• Increased susceptibility to infections
  • RED-S can compromise the immune system, making athletes more prone to infections such as upper respiratory tract infections.
  • Delayed wound healing
  • RED-S can slow down the healing process of wounds due to the reduced availability of essential nutrients and energy.
  • Increased inflammation
  • RED-S can cause chronic low-grade inflammation in the body, which can increase the risk of chronic diseases such as type 2 diabetes and cardiovascular disease.
  • Impaired immune cell function
  • RED-S can lead to a decrease in the number and function of immune cells such as T cells and B cells, making it harder for the body to fight off infections.
  • Impaired vaccine response
  • RED-S can reduce the effectiveness of vaccines, making athletes more susceptible to vaccine-preventable diseases.
  • Constipation (due to decreased bowel motility)
  • Diarrhea
  • Bloating
  • Gastrointestinal distress (nausea, vomiting, abdominal pain)
  • Gastroesophageal reflux disease (GERD) (due to reduced lower esophageal sphincter pressure and increased gastric acid secretion)
  • **These symptoms may also be indicative of other medical conditions, so it's important to consult with a medical professional for proper diagnosis and treatment.
  • Reduction in heart size, function, and output
  • Results in reduced blood flow to the muscles and other organs, reducing exercise capacity and overall performance.
  • Decrease in blood volume
  • Increase the risk of dehydration and heat illness, particularly during exercise.
  • Increase cholesterol levels in the blood
  • Increase the risk for cardiovascular disease
  • In female athletes, amenorrhea or oligomenorrhea can result in decreased estrogen levels
  • A decrease in estrogen levels can increase the risk of cardiovascular disease, including the development of atherosclerosis and coronary artery disease
  • **These cardiovascular effects can be prevented or reversed with appropriate treatment, including addressing the energy deficiency and increasing nutrient intake.
  • Mood Changes
  • Depression, anxiety, irritability, and mood swings.
  • Cognitive Function
  • Difficulty concentrating, memory problems, and a decline in overall cognitive performance.
  • Body Image
  • Preoccupation with their body weight and shape, leading to negative body image and disordered eating behaviors
  • Eating Disorders
  • RED-S is associated with a higher risk of developing eating disorders, such as anorexia nervosa, bulimia nervosa, and binge eating disorder.
  • Fatigue and Sleep Disorders
  • Athletes with RED-S may experience fatigue and have difficulty sleeping, which can further impact their physical and mental health.
  • Social Isolation
  • RED-S can cause athletes to withdraw from social activities, leading to feelings of loneliness and isolation
  • **It is important to note that the psychological impacts of RED-S can exacerbate the physical symptoms and should be addressed as part of the treatment plan.
  • Delayed onset of puberty and/or menstrual cycles in girls
  • Impaired bone growth and mineralization, leading to decreased bone density and increased risk of fractures
  • Stunted growth and short stature in adolescents
  • Delayed growth in children and adolescents
  • Decreased muscle mass and strength
  • **These symptoms may also be indicative of other medical conditions, so it's important to consult with a medical professional for proper diagnosis and treatment.
  • Anemia
  • Due to decrease in the production of red blood cells.
  • Reduced blood volume
  • This results in a decreased ability to deliver oxygen and nutrients to the body's tissues
  • Increased risk of infection:
  • Due to decrease in the production of white blood cells
  • Delayed wound healing:
  • Due to decrease in the production of white blood cells
  • Increased risk of blood clots
  • Due to changes in blood coagulation factors
  • Decreased resting metabolic rate (RMR)
  • RMR is the amount of energy your body burns at rest
  • In RED-S, the body decreases RMR to conserve energy, which can lead to further energy deficiency.
  • Decreased insulin-like growth factor-1 (IGF-1)
  • IGF-1 is a hormone that promotes growth and repair of muscles and bones.
  • RED-S can decrease IGF-1 levels, leading to decreased muscle and bone health.
  • Decreased glucose uptake
  • RED-S can lead to a decreased ability of the body to take up glucose, which is the primary source of fuel for the body during exercise.
  • Increased cortisol
  • Cortisol is a hormone that is released by the body during times of stress.
  • In RED-S, cortisol levels can increase due to the body being in a state of energy deficiency and stress.
  • Decreased glycogen stores
  • Glycogen is the stored form of glucose in the body.
  • In RED-S, glycogen stores can become depleted due to the decreased energy availability, leading to decreased performance and increased fatigue.
