Thom Downing
05-27-2006, 02:19 AM
Are Cytokines to Blame for Overtraining?
Overtraining occurs when an athlete is training intensely,
but, instead of improving, performance deteriorates, even
after an extended rest period. The first noticeable
difference is in an athlete’s performance, and may extend
over a period of weeks or months.
Overtraining syndrome (OTS) and exhaustion are a
consequence of an imbalance between stress and recovery.
Ideally, when an athlete trains, his/her performance should
be constantly improving. However, when the adaptations of
training develop longer than the initiation of exercise, the
body is receiving a repeated stress that it needs to recover,
but it does not recover adequately. During OTS, an
individual may experience frequent infections and
depression that occur following hard training and
competition.
The following table lists a number of the signs and
symptoms of OTS. Keep in mind that not all appear at the
same intensity, all the time, in all individuals. One to
several of these signs and symptoms may appear.
Table 1. Signs and symptoms of OTS
Performance Parameters
Decreased performance
Unable to achieve previous standards
Prolonged recovery
Reduced toleration of loading
Decreased muscular strength
Decreased work capacity
Physiological
Change in blood pressure
Change in heart at rest, during exercise, and during
recovery
Increased breathing frequency
Fat loss
Muscle loss
Elevated metabolism
Psychological
Constant fatigue
Reduced appetite
Need more or less sleep than normally
Depression
General apathy
Decreased self-esteem
Emotional instability
Fear of competition
Easily distracted
Gives up easily
Information processing
Loss of coordination
Reappearance of previously corrected mistakes
Difficulty concentrating
Unable to deal with large amounts of information
Biochemical parameters
Rhabdomyolysis
Elevated C-reactive protein and creatine kinase
Greater loss of nitrogen (urea and uric acid production)
Decreased free testosterone
Increased serum cortisol
Decreased iron and ferritin
Immunological parameters
Constant fatigue
Sore and tender muscles and joints
Headaches
Nausea
Gastrointestinal disturbances
Increased susceptibility to and severity of illnesses, colds,
and allergies
Swelling of lymph glands
Generally, the first indication of impending OTS is a change
in mood although it is the decline in performance that
usually captures the attention of the athlete, personal
trainer and/or coach.
Unfortunately, scientists do not have a universal agreement
of the diagnostic criteria for OTS. There are a number of
hypotheses in the literature, but each explains only one or
a couple aspects of OTS.
In 2000, Dr. Lucille Lakier Smith published an article
describing the potential mechanism of OTS. She proposed
that excessive training/competing causes repetitive tissue
trauma, either to muscle and/or connective tissue and/or to
bony structures, and that this results in chronic
inflammation. The traumatized tissue synthesizes a group
of inflammatory molecules called cytokines.
This article will present a brief review of the other proposed
mechanisms of OTS and how cytokines may be the “lost
mechanism.”
Glycogen Depletion
Some of the complaints of OTS are “heavy legs” and
general fatigue. The glycogen depleting hypothesis
suggests that these symptoms occur as a result of a lack of
energy. Therefore, symptoms of OTS should be avoided if
enough carbohydrates are eaten to fill muscle energy
stores (i.e. muscle glycogen). However, when scientists
tried this in cyclists, the cyclists still elicited signs of
overreaching (short-term overtraining) and might have met
the criteria for overtraining had the subjects been followed
for a longer period of time.
Central Fatigue
This hypothesis suggests the general complaints of fatigue
(low blood glycogen) may be due to an excess of an amino
acid called tryptophan in the brain and spinal cord. This is
the same amino acid that is found in turkey and blamed for
that “Thanksgiving Coma” we get after eating that big
meal. Strenuous exercise may create an increase in a
neurotransmitter called serotonin via the extra tryptophan
in the blood. This causes lethargy, depresses neural
excitability, alters hormonal functions, decreases muscular
contractions, and may impair judgment.
However, this was demonstrated in rats and has not yet
been demonstrated in humans. Also, it does not explain the
tendency for infections that typically occurs in OTS.
