Overtraining syndrome: Causes, consequences, and methods for prevention

Abstract

Exercise has the potential to improve the fitness level of an individual if he or she is able to optimally recover from the training stress. If unable to recover fully, the individual runs the risk of developing overtraining syndrome (OTS). Overtraining syndrome is a complex occurrence in the body, which can result from several training and non-training factors. Fortunately, there are several ways to avoid the development and detrimental effects of OTS. This article will discuss the causes, consequences, and methods for prevention for OTS.

Full text

Carter, JG, Potter, AW, and Brooks, KA. Overtraining syndrome: Causes, consequences, and
methods for prevention. J Sport Human Perf 2014;2(1):1-14.
DOI: 10.12922/jshp.0031.2014
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OVERTRAINING SYNDROME: CAUSES,
CONSEQUENCES, AND METHODS FOR PREVENTION
Carter, JG1, Potter, AW2, and Brooks, KA3
1Texas A&M University College Station, TX 77843
2New England Baptist Hospital, Boston, MA 02120
3Texas A&M University Corpus Christi, TX 78412
.
Keywords: OTS; training; fatigue; muscle weakness; physical activity
INTRODUCTION
According to the specific adaptations
to imposed demands (SAID) principle, the
body specifically adapts to the imposed
demands placed upon its systems (1).
Therefore, in order to elicit the greatest
adaptations from a training program, a
strength coach needs to prescribe a
systematic, progressive, and specific training
regimen for their athlete(s). The concepts and
philosophies of modern day periodization
allow strength coaches to prescribe
systematic, progressive, and specific training
programs by manipulating exercise
programming variables (i.e. intensity,
volume, frequency, mode, consistency,
variation, etc.) in a scientific and evidence
based format allowing the athletes to obtain
the desired training outcomes. Although the
SAID Principle is an agreed upon standard in
the strength and conditioning community,
strength coaches often focus primarily on the
training aspect of the principle, and
emphasize to a lesser extent the recovery
portion of the SAID Principle. The recovery
aspect of training is often overlooked (2), and
according to the SAID Principle, if the
recovery portion of training is neglected the
body will be maladaptive in responding to the
stress placed upon it. If the individual is
REVIEW OPEN ACCESS
ABSTRACT
Exercise has the potential to improve the fitness level of an individual if he or she is able to optimally
recover from the training stress. If unable to recover fully, the individual runs the risk of developing
overtraining syndrome (OTS). Overtraining syndrome is a complex occurrence in the body, which
can result from several training and non-training factors. Fortunately, there are several ways to avoid
the development and detrimental effects of OTS. This article will discuss the causes, consequences,
and methods for prevention for OTS.

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unable to recover for a continued duration, he
or she increases their chance for developing
overtraining syndrome (OTS). Fortunately,
there are several ways to avoid the
development and detrimental effects of OTS.
This article will discuss the causes, the
consequences, and the methods for preventing
OTS.
OVERTRAINING SYNDROME
Positive adaptations from exercise
occur only when the anabolic response is
greater than the catabolic dosage. According
to the Overload Principle, in order to elicit
continued adaptations from training, the body
needs to be overloaded to stimulate adaptive
and anabolic processes in the body in order to
reach new levels of fitness (3). While
overloading the body through training, the
body may reach a state of overreaching (OR)
and/or overtraining. Overreaching has been
defined as, “an accumulation of training and
nontraining stress resulting in a short-term
decrement in performance capacity with or
without related physiological and
psychological signs and symptoms of
overtraining in which restoration of
performance capacity may take from several
days to several weeks” (4). Whereas,
overtraining has been defined as, “an
accumulation of training or nontraining stress
resulting in long-term decrement in
performance capacity with or without related
physiological and psychological signs and
symptoms of overtraining in which
restoration of performance capacity may take
several weeks or months” (4). For trained
athletes, it may be necessary and beneficial to
induce a state of OR in order to bring about
greater performance (5).
There are two types of OR, functional
OR (FOR) and nonfunctional OR (NFOR).
Functional OR is when, through the process
of supercompensation, the body has positive
improvements in fitness because recovery has
occurred. Nonfunctional OR is when recovery
does not occur, and therefore, detriments in
performance and fitness begin to surface. If
the body is not allowed to recover after
having reached NFOR, the individual can
develop OTS. Currently, there is no clear
distinction or assessment for determining if
an individual has reached a state of NFOR
and/ or OTS. The difference between FOR,
NFOR, and OTS are dependent upon the time
necessary for the body to recover (6-8).
Functional OR may take between days to
weeks to recover, NFOR between weeks to
months, and OTS between months to years to
fully recover (6, 9).
An athlete in preparation is always
along a training continuum where at one end
is acute fatigue from an exercise session and
on the opposite end is OTS (6). Despite the
amount of research on OTS, there is currently
no agreed upon theory on its development.
Although there have been several theories on
what causes OTS such as glycogen depletion
(10, 11), central fatigue (12), tissue trauma/
increased cytokine levels (13, 14), and
glutamine depletion (15), none of these
proposed OTS mechanisms fully explain the
development of OTS. However, the common
theme for the development of OTS is the
improper ratio of recovery to stress.
Overtraining syndrome is a
complicated issue to study because 1) its
effects are highly individualistic, 2) people
have different stress capacities, and 3) you
cannot truly determine if an individual has
developed OTS or NFOR until after the
conclusion of the study or episode (4, 6).
Currently, there are no biomarkers to
determine if an individual is in a stage of
FOR, NFOR, or OTS (6, 9). For example, a
high level of creatine kinase (a marker of
muscle damage) has been seen in both
overtrained and non-overtrained individuals.
However, creatine kinase appears to be more

