For elite athletes, there is always a fine balance between training and recovery: they must push their bodies to the limits in order to meet performance goals, but also allow their bodies to recover so adaptations can occur. If this balance is disrupted, overtraining syndrome can occur.
Even though the term “overtraining syndrome” is used frequently in athletic circles, there is still a lot of confusion about what overtraining is, whether it even exists, and how to avoid it. In a recent Nduranz podcast episode with Triathlon Coach Mario Schmidt-Wendling, we tackled these questions.
Don't want to read? Listen to the full episode below.
What Is Overtraining Syndrome?
Overtraining syndrome is a state of extreme fatigue that results in a long-term decline in performance. The condition seems particularly prevalent in endurance sports like long-distance triathlons where athletes put in very long hours of training.
Overreaching vs. Overtraining
It is normal for athletes to experience fatigue and temporary declines in performance, especially after intense training. However, athletes must recognize when fatigue is a sign of proper adaptation and when it indicates a deeper issue.
This distinction comes down to understanding the difference between overreaching and overtraining.
- Functional Overreaching (FO): This occurs when athletes push themselves beyond normal training loads, resulting in temporary fatigue and performance declines for approximately 2 weeks. However, if recovery is adequate, they actually bounce back stronger because supercompensation occurs.
- Nonfunctional Overreaching (NFOR): This also occurs from training overload. However, unlike with FO, performance declines for 3-4 weeks and supercompensation does not occur. It is a clear indication that recovery is inadequate.
- Overtraining Syndrome (OTS): The most severe stage, overtraining occurs when the body can no longer handle the cumulative demands of training. Even with adequate rest, performance may continue to decline for months or years.
Functional overreaching is desirable because it results in supercompensation. Image credit: Supercompensation Graph by Haus, CC BY-SA 3.0 License
Does Overtraining Really Exist?
There is actually very little research on overtraining syndrome. Most research is based on anecdotal information or on athletes with nonfunctional overreaching.
As a result, there is an ongoing debate about whether overtraining even exists and some athletes and coaches prefer to use the term “under-recovery” instead of “overtraining.”
What Happens in the Body during Overtraining?
While there isn’t too much research on overtraining syndrome, there are several theories about what happens to the body during overtraining.
- Central Fatigue Hypothesis: Prolonged exercise increases free tryptophan in the blood, which leads to more serotonin production in the brain which then causes lethargy and low energy.
- Glycogen Hypothesis: Depletion of glycogen during exercise not only causes muscle fatigue, but causes the body to oxidize branched-chain amino acids for energy and also results in increased serotonin.
- Cytokine Hypothesis: Exercise naturally causes oxidative stress (damage to muscle cells), which helps repair tissue. However, too much oxidative stress can lead to chronic inflammation, which affects the central nervous system, hormonal, and metabolic function.
- Hypothalamic Hypothesis: Overtraining disrupts the hypothalamic-pituitary-adrenal (HPA) axis, affecting hormones like cortisol, testosterone, and growth hormone. These hormonal changes contribute to fatigue and performance issues in overtrained athletes.
How to Diagnose Overtraining Syndrome?
Currently, there is no reliable lab test for diagnosing overtraining syndrome. Some biomarkers—such as cortisol, creatine kinase, glutamine, and inflammatory cytokine levels—have been linked to overtraining syndrome, but none are definitive.
Instead, overtraining is usually diagnosed with questionnaires like the Borg Rating of Perceived Exertion (RPE). Athletes with overtraining syndrome typically report higher effort levels (RPE) but actual performance is still declining.
By contrast, it is easier to diagnose nonfunctional overreaching: If performance improves after several days or weeks of reduced training, NFOR was likely the cause. However, with OTS, performance declines for months even with adequate rest.
Symptoms of Overtraining
- Elevated resting heart rate
- Decreased heart rate during performance
- Persistent fatigue despite rest
- Insomnia or disturbed sleep
- Loss of motivation
- Decreased strength or endurance
- Increased susceptibility to illness
- Mood disturbances such as irritability or depression
- Weight loss
- Burning sensation in muscles
Who Is At Risk of Overtraining?
Overtraining syndrome can occur with all types of athletes. However, certain types of athletes seem to be more susceptible to it.
Amateur Athletes
While pro athletes train at higher volumes, overtraining may actually be more common with amateur athletes. Unlike the pros, amateur athletes have to juggle fulltime jobs, family responsibilities and other stressors that impact their ability to recover.
Mario says weekend warriors are particularly at risk because they try to fit a week’s worth of training into two days. They also usually don’t have coaches to guide them and may look at Strava too much.
Alpha Guys
As Mario Schmidt-Wendling points out, there are some types of “alpha guys” that follow the “no pain, no gain” idea and really want to hurt themselves every single session. They particularly lack intensity control, which leads them to overreach. When working with these types of athletes, Mario even has to adjust his training prescriptions.
