What Causes Overtraining Syndrome and How to Prevent It

Endurance training involves a combination of duration, frequency, and intensity of training loads. The impact of short, high-intensity training versus longer, slower distance training has been studied and debated for decades among athletes, coaches, and scientists (Kreher, 2016). Endurance athletes are prone to persistently high volumes and intensities of training in the hopes of achieving improved performance. What is often forgotten is that the physiological adaptation that creates improved performance occurs during the resting period following workouts (Montesano, Di Silvestro, Cipriani, & Mazzeo, 2019). Without maintaining a proper balance between training and recovery, complete regeneration cannot occur, performance can plateau and will eventually decline resulting in the potential for overtraining syndrome.

What is Overtraining Syndrome?

There are two types of overtraining syndrome consisting of sympathetic and parasympathetic. Overtraining associated with the sympathetic system is more common in the anaerobic dominant sports such as sprinting or soccer (Meeusen & De Pauw, 2019). The sympathetic nervous system is often associated with preparing the body for fast movements such as the fight or flight response. An athlete’s heart rate is elevated and glucose is released from the liver. Athletes who are suffering from sympathetic overtraining syndrome generally have increased heart rate and blood pressure, decreased appetite and body mass, sleep disturbance, along with irritability (Meeusen & De Pauw, 2019). 

Overtraining associated with the parasympathetic form is often associated with aerobic dominant and endurance sports (Meeusen & De Pauw, 2019). The parasympathetic nervous system is accountable for stimulating actions when the body is at rest, such as urination and digestion. Athletes who are suffering from parasympathetic overtraining syndrome generally have a decreased resting heart rate and resting arterial pressure, extended periods of sleep, and depression (Kreher, 2016). Many studies have demonstrated that endurance athletes, in particular, can present symptoms associated with both sympathetic and parasympathetic overtraining.

How Can Overtraining Syndrome be Prevented?

Overtraining syndrome can be prevented by manipulating the key training variables of intensity, duration, and frequency of training. Getting the right mix helps to maximize physiological adaptation over time while minimizing risk of overtraining.
Training intensity is best determined from the athletes known metabolic thresholds. This ensures the stage is set for the right performance adaptation to occur for each type of workout and reduces the chance of accidentally over training with too much intensity.
Volume is manipulated with respect to the frequency of each workout type. More training volume can be safely accumulated at lower intensities than at higher intensities. Some guiding lights are doing 80 percent of your sessions at or below your VT1, and 20 percent of your sessions can contain harder efforts above your VT2.
Work to rest ratios are important to guide the appropriate intensity and recovery for different interval types. The ratio refers to the number of minutes spent during the "work" portion of an interval relative to the "recovery" portion. So an interval session that calls for a 3 minute interval portion and 1 minute of rest has a ratio of 3:1. A good starting point for work to rest ratios during interval sessions are 5:1 for VT2 intervals, 3:1 to 1:1 for VO2max intervals, and 1:5+ for sprints.
Recovery and rest days are as essential to an athlete as workdays in increasing performance and preventing overtraining. It's important for you as an athlete to develop a sense of knowing where your body is at. The right tools and technologies can help by providing objective data to build your awareness and compare and contrast with your perception.

References

1. Kreher, J. B. (2016). Diagnosis and prevention of overtraining syndrome: an opinion on education strategies. Journal of Sports Medicine, 7(1), 115-122. 
2. Meeusen, R., & De Pauw, K. (2019). Overreaching and overtraining syndrome: Causes, prevention, and remedy. APA handbook of sport and exercise psychology, 2(1), 147-157. 
3. Montesano, P., Di Silvestro, M., Cipriani, G., & Mazzeo, F. (2019,1). Overtraining syndrome, stress and nutrition in football amateur athletes. Journal of Human Sport and Exercise, 957-969.