Endurance cycling can be addictive, driving athletes to push their limits constantly. In my case, the moment I started beating my own records and times, it left me hungry for more. This pursuit isn’t just for adults—even teenagers are drawn to the challenge, often adopting strict diets and workout routines to excel. However, the pressure to perform better can lead some to obsess over their body image, which can result in a cycle of underfueling.
Various factors contribute to underfueling, including intense workouts without adjusting food intake and anxieties about weight and performance. Regardless, this behavior can hamper athletic performance and pose health risks. Coaches should prioritize ensuring young endurance cyclists get adequate nutrition to prevent underfueling and safeguard their future well-being. Learn more about the long-term consequences of underfueling and some strategies to help young cyclists reach their full potential.
Underfueling Translates to Higher Risk of RED–S
Proper nutrition is vital for athletes but most crucial among still-growing teens. Those with suboptimal energy intake may be at greater risk of underfueling, which happens when total caloric and macronutrient intake is low.
Inadequate energy intake poses a higher risk of Relative Energy Deficiency in Sport (RED-S), which is defined by the International Olympic Committee (IOC) as “a syndrome of impaired physiological and/or psychological functioning experienced by female and male athletes caused by problematic low energy availability (LEA).”
LEA can be intentional or unintentional. Intentional LEA happens when athletes restrict their dietary intake to control body weight or composition. Pervasive issues around body image and traditional beliefs—such as “eating is cheating”—can result in intentional LEA. One study suggests cycling is a sport with a high prevalence of eating disorders, such as binge eating, anorexia nervosa, and bulimia nervosa. Furthermore, cyclists perceive leanness as vital to their success and can thus manipulate their nutritional intake.
Regardless of the sport and sex, a team’s culture can also contribute to intentional LEA. A culture where people insult other athletes’ body weight and shape can push victims to overexercise and eat less.
Unintentional low energy availability (LEA) happens when cyclists fail to meet the energy requirements of the sport due to a lack of knowledge. Share on XConsequently, unintentional LEA happens when cyclists fail to meet the energy requirements of the sport due to a lack of knowledge. It can be quite common for young athletes to underfuel since they’re unaware of training demands. Financial problems and low appetite can also contribute to this condition.
Long-Term Implications of Underfueling
According to Rebecca McConville RD, LD, CSSD, CEDS, RED-S-related problems can happen when the body has 250 calories less than its daily requirement over five days. Young endurance cyclists who don’t have enough energy intake could face long-term implications.
Significant fatigue during training sessions conducted after proper rest can indicate inadequate energy levels. According to Jessica Crandall, RDN, CDE, feeling lethargic, weak, and sore are signs of improper fueling, which may lead to a weakened immune system. Coaches can also detect signs of fatigue through body language and other non-verbal communication cues, including mood changes and a lack of willingness to train for long periods.
Underfueling can delay muscle glycogen replacement and repair of muscle tissue, hindering training. Not getting enough energy requirements may also lead to decreased immunity, increasing susceptibility to injury and illnesses.
Severe calorie deficiency among women can cause estrogen levels to drop, delaying the menstrual cycle and the onset of puberty. This symptom is a sign of a subcategory of RED-S called “the female athlete triad,” which describes the three interrelated issues of irregular menstruation, bone loss, and disordered eating. Someone can have one, two, or all three parts of the triad. Signs to look out for include missed periods, weaker bones, and low BMI.
Figure 1. Recommended daily carbohydrate intake by weight. Data Source: Gatorade Sports Science Institute.
Most bone density is formed during the teenage years. Reduced bone formation in early adulthood can lead to long-term issues with osteoporosis and bone weakness. The loss of estrogen can lead to a lack of bone density and may put female endurance riders at a higher risk of stress fractures and osteoporosis.
Though the majority of research on underfueling and LEA has been on females, the IOC now recognizes its negative implications among males, including reduced testosterone production. A study shows male endurance athletes who have LEA are at risk of insufficient testosterone production, which may lead to decreased bone mineral density. However, more research is necessary to understand the effects on men better.
Nearly one in three adolescents ages 13 to 18 will experience anxiety disorder in the United States. The pressures of staying fit can affect the mental health of athletes. Stress levels and mood are also affected if the body isn’t fueled enough. For instance, 90% of serotonin is synthesized by enterochromaffin cells in the intestinal epithelium. This chemical is crucial for mood regulation, appetite, and sleep cycle.
Poor energy intake can backfire on the athlete’s performance through decreased endurance, training response, and motivation. Unfortunately, they may respond to decline through more extensive training, which can deplete more of the energy they need to function.