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prevalent in contact sports over nonimpact
sports, and is more indicative of muscle
damage and not OTS (16, 17). The ratio of
testosterone and cortisol, although indicative
of the anabolic to catabolic environment of
the body, is not a reliable tool for diagnosing
OTS since it reflects the physiological strain
of an athlete (18). Furthermore, certain
populations when overtrained may exhibit
sympathetic responses (i.e. elevated resting
heart rate), whereas others may develop
parasympathetic responses (i.e. decreased
resting heart rate) (19). Parasympathetic
overtraining has been shown more likely to
occur for endurance athletes, whereas
sympathetic overtraining is more likely to
occur in anaerobic athletes and/ or a result of
nontraining stress (20, 21). However, resting
heart rate has also been seen to go unaltered
in some individuals who develop overtraining
syndrome (22, 23).
It is beyond the scope of this article to
discuss the research on overtraining fully, but
the reader should note that there are review
articles (6, 13, 24-26), book chapters (21),
and books (4) also dedicated to the topic. The
amount of theories on OTS (10-15) illustrates
the complexity of OTS and furthermore, this
demonstrates that the development of OTS is
multifaceted. Overtraining simply occurs
from the body being unable to recover, which
can be caused from several factors. For
example, OTS can occur due to excessive
exercise volume, frequency, and duration (19,
27-29). It has also been shown as a product of
high intensity exercise (19), inadequate and
poor nutrition (6, 21, 24), monotonous
training (30), abrupt increases in training
volume-load (31), or training multiple times
per day (31). Overtraining has also been
found to occur in response to insufficient
quantity/ quality of sleep (27, 32), and/or
uncontrolled or excessive emotional,
environmental, occupational, and
psychological stress (4, 9, 24, 33), and is
related to the individual’s stress capacity (34).
Furthermore, OTS can occur from a lack of
communication between the athlete and coach
on the training load’s perceived exertion (19),
athletes training too hard on recovery sessions
(25), prior or reoccurring illnesses (6), or
long/ multiple consecutive competitive
seasons (35). It should be noted that
monotonous training is not just mode specific
(i.e. long distance running), but also effort
specific. For example, monotonous training
could involve continuous training at the same
level of intensity/ effort by not including
light, moderate, and hard days/ weeks in the
training program (19). If the body is unable to
recover for a prolonged period of time, a
person is at risk of becoming overtrained,
which ultimately decreases an individual’s
performance.
A distinction should be made between
burnout and OTS. An athlete who experiences
burnout will lose motivation, whereas an
athlete suffering from OTS could still possess
high levels of motivation (36). Therefore,
highly motivated athletes are at risk of
becoming overtrained because they might
neglect the recovery portion of their training
by opting to increase their training volume,
frequency, or intensity in order to achieve
greater results, especially when they notice a
decrease in performance (19, 25, 37).
Endurance athletes are particularly prone to
developing OTS (4, 31). Research (6, 38-41)
has suggested that the incidence of OTS may
vary from 7 to 64%, and an individual is
prone to relapse once he or she has developed
OTS (6). However, it has been suggested that
the incidence of developing OTS is over
reported and more than likely the athlete has
reached a state of NFOR compared to OTS
(9).

