there are positive effects from sports participation with lower rates of sexual activity, pregnancy, and sexual risk-taking in high school and collegiate girls who participate in sports than in boys and nonathletes.

  • Moreover, high school and collegiate female athletes exhibit lower rates of smoking, marijuana use, steroid use, and other illicit substance use than nonathletes.

  • Alcohol use is much higher in the adolescent athlete population regardless of gender or race.


  • Girls achieve physiologic maturity quicker than boys, thus achieving earlier peak height velocity (11.5 years [y] vs. 13.5 y) and skeletal maturity (13.5 y vs. 14.3 y). Along with hormonal changes at the time of puberty, there are many physiologic differences between male and female athletes.

  • Tables 12.1 and 12.2 enlist the effects of estrogen and progesterone.

    TABLE 12.1


    System Effect

    • ↑ in thrombosis

    • ↓ total cholesterol

    • ↓ low-density lipoprotein (LDL) levels

    • ↑ high-density lipoprotein (HDL) levels

    • Vasodilates vascular smooth muscle

    • ↑ blood pressure


    • ↑ intramuscular and hepatic glycogen storage and update

    • Glycogen sparing (↑ lipid synthesis, ↑ lipolysis in muscle, and ↑ utilization of free fatty acids)

    • ↑ insulin resistance and ↓ glucose tolerance

    • Deposition of fat in the breasts, buttocks, and thighs

    Bone metabolism Facilitates uptake of calcium into bone
    Neurologic Cognitive function and verbal memory in postmenopausal women

    TABLE 12.2


    System Effect
    Thermoregulation ↑ core body temperature of 0.3°C–0.5°C
    Respiratory ↑ minute ventilation
    ↑ ventilatory response to hypoxia and hypercapnia
    Metabolic Fluid retention
    ↑ dependence on fat as a substrate
    Induce peripheral insulin resistance


  • Female athletes typically have a slightly higher resting HR and a lower systolic BP than male athletes. With exercise, female athletes exhibit a lower absolute change in their systolic BP.

  • While males typically have larger hearts at baseline, both males and female athletes demonstrate physiologic cardiac hypertrophy in response to training.

  • The mechanism for hypertrophy may be different in females compared with testosterone-driven muscle hypertrophy in males. Females have a higher Ca 2+ /calmodulin-dependent kinase (CaMK) and protein kinase B/glycogen synthase kinase-3-beta (AKT/GSK-3) pathway signaling as well as increased fatty acid metabolism, which may contribute more to female-specific physiologic cardiac hypertrophy.

  • Pathologic cardiac hypertrophy and arrhythmias are less common in female athletes and considered secondary to estrogen’s protective cardiac effects against harmful remodeling.

  • Gender differences in cardiac functioning and contribution to maximal oxygen consumption (VO 2 max) may be more related to the larger size of male hearts that have greater stroke volume compared with smaller female hearts.


  • Beginning at around 2 years of age, male lungs are larger than female lungs even when normalized to height/length.

  • Females have smaller lung volumes and lower expiratory flow rates compared with males. In addition, with regard to total lung volumes, females have considerably smaller airways, which can contribute to expiratory flow limitations.

  • On approaching maximal exercise, females increase their end expiratory lung volumes back toward resting, hyperinflating their lungs in response to these expiratory flow limitations. Simultaneously, higher end inspiratory lung volumes are required to maintain tidal volume. Ultimately, the intensity of breathing is greater in females, approximately twice as high at maximal exercise.

  • The prevalence of arterial oxyhemoglobin desaturation is higher in females than in males owing to smaller lung volumes, smaller airways, lower resting diffusion capacity, and lower maximal expiratory flow rates.

  • Moreover, females experience less exercise-induced diaphragmatic fatigue.

Metabolism, Nutrition, and Hydration

  • 17 β-estradiol promotes lipid oxidation during endurance exercise, and female athletes have been shown to have a greater dependence on lipid oxidation during endurance events. In addition, 17 β-estradiol promotes hepatic glycogen sparing.

  • This enhanced capacity of lipid oxidation, as well as a greater ability to maintain plasma glucose, may account for the ability of female athletes to outperform male athletes at very high distances.

  • Females have a lower leucine oxidation rate at rest and during exercise, which accounts for their lower protein requirements.

  • There is some evidence that female athletes do not obtain the same benefits from traditional carbohydrate loading compared with male athletes, and in fact need to ingest a proportionally higher amount of carbohydrates in order to gain the same effects.

  • Lower ferritin and total body iron tends to be associated with higher oxidative stress. Female athletes are frequently shown to have higher levels of reactive oxygen metabolites and lower iron stores than their male counterparts.

  • Throughout the menstrual cycle, from early follicular phase to luteal phase, total body water in females can increase by as much as 2 L. Females have been shown to have lower urine osmolality than do males at rest, with daily activities and with exercise, most likely owing to differences in arginine vasopressin (AVP) concentrations.

  • In a study of endurance cyclists matched for BMI and performance, no differences were observed in the ratings of thirst and thermal sensation or the rate of perceived exertion; however, marked differences were noted in terms of female cyclists having a greater total fluid intake, greater percentage of change in body mass, lower urine specific gravity of urine, and lighter color of urine.