"If I know this is an alpha guy and want to write 200W, I would prescribe 180W instead because I know he is doing 20W over every time."
Women
Women are also more prone to overtraining because they often don’t eat enough. Over time, the energy deficiency leads to a downward spiral of suboptimal recovery and adaption.
Historically, female athletes have faced a lot of pressure related to body composition. Luckily, there is a growing awareness that proper fueling is more important than body composition, and more recognition of conditions like RED-S.
Read about RED-S and its dangers here.
How to Prevent Overtraining Syndrome
To prevent functional overreaching from turning into nonfunctional overreaching or overtraining syndrome, follow these guidelines.
1. Prioritize Sleep
While most athletes know that sleep is important, they don’t always prioritize it. As Coach Mario says, this is particularly true with amateur athletes because they have such busy lifestyles.
Amateurs might, for example, have a morning session at 5am before work, another session after work, and then fall asleep at 11pm. That gives only 6 hours of sleep for recovery. Over the long term, this cumulative lack of sleep has a very detrimental effect. He suggests skipping training sessions sometimes if it means getting the right amount of sleep.
2. Focus on Carbohydrates
Carbohydrates, especially simple sugars, are endurance athletes' main source of fuel. Unfortunately, a lot of athletes are still afraid of carbohydrates and try to restrict them. But, without them, the body simply doesn’t have the energy it needs for performance.
Carbohydrates are also important for the recovery process. Athletes should consume fast carbohydrates with 30 minutes of completing their workout. This is when the muscles are best primed to store glycogen, which can be used for fuel for the next workout.
Also read: Why Athletes Need Carbohydrates and our Guide to Fueling
Endurance athletes should consume carbohydrates during exercise to stay fueled. Each Nduranz Nrgy Gels 45 contains 45 g of fast-absorbing carbohydrates.
3. Plan Nutrition
Just like you might pack your bag at night for an early swim session, you should also plan your nutrition.
Coach Mario gives this example:
Imagine you have a double training session tomorrow—swimming in the morning and cycling in the afternoon. What you eat today directly affects your performance and recovery. To ensure your glycogen stores are topped up, you should prioritize carbohydrates at dinner, especially if you won’t have time for a full meal before your morning workout.
By contrast, athletes who don’t plan nutrition will end up skipping meals. They then come home completely exhausted and eat whatever they find in the fridge, which might not be the ideal food.
4. Periodize, but in the Short-Term
While periodization is trendy with endurance athletes, Coach Mario doesn’t recommend it because it’s too rigid. He says you can’t just separate an entire season into phases and stick to those phases without adjusting.
In his perspective, periodization must be in a very short time window. He won’t plan more than a week in advance. This allows him to assess factors including the athlete’s recovery state, sickness, injury, and even the weather conditions.
“Today's training has an impact on tomorrow's training. This is my way of periodization.”
5. Stop Looking for Shortcuts
When talking about nutrients, it should go: Carbohydrates, protein, and then fat. Only once those basic nutrients are covered can we start talking about supplements.
Unfortunately, a lot of athletes—especially amateurs—are hoping that supplements will give them a shortcut, but recovery doesn’t work that way.
6. Communicate with Coach
Training data only tells one part of the story.
Coach Mario talks to his athletes and asks questions like: “How do you feel today?” Some athletes are surprised by this. “Why are you asking?” they think. “You have all my data in TrainingPeaks.”
But, while data is useful, it only tells part of the story. Coaches need to know if their athletes are struggling with an interval session, feeling drained despite hitting the numbers, or experiencing stress at home. Otherwise, they’re working blind and won't be able to prescribe the right training.
Remember, training plans are based on science, but they’re still an educated guess—an experiment in how your body responds to a given stimulus. The only way to know if that stimulus is working? Honest feedback.
7. Consistency Over Intensity
You’ve heard it before: Consistency is what matters most. Despite this, a lot of athletes make the mistake of thinking that only high-intensity training sessions are worthwhile. Yet, Mario says to focus on what you can do frequently. This is what builds endurance and a good fat metabolism.
“It’s not quality before quantity. Quantity is quality.”
8. Don’t Do Fasted Trainings
Another trend that Coach Mario says to avoid is fasted training. If you have a carbohydrate deficit, you won’t be able to train at the highest quality. You’ll find yourself struggling even through “easy” training sessions.
If you don’t have time to digest a proper meal before your workout session, at least have a quick sip of an energy drink or eat a fueling bar with fast carbohydrates.
Remember: Even if you ate carbohydrates before bed, your liver glycogen levels decrease during sleep because the brain uses them for fuel. You will need to replace this glycogen before a workout by eating carbohydrates.
Want to learn more? Listen to the full podcast episode with Coach Mario Schmidt-Wendling.