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Figure 1: Causes of Overtraining Syndrome
Overtraining has been associated with
disturbances in physiological performance,
psychological/ information processing,
biochemical markers, and immunological
function (6, 13, 19, 33, 42, 43). This can lead
to such things as depression, irritability,
chronic fatigue, decreased performance, loss
of competitive desire, frequent illnesses/
infections, altered sleep patterns, changed
responses to catecholamine sensitivity,
suppressed reproductive function, decreased
testosterone, elevated cortisol, loss of
appetite, reduced thirst, premature fatigue
during exercise, reduced neuromuscular
excitability, decreased running economy,
altered lactate response, competition anxiety,
reduced cognition/ ability to process large
amounts of information, constant soreness,
and increased injuries (6, 13, 19-21, 31-33,
35, 41-45). Depending on the severity of
overtraining, the symptoms and decrease in
performance could last from several months
to years (6, 9, 26, 46, 47). Since OTS has
symptoms such as apathy, chronic fatigue,
decreased performance, and frequent
illnesses, strength coaches and health
professional should ensure that their athletes
do not have an illness or disorder such as
anemia or an infection (6).
Moderate intensity exercise has been
shown to improve immunity, whereas high
intensity exercise can impair an individual’s
ability to fight off infection even without the
development of OTS (31, 48). Cortisol, a
catabolic and proteolitic hormone released in
times of stress, has been linked to the
suppression of the immune system following
intense exercise (43). Impaired immunity has
been linked to the environment, stress,
injuries, and nutrition (49), and exercise can
impair immunity for several hours following
the exercise bout (31). Overtraining syndrome
and intense exercise have been associated
with an impaired immune system, increased

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infection rates, and a high incidence rate of
upper respiratory tract infections, especially
for endurance athletes (6, 31).
Since OTS is the result of the inability
to recover from the cumulative stresses
placed upon the body, frequent illnesses
further impair the body’s ability to recover. It
should be mentioned that individuals will
handle training loads and additional stresses
differently due to genetics, training history,
initial status on the OTS continuum entering
the training program (50), and their stress
capacity (34). That is to say, some individuals
can tolerate more stress than others due to a
higher stress capacity (34), and their
disposition on the situation affects their
reaction to the training load and outside stress
(9). Furthermore, exercise selection and
execution plays a role in OTS. For example,
training with free weights taxes the body
more than training with weight machines
(51), and training to failure repeatedly
throughout the micro, meso, and macrocycle
can lead to OTS (52).
Figure 2: Consequences of Overtraining Syndrome
METHODS TO REDUCE OTS
Hoffman and Meir (37) state that,
“overtraining may be the culmination of
repeated warnings that went unacknowledged
or unnoticed by the athlete or coach.”
Lehmann et al (20), state that, “the risk of
overtraining is increased by 1) one-sided,
monotonous training without altering hard
and easy training days, 2) a lack of one
complete rest day per week, 3) a high total
and increasing training load combined with
additional significant nontraining stress, and
4) too many competitions.” As mentioned,
there is no agreed upon marker for
determining the onset of OTS, and an athlete
could be moving along the continuum

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towards OTS until there is a noticeable
detriment in performance, which is too late.
Therefore, it is agreed upon that the best
method to manage the effects of OTS is to
prevent it from occurring, especially
considering athletes who develop OTS are
more likely to experience a repeated episode
in the future compared to individuals who do
not develop OTS (6). Furthermore, an athlete
who develops OTS has the potential to harm
their health (9). Therefore, the authors will
briefly discuss several methods to reduce
OTS in order for the reader to gain the best
outcomes for their training population.
Periodization: Periodization is a concept that
involves “preplanned, systematic variations in
training specificity, intensity, and volume
organized in periods or cycles with an overall
program (53)” in efforts to elicit optimal
training adaptations. It is beyond the scope of
this article to discuss periodization fully, but
the reader should note that there are several
appropriate articles (54-56), book chapters
(53, 57), and books (58, 59) dedicated solely
to the topic of periodization. Periodization has
been shown to be the superior training
philosophy in the strength and conditioning
realm (60). Periodization and its concepts
have shown that providing athletes with
recovery days within a microcycle (30, 54), a
full recovery microcycle (19, 54), and/ or a
period of tapering (54, 55, 61, 62) allows the
body to recover. Through the process of
supercompensation, the body returns to
baseline or preferably to a new higher level of
fitness, which has the potential to reduce
OTS, overuse syndrome, physical/ mental
exhaustion, and injuries (63).
Research has shown that abrupt
increases in volume-load (31), as well as
training for three weeks or more without a
restoration microcycle, can potentially lead to
OTS (27, 41). Therefore, it is often prescribed
to arrange mesocycles into a 3:1 loading
paradigm where the athlete gradually
increases their volume-load over three weeks
followed by a fourth week of recovery (54). If
the goal is to achieve a state of FOR, the
coach might prescribe a loading paradigm of
4:2 to facilitate supercompensation by
overloading the athlete for four weeks then
providing a two week tapered training period
(54). The appropriate ratio of training to rest
is needed to avoid a state of NFOR or OTS,
as this will likely impact the macrocycle or
interfere with competitions. If the athlete
reaches NFOR or OTS, the recovery period
should be prolonged to ensure restoration. An
increase in the duration of restoration could
lead to deconditioning. Therefore, to avoid
both deconditioning and OTS, appropriate
periodized training programs will be
systematic and progressive in nature, will not
have drastic increases in volume or intensity,
avoid several consecutive high volume-load
microcycles (i.e. >3-4 weeks), and
incorporate adequate recovery periods.
Monitoring Training and Recovery:
Avoidance of OTS should be of significant
concern for both the coach and the athlete
throughout the training and competitive
seasons. Therefore, it is important to monitor
for OTS by administering tests and
monitoring elements of their training (i.e.
resting heart rate, profile of mood states
(POMS), rate of perceived exertion (RPE)
scales, body mass, sprints, 1RM tests, muscle
soreness, and sleep patterns). Furthermore, it
is beneficial to have the athlete keep a
training journal to assess their response to the
training dosage routinely throughout the
macrocycle (6, 13, 19, 21, 25, 31, 37, 63-65).
Often times, the first noticeable
change for an athlete who has developed OTS
is a reduction in performance (6, 37).
Performance detriments can be in the form
altered lactate threshold, power, strength,
endurance, RPE, coordination, and overall

