Researchers Debate 'Male Athlete Triad' Syndrome

Laird Harrison


November 16, 2017

You can pump iron all day, but to get high-definition muscles, you'll also have to shed fat. Preparing for a bodybuilding contest, one man shifted to a high-protein, low-carbohydrate diet while ramping up his aerobic exercise for 6 months. As planned, he pared away more than half his body fat. But at the same time, his testosterone level dropped by two thirds. His resting heart rate, strength, and mood sank, too.

The question facing sports medicine researchers now: Did he suffer from "male athlete triad," in which an energy deficit threatened his health?

Such a syndrome has not been definitively described—yet. But the American College of Sports Medicine plans to convene a panel at its annual meeting next year in Minneapolis to take on that task. "It's likely the term 'male athlete triad' will be used," says Mary Jane De Souza, PhD, a professor of kinesiology and physiology at the Pennsylvania State University in University Park.

The Concept of a Female Athlete Triad

To anyone who keeps up with sports medicine, that phrase will sound familiar. Since 1992, researchers have been elaborating on the concept of a female athlete triad, officially defined by the American College of Sports Medicine as "energy deficiency with or without disordered eating, menstrual disturbances and amenorrhea, and bone loss and osteoporosis."[1] The American Orthopaedic Society for Sports Medicine has given the term its imprimatur as well.

Multiple studies have documented the threat of bone fractures and reproductive disorders in women and girls who burn more energy by exercising than they consume by eating, and some have investigated psychological and cardiologic problems as well.[1,2]

One reason for putting a name to the syndrome is to focus attention, giving researchers and clinicians a framework for understanding it and providing a way to explain to their female patients what they're experiencing and how to avoid it. One of the most recent studies has shown that clinicians can reverse the syndrome by coaching exercising women to eat more.[3]

But the underlying concepts are much older than the term; researchers have long known that deficits of nutrients can provoke changes in bone health[4], sex hormones,[5] and mood[6] in males as well as females. In fact, some of the earliest careful studies on the effects of an energy deficit were conducted in men.[5]

'RED-S Syndrome' Replaces 'Triad'

Some experts argue that there's no reason to assign separate syndromes to males and females. "I am not sure why there is a need to separate the genders if the underlying issue addresses both genders," says Margo Mountjoy, MD, PhD, an associate professor of family medicine at McMaster University in Hamilton, Ontario, Canada. "For example, ACL [anterior cruciate ligament] tears affect both genders, but we don't call them 'female ACL [tears]' and separately 'male ACL tears.'"

Dr Mountjoy was the lead author of a 2014 consensus statement by the International Olympic Committee in which the organization abandoned the term 'female athlete triad' in favor of 'relative energy deficiency in sport (RED-S).'[7] Not only does the syndrome affect both males and females, she and her colleagues argued, it isn't really a triad, because more than three phenomena are involved. "The syndrome of RED-S refers to impaired physiological function including, but not limited to, metabolic rate, menstrual function, bone health, immunity, protein synthesis, cardiovascular health caused by relative energy deficiency," they wrote.

Dr De Souza responds that men on average have different levels of sex hormones and bigger bones. "There may be important differences, and it's important to define those differences," she says. The research in men has not caught up to the research in women.

Examining Bone Density and Hormonal Changes in Male Athletes

Most of what's known about men, particularly about the relationship between energy intake and bone health, comes from observational studies. One found that male jockeys—who seek to maintain a low body weight—have lower bone density than boxers.[8] Bone density appears to be particularly low in the lumbar spines of male runners and cyclists.[9] Similar effects have shown up in the sperm and testosterone levels in male endurance athletes.[10]

But these studies don't show that men suffered any serious health effects, such as bone fractures. Hormone levels, for the most part, remained within the normal range. And observational studies can't show cause and effect; it's particularly hard to know how studies in one sport might apply to another, says Petter Fagerberg, a researcher at Karolinska Institute in Stockholm, Sweden. Do men who eat less while exercising the same amount experience the same effects as men who eat the same amount while exercising more? Does it matter whether the exercise is resistance training or endurance training?

A couple of prospective, controlled trials have verified that men who exercise do experience hormone changes, but they were too short-term to show any effects on bone density.[10,11]

Much more research is needed, says Dr De Souza. "We've done training studies to see what degree of exercise induces menstrual disturbances. We don't have similar experiments like that in men, where you take men with normal testosterone and normal semen and you frame the studies to see at what level you see disturbances."

She'd like to know more about the effects in men on other hormones, such as insulin and insulinlike growth factor 1.

The debate isn't purely academic, both sides argue. It could affect the way clinicians see their patients, and the way athletes see themselves. "If you're not aware of it, you're not going to look for it," says Adam S. Tenforde, MD, an assistant professor of physical medicine and rehabilitation at Harvard Medical School in Cambridge, Massachusetts, who published a review of the literature on this topic.[12]

He favors terminology that is not gender-specific. "With so much of the concern on female athletes, is this potentially stigmatizing one sex from seeing the value of participation in sports?" he asks.

Although such questions will influence the approach clinicians take in the future, experts aren't waiting for the debate to end before they look for men and boys who aren't getting enough calories. When Dr Tenforde suspects this problem in male patients, he asks them about eating behavior and about changes in libido. If patients have fewer morning erections, that could be a sign of a hormonal change, he says.

If an athlete has fractured a bone, Dr Tenforde may request dual-energy x-ray absorptiometry. Sometimes he will measure free and total testosterone in a morning blood sample, but he warns that it can be difficult to interpret these findings, because athletes can by symptomatic when their testosterone is within normal levels.

Dr Mountjoy also sometimes checks body composition, white blood cell counts, and glucose metabolism. "I'll see changes in these along with mood states, and look at [the athletes'] performance parameters," she says. "Unraveling all that is not simple. It's not like a pregnancy test. It's being suspicious, treating the injury, and looking at the underlying causes so the same thing doesn't happen again and again."

Eating Enough Calories to Fuel the Athletic Flame

The basic prescription for athletes who aren't eating enough is, not surprisingly, more food. Just like anyone else, they should eat a healthy diet, including adequate calcium and vitamin D. That sounds simple, but the devil is in the details, says Dr Mountjoy. She points out that athletes should eat regular meals, not skip breakfast and gorge at dinner. "You can have within-day deficits," she says.

Convincing athletes to eat more can be particularly challenging in those who are deliberately restricting their intake. Some athletes, such as wrestlers, diet to stay within a weight class. Others, such as ski jumpers and jockeys, gain an advantage by being light. Dr Tenforde is hoping to see changes in rules to discourage this kind of behavior—another benefit that could come from a consensus on how the syndrome should be described.

One key to motivating athletes is to point out that eating well can make them better at the sport they love. "They are motivated to improve performance," says Dr Mountjoy. "If I say 'osteoporosis,' their eyes glaze over. If I say, 'Would you like to run faster?' then they're interested."

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