Glutamine Hypothesis
Glutamine is an important amino acid involved in optimal
functioning of the immune system. Lower blood glutamine
levels have been measured in overtrained athletes. This
may be the cause for the increase in infections associated
with OTS, however, it does not explain the change in mood
or decrease in energy levels when an infection does not
occur.
Nervous System and the Endocrine System
The adaptations and performance of exercise is dependent
on the intricate links between the central nervous system
(the brain and spinal cord) and the endocrine system (the
hormonal system). Any changes in either of these will
affect performance in the muscle system. The endocrine
system in particular controls an intricate group of glands
whose hormones are vital to all aspects of life.
When overtraining occurs, then there must be a
disturbance of some sort with the endocrine system and
the factors that control it – namely, the autonomic nervous
system (which is composed of the sympathetic and
parasympathetic nervous systems).
The following lists the signs and symptoms of two types of
overtraining called A-overtraining and B-overtraining with
regard to the same conditions.
a) A-overtraining (Addisonic overtraining), named after
Addison’s disease, involves the parasympathetic nervous
system and it is associated with diminished activity of the
adrenal glands, which prepare muscle for physical activity
in the face of stress. This is difficult to detect early because
of the absence of any dramatic symptoms. This is usually
not diagnosed until a decrease in performance happens.
b) B-overtraining (Basedowic overtraining), named after
Basedow’s disease, involves the sympathetic nervous
system and it is associated with thyroid hyperactivity,
affecting internal stress management and metabolism. This
is the classical type of overtraining with its abundance of
symptoms.
A-Overtraining
1. Blood pressure: diastolic increase to over 100mm Hg,
during & after physical stress
2. Coordination: impaired
3. Bodymass: normal
4. Endurance: slight increase in tiredness
5. Sleep requirements: no increase
6. Resting pulse: low
7. Body temperature: normal
8. Appetite: normal
9. Metabolism: normal
10. General muscle soreness: little or none
11. General resistance: normal
12. Recovery time: normal or slightly increased
13. Psychological changes: none, other than slight loss in
motivation
B-Overtraining
1. Blood pressure: slight increase
2. Coordination: impaired, with increased reaction time
3. Bodymass: decrease
4. Endurance: tendency to tire easily
5. Sleep requirements: increase
6. Resting pulse: elevated
7. Body temperature: slightly increased
8. Appetite: reduced
9. Metabolism: altered, with increased tendency to sweat;
abnormally increased breathing rate under stress
10. General muscle soreness: mild to pronounced, with
tendency to muscle stiffness and pain
11. General resistance: tendency to headaches, colds,
fever blisters; prolonged recuperation
12. Recovery time: increased
13. Psychological changes: nervousness, poor motivation,
inner unease, eventual depression
The Hypothalamic-Pituitary Axis Hypothesis
The hypothalamus and pituitary gland are located very
closely together in the brain. When the hypothalamus
receives a message from the body, it uses the pituitary
gland to carry out its “orders” by the using various
hormones. As such, it is commonly referred to as the
“neuroendocrine system.”
A natural response to increased workload is increased
levels of stress hormones. During overtraining, an
individual will create oddly high or low concentrations of
several of these hormones.
Much of the scientific literature on overtraining is based on
aerobic activities, despite the fact that resistance exercise
is a large component of many exercise programs. Because
of various resistance training programs, chronic resistance
exercise can result in differential responses to overtraining
depending on whether either training volume or training
intensity is excessive. The neuroendocrine system is a
complex physiological entity that can influence many other
systems. Neuroendocrine responses to high volume
resistance exercise overtraining appear to be somewhat
similar to overtraining for aerobic activities. On the other
hand, excessive resistance training intensity produces a
distinctly different neuroendocrine profile. As a result, some
of the neuroendocrine characteristics often suggested as
markers of overtraining may not be applicable to some
overtraining scenarios. This hypothesis lacks consistency in
individuals. Therefore, further research is needed to better
understand the role of the hypothalamic-pituitary axis in
OTS.
Cytokines: The Answer?
