RED-S in Distance Runners
Relative Energy Deficiency in Sport (RED-S) describes a collection of symptoms that can result from acute or chronic low energy availability in athletes. For years professionals identified the Female Athlete Triad (presence of bone density loss, amenorrhea and disordered eating) as the staple diagnosis of low energy availability in female athletes. However, the term RED-S was coined to encompass the wider variety of body systems affected as well as athletes of all genders. Suspicions of a RED-S diagnosis typically follows some level of decline in athletic performance.
RED-S can affect all athletes, regardless of gender.
A cornerstone concept of RED-S is low energy availability (LEA). An athlete will experience acute LEA following a hard workout though will usually recover with adequate nutrition and rest. When an athlete is consistently not taking in enough calories to match/exceed their energy expenditure, the body will respond to this imbalance in a number of ways. Most simply put, other body systems will be compromised.
Skeletal System: Bone remodeling occurs in a healthy balance between cells that break down and build up tissue. This balance becomes disrupted when an athlete stays in a state of LEA and there is not enough activity to build up bone, leading to increased risk of injuries such as stress fractures.
Cardiovascular System: Slowed heart rate affects the ability of the heart to properly pump blood to muscles/organs for normal function.
Immune System: Athletes in a chronic caloric deficit will start to find themselves getting sicker more often due to their body’s inability to fight infections and other illnesses.
Reproductive System: The most common symptom observed in females is menstrual dysfunction (irregular or lost periods). This can lead to long term reproductive health complications if it is not addressed properly.
Psychological System: Athletes with RED-S may find themselves to be more irritable, moody or even depressed.
Left untreated, RED-S can start to negatively affect a number of different normal body functions.
Because of the common misconception in endurance sports that being smaller or thinner equals improved performance, it is common for distance runners to develop RED-S. Some athletes may even find themselves victim to this syndrome unintentionally as they train. The focus on increasing intensity and volume for performance without adjusting your caloric intake is an easy trap to fall into for endurance athletes. Recognizing common signs of RED-S allows an athlete/coach to make the necessary changes in training to prioritize the athlete’s overall health.
Fatigue during runs/workouts
Rapid weight loss (unintentional or intentional)
Longer recovery times needed between efforts
Frequent illnesses
Missed periods (female athletes)
Mood changes or trouble concentrating
Difficulty sleeping
RED-S can be subtle. Knowing the signs to lookout for is important.
Management of RED-S involves a multi-disciplinary team of providers to address the multiple aspects of the syndrome. The most important step of treatment is restoring adequate caloric intake. From there, athletes should work with a dietician/nutritionist, psychologist and physician to monitor their health. If an athlete suffers an injury as a result of RED-S, a running physical therapist may be consulted.
Increasing awareness of RED-S in distance running is the first step in prevention.
There are tools available, such as the RED-S Clinical Assessment Tool, that can be used to screen athletes for RED-S by classifying them into risk categories. This can help athletes and coaches to act accordingly in preventing the negative affects of RED-S on the athlete’s health and performance.
