Sports Medicine and the Woman Athlete

Contents

1. The anterior cruciate ligament tears more often in women
2. Low energy availability links fuel, cycles and bone
3. A new name revived an old argument

Candace Cooley skis, rides a bike and runs for pleasure, and the measurement that frames much of sports medicine’s thinking about women in those sports is energy availability, counted in kilocalories per kilogram of fat free mass per day. The American College of Sports Medicine’s 2007 position stand on the female athlete triad, which the college publishes in a Chinese translation, defines it as the energy taken in from food minus the energy spent in exercise, divided by fat free mass. Its worked example is an athlete who eats 2,000 kilocalories a day, spends 600 of them in exercise and carries 51 kilograms of fat free mass, leaving 27.5 for everything else the body does.⁹ Below roughly 30 on that scale, the statement says, the body trims the energy it gives to cell maintenance, temperature control, growth and reproduction, and harm to menstrual function and to bone follows.⁹ Energy is one of two problems that set the woman athlete apart. The other is the knee.

The anterior cruciate ligament tears more often in women

The anterior cruciate ligament, or ACL, steadies the knee against twisting. Jenny Robinson, a University of Washington researcher in women’s sports medicine, told UW News that ACL tears are two to eight times more common in women than in men playing the same sports, and that they cluster in activities built on cutting, pivoting and quick changes of direction, downhill skiing among them.¹ The possible reasons she listed include anatomical differences that change how the joint moves, differences in the structure of the tissue, and sex hormones, including their swings across the menstrual cycle. She added that most of the research rests on men’s bodies or on bodies whose sex was never reported.¹

On the slopes the knee is a frequent casualty. The American Academy of Orthopaedic Surgeons cites federal figures of more than 76,000 skiing injuries treated in hospitals, doctors’ offices and emergency rooms in 2018, and names knee injuries, particularly of the ACL, as very common among them.² The academy’s guide to ACL treatment explains that most tears are complete or nearly so, that about half come with other damage such as meniscus tears, and that a torn ligament is usually reconstructed with a tendon graft rather than stitched, because its poor blood supply and the fluid around it make repair fail. Most patients return to full sport within six to twelve months.⁵

Figure

Partial and complete ACL tears

	Partial tear	Complete tear
How common	Rare	Most ACL injuries are complete or near complete
Usual approach	Progressive physical therapy and rehabilitation	Surgical reconstruction with a tendon graft
Why	The knee can stay stable for lower intensity activity	Patients often feel the knee is loose or might give way

Elite racers show the arc. Kjersti Moritz, a Vail racer in her rookie season on the national development squad, tore her left ACL and meniscus in a super G in January 2023, spent seven weeks on crutches, and described relearning how to stop and turn when she first returned to snow that autumn.⁴ In January 2026 Lindsey Vonn, then 41, crashed in Crans Montana days before her last Olympics and reported a completely ruptured ACL in her left knee, with bone bruising and meniscal damage; she said she meant to race in a knee brace.³

Low energy availability links fuel, cycles and bone

The second problem was named in the 1990s. The sports physician Kate Ackerman told Outside that the term female athlete triad arose because the standing message to women athletes had been to train harder, and that in 1997 the American College of Sports Medicine described it as three distinct conditions: disordered eating, amenorrhea and osteoporosis.⁶ The college’s 2007 update recast those as three linked spectra, energy availability, menstrual function and bone mineral density, each running from health to disease, so that an athlete can be affected without having all three.⁹ It set the terms precisely: amenorrhea means no period for more than 90 days, oligomenorrhea means cycles longer than 35 days, and stress fractures are two to four times as frequent in amenorrheic athletes as in those with regular cycles.⁹

Outside describes the mechanism as a cascade. When intake falls short of what training costs, the body moves resources to survival, suppresses costly processes such as menstruation and growth, and loses the monthly estrogen surge that builds bone in adolescence and early adulthood.⁶ The same report cites estimates that up to 60 percent of exercising women may show one component, and that a study of 240 health care providers found fewer than half of physicians and physical therapists could name all three.⁶

Figure

How often triad components appear

may have one component of the triad

up to 60%

may have two components

up to 27%

present all three

about 16%

The risk compounds. CBS News reported on a study led by the orthopaedic surgeon Elizabeth Matzkin finding that one triad component was associated with a 15 to 21 percent rise in bone stress injuries, two with a 21 to 30 percent rise, and all three with a 29 to 50 percent rise; she noted that bone density is largely built by about age 25.¹⁰ Planning can hold the line. A 2017 Outside account of the Canadian middle distance runner Hilary Stellingwerff described how she varied her body composition by season while tracking energy availability, and kept regular cycles, above normal bone density and a record of only two injuries that cost her a week or more of training.⁸ The same principles carry into other seasons of an active life, the subject of the entry on exercise during pregnancy.

A new name revived an old argument

In 2014 the International Olympic Committee proposed relative energy deficiency in sport, a broader term covering effects on immunity, the heart, protein synthesis and mood, and including men.⁶ Triad researchers objected the same year. Mary Jane De Souza, Nancy Williams, Aurelia Nattiv, Anne Loucks and dozens of coauthors published a review in the British Journal of Sports Medicine whose title set out to refute the committee’s consensus statement as a misunderstanding of the triad.⁷ Nattiv and colleagues also issued 2014 guidelines advising care from a team that includes a physician and a dietitian.⁶

The dispute echoes the knee. Orthopaedic surgeons long ago named their own triad, the unhappy triad of ACL, medial collateral ligament and medial meniscus injuries seen in football players and skiers.⁵ In both cases a cluster of injuries that tended to arrive together earned a single name, and in both the name has outlived arguments about what belongs inside it, while Robinson’s point stands that women’s bodies remain understudied.¹ How any one athlete trains, eats and recovers is a decision for her and a clinician who has her history in front of them; mountain conditions add their own variables, covered under altitude acclimatization.