Download The basis for all modern sport training is the general adaptation

© Christine Brooks (draft)
How the athlete adapts to training
Introduction
When the athlete's performance is edging toward its genetic ceiling it is because the body
is growing both externally and internally. After puberty anthropometric growth (I.e. the
external structural build of the athlete) slows and eventually stops. The athlete's
genetically determined anthropometric characteristics will impact the sport for which he or
she is most suited. Here you see the physique of various athletes and the sport in which
they excel.
Training works to improve the athlete's performance because the internal structures of
the body are only maintained at a 'survival need level' depending on current chronic daily
activity. There is significant untapped capacity that remains undeveloped. Training 'tricks'
the body into thinking it needs more capacity to survive and it adapts the internal
structures, improves their working capacity and mobilization of stored fuel for ATP
production, etc., to meet survival requirements. Adaptation is a critical training science
concept because if you don't understand it you will not be able to design a training
program and completely understand how all the parts fit together so the athlete's sport
performance improves.
When you watch your athletes training it is easy to forget about the millions of cells,
invisible to the naked eye, that are adapting to the stress of training so they become
stronger and function at increasingly higher levels of efficiency. The performance each
athlete attains depends on your ability to stimulate the correct adaptations at this cellular
level. You are, in essence, training the athlete's basic molecular structures.
What you will learn
The goal of this module is to take your understanding of adaptation and its relationship to
training to a deeper level of understanding. You will learn more about the important
notion of homeostasis – a physiological concept that is at the very heart of how training
improves the athlete's physiological work capacity.
The homeostasis concept:
To understand adaptation you must first have a background knowledge in the concept of
homeostasis. So let’s develop your understanding of homeostasis a bit further. As you
know, homeostasis refers to the normal preset range of conditions within the body’s
internal environment. The body has a preset normal range for temperature, the salt and
acid conditions of blood and cells, and the desirable nutrient and waste balance. If any of
these move outside the preset range athletes lose their ability to perform at their optimum
level.
One of the most remarkable characteristics of the human body is its ability to maintain
reasonable control over its internal environment even when severely challenged. For
example, whether sweating profusely in a sauna, or exercising in the cold, the body
makes the adjustments necessary to ensure all its cells are kept at a constant or steady
temperature.
Adaptation to training stresses is always directed toward maintaining or restoring the
internal environment of cells, tissues and organ systems to the preset range. Training
programs are designed to 'trick' the body into thinking it needs to adjust to a new and
more stressful environment. The adaptive mechanism doesn’t know you are simply
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© Christine Brooks (draft)
manipulating the stress the athlete’s body experiences so it can perform an extraordinary
athletic feat of some kind. A well-designed training program induces the body’s adaptive
mechanism to make structural and chemical changes to produce a very specific athletic
performance.
Maintaining the body’s homeostasis involves a complex set of monitoring strategies to
sense when critical environmental conditions are unsafe for the cells. The actions often
stimulated involve building more protein structures to cope with higher physical demands
so the body is more easily able to work within the desirable range under the new level of
physical stress. Whenever the body’s internal environment moves away from the set
normal range this is referred to as 'putting it under stress' and this is what you will use
your training stimulus to accomplish.
The endocrine system is important in homeostasis
The endocrine system is a critical player in maintaining a stable internal environment for
the cells. The endocrine system 'oversees' homeostasis and in this way enables all the
organs and organ systems in the body to function properly. Without the Endocrine system
the athlete would not adapt to training, and therefore, not be able to improve
physiological working capacity.
The organs of the endocrine system are small and dispersed throughout the body. They
all produce chemical messengers called hormones that are secreted into and carried by
the bloodstream. Hormones are the mechanism by which the brain controls
environmental conditions in the body.
For example, one important function of hormones is to control of the amount of sugar (or
glucose) in the bloodstream. Glucose is toxic to blood vessels in high dosages so, shortly
after eating a meal high in sugar or carbohydrate, signals are sent to the pancreas to
secrete the hormone, insulin, into the blood stream. Insulin then opens channels in the
cell membranes so glucose molecules can move from the bloodstream into the cell. Once
inside the cell glucose is used for energy, or stored as glycogen. In this way the blood
glucose level returns to the normal range quite quickly. If blood glucose dips below the
preset range the pancreas releases another hormone called glucagon that tells the liver
to release glucose from its glycogen stores into the blood stream. When the level of
glucose in the blood has once again returned to the normal range, the pancreas will stop
producing glucagon, and the liver will stop breaking down its store of glycogen into
glucose molecules.