Poor energy intake can backfire on the athlete’s performance through decreased endurance, training response, and motivation. Share on XIdentifying and Managing RED-S
According to a study conducted by Cycling Weekly, 30% of female respondents and 15% of males have RED-S symptoms. Among female cyclists who were not on hormonal contraception, 39% cited menstrual problems.
Athletes and coaches can monitor RED-S if the levels of metabolic hormones and substrates—including 3,3,5-triiodothyronine (T3), growth hormone, leptin, cortisol, and glucose—have been altered. Validated tools such as the RED-S Clinical Assessment Tool can also be used by a trained sports medical physician to assess a young cyclist’s risk of this condition.
This instrument features biochemical markers and functional issues because of LEA, such as recurring bone stress injuries. While physical qualities such as body weight and fat are also assessed, some individuals with RED-S may have standard body mass.
Strategies for Optimizing Energy Balance
Optimal energy intake should be the cornerstone of every athlete’s diet. Nutritional and calorie requirements depend on age, sex, and activity. Since adolescent cyclists are still developing, their consumption should match their activity level and support their growth.
Active teenage males need 2,600–3,200 calories daily, while females in the same age bracket require about 2,200–2,400 calories a day. However, the more active adolescents are, the more calories they need. The body’s required energy is known as basal metabolic rate (BMR), ranging from around 1,200 to more than 3,000 calories per day.
A BMR calculator can help coaches personalize an athlete’s daily caloric requirements for various activity levels. However, this tool only guides coaches when creating a diet plan, not as a prescription for health and nutrition. The BMR formulas for men and women are as follows:
- Men: BMR = 88.362 + (13.397 x weight in kg) + (4.799 x height in cm) – (5.677 x age in years)
- Women: BMR = 447.593 + (9.247 x weight in kg) + (3.098 x height in cm) – (4.330 x age in years)
After identifying the BMR, coaches can help combat LEA by ensuring an athlete’s diet is enough to cover their needs. They can achieve energy balance by computing energy availability (EA) using the equation:
- EA(kcal/kgFFM/day) = [EI(kcal/day)−EEE(kcal/day)] / FFM (kg)
- EI = energy intake, EEE = exercise energy expenditure
Nutritional Strategies
Adolescent athletes need appropriate food to fuel their bodies. When creating a nutritional plan, consider including sources that help boost performance and recovery. For instance, one cup of blueberries offers 24% of an individual’s daily value of vitamin K and 22% of manganese, which help boost bone density and reduce proneness to muscular strains. Choosing nutrient-dense foods can help athletes manage a healthy weight and enhance muscle strength.
Carbohydrates are the most essential fuel for an adolescent cyclist. Because carbs are stored as fuel, cyclists need them before training. On the other hand, fats usually get a bad reputation because they are about twice as calorie-dense as carbs and proteins. However, fats are essential for nutrient absorption and hormonal production.
According to exercise physiologist Dr. Tim Podlogar, athletes must utilize fats and carbohydrates efficiently since glycogen stores are limited. Fat stores are larger but only work in aerobic activities, so the body requires oxygen to translate fat into energy. Stores of carbohydrates are smaller, but the body can utilize them in anaerobic processes, meaning it can get energy even without oxygen.
The body needs time to adjust breathing when cycling. During this anaerobic process, the body requires glycogen, so it must get energy from sources that don’t need oxygen.
Figure 2. Recommended carbohydrates in relation to exercise. Data source: Gatorade Sports Science Institute.
Carbohydrate intake should range from 7 to 12 g·kg-1 body mass (BM) to ensure optimal muscle glycogen availability during competition and intense training. For exercise lasting more than 60 minutes, it is recommended to consume carbohydrates of 1 to 4 g·kg-1 BM one to four hours before activity.
Endurance athletes should ensure half of their plate consists of carbohydrate sources—rice, bread, oats, and tortillas—on heavy training days. The standard carbohydrate recommendation for high school athletes is 360–500 grams daily.
Junior athletes can struggle to identify thirst during a ride, so starting hydrated is always recommended. Share on XGood hydration is also crucial for optimal performance and recovery. Junior athletes can struggle to identify thirst during a ride, so starting hydrated is always recommended. Less than 2% dehydration of total body weight can significantly reduce skill, exercise, and mental performance.
Fuel Well for Optimal Health and Performance
RED-S can impact anyone, but its effects are more pronounced in young athletes who are still developing. As a coach, it’s essential to understand cycling is not just a sport—it’s a lifelong pursuit for teens that requires sustainable habits on and off the track.
Help the future generation of cyclists achieve their best health and performance by prioritizing proper nutrition, adequate rest, and long-term health over immediate results. Along with a personalized nutritional plan, regularly monitoring food intake and performance can help ensure proper caloric balance and instill self-care habits that will benefit teens throughout their lives.
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Underfueling harms young cyclists’ performance and health. Prioritize proper nutrition.