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									Endocrine Responses to
  Resistance Exercise
        ESC 105
Naturalistic Theory

• Theorized that the endocrine system can
  be manipulated naturally with resistance
  training to enhance the development of
  various target tissues, thereby improving
• Non-Naturalistic Theory
  – Exogenously augmented hormone levels

• Hormones - Chemical messengers that are
 synthesized, stored in, and released in the
 blood by the endocrine glands.
Function of Hormones

• Regulating reproduction
• Maintenance of the internal environment
• Energy production, utilization and storage
• Growth and development
Lock and Key Theory

• Hormones have very specific interaction
 sites called receptors
  – Lock = receptor
  – Key = hormone
Endocrine Glands
•   Hypothalamus
•   Pituitary gland
•   Thyroid gland
•   Parathyroid glands
•   Heart
•   Liver
•   Adrenal glands
•   Kidneys
•   Pancreas
•   Testes
•   Ovaries              Table 6.1
Endocrine release

• Autocrine
  – the cell releases the hormones inside itself
    (does so with external stimulus)
  – Never leaves the cell that produced hormone
• Paracrine
  – Interact with adjacent cells without the need
    for circulation
Feedback Loops
Steroid Hormones

• Hormones from the adrenal cortex and
  – Testosterone, D4

Polypeptide Hormones
• Made of amino acids
  – Growth hormone and insulin
Muscle and Hormones
• Mediates changes in metabolic and cellular
    processes by resistance training
•   Muscle remodeling
    – Break down and building up of tissue
• Inflammatory response
• Neuroendocrine-immunology
    – Muscle remodeling
• Increase in contractile proteins
    – Protein synthesis
Anabolic Hormones

• Testosterone
• Growth Hormone
• Insulin-like growth factors
Heavy resistance training and
hormonal increase
• Enhanced development of muscle protein
• Initiate muscle action via neural response
• Metabolic demands
• Recovery and adaptation to acute exercise
Hormonal changes in Blood

• Fluid volume shifts
• Tissue clearance rates
• Hormonal Degradation (breakdown)
• Venous pooling of blood
• Interactions with binding proteins
• Receptor interactions
          Posterior Pituitary

• ADH - antidiuretic hormone - acts on renal
 tubule to induce water retention leading to
 urine concentration

• Oxytocin - postpartum milk “let down”
• Secretion regulated by osmotic pressure of
  body fluids (osmoreceptors)-on cartotid
• Secretion influenced by change in blood
  volume or blood pressure (>10%)
• Secretion influenced by nausea, smoking,
  pain, Alcohol
• Diabetes Insipitus
         Anterior Pituitary

• Prolactin             LH
• Growth Hormone        FSH
• ACTH                  TSH
Anterior Pituitary Feedback

• CRH - ACTH - Cortisol
• TRH - TSH - T4/T3
• GnRH - LH/FSH - estradiol/testosterone
• GHRH - GH - IGF-1
• GnRH - Dopamine(-) - Prolactin (no
Growth Hormone

• Secreted by pituitary gland
• Enhances cellular amino acid uptake
• Enhances protein synthesis
  – Hypertrophy in type I and II fibers
GH physiological roles
•   Decrease glucose utilization
•   Decrease glycogen synthesis
•   Increase amino acid transport
•   Increase protein synthesis
•   Increase fatty acid utilization
•   Increase lipolysis
•   Increase collagen synthesis
•   Stimulates cartilage growth
•   Increases renal plasma flow/filtration
•   Promotes compensatory renal hypertrophy
•   Enhanced immune cell function
GH Responses to Stress

• Increased due to breath holding
• Increased due to hyperventilation
• Increased due to hypoxia
• Sensitive to volume changes
Growth Hormone in Women

• Higher during menstruation
• Short rest periods with moderate
• Pregnancy and training
          Thyroid Anatomy and
• Thyroid hormone production dependent on Iodine
• 90% of body stores of Iodine found in thyroid
    gland most of which is bound to thyroglobulin
•   Comes from dietary sources ~700ug day
•   Thyroglobulin traps iodide and oxidizes into
•   Thyroid disorders are common, occurring in as
    much as 10% of the general population.
    Transport and Metabolism of
         Thyroid Hormone
• Thyroid Hormones Poorly soluble in
•   Only free T3 &T4 can penetrate cellular
    membranes and exert biologic activity
•   Three major plasma proteins responsible
    for transport
        • TBG- Thyroxine Binding Globulin
        • TBPA-Thyroxine binding pre-albumin
        • Albumin
Thyroid Problems
              Signs & Symptoms
• Fatigue, cold intolerance, dry skin, hair loss
• Dyspnea, hoarse voice
• Menorrhagia- a lot
• Paresthesias and more inflammation
• Low body fat, thin hair, loss of lateral brawl, high pulse
• Iodine supplement or lithium
• Graves Ophthalmopathy
          Adrenal Cortex

• Glucocorticoids- cortisol
• Mineralocorticoids- aldosterone
• Adrenal androgens- DHEA, DHEA-S
Glucocorticoid Physiology
• Intermediary metabolism to enhance production
    of high energy fuels
•   Catabolic action on protein
•   Anti-inflammatory properties
•   “Stress” hormone
•   Regulated by ACTH
•   Converts amino acids to carbs
•   Inhibits protein synthesis
Adrenal hormones

• Cortisol
  – Converts amino acids to carbs
  – Increases levels of enzymes which break
    down proteins
  – Inhibits protein synthesis
   Mineralocorticoid Physiology

• Major regulator of extracellular fluid
  volume and potassium
• Aldosterone effect on collecting duct of
  kidney to increase Na retention and
  increase K excretion
• Regulated by A II, K, ACTH
• Angiotension
Adrenal Androgen Physiology

• Regulate male secondary sex
• Can cause hirsutism in females
• Regulated by ACTH
Cushing’s Disease
         Signs & Symptoms
• Central obesity   Moon facies
• Thin skin         Easily bruise
• Hypertension      DM
• Muscle weakness   Acne/hirsutism
• Psychiatric       Short stature
Adrenal hormones and training

• Use high volume, large muscle groups,
  short rest periods
• Vary program to allow gland to recover

• Promotes growth hormone response in
 pituitary gland
  – Protein synthesis
• Influences strength and size of skeletal
  muscle via the nervous system
• Upon skeletal muscle

• Secreted from testes
• Increase levels after resistance training
 and aerobic exercise
Stimulus for testosterone
• Large muscle group exercises
• Heavy resistance (85-95%)
• Moderate to high volumes
• Short rest intervals (30s to 1 min)
• 2 years or more resistance training
Testosterone in women

• 10-15 fold lower
• Unsure of changes following exercise
• Reported to have a modest increase
Training adaptations to
• Experience of lifters
  – As experience increases the threshold to
    stimulate testosterone production increases
• 5-10 RM
• Augmented levels over time may
  contribute to enhanced neuro-
• Drug testing
Insulin-like Growth Factors

• Somatomedins
• Protein anabolism
• Released from liver and other storage
IGF and Training

• Changes are based on starting
 concentrations before training

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