Don’t forget recovery
When you challenge the body's ability to keep the internal environment within the
desirable range, the adaptive mechanism will require recovery time to reestablish
homeostasis. Recovery permits repair of any structural damage caused when training
forces the cells and organ systems to work at a higher capacity. Relevant protein
structures are also strengthened so the organ systems can meet the additional stress of
the next training session and have an easier time maintaining homeostasis.
Here is an important point. If any organ system in the body has to work at consistently
high levels without adequate recovery and repair time things can begin to breakdown. A
diet high in refined carbohydrate, for instance, results in a glucose stress. The insulin
receptors located in the cell membrane responsible for opening up the special gates for
glucose to enter the cell must work very hard. When insulin receptors are overworked
they fatigue and the entry gates for glucose don’t open with normal levels of insulin
stimulation. The body goes through an adjustment period where it responds to the higher
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© Christine Brooks (draft)
glucose levels by gradually releasing more insulin into the bloodstream. Ultimately, the
fatigued insulin receptors will quit working altogether because there has been no time to
make the necessary structural repairs to the receptors and the glucose control
mechanism breaks down. The individual becomes diabetic because their cells are
starved for glucose due to the lack of glucose passageways in the cell walls. Excess
glucose in the blood is toxic to capillaries and after a period of time will cause structural
damage to the capillary cell walls. This is the reason delicate kidney capillaries fail
resulting in kidney malfunction and blood vessels in the eyes burst leading to blindness.
The long-term health consequences of diabetes can be fatal.
This same type of structural overuse phenomenon can also occur when you train an
athlete above their tolerable physical stress, or if you do not provide adequate recovery
time after the training session. Fatigue of the protein structures affects the ability of
homeostatic control mechanisms to work efficiently. This can lead to a serious condition
referred to as overtraining syndrome if corrections in the training program are not made.
General Adaptation Syndrome:
In the 1930s, biochemist, Hans Selye described the general adaptation syndrome, or
GAS for short. Stress is a major cause of disease because chronic stress causes longterm chemical changes and structural breakdown. During his research Seyle observed
how the body responded to external sources of stress in a predictable way in an attempt
to restore the body’s internal homeostasis. Selye called the process of the body’s
struggle to maintain balance as the General Adaptation Syndrome. Pressure, tensions,
and other stressors can greatly influence normal metabolism and Selye’s research
showed how the limited supply of adaptive energy to deal with stress is easily depleted if
the stress is not removed.
Selye devoted his life to understanding the role stress played in both health and diseased
states. He defined stress as the non-specific response of the body to any kind of demand
beyond normal operating conditions. It is not possible to avoid stress because it is part of
life. However, Selye distinguished between the side effects of bad stress from good
stress. He referred to bad stress as distress and demonstrated how bad stressors, such
as those we encounter as a consequence of the hectic nature of modern day life, causes
the body to adapt in a way we now recognize as a diseased state. High blood pressure,
for example, is one outcome of constant day-to-day pressures of trying to get everything
done. One of the adaptations the body makes in response to stress is to increase blood
pressure. If blood pressure is never allowed to return to normal the brain resets the
preset range for blood pressure to a higher level. Distress needs to be managed and kept
to a minimum and many common diseases beside high blood pressure are largely due to
errors in our adaptive response to distress. Selye referred to these as diseases of
adaptation. Today, we generally refer to diseases occurring due to lifestyle as
maladaptation diseases.
Three distinct phases
Selye described three stages of a body’s adaptation to stress.
Alarm stage: The first stage is the alarm reaction stage where hormones are released to
help the body cope with the stress. The necessary regulatory mechanisms are activated
in an effort to restore homeostasis. Once the cause of the stress is removed – that is,
during the recovery phase - the body will readjust everything back down to a normal
level of activity.
Resistance stage: If the cause of the stress is not removed and/or continues to return on
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© Christine Brooks (draft)
a chronic basis, the general adaptation syndrome moves into its second stage – the
resistance or adaptation phase. During this stage the body makes adjustments in its
structures or enzyme levels to provide added protection against this stress. You can think
of this as the body’s defense mechanism. When the body’s structures are strengthened
stress hormones are not elevated as easily. When they are elevated, it is easer for the
body to return them back to normal quite quickly. If the stressful condition persists,
overuse of the cells and organ systems eventually leads to structural fatigue and
ultimately to functional breakdown. The adaptation phase must have periods of rest so
the body can recover and rebuild its structural strength. If the defense mechanisms are
stimulated for prolonged periods of time without a period of recovery to counterbalance
the stress response the athlete will become prone to fatigue and irritability. That is, their
body enters a state of distress.
