Physiologists define stress as how the body reacts
to a stressor, a stimulus that causes stress. Acute stressors affect an
organism in the short term; chronic stressors over the longer term.
Alarm is
the first stage, which is divided into two phases: the shock phase
and the anti-shock phase.
·
Shock
phase: During this
phase, the body can endure the stressor effect. The organism's resistance to
the stressor drops temporarily below the normal range and some level of shock
may be experienced.
·
Anti-shock
phase: When the threat
or stressor is identified or realized, the body starts to respond and is in a
state of alarm. During this stage, the locus coeruleus/sympathetic nervous
system is activated and catecholamines such as adrenaline are being produced,
hence the fight-or-flight response. The result is: increased muscular
tonus, increased blood pressure due to peripheral vasoconstriction and
tachycardia, and increased glucose in blood. There is also some activation of
the HPA axis, producing glucocorticoids (cortisol, aka the S-hormone or
stress-hormone).
Resistance is
the second stage.
Increased secretion of glucocorticoids plays a
major role, intensifying the systemic response—they have lypolytic, catabolic
and anti-anabolic effects: increased glucose, fat and aminoacid/protein
concentration in blood. Moreover, they cause lymphocytopenia, eosinopenia,
neutrophilia and polycythemia. In high doses, cortisol begins to act as a
mineralocorticoid (aldosterone) and brings the body to a state similar to hyperaldosteronism. If the stressor persists, it becomes
necessary to attempt some means of coping with the stress. Although the body
begins to try to adapt to the strains or demands of the environment, the body
cannot keep this up indefinitely, so its resources are gradually depleted.
Exhaustion or Recovery
will define the
third stage.
Recovery stage
follows when the system's compensation mechanisms have successfully overcome
the stressor effect (or have completely eliminated the factor which caused the
stress). The high glucose, fat and aminoacid levels in blood prove useful for
anabolic reactions, restoration of homeostasis and regeneration of cells.
·
Exhaustion is the alternative third stage in
the GAS model. At this point, all of the body's resources are eventually
depleted and the body is unable to maintain normal function. The initial autonomic nervous
system symptoms may
reappear (sweating, raised heart rate, etc.). If stage three is extended,
long-term damage may result (prolonged vasoconstriction results in ischemia
which in turn leads to cell necrosis), as the body's immune system becomes
exhausted, and bodily functions become impaired, resulting in de-compensation.
Relevance to athletes:
The above thumb nail sketch of stress response is
(or should be) the framework of all training protocol and workout design!
Read, ReRead and think………….
B.”EvilGenius”Chavez
www.EvilGSP.com
www.EvilGSP.com
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