Recently, other authors have recognized the “cytokine
hypothesis” as the most attractive hypothesis that accounts
for the observed neuro-endocrine-immune disregulation of
OTS. As you can see from what has already been
mentioned in this article, there is a wide array of variability
of symptoms that fall under OTS, yet it is impressive to find
one source for all of these.
There are several families of cytokines and many different
cytokines within a family. This article will refer primarily to
the pro-inflammatory cytokines: interleukin-1ß (IL-1ß),
tumor necrosis factor-? (TNF-?) and interleukin-6 (IL-6).
These three have a natural and specific role in promoting
inflammation in order to complete the healing process.
This hypothesis proposes that because OTS is a response to
excessive training/competing with insufficient time for rest
and recovery, this results in some form of tissue trauma
and associated chronic inflammation, with the resulting
release of pro-inflammatory cytokines. These cytokines
increase in the blood and are capable of accessing the
central nervous system and stimulating specific brain
areas, resulting in changing behaviors such as depression,
loss of appetite, and sleep disturbances, etc. These
behaviors are associated with OTS.
In terms of what is found in the blood during OTS,
cytokines are capable of increasing certain blood markers
associated with OTS such as C-reactive protein and ferritin.
In terms of athletes becoming more susceptible to
infections and allergies, in an overtrained athlete, the
immune system becomes more susceptible to viral or
bacterial infections. This renders the individual susceptible
to developing an infection, and genetically predisposed
individuals may develop allergies.
All three of the above conditions can affect an individual
physically by decreasing performance.
The Solution
In a word: rest and try some recovery techniques. All of
these symptoms create an adaptive type of response in the
body such that they promote withdrawal from training and
encourage rest in order for recovery to happen.
How much rest? That is largely dependent on the
individual. As mentioned earlier, it could be something as
little as one week to one year or even longer. Make resting
days a part of your overall program. They are something
your body truly needs.
Some recovery techniques are massages, meditation,
contrast baths, contrast showers, sauna and/or
hydrotherapy.
Scott Kolasinski, FIT Metabolic Science Director
Overtraining occurs when an athlete is training intensely,
but, instead of improving, performance deteriorates, even
after an extended rest period. The first noticeable
difference is in an athlete’s performance, and may extend
over a period of weeks or months.
Overtraining syndrome (OTS) and exhaustion are a
consequence of an imbalance between stress and recovery.
Ideally, when an athlete trains, his/her performance should
be constantly improving. However, when the adaptations of
training develop longer than the initiation of exercise, the
body is receiving a repeated stress that it needs to recover,
but it does not recover adequately. During OTS, an
individual may experience frequent infections and
depression that occur following hard training and
competition.
The following table lists a number of the signs and
symptoms of OTS. Keep in mind that not all appear at the
same intensity, all the time, in all individuals. One to
several of these signs and symptoms may appear.
Table 1. Signs and symptoms of OTS
Performance Parameters
Decreased performance
Unable to achieve previous standards
Prolonged recovery
Reduced toleration of loading
Decreased muscular strength
Decreased work capacity
Physiological
Change in blood pressure
Change in heart at rest, during exercise, and during
recovery
Increased breathing frequency
Fat loss
Muscle loss
Elevated metabolism
Psychological
Constant fatigue
Reduced appetite
Need more or less sleep than normally
Depression
General apathy
Decreased self-esteem
Emotional instability
Fear of competition
Easily distracted
Gives up easily
Information processing
Loss of coordination
Reappearance of previously corrected mistakes
Difficulty concentrating
Unable to deal with large amounts of information
Biochemical parameters
Rhabdomyolysis
Elevated C-reactive protein and creatine kinase
Greater loss of nitrogen (urea and uric acid production)
Decreased free testosterone
Increased serum cortisol
Decreased iron and ferritin
Immunological parameters
Constant fatigue
Sore and tender muscles and joints
Headaches
Nausea
Gastrointestinal disturbances
Increased susceptibility to and severity of illnesses, colds,
and allergies
Swelling of lymph glands
Generally, the first indication of impending OTS is a change
in mood although it is the decline in performance that
usually captures the attention of the athlete, personal
trainer and/or coach.
