Chapter 4 - Endocrine Responses to Resistance Exercise

Question 1

General Adaptation Syndrome

Answer 1

How the adrenal gland responds to a noxious stimulus (stressor).
Increase in resistance to the stress is referred to as adaptation.
When the stressor is exercise, it is called training adaptation.

Question 2

Hormones

Answer 2

Chemical messengers that are synthesized, stored, and released into the blood by endocrine glands and certain other cells.

Question 3

Principle Endocrine Glands and Glands that Secrete Hormones

Answer 3

Hypothalamus
Pituitary Gland
Thyroid Gland
Parathyroid Gland
Heart
Liver
Adrenal Gland
Pancreas
Kidneys
Testes (male)
Overies (female)

Question 4

Muscle as a target for hormone interactions

Answer 4

Hormonal mechanisms are a part of an integrated signaling system that mediates change in the metabolic and cellular process of muscle as a result of resistance exercise and training.
Hormones are intimately involved with protein synthesis and degradation mechanisms that are part of muscle adaptation to resistance exercise.

Question 5

Anabolic Hormones

Answer 5

Hormones that promote tissue building, such as: insulin, insulin-like growth factors (IGFs), testosterone, and growth hormone.

Question 6

Catabolic Hormones

Answer 6

Can degrade cell protein, such as: cortisol and progesterone.

Question 7

Role of Receptors in Mediating Hormonal Changes

Answer 7

The signal from a hormone (and thereby its biological effect) is relayed only to cells that express the receptor for that specific hormone.

Question 8

Lock-and-Key Theory

Answer 8

Receptor is the lock and the hormone is the key

Question 9

Down-regulation

Answer 9

Inability of a hormone to interact with a receptor.
When adaptation is not longer possible (i.e. the maximal amount of protein has been added to the muscle fiber) or “overstimulation” by a hormone has occurred, receptors can become less responsive or even non responsive to a specific hormone, preventing it from stimulating further action in the cell.

Question 10

Categories of Hormones

Answer 10

Steroid
Polypeptide (aka Peptide)
Amine

Question 11

Steroid Hormone Interaction

Answer 11

Includes; cortisol, testosterone, and estradiol.
Fat soluble and passively diffuse across sarcolemma of a muscle fiber.
Binds with its receptor to form a Hormone-Receptor Complex (H-RC), causing shift in receptor (aka receptor activation.
H-RC binds with another H-RC a moves to cell’s nucleus and “open” the double stranded DNA in order to expose transcriptional units that code for the synthesis of specific proteins.
RNA polymerase II binds to the promoter associated with specific upstream regulatory elements for H-RC.
RNA polymerase II transcribe gene by coding for the protein dictated by steroid hormone.
Messenger RNA (mRNA) is processed and moves into sarcoplasm of cell, where it’s translated by the ribosome into the specific protein.

Question 12

Polypeptide Hormone Interaction

Answer 12

Made up of chains of amino acids (ex. growth hormone and insulin).
They’re not fat soluble and thus cannot cross cell membrane.
Secondary messengers are inside cell are activated by conformational change in receptor.
In general, the signaling cascades initiated by polypeptide hormones affect metabolic process, DNA transcription, or mRNA translation initiation at the ribosome.
Ex. One of the signals from insulin induces translocation of specific glucose transporters (GLUT4) from cytosol to cell membrane, allowing for increase glucose uptake.

Question 13

Amine Hormone Interactions

Answer 13

Synthesized from amino acid tyrosine (e.g., epinephrine, norepinephrine, and dopamine) or tryptophan (e.g., serotonin).
Similar to Polypeptide hormones, in which the bind to membrane receptors and act via secondary messengers. However, they are not regulated by negative feedback.

Question 14

Heavy Resistance Exercise and Hormonal Increases

Answer 14

Long-term consistent RT brings significant adaptive responses (enhanced size, strength and power) of trained muscles.
Physiological systems, including endocrine, are sensitive to needs of activated muscle, and therefore the type of exercise protocol determines the extent of a given system’s involvement (hormonal response. to exercise protocol).
1-2 heavy RT sessions can increase number of androgen receptors (testosterone receptor) in muscle.
If stress is too great, catabolic actions in muscle occur (down regulation).

Question 15

Mechanisms of Hormonal Interactions

Answer 15

Interactions with receptor are greater when exercise acutely increases blood concentrations of hormones.
Receptors are LESS sensitive when:
Physiological function to be affected is already close to a genetic maximum.
Resting hormone levels are chronically elevated due to disease or exogenous drug use.
Mistakes are made in exercise prescriptions.

Question 16

Hormonal Changes in Peripheral Blood

Answer 16

Contributing mechanisms includes:
Fluid volume shifts.
Tissue clearance rates.
Hormonal degradation.
Venous pooling of blood.
Interactions with binding proteins in the blood.

These mechanisms interact to produce certain concentrations of hormones in the blood, which influences the potential for interaction with receptors.
Hormone responses are tightly linked to the characteristics of the resistance exercise protocol.

Question 17

Potential Types of Adaptations of the Endocrine System from Resistance Training

Answer 17

Amount of synthesis and storage of hormones.
Transport of hormones via binding proteins.
Time needed for the clearance of hormones through liver and other tissues.
Amount of hormonal degradation that takes place over a given period of time.
How much blood-to-tiissue fluid shift occurs with exercise stress.
How many receptors are in the tissue.

Question 18

Primary Anabolic Hormones

Answer 18

Testosterone
Growth hormone (GH)
Insulin-like growth factors (IGFs).

Question 19

Testosterone

Answer 19

Primary androgen hormone that interacts with skeletal muscle tissues.

