Hormones In Exercise PDF

Hormones in Exercise MEDI221/EXSC221 Lecture objectives Describe hormonal response to exercise and specific triggers Describe types of hormones, their function and modulators Describe the effect of hormones in exercise  Reading Chapter 20. The Endocrine System: Organization and Acute...

Hormones in Exercise MEDI221/EXSC221 Lecture objectives Describe hormonal response to exercise and specific triggers Describe types of hormones, their function and modulators Describe the effect of hormones in exercise  Reading Chapter 20. The Endocrine System: Organization and Acute and Chronic Responses to Physical Activity McArdle, W.D., Katch, F.I. and Katch, V.L. Exercise Physiology: Nutrition, Energy and Human Performance. Lippingcott, Williams and Wilkins, Sydney, NSW, 2014. ISBN/ISSN: 9781451191554.  Stimulus (neural, hormonal, humoral) Host organ (gland) Steroid Hormone OR Peptide Hormone -Made on demand -Made in advance -Water insoluble -Water soluble Examples (hormone types) Steroid hormones Peptide hormones Cortisol Growth hormone Estrogen Insulin Testosterone Glucagon Aldosterone Adrenaline and NorAd. Antidiuretic hormone (ADH) What determines hormone activity? Hormone concentration in blood Rate of secretion Rate of inactivation (counteracting hormone concentration) or excretion Transport protein availability (for steroid hormones Plasma volume (note PV decreases with exercise in heat or hard and long exercise) Hormone-receptor Interaction Blood hormone levels Number of target cell receptors I.e., glucose transporters move to cell surface in and increase with exercise or feeding (insulin hormones) McArdle: Fig 20.2 Affinity of Binding Neuroendocrine pathways of catabolism & anabolism Effects of acute and chronic exercise on selected hormones Catecholamines Adrenaline & Noradrenaline FAST and VITAL RESPONSE 2-6 fold (non linear) Mediates actions through 2nd messengers Many effects: Cardiovascular responses: ↑ heart rate, blood pressure, increased muscle blood flow (vasodilation and constriction) and ↑ contractility (↑SV) Substrate mobilisation ↑ glucose availability (glycogenolysis in liver) via glucagon AND ↑ lipolysis (fatty acid availability) Fig 20.10 Text book Facilitates other catabolic hormones Immune mobilisation  Catecholamine response is enhanced with exercise training Figure 20.21 Text book Insulin vs Glucagon Insulin = anabolic ‘storage hormone’ Stores glucose in skeletal muscle & liver & adipose tissue Main function -> ↓ blood glucose ↓ during exercise Glucagon = catabolic Releases glucoses from liver into blood Main function -> ↑blood glucose ↑ during exercise Growth hormone and exercise Released from anterior pituitary Has anabolic and catabolic effects ↑ Secretion with exercise ↑ CHO utilisation ↑ Fat mobilisation ↑ Gluconeogenesis ↑ Protein synthesis Esp. by facilitating IGF-1 Fluid & Electrolyte Balance in Exercise Fluid Shifts and/or loss occurs mainly via: Sweating (initially from Interstitial fluid) ↑ Blood Pressure (hydrostatic pressure) ↑ Osmotic Pressure in muscle; metabolite accumulation early at exercise onset In gut; if eat/drink high particle load. Extent of shifts or loss is related to exercise intensity, muscle mass used, duration, eating/drinking, and environment. Two hormones help regulate fluid balance in exercise: Antidiuretic hormone (ADH) / Vasopressin = Action is to retain water- Water retention Aldosterone = Sodium retention Conclusions Hormones fundamental in exercise: acutely and chronically (for adaptation) Have various functions (e.g., change rate of protein synthesis) Several differences between Steroid and Peptide hormones. Several hormones coordinate multiple processes to maintain blood glucose: Glycogenolysis in liver (and muscle), Lipolysis and transport of FFA to muscle, Gluconeogenesis from amino acids, lactate and glycerol, Blocking of blood glucose uptake into muscle, Insulin release and action is suppressed Ad & NAd work fastest; Cortisol and GH work more slowly & permissively. Fitness allows for much reduced hormone responses to same absolute ex intensity