Unfortunately, scientists do not have a universal agreement
of the diagnostic criteria for OTS. There are a number of
hypotheses in the literature, but each explains only one or
a couple aspects of OTS.
In 2000, Dr. Lucille Lakier Smith published an article
describing the potential mechanism of OTS. She proposed
that excessive training/competing causes repetitive tissue
trauma, either to muscle and/or connective tissue and/or to
bony structures, and that this results in chronic
inflammation. The traumatized tissue synthesizes a group
of inflammatory molecules called cytokines.
This article will present a brief review of the other proposed
mechanisms of OTS and how cytokines may be the “lost
mechanism.”
Glycogen Depletion
Some of the complaints of OTS are “heavy legs” and
general fatigue. The glycogen depleting hypothesis
suggests that these symptoms occur as a result of a lack of
energy. Therefore, symptoms of OTS should be avoided if
enough carbohydrates are eaten to fill muscle energy
stores (i.e. muscle glycogen). However, when scientists
tried this in cyclists, the cyclists still elicited signs of
overreaching (short-term overtraining) and might have met
the criteria for overtraining had the subjects been followed
for a longer period of time.
Central Fatigue
This hypothesis suggests the general complaints of fatigue
(low blood glycogen) may be due to an excess of an amino
acid called tryptophan in the brain and spinal cord. This is
the same amino acid that is found in turkey and blamed for
that “Thanksgiving Coma” we get after eating that big
meal. Strenuous exercise may create an increase in a
neurotransmitter called serotonin via the extra tryptophan
in the blood. This causes lethargy, depresses neural
excitability, alters hormonal functions, decreases muscular
contractions, and may impair judgment.
However, this was demonstrated in rats and has not yet
been demonstrated in humans. Also, it does not explain the
tendency for infections that typically occurs in OTS.
Glutamine Hypothesis
Glutamine is an important amino acid involved in optimal
functioning of the immune system. Lower blood glutamine
levels have been measured in overtrained athletes. This
may be the cause for the increase in infections associated
with OTS, however, it does not explain the change in mood
or decrease in energy levels when an infection does not
occur.
Nervous System and the Endocrine System
The adaptations and performance of exercise is dependent
on the intricate links between the central nervous system
(the brain and spinal cord) and the endocrine system (the
hormonal system). Any changes in either of these will
affect performance in the muscle system. The endocrine
system in particular controls an intricate group of glands
whose hormones are vital to all aspects of life.
When overtraining occurs, then there must be a
disturbance of some sort with the endocrine system and
the factors that control it – namely, the autonomic nervous
system (which is composed of the sympathetic and
parasympathetic nervous systems).
The following lists the signs and symptoms of two types of
overtraining called A-overtraining and B-overtraining with
regard to the same conditions.
a) A-overtraining (Addisonic overtraining), named after
Addison’s disease, involves the parasympathetic nervous
system and it is associated with diminished activity of the
adrenal glands, which prepare muscle for physical activity
in the face of stress. This is difficult to detect early because
of the absence of any dramatic symptoms. This is usually
not diagnosed until a decrease in performance happens.
b) B-overtraining (Basedowic overtraining), named after
Basedow’s disease, involves the sympathetic nervous
system and it is associated with thyroid hyperactivity,
affecting internal stress management and metabolism. This
is the classical type of overtraining with its abundance of
symptoms.