  • **These metabolic changes can further exacerbate the energy deficiency in RED-S, leading to a cascade of negative effects on the body's physiology and overall health.
  • **hormones changes can occur even with a SINGLE day of low energy availability
  • Particularly inc cortisol and dec testosterone
  • Decreased levels of estrogen in females
  • This can lead to menstrual disturbances and decreased bone density, which can result in increased risk of stress fractures and osteoporosis.
  • Decreased testosterone levels in males
  • This can result in decreased muscle mass, strength, and endurance.
  • Decreased levels of thyroid hormones
  • This can lead to decreased metabolic rate, decreased energy levels, and increased susceptibility to infections.
  • Increased levels of cortisol
  • This hormone is produced by the adrenal glands in response to stress, and increased levels can result in decreased muscle mass, increased fat storage, and impaired immune function.
  • Decreased insulin-like growth factor 1 (IGF-1) levels
  • This hormone plays a crucial role in bone growth and repair, and decreased levels can result in decreased bone density and increased risk of fractures.
  • 90% of peak bone mass is attained by age 18, so adolescence is a key bone building time that determines the amount of bone mass an individual holds for the remainder of their life. In other words, if a female has low bone mass during adolescence, they will likley have low bone mass for the remainder of their lives. If LEA occurs during these crucial bone building years, an individual may never reach their peak bone mass due to a lack of "catch up" effects during the narrow window of peak bone accrual in puberty.
  • In normal circumstances, exercise can promote bone health, with athletes having higher bone mineral density (BMD), stronger bones, and more favorable bone microarchitecture compared to sedentary individuals. However, engaging in exercise while experiencing energy deficiency can have negative effects on bone health. Participation in sports that convey a high level of mechanical loading may attenuate the negative influence that reduced EA already has on bone health.
  • The negative effects of RED-S on bone health is attributed to low estrogen (and other hormones) which results in deficiencies in vitamin D and calcium
  • The deficiency in estrogen if why low bone density is more common in females with RED-S
  • RED-S can cause
  • Decreased bone mineral density (BMD)
  • Osteopenia in amenorrheic athletes: 22% and 50%
  • Osteoporosis: 0% to 13%
  • Increased risk of stress fractures
  • Delayed bone growth and development in adolescents
  • Increased risk of osteoporosis and fractures later in life
  • Impaired bone healing after a fracture or surgery.
  • Affects bone mineralization and compromises bone health and density
  • Amenorrhea (absence of menstrual periods)
  • The suppression of the menstruation during low energy availability is an adaptive response to prevent pregnancy and conserve energy for essential body functions.
  • Secondary amenorrhea was as high as 69% in dancers and 65% in long-distance runners.
  • Oligomenorrhea (infrequent menstrual periods)
  • Athletes with irregular periods were more likely to have disordered eating
  • Shortened luteal phase (second half of menstrual cycle)
  • Anovulatory cycles (cycles without ovulation)
  • Delayed menarche (onset of menstrual periods)
  • Irregular menstrual cycles
  • Changes in hormone levels, such as decreased estrogen and progesterone levels
  • Increased risk of fertility problems in the future.
  • **Menstrual abnormalities can occur as early as 5 days after entering a state of low energy availability.
  • Decreased endurance
  • Reduction in the body's ability to sustain high levels of physical activity over a prolonged period of time, leading to a decline in endurance performance.
  • Decreased muscle strength
  • Due to loss of muscle mass and strength, which can impair athletic performance, particularly in power-based sports.
  • Decreased cognitive function
  • Worsened attention, reaction time, and decision-making ability, which can impair performance in sports that require quick decision-making.
  • Increased risk of injury
  • Increased risk of injury due to decreased muscle strength, decreased bone density, and impaired cognitive function.
  • Delayed recovery
  • Delay in the body's ability to recover from training and competition, making it harder for athletes to perform at their best consistently.
  • Decreased speed
  • Decline in speed, particularly in sports that rely on high-speed movements such as sprinting
  • Decreased power
  • Impairment in power-based activities such as jumping, throwing, and sprinting due to the loss of muscle mass and strength.

Reading Passage: Health Consequences of Low Energy Availability

Module 5: Health Consequences of Low Energy Availability

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Growth +
Bone Health
Menstrual Function
Athletic Performance
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