Hormones correlated with tibial failure load
When these characteristics were evaluated in the context of mean tibial failure load, a metric related to strength, there was a strongly significant positive association with lean body mass (R = 0.85; P < 0.001) and estradiol level (R = 0.66; P = .007). The relationship with leptin also reached significance (R = 0.59; P = .046).
Unexpectedly, there was no relationship between testosterone and tibial failure load. The reason is unclear, but Dr. Haines’s interpretation is that the relationship between specific hormonal disturbances and bone density loss “might not be as simple” as once hypothesized.
The next step is a longitudinal evaluation of the same group of athletes to follow changes in the relationship between these variables over time, according to Dr. Haines.
Eventually, with evidence that there is a causal relationship between nutrition, hormonal changes, and bone loss, the research in this area will focus on better detection of risk and prophylactic strategies.
“Intervention trials to show that we can prevent stress factors will be difficult to perform,” Dr. Haines acknowledged, but she said that preventing adverse changes in bone at relatively young ages could have implications for long-term bone health, including protection from osteoporosis later in life.
Dr. Siobhan M. Statuta
The research presented by Dr. Haines is consistent with an area of research that is several decades old, at least in females, according to Siobhan M. Statuta, MD, a sports medicine primary care specialist at the University of Virginia, Charlottesville. The evidence that the same phenomenon occurs in men is more recent, but she said that it is now well accepted the there is a parallel hormonal issue in men and women.
“It is not a question of not eating enough. Often, athletes continue to consume the same diet, but their activity increases,” Dr. Statuta explained. “The problem is that they are not supplying enough of the calories they need to sustain the energy they are expending. You might say they are not fueling their engines appropriately.”
In 2014, the International Olympic Committee published a consensus statement on RED-S. They described this as a condition in which a state of energy deficiency leads to numerous complications in athletes, not just osteoporosis. Rather, a host of physiological systems, ranging from gastrointestinal complaints to cardiovascular events, were described.
RED-S addresses health beyond bones
“The RED-S theory is better described as a spoke-and-wheel concept rather than a triad. While inadequate energy availability is important to both, RED-S places this at the center of the wheel with spokes leading to all the possible complications rather than as a first event in a limited triad,” Dr. Statuta said in an interview.
However, she noted that the term RED-S is not yet appropriate to replace that of the male and female athlete triad.
“More research is required to hash out the relationship of a body in a state of energy deficiency and how it affects the entire body, which is the principle of RED-S,” Dr. Statuta said. “There likely are scientific effects, and we are currently investigating these relationships more.”
“These are really quite similar entities but have different foci,” she added. Based on data collected over several decades, “the triad narrows in on two body systems affected by low energy – the reproductive system and bones. RED-S incorporates these same systems yet adds on many more organ systems.
The original group of researchers have remained loyal to the concept of the triad that involves inadequate availability of energy followed by hormonal irregularities and osteoporosis. This group, the Female and Male Athlete Triad Coalition, has issued publications on this topic several times. Consensus statements were updated last year.
“The premise is that the triad leading to bone loss is shared by both men and women, even if the clinical manifestations differ,” said Dr. Statuta. The most notable difference is that men do not experience menstrual irregularities, but Dr. Statuta suggested that the clinical consequences are not necessarily any less.
“Males do not have menstrual cycles as an outward marker of an endocrine disturbance, so it is harder to recognize clinically, but I think there is agreement that not having enough energy available is the trigger of endocrine changes and then bone loss is relevant to both sexes,” she said. She said this is supported by a growing body of evidence, including the data presented by Dr. Haines at the Endocrine Society meeting.
Dr. Haines and Dr. Statuta report no potential conflicts of interest.