A-Overtraining
1. Blood pressure: diastolic increase to over 100mm Hg,
during & after physical stress
2. Coordination: impaired
3. Bodymass: normal
4. Endurance: slight increase in tiredness
5. Sleep requirements: no increase
6. Resting pulse: low
7. Body temperature: normal
8. Appetite: normal
9. Metabolism: normal
10. General muscle soreness: little or none
11. General resistance: normal
12. Recovery time: normal or slightly increased
13. Psychological changes: none, other than slight loss in
motivation
B-Overtraining
1. Blood pressure: slight increase
2. Coordination: impaired, with increased reaction time
3. Bodymass: decrease
4. Endurance: tendency to tire easily
5. Sleep requirements: increase
6. Resting pulse: elevated
7. Body temperature: slightly increased
8. Appetite: reduced
9. Metabolism: altered, with increased tendency to sweat;
abnormally increased breathing rate under stress
10. General muscle soreness: mild to pronounced, with
tendency to muscle stiffness and pain
11. General resistance: tendency to headaches, colds,
fever blisters; prolonged recuperation
12. Recovery time: increased
13. Psychological changes: nervousness, poor motivation,
inner unease, eventual depression
The Hypothalamic-Pituitary Axis Hypothesis
The hypothalamus and pituitary gland are located very
closely together in the brain. When the hypothalamus
receives a message from the body, it uses the pituitary
gland to carry out its “orders” by the using various
hormones. As such, it is commonly referred to as the
“neuroendocrine system.”
A natural response to increased workload is increased
levels of stress hormones. During overtraining, an
individual will create oddly high or low concentrations of
several of these hormones.
Much of the scientific literature on overtraining is based on
aerobic activities, despite the fact that resistance exercise
is a large component of many exercise programs. Because
of various resistance training programs, chronic resistance
exercise can result in differential responses to overtraining
depending on whether either training volume or training
intensity is excessive. The neuroendocrine system is a
complex physiological entity that can influence many other
systems. Neuroendocrine responses to high volume
resistance exercise overtraining appear to be somewhat
similar to overtraining for aerobic activities. On the other
hand, excessive resistance training intensity produces a
distinctly different neuroendocrine profile. As a result, some
of the neuroendocrine characteristics often suggested as
markers of overtraining may not be applicable to some
overtraining scenarios. This hypothesis lacks consistency in
individuals. Therefore, further research is needed to better
understand the role of the hypothalamic-pituitary axis in
OTS.
Cytokines: The Answer?
Recently, other authors have recognized the “cytokine
hypothesis” as the most attractive hypothesis that accounts
for the observed neuro-endocrine-immune disregulation of
OTS. As you can see from what has already been
mentioned in this article, there is a wide array of variability
of symptoms that fall under OTS, yet it is impressive to find
one source for all of these.
There are several families of cytokines and many different
cytokines within a family. This article will refer primarily to
the pro-inflammatory cytokines: interleukin-1ß (IL-1ß),
tumor necrosis factor-? (TNF-?) and interleukin-6 (IL-6).
These three have a natural and specific role in promoting
inflammation in order to complete the healing process.
This hypothesis proposes that because OTS is a response to
excessive training/competing with insufficient time for rest
and recovery, this results in some form of tissue trauma
and associated chronic inflammation, with the resulting
release of pro-inflammatory cytokines. These cytokines
increase in the blood and are capable of accessing the
central nervous system and stimulating specific brain
areas, resulting in changing behaviors such as depression,
loss of appetite, and sleep disturbances, etc. These
behaviors are associated with OTS.
In terms of what is found in the blood during OTS,
cytokines are capable of increasing certain blood markers
associated with OTS such as C-reactive protein and ferritin.
In terms of athletes becoming more susceptible to
infections and allergies, in an overtrained athlete, the
immune system becomes more susceptible to viral or
bacterial infections. This renders the individual susceptible
to developing an infection, and genetically predisposed
individuals may develop allergies.
All three of the above conditions can affect an individual
physically by decreasing performance.
The Solution
In a word: rest and try some recovery techniques. All of
these symptoms create an adaptive type of response in the
body such that they promote withdrawal from training and
encourage rest in order for recovery to happen.
How much rest? That is largely dependent on the
individual. As mentioned earlier, it could be something as
little as one week to one year or even longer. Make resting
days a part of your overall program. They are something
your body truly needs.
Some recovery techniques are massages, meditation,
contrast baths, contrast showers, sauna and/or
hydrotherapy.
Scott Kolasinski, FIT Metabolic Science Director