PPT 8 - Endocrine Responses to Resistance Exercise (Ch4) Flashcards
Intracrine
The cell secretes a hormone that acts upon itself by binding to intracellular receptors.
Autocrine
The cell secretes a hormone that acts upon itself by binding to membrane receptors.
Paracrine
The cell secretes a hormone that interacts with adjacent cells, but never enters the blood circulation.
Endocrine
Hormones released by endocrine glands into the circulation, which carry information to hormone-specific receptors on target tissues or directly to DNA in the nucleus of the cell.
e.g., testosterone, growth hormone, cortisol, & insulin.
Neuroendocrine
Hormones that are released into the bloodstream or lymphatic system following stimulation of the nervous system.
e.g., norepinephrine.
Endocrine system helps body to respond to (internal/external) stimuli.
external
Peripheral concentrations of hormones in the blood do not indicate which 2 things?
1) the status of the various receptor populations, or
2) the effects of a hormone within the cell.
Which hormones play role in tissue remodeling?
catabolic and anabolic hormones
Catabolism
initiates tissue remodeling during resistance exercise.
Anabolism
predominates in the recovery period leading to growth & repair.
Primary anabolic hormones involved in muscle tissue growth & remodeling are:
Testosterone,
Growth hormone, &
Insulin-like growth factors.
Testosterone
is the primary androgen hormone that interacts with skeletal muscle tissue.
stimulates growth.
increases protein anabolism.
develops & maintains male sex characteristics.
What does testosterone transport?
sex hormone binding gobulin (SHBG)
Receptor of testosterone
binds to the nuclear androgen receptors in its target tissues.
Women secrete testosterone from where?
ovaries and adrenal glands
Testosterone indirect and direct effects on muscle tissue.
INDIRECT: increase GH release, influence protein changes
DIRECT: directly interact with skeletal muscle via nuclear androgen receptors.
Free testosterone accounts for only____ to ____% of total testosterone.
0.5 to 2.0
Performance of (smaller/larger) muscles before the other was shown to elevate testosterone levels.
large muscle mass prior to small
The LARGEST acute T response happens when?
during increased intensity and constant reps.
When is there little or no testosterone response?
at very low relative intensities
e.g., 40% 1RM.
at very high relative intensities
e.g., 100% 1RM.
Weightlifting years vs testosterone.
> 2 yrs lifting experience was greater than
Which load, volume and rest period shows highest testoserone?
Moderate load, high volume, short rest periods
MORE SO than high load, low volume, long rest
Does resistance training increase or decrease muscle androgen receptor content?
mostly increase
What does GH stimulate?
IGF1
GH binds to what
GH specific binding procteins
GH binds to receptors located where?
in cell membrane
Main Physiological Roles of GH
Decreases glucose utilization.
Decreases glycogen synthesis.
Increases amino acid transport across cell membranes.
Increases protein synthesis.
Increases utilization of fatty acids.
Increases lipolysis.
Increases availability of glucose & amino acids.
Increases collagen synthesis.
Stimulate cartilage growth.
Increases the retention of nitrogen, sodium, potassium, & phosphorus.
Increases renal plasma flow & filtration.
Promotes compensatory renal hypertrophy.
Enhances immune cell function.
GH exists as a family of polypeptide molecules which are
22 kDa, 20 kDa, 17 kDa, 5 kDa, & other isoforms exist
Primary form of GH
22kD
GH is highest at what time of day
at night during sleep
How is amplitude & number of pulses affected by GH?
increase by exercise
Does resistance training affect GH?
Yes! GH concentration and Gh variants
little change in single measurements of resting GH concentrations in elite lifters.
What intensity, volume and rest period most notably affects GH?
Moderate- to high-intensity, high volume programmes (bodybuilding program) using short rest periods have shown the greatest acute GH response
Protocols that elicit (high/low) blood lactate values
tend to produce the most substantial GH responses.
high
What is potentially the primary factor influencing GH release?
H+ accumulation hence acidosis
During menstrual cycle, is GH high or low?
high due to due to greater frequency & amplitude of secretion.
Rest: [GH] women > [GH] men.
In response to acute resistance exercise, explain GH between women and men.
Postexercise: [GH] women = [GH] men.
In response to acute aerobic endurance exercise, explain GH between women and men.
Postexercise: [GH] women > [GH] men.
Insulin-Like Growth factors
are structurally related to insulin. are also called somatomedins. mediate many of the actions of GH. are small polypeptide hormones. IGF-1 (70 amino acids) is studied the most. IGF-2 (67 amino acids).
IGF are secreted why and by what?
are secreted as they are produced by the liver in response to GH-stimulated DNA synthesis:
this process takes about 8 to 24 hours.
Two forms of IGF
IGF-1Ea
MGF
How are IGFs transported?
are transported in the blood by IGF binding proteins (IGFBPs):
IGFBP-1, IGFBP-2, IGFBP-3, IGFBP-4, IGFBP-5, & IGFBP-6
Low basal concentrations, what happens to IGF-1?
increase
High basal concentrations, what happens to IGF-1?
decreases
Adrenal medulla responds to
exercise stress
Adrenal medulla releases?
releases the catecholamines: epinephrine & norepinephrine.
Adrenal cortex responds to?
exercise stress
Adrenal cortex is stimulated by?
adrenocorticotropic hormone (ACTH), which is released by the anterior pituitary gland.
Adrenal cortex releases?
cortisol
What does cortisol do?
converts amino acids to carbohydrates
gluconeogenesis.
increases the level of proteolytic enzymes.
stimulates protein degradation.
inhibits protein synthesis.
inhibits amino acid incorporation into proteins.
Cortisol is a primary signal hormone for…
carb metabolism (PROMOTES THE USE OF FAT)
Cortisol receptors
glucocorticoid receptors.
How are cortisol circulated
freely (10%),
bound to albumin (15%), &
bound to corticosteroid-binding globulin (75%).
Acute resistance training affects on cortisol
Significant elevations of cortisol & ACTH in men & women.
Intensity, volume and rest for cortisol release and elevation.
high volume, moderate to high intensity, & short rest periods.
which may contribute to muscle tissue remodeling.
Conventional strength/power training effects on cortisol.
Little change in lactate & cortisol blood concentrations have been observed.
Effects of catecholamines.
Increase force production via central mechanisms.
Increase metabolic enzyme activity.
Increase muscle contraction rate.
Increase blood pressure.
Increase energy availability.
Increase blood flow.
Augment secretion rates of other hormones such as testosterone.
How does ACUTE BOUT of resistance affect norepi and epi and dopamine?
increases
How does heavy resistance affect norepi and epi and dopamine?
increased epi
How does resistance affect norepi and epi and dopamine?
may decrease the catecholamine response to acute resistance exercise (Guezennec et al., 1986).
Whats bad about secondary responses of cortisol?
negative effects on the immune system & protein structures.
How to avoid secondary responses to cortisol?
training protocols that are varied (which also allows the adrenal gland to engage in recovery processes).