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fatigue. Performance assessments should be
included regularly in training programs to
ensure the athlete is responding positively.
However, as mentioned, OTS is multifaceted
and often times can be developing under the
surface without noticeable performance
detriments (50). Fry et al (51) suggest not
relying solely on specific strength
measurements (i.e. 1RM) since OTS can be
developing and impairing other performance
variables without affecting an individual’s
maximal strength (i.e. 1RM). It appears that
maximal strength is not as sensitive to the
detrimental effects of OTS as early as power
or speed (6), which is why Hoff and Meir
suggest using sprints to monitor the training
response and onset of OTS (37).
A unique way of monitoring the
training load is by using the session-rating
RPE scale, which monitors the internal
training load of the exercise session (19, 25)
The internal training load is subjectively
based on the athlete’s perception of the
difficulty of the exercise session, whereas the
external training load is more objectively
based (i.e. how much distance is covered,
how many sets are performed, the elevation in
the athlete’s heart rate, the amount of weights
lifted, etc.). Compared to monitoring the
external training load, monitoring the internal
training load takes into account that each
athlete will perceive the training load
differently based upon their fitness level,
status along the OTS continuum, nutrition,
amount of sleep, and nontraining stress. The
session-rating RPE method measures the RPE
of the exercise session using a 10 point Borg
scale taken 30 minutes after the exercise
multiplied by the duration of the exercise
session. For example, an athlete who
exercised for 45 minutes at an overall RPE
level of 8 would receive a value of 360 in
arbitrary units. By using the session-rating
RPE scale, the coach can determine how the
athlete responded to the training session, and
this method can be used throughout the
training program to ensure that the athlete is
not having consecutive hard training days. In
their research, Wallace et al (19) showed that
the way coaches and athletes perceive the
difficulty level of training sessions are not
always consistent. For example, Wallace et al
(19) demonstrated that the coach perceived
lighter designed training sessions as being
easier than the way the athlete perceived
them, and the coach perceived the harder
designed training sessions as being harder
than the way the athletes perceived them.
Therefore, the session-rating RPE scale can
be a valuable assessment tool for the coach
and the athlete throughout the entire
macrocycle.
Nederhof et al (9) suggest that when
using markers to determine OTS that it should
fulfill six criteria: 1) objectivity, 2) not easily
manipulated, 3) applicable during training, 4)
not demanding upon the athlete, 5) affordable
to the majority of the athletic population, and
6) selection of the assessment be based off a
sound theoretical framework. A potentially
effective way of monitoring exercise
performance, recovery, and OTS is through
psychomotor tests such as reaction time (6,
9). Individuals who develop OTS have also
been shown to be prone to depression and be
chronically fatigued. Furthermore, individuals
who suffer from chronic fatigue syndrome
(66, 67), depression (68), and OTS (6, 69)
have reported cognitive decline, and this
cognitive decline affects reaction time and
decision making (9, 69). Therefore,
employing psychomotor assessments such as
reaction time/ choice tests in a training
program may be able to detect the
development of OTS earlier in the continuum.
The ability to predict OTS early on
from using reaction time tests is potentially
valuable since it is non-invasive, quick,
objective, not taxing to the athlete, affordable,
and can be easily administered using