  • Female athletes do not sweat as much as male athletes do, but they sweat over a greater proportion of their body. In general, studies have shown that females tend to overconsume water in relation to their body size and metabolic rate.

  • A study evaluating the relationship between blood lactate and cortical excitability during exercise revealed that females exhibited a significantly greater improvement in excitability of the primary motor cortex in response to increased lactate levels; this was attributed to the excitatory role of estrogens on the cerebral cortex.


  • Female athletes have been shown to have a similar composition of muscle fibers and enzymatic activity as their male counterparts do when involved with similar sports and activities; however, female muscle fibers are smaller.

  • Female athletes are able to achieve significant strength gains with training, but they cannot achieve the same strength levels or hypertrophy as a similarly sized and trained male athlete owing to the difference in testosterone.

  • Before puberty, both boys and girls have similar strength and joint laxity. At puberty, estrogen contributes to increased joint laxity in girls, while testosterone contributes to muscle hypertrophy in boys.

  • Certain studies have shown lower collagen synthesis in tendons of combined oral contraceptive users, although not all studies have reported differences in tendon properties across the menstrual cycle.

  • Some of the increased injury risk seen in female athletes after the age of puberty is attributed to lax joints and strength imbalance caused by these hormonal changes.

Gastrointestinal Symptoms

  • The incidence of gastrointestinal symptoms and complaints is higher in female endurance athletes.

  • In addition, studies have revealed a higher incidence of gastrointestinal ischemia in female athletes than in male athletes; however, the underlying pathophysiology remains unknown.

Female Athlete Triad

  • The female athlete triad is a spectrum of three components: low energy availability (EA), menstrual dysfunction, and low bone mineral density (BMD). Female athletes may have one or more of these components. Each component is on a spectrum of worsening intensity, ending with low EA with or without an eating disorder, functional hypothalamic amenorrhea, and osteoporosis (see Figure 12.1 ).

    Figure 12.1

    Female athlete triad continuum.

    (From Nattiv A, Loucks AB, Manore MM, et al. American College of Sports Medicine position stand. The female athlete triad. Med Sci Sports Exerc . 2007;39[10]:1867-1882.)

  • Low EA can cause disturbances in menstrual hormone levels, which can negatively affect BMD. In addition, low EA can independently have negative effects on BMD.

  • Females with female athlete triad are at a risk of short- and long-term health consequences (see Box 12.1 ).

    Box 12.1

    Health Consequences of the Female Athlete Triad

    • Fatigue

    • Decreased recovery time

    • Decreased training response

    • Impaired performance

    • Increased risk for heat illness

    • Impaired endothelial-dependent arterial vasodilation

    • GI changes

    • Nutrient deficiencies

    • Elevated LDL

    • Vaginal dryness

    • Impaired skeletal muscle oxidative metabolism

    • Cardiovascular consequences

    • Increased risk osteoporosis and fractures

    • Reproductive dysfunction

    • 2–4 times increase in stress fractures

Energy Availability (EA)

  • Low EA occurs when daily caloric intake does not meet the caloric expenditure needs of a female athlete. EA is the energy available for daily physiologic functioning after the body has used energy for exercise.

  • Reduction in total EA results in adaptations over time to conserve energy. Chronic reduction in EA can lead to suppression of metabolic and menstrual hormones.

  • In studies controlling for exercise levels, low EA alone is enough to cause amenorrhea, while restoration of the energy balance by meeting caloric needs is able to restore ovulation.

  • Reduction in the total available energy in terms of caloric intake may be intentional or unintentional. Female athletes may not be aware that increased activity levels require increased caloric intake and may inadvertently find themselves with low EA.

  • Low EA may also be the result of eating disorder concerns (for more information on eating disorders, see Chapter 27 : Eating Disorders in Athletes).

  • As caloric demands increase with activity, female athletes need to balance their EA by increasing caloric consumption.

Menstrual Dysfunction

  • Low EA leads to lower levels of menstrual hormones, which leads to menstrual dysfunction.

  • Menstrual dysfunction begins with suppression of progesterone levels resulting in a luteal phase that is <11 days.

  • Functional hypothalamic amenorrhea occurs when there is a disruption in gonadotropin-releasing hormone pulsatility; this disruption leads to decreased follicle stimulating hormone and luteinizing hormone levels and ultimately suppression of estrogen levels.

  • Menstrual dysfunction due to low EA has been studied and can be reversed with restoration of appropriate energy balance.

Low Bone Mineral Density (BMD)

  • Suppression of menstrual hormones causes low BMD due to decrease in estrogen, androgens, insulin-like growth factor 1 (IGF-1), and growth hormone. Each of these hormones plays a role in increased bone deposition.

  • Reduction of caloric intake resulting in low EA further reduces BMD by restricting available nutritional resources to build new bone.

  • 90% of peak BMD is achieved by the age of 18 years. Adolescence is a critical age for achieving optimum BMD. Disruptions in bone mass accrual during this critical time period can have lasting consequences.

  • American College of Sports Medicine (ACSM) defines low BMD as a Z score of <−1.0 in female athletes playing weight-bearing sports.

  • Low BMD places the athlete at a higher risk of stress injury.

  • Low BMD has been studied and shown to be reversible with restoration of EA.


Jul 19, 2019 | Posted by in SPORT MEDICINE | Comments Off on The Female Athlete

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