Before digging into the signs of RED-S for female athletes we must first define it!
RED-S stands for Relative Energy Deficiency in Sport, a term coined by the International Olympic Committee to describe impaired physiological functioning due to Low Energy Availability (1).
These impairments include a variety of metabolic, hormonal, endocrine, gastrointestinal, musculoskeletal, cardiovascular, immunological, and psychological symptoms. In essence, every important function of a female athlete’s body is negatively affected when she does not have adequate energy availability.
You can understand how more about RED-S and low energy availability by listening to the Female Athlete Nutrition Podcast Episode #03: "What is RED-S?"
Diagnosis of RED-S is best from a combination of Sports Dietitians, Sports Physicians, and potentially endocrinologist. However being aware of the signs and symptoms of RED-S can help you seek help early and before things get too severe!
The images below, direct from the IOC Consensus statement, show the potential health and performance consequences of RED-S.
In day-to-day life, signs of RED-S that female athletes may notice include:
1. Not seeing progress in training despite following a training plan.
Due to hormone suppression and low energy availability, female athletes with RED-S will not adapt to a training plan as their adequately fueled counterparts. Reduced strength & endurance performance are inevitable as RED-S progresses. A female athlete may be feeling exhausted, run down, under-recovered, sore, fatigued, and frustrated that they are not performing at the level they want!
2. Repeated, chronic, or lingering injuries of any kind.
Stress fractures, specifically, are a common injury seen in RED-S (see sign #3 below). However even musculoskeletal injuries are common in RED-S since the body is not able to manage the intensity of training nor is it properly recovering. When an athlete is constantly injured and never fully recovering this could be a sign that RED-S is at play.
3. Low bone mineral density diagnosed as osteopenia or osteoporosis.
Because the hormones estrogen and insulin-like growth factor 1 (IGF-1) are often suppressed in RED-S, bone health suffers. With low bone density, the bones are at increased risk of fractures, especially when the athlete continues to engage in sport placing physical stress on the bones.
4. Abnormal or missing menstrual cycles.
A menstrual cycle that is completely missing, known as amenorrhea, is a well known sign of RED-S as it means the body does not have adequate energy to support hormone production. However even inconsistent periods, such as skipping a few months or having exceedingly long cycles, >42 days in length can be a sign of RED-S. This is further supported by bloodwork showing low estrogen, progesterone, follicle stimulating hormone, and luteinizing hormone. Unfortunately, many female athletes take some form of birth control which can mask this symptom of RED-S. Taking “the pill” may produce a monthly bleed but does not exempt somebody from having RED-S.
5. Low heart rate at rest (<60 beats per minute, bradycardia), but potentially higher than expected during training.
It is well known that athletes often have heart rates below 60 beats per minute because their cardiovascular system is well trained -- and this can be healthy and normal! However, when combined with other signs and symptoms of RED-S the low heart rate could be an indicator of a weakened cardiovascular system. Despite a low heart rate at rest, an athlete with RED-S may experience a higher than expected heart rate, or one that feels out of control, during exercise or activities of daily life, like walking up the stairs. The elevated heart rate during exercise, despite low heart rate at rest, means the heart is over-worked.
6. Bloating and digestive irregularities.
Female athletes with RED-S often have a challenging time digesting food, due to alterations in digestive enzymes & the gut microbiome. This can result in extreme bloating, early onset fullness, leaky gut, constipation, or a combination of diarrhea & constipation throughout any given week. Further, because the gut is not optimized, many nutrients are not absorbed. Female athletes may become deficient in key nutrients, including iron, partly due to digestive malfunction.