Cytokine Hypothesis of Overtraining

Overtraining is a topic that has been highly debated in the strength world for quite some time now. I remember Glenn Pendlay saying that he didn’t believe in overtraining – only under-recovering. I think you will see from this research article review that it’s quite easy to discern between overtraining and overreaching.

Last week I read an interesting abstract from (Smith, 2004.) citing 75 studies backing her claims regarding the Overtraining Syndrome (OTS). My goals for this short article is to help all of you understand:

  • What is the Overtraining Syndrome?
  • How does one distinguish between OTS and overreaching?
  • What are cytokines and what is their purpose?
  • What distinguishes between acute/local and chronic/systemic inflammation?
  • How do cytokines affect the brain?
  • Difference between cell-mediated vs. humoral immunity?
  • Which branch of the immune system is altered by cytokines?
  • And consequently, how is the activity of the other branch affected, and with what result?
  • More importantly to you and your athletes, how does one avoid the Overtraining Syndrome?

What is the Overtraining Syndrome (OTS)? And what distinguishes OTS from “overreaching”? What is the most consistent symptom of OTS?

By definition overtraining syndrome is a decline in performance due to an amount of intensity in which the amount of recovery is not being met. This decrease in performance remains even after an extended rest period. OTS can last several weeks to months – and in some occasions for the duration of the athlete’s career.

The difference in OTS and overreaching is that overreaching is a training stimulus to promote adaptation leading to improved performance. This is the main premise behind supercompensation that we all strive to elicit with our athletes. The short decrease in performance only lasts a few days with overreaching, and most coaches would agree that overreaching is a planned stimulus that ends with increased performance.

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The most consistent symptom is a decrease in performance that persists even after prolonged rest periods. However, a change in mood is normally the first indicator leading me to believe a solid athlete monitoring program could help avoid OTS. There are several other symptoms that we will discuss later on that could easily be monitored with the most basic of monitoring systems.

How can exercise lead to an excess production of cytokines? What distinguishes regional inflammation from systemic inflammation?

Exercise is known to cause microtrauma. That’s the whole point of exercise – or in the case of weightlifters, powerlifters, and strength and conditioning athletes, the whole point of weight training. The trauma is healed by regional inflammation (aka acute) with a well-orchestrated response that leads to the healing and regeneration of tissue. This is why preparing wisely for performance is so important.

However, if the acute inflammation isn’t resolved with proper recovery, then chronic aka systemic inflammation is the result. After certain intervals of time regarding traumatized tissue, specifically white blood cells show up on the scene to aid with healing – and those WBCs are directed by cytokines. Cytokines in the bloodstream are a primary way of determining that acute inflammation is now systemic. Now the different organ systems of the body become involved, directed by the cytokines.

What are some specific effects of cytokines on the brain? Which regions of the brain have been found to be affected by cytokines?

Hormonal effects in the form of lower testosterone and higher cortisol are due to the effect of cytokines on the hypothalamus – also causing lower libido and a drop in appetite. The hypothalamus is also to blame for the lower energy levels and even depression associated with cytokines. A simple questionnaire would easily quantify this issue. I recommend asking questions like:

  • How was last night’s quality of sleep on a scale from 1-5 – with 5 being perfect? If their normal answer is 4 or 5 and all of a sudden you get a 2, it’s time for further conversation.
  • How is stress outside the gym (ex. relationships, school, or work) on a scale from 1-5? The goal is to look for an out of ordinary number.

The hippocampus is also affected by cytokines during systemic inflammation – which disrupts learning, memory, and academic performance. This again could lead to simple questions to encourage intervention to avoid a case of OTS. Also simply being aware of your athletes could help prevent OTS. Do they look mentally fatigued or in a fog? If so, don’t be afraid to ask some follow up questions.

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Which branch of the immune system is altered by cytokines? And consequently, how is the activity of the other branch affected, and with what result?

Cell-mediated immunity is related to the elimination of intracellular viruses and bacteria. Humoral immunity focuses on eliminating extracellular pathogens operating in the fluid of the body, such as blood and other extracellular fluid. It is thought that humoral immunity is increased while cell-mediated immunity is suppressed – mainly due to the research pertaining to responses to major surgical trauma. If this hypothesis is correct, chronic inflammation associated with OTS leaves the athlete open to viral or bacterial infection.

This hypothesis makes total sense when you look at the common side effects related to overtraining. This is why so many athletes get sick close to competition. They are a few days before a taper – meaning they are beatdown – and then boom, they get the flu. Avoiding going so far as to cause chronic inflammation is the way to avoid a lot of these negative side effects.

Here are some of the author’s recommendations to avoid overtraining that relate specifically to exercise programming:

  • Maintain meticulous records of training and competition. Monitoring your athlete in the following areas: choice of exercise, order of exercise, volume, average intensity, and rest between sets.
  • Don’t increase volume more than 10% per week.
  • Have at least one day of complete rest per week and also make note of required rest between sets and exercises.
  • Preferably vary loads and exercises at least somewhat from day to day – even if total load stays the same week to week. They’re referring to monotony, which is actually a measurable marker.
  • Vary hard and light days.
  • On heavy days, split loads if possible and avoid long durations on high intensity days.
  • Include seasonal variety including the use of macrocycles, mesocycles, and microcycles.
  • Avoid too many competitions.
  • Eat a well balanced diet, and possibly use a vitamin supplement and increase intake of antioxidants.
  • Monitor stress and axiety away from training ex. Family, relationships, school and work.
  • Make use of rest and recovery.

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This was a great article to read, and one that I will consider as I build my athlete monitoring system. Several of these are easily monitored, assuming that athletes are honest on daily questionnaires. This article will definitely lead to an article from me focused on prevention.

Here’s a list of signs and symptoms from the author to look out for:

I hope you enjoyed this short article, and I hope that it helps you and your athletes.

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