Exhaustion stage: Exhaustion occurs when the stress has continued for some time
without adequate recovery and the adaptive capacity of the body becomes overwhelmed.
Cells are severely damaged and must be dismantled. In this stage the body has run out
of its reserve of energy and its defense resources are stretched beyond their capacity.
Mental, physical and emotional abilities of the athlete all suffer a heavy toll.
In other words, the adaptation process ends and the body has entered the stage of the
general adaptation syndrome most hazardous to health. Chronic stress damages nerve
cells in tissues and organs. Particularly vulnerable is the hippocampus section of the
brain that plays an important role in memory and spatial navigation. Thinking and
memory become impaired and there is a tendency toward anxiety and depression. These
are all symptoms of overtraining.
GAS and training theory
The General Adaptation Syndrome became the basic theoretical framework for sport
training in the 1960s even though it does have some problems in explaining all the
relationships between training and adaptation. GAS suggested that the best training
effect occurred when training loads “stressed” the athlete’s body. However, with this
approach the problem became one of how to avoid overtraining the athlete by stimulating
the exhaustion phase.
GAS theory was particularly valuable to sport training theorists because it explained a
physiological rational as to why adequate recovery was as essential part of the athlete’s
training program. The key question became one of understanding the main notions
behind the physiology of adaptation as it related to training athletes. A good place to start
is to divide the homeostasis structures into two broad categories of parameters – the
rigid category that could not be changed, and the plastic category meaning that they
could be trained.
The basic explanation of the rigid and plastic variables can be a bit complicated – so we
will first discuss the notion of rigid and plastic parameters in a general way, then we will
come back and talk about them as the specifically apply to training. Don't get too
stressed out about understanding everything – by the time you complete this module you
will have a fairly reasonable idea as to what is going on.
As you work through this section keep these two key points in mind:
•
•
Adaptation is directed toward maintaining or restoring homeostasis
Adaptation is the basis of improvement in sport performance.
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© Christine Brooks (draft)
Physiology of homeostatic parameters
Rigid parameters: These are tightly controlled because they affect enzyme
activity. Enzymes are proteins and only work within a narrow range of both acidity and
temperature. There is nothing a coach can do to change the desirable range for rigid
parameters. Whenever the athlete’s body goes outside the range for temperature or
acidity the body shuts down. The athlete must wait for the temperature and acidity level
to return to the normal range before attempting another bout of exercise.
High body temperature can be a particular problem for an athlete. The body generates
heat due to metabolism and under normal conditions excess heat is dissipated by
radiation through the skin, or by evaporation of sweat. However, training in extreme heat,
high humidity, or under a hot sun makes it difficult for the body to dissipate sufficient heat.
Under very severe conditions core body temperature can rise to a life-threatening 106°F
(41.1°C) or higher. The athlete will experience symptoms indicative of heat stroke
indicating the protein enzyme structures are being damaged and unable to work properly.
Another cause of heat stroke is dehydration. A dehydrated athlete cannot sweat fast
enough to dissipate excess heat and this causes body temperature to rise. Excess body
temperature interferes with enzyme activity and death can, and has occurred, as a result.
Acid conditions in the body, on the other hand, never reach dangerous levels in healthy
individuals. The pain forces the athlete to stop before the situation becomes life
threatening.
Plastic homeostatic parameters
The term “plastic” means that structures can be built to cope with the higher workload.
Plastic parameters support rigid parameters by helping maintain them within their normal
range. For example, training can induce a more efficient acid buffering capacity to help
control the acidic environment for enzymes during intense training sessions. From a
temperature perspective more blood vessels are built to the skin to improve the cooling
mechanism.
Three important plastic parameters affected by training include those responsible for:
(a) mobilizing energy resources
(b) building additional structural capacity
(c) improving the body’s defense (immune system) capacity.
In each case the athlete's genetics determines the upper limit to structural growth.
Strengthening plastic parameters usually involves mobilizing the ability of the cells to
synthesize protein. This could be protein for muscle, protein to build more enzymes, or to
build channels in the cell walls for the entry of fuels supply and the removal of waste.
Most structural proteins are built during the recovery periods between training sessions.
The body’s immune system, is essential to adaptation because training damages cellular
structures and repairing this damage requires the immune system. The immune system
dismantles damaged cells and replaces them with new ones.
The type of training the athlete performs determines the type of protein synthesized. In
other words, the adaptive response to training is very specific. A speed training session,
for example, will stimulate strengthening structures involved in producing speed.
Mobilization of the immune system is one of the more critical responses to training.