Question 20

Effects of Testosterone on Muscle Tissues

Answer 20

Causes GH release that leads to protein synthesis, increased strength and size of skeletal muscle, increased force production potential and muscle mass.
Large muscle group exercises result in acute increased serum total testosterone concentrations in men.

Question 21

Diurnal variations (normal fluctuations of hormone levels during the day) of Testosterone – Men and Women

Answer 21

Men: concentration typically highest in the morning and drop as the day goes on, but increases can occur at any point with exercise.
However, an already small resting concentration of testosterone leads to smaller magnitude of change with exercise.
Women: there are lower concentrations and little variation during the day.
However, the response of their androgen receptors is very dynamic with a much faster up regulation than in men, likely to better use the amount of testosterone with a RT stimulus.

Question 22

Free Testosterone and Sex Hormone-Binding Globulin

Answer 22

A higher total (bound) testosterone level allows for the potential of more free testosterone.
The free hormone hypothesis states that only the free hormone interacts with target tissues.

Question 23

Testosterone Responses in Women

Answer 23

Women have 15- to 20-fold lower concentrations of testosterone than men, and increases occur after resistance training, they are small increases.

Question 24

Training Adaptations of Testosterone

Answer 24

It appears that training time and experience may be very important factors in altering the resting and exercise induced concentrations.

Question 25

Growth Hormone (GH)

Answer 25

Secreted by pituitary gland.
Interacts directly with target tissues, which include bone, immune cells, skeletal muscle, fat cells, and liver tissue.
Regulated by neuroendocrine feedback mechanisms and mediated by secondary hormones.
GH release patterns alters by age, gender, sleep, nutrition, alcohol consumption, and exercise.

Question 26

Efficacy of Pharmacological GH

Answer 26

Use of has unknown and unpredictable results.

Question 27

GH Responses to Stress

Answer 27

Responds to exercise stressors (ex. resistance training).
Response depends on load, rest, and volume of exercise (ex. less rest = high GH; 10RM = higher GH; 3 sets = higher GH).
GH release is affected by type of resistance training protocol used (duration and rest periods).
Short rest period types of workouts result in greater serum concentrations compared to long rest protocols of similar total work.

Question 28

GH Responses in Women

Answer 28

GH concentrations and responses to exercise vary with menstrual phase.
Women have higher blood levels of GH than men.

Question 29

Training Adaptations of GH

Answer 29

There is little change in single measurement of resting GH concentrations in resistance-trained individuals.
Training-related changes in GH include a reduction in GH response to an absolute exercise stress and alterations in GH pulsatility characteristics.

Question 30

Insulin-Like Growth Factors (IGF)

Answer 30

IGF-1 is most studied because of its role in protein anabolism.
Exercise results in acute increases in blood levels of IGF-1.

Question 31

Training Adaptations of Insulin-Like Growth Factors

Answer 31

Changes in IGF-1 appear to be based on the starting concentrations before training.
If basal concentrations are low, IGF-1 increases.
If basal concentrations are high, there’s no change or it decreases.

Question 32

Adrenal Hormones

Answer 32

Cortisol
Catecholamines (epinephrine, norepinephrine, dopamine).

Question 33

Role of Cortisol

Answer 33

Catabolic effects; converts amino acids to carbohydrates, increases the level of enzymes that break down proteins, and inhibits protein synthesis.

Question 34

Resistance Exercise Responses of Cortisol

Answer 34

Cortisol increases with RT.
Training may reduce negative effects of this increase.
Vast differences are observed in the physiological role of cortisol in acute v. chronic responses.
Resistance exercise protocols that use high volume, large muscle groups, and short rest periods result in increased serum cortisol values. Though chronic high levels of cortisol may have adverse catabolic effects, acute increases may contribute to the remodeling of muscle tissue.

Question 35

Catecholamines

Answer 35

Epinephrine
Norepinephrine
Dopamine

Question 36

Role of Catecholamines

Answer 36

Increase force production via central mechanisms and increased metabolic enzyme activity.
Increase muscle concentration rate.
Increase blood pressure.
Increase energy availability.
Increase blood flow.
Augment secretion rates of other hormones, such as testosterone.

Question 37

Training Adaptations of Catecholamines

Answer 37

Heavy RT has been shown to increase the ability of an athlete to secrete greater amounts of epinephrine during maximal exercise.
Training protocols must be varied t allow the adrenal gland to engage in recovery process and to prevent the secondary responses of cortisol, which can have negative effects on the immune system and protein structures.

Question 38

To increase Testosterone – Manipulating the Endocrine System with RT

Answer 38

Large muscle exercises (deadlifts, squats, power clean).
Heavy resistance (85-95% 1RM).
Moderate-High volume of exercise achieved with multiple sets or exercise.
Short rest intervals (30s to 1 min).
2+ years of RT experience.

Question 39

To increase GH – Manipulating the Endocrine System with RT

Answer 39

Use high intensity (10RM or heavy resistance).
3 Sets of each exercise (high total work).
Short (1 min) rest periods.
Supplement diet with carbohydrate and protein before and after workout.

Question 40

Optimal Response of Adrenal Hormones

Answer 40

High volume.
Large muscle groups.
Short rest periods.
Vary all these factors to allow adrenal gland to engage in recovery process.

Question 41

Other Hormonal Considerations

Answer 41

Many other hormones create an optimal environment in which the primary hormonal actions can take place.
Insulin, thyroid hormones, and beta-endorphins affect growth, repair, and exercise stress mechanisms.
Improvements in insulin resistance with Rt may reflect only an acute effect from the most recent exercise session.
Researchers have found slight, nonsignificant decreases in serum concentrations of total and free thyroxine after 20 weeks of RT.