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specialized software. It appears that the
reaction time test needs to be complex in
nature, since simple reaction tests do not
appear to be sensitive to OTS (9). However,
further research is needed in this area to
determine its sensitivity and effectiveness for
determining OTS (6, 9).
Sleep: One way to reduce the potential of
developing OTS, is to obtain adequate quality
and quantity of sleep (27, 70). While
sleeping, the body can devote its functions to
rebuilding the body. Furthermore, growth
hormone, which has anabolic properties, is
secreted via the pituitary gland during sleep.
Sleep becomes more important during intense
training periods (27, 71, 72), and inadequate
sleep is a major contributor to perceived
fatigue in elite and competitive athletes (24,
28, 29). Besides impairing recovery,
inadequate sleep can affect mood, reaction
times, arousal, attention, neuroendocrine
function, cardiovascular performance, and
cognition (27, 30). Anxiety can impair sleep
quality (46), and improving sleep habits in
collegiate basketball players not only
improved their level of fatigue, but improved
performance (sprinting and shot accuracy)
and mental wellness (61) A person’s sleep
debt can accumulate over a period of time and
can greatly affect the individual in every
aspect of life. Three suggestions for
improving one’s sleep include: 1) identifying
the amount of sleep needed per individual, 2)
keeping a regular sleep schedule, and 3)
creating an optimal sleeping environment
(30).
Nutrition: Nutrition is intuitively important
because without the correct amount and
proportions of macro and micronutrients, the
athlete will not have the building materials or
energy necessary for recovery. Deficiencies
in either the macro or micronutrients can
impair the immune system, hinder recovery,
and impair performance, thus moving the
athlete along the OTS continuum (73).
Overtraining syndrome has been shown to
decrease an individual’s appetite, which is
counterproductive since continuous caloric
deficits while training elevate both the stress
hormone and cytokine response to exercise.
This further moves the athlete along the OTS
continuum (6). It has been proposed that
cytokines could be a major contributor to the
development of OTS (13, 14). To ensure
adequate nutrition for their athlete, the health
professional should seek guidance from a
sports nutritionist or registered dietician, as
well as be up to date on the latest research on
sports nutrition.
Communication between the Coach and
Athlete: Communication between the coach
and athlete is critical. It has been observed
that often times mood states will change prior
to a drop in performance (13, 23, 45, 74).
Furthermore, an increase in nontraining stress
can lead to the development of OTS several
weeks later (75). Therefore, a strong
relationship between the coach and athlete
can potentially reduce OTS, which promotes
both health and performance for the athlete.
Communication between the athlete and
coach allows for education on OTS, as well as
education on the methods to reduce OTS and
enhance performance.
Education on OTS: The strength coach needs
to educate their athletes on proper methods to
enhance recovery, the warning signs and
consequences of OTS, and how “less is
sometimes more” in regards to training
volume and intensity. As mentioned, research
(6, 38-40) has suggested that the incidence of
OTS may vary from 7 to 64%, and an
individual is prone to relapse once he or she
has developed OTS (6). Therefore, educating

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the athlete on proper training philosophies
can make a significant difference on
potentially reducing OTS, improving
performance, and maintaining health. This
can include education on proper dietary
practices, sleep habits, training principles, and
possibly the addition of certain safe and
effective supplements to the athlete’s diet. A
previous article (2) on educating athletes
about OTS suggests educating athletes on
three elements of the training program: 1)
training load, 2) recovery ability, and 3)
summative stresses.
Figure 3: Methods to Prevent Overtraining Syndrome
SUMMARY
Overtraining syndrome results from
the inability to recover optimally. The
development of OTS is multifaceted (Figure
1), and there are several negative
consequences of OTS (Figure 2). The authors
have presented several methods to help the
strength coach and athlete mitigate the risk
for developing OTS (Figure 3). To enhance
recovery and promote positive adaptations
from training, the athlete should be educated
on the symptoms and consequences of OTS.
Education should encompass and promote
proper nutrition, the safety/ effectiveness of
certain supplements, training philosophies,
and the necessity of adequate sleep. The
coach/ health professional can help reduce
OTS by being educated and current with the
latest research and methodologies to enhance
recovery. The field of strength and
conditioning is always progressing, and
tactics such as cold water immersion (76) and
reaction time tests (6, 9) appear to be
promising in recovery and monitoring
exercise, respectively.

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