During very stressful training periods the immune system can become overworked and
this is one reason an athlete can get a cold or a respiratory system infection.
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© Christine Brooks (draft)
Key points to remember:
Point 1: The purpose of training is to cause adaptation to cells, organs and organ
systems. This, in turn, improves the physiological functioning of the body so it has an
easier time maintaining the normal range of environmental conditions (especially acidity
levels and temperature). Enzymes are particularly sensitive to acidic and temperature
conditions above or below the normal preset range. Every athlete’s performance is
constrained by the preset range of the internal environmental conditions. Physical training
is beneficial only as long as it forces the body to adapt.
The basic purpose of training is threefold:
• First, training mobilizes the body’s building capacity in order to strengthen the
physiological systems and increase the number of enzymes.
• Second, the body’s adaptive mechanism “learns” how to quickly mobilize the
energy systems and fuel supplies into action while the athlete is exercising.
• Third, training improves mobilization of the immune response so damaged cells
can be quickly dismantled and rebuilt.
Point 2: Train each athlete according to their current level of physiological functioning. At
the beginning of each training year the athlete’s body is operating at a specific level of
physiological functioning. The athlete’s training age, and biological age impacts the level
of suitable training stress. An athlete at zero training age will have a lower physiological
functioning, and thus a lower tolerance to high training stress than an athlete who has
been training for more years.
Point 3: Use a training stress that produces a recoverable level of fatigue within a
reasonable amount of time. The optimal training program stimulates adaptations by
causing a recoverable level of fatigue to the cells and organ systems. From a coaching
standpoint the really tricky aspect of coaching is deciding on the training intensity and the
subsequent recovery time. If the training session is too hard for the athlete’s present
physiological functioning it can overwhelm the body’s building capacity reserves. You
want recovery to occur within a 24 hr period. Taking the body into a very depleted state
can threaten health because the immune system is busy repairing damage cells and
doesn’t have the resources to fight infections. It’s not uncommon for a runner to get a
cold or some other respiratory infection after completing a marathon. Your goal is to
introduce the athlete to the least training stimulus possible and still achieve a 24-hour
recoverable adaptation response. After each bout of training the athlete should feel
fatigued to some degree, but not so exhausted homeostasis is disturbed to the point of
causing overtraining syndrome.
Point 3: Always incorporated the recovery time as a recognizable part of the athlete’s
training program. During recovery the acute changes occurring during the exercise
permitting an immediate ability to maintain homeostasis will return to normal quite quickly.
The increase in heart rate and increase in respiration will return to almost normal within a
few minutes. However, the training effects on the internal structures do not respond on
the spot. The cell requires time to pull all the components it needs together to build the
protein. Once the structural and enzyme protein adaptations have occur the body will be
at a higher physiological level of functioning.
Point 4: Recovery should be long enough to allow for supercompensation. During
supercompensation the internal body structures, enzymes, energy and fuel stores build
beyond the normal biological state. The effect is specific. The portions of the athlete’s
body stressed during the training bout adapt their capacity so subsequent bouts of
training stress will be less of a threat to homeostasis. The effectiveness of the training
stress for stimulating the adaptive response is specific to each athlete. As well, recovery
will be different for each athlete. It will take some time for you to learn how much recovery
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© Christine Brooks (draft)
each type of training stimulus will require. When we discuss the different types of training
stimuli we will talk about this timing process.
While the goal is for the total recovery period for younger athletes, including
supercompensation to be around 24 hours this could be as short as 8 hours or longer
than 24 hours for the higher training aged athletes. It depends on the type and intensity of
training. Intense training places such a high demand on the central nervous system
recovery may take longer than 24 hours – sometimes as much as 36 to 48 hours before
supercompensation occurs.
Point 5: Remember the principle of reversibility. You don’t want the athlete to have such
a long recovery time you violate the principle of reversibility and detraining begins to
occur. The body is very efficient – it won’t maintain proteins it doesn’t need and it will
dismantle unnecessary capacity if it is not stimulated to maintain them within a
reasonable period of time. This is the reason a sedentary individual has a very low level
of physiological functioning when compared to athletes.
References
Hoppeler, H., and M. Flück. Plasticity of Skeletal Muscle Mitochondria: Structure and
Function. Med. Sci. Sports Exerc., Vol.
35, No. 1, pp. 95–104, 2003.
Selye, Hans. The Stress of Life. McGraw-Hill, Inc, New York. 1984.
Viru, Atko. Hormones in Muscular Activity (Vols 1 and 2). CRC Press, Inc, Boca Raton,
Florida. 1985.
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