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Endocrine System and Resistance Training

Endocrine System and Resistance Training. CHAPTER 6. Objectives. Understand hormones and target tissue Explain anabolic and catabolic hormones Describe hormone responses to strength training Design training programs to stimulate hormone secretion. Endocrine Glands.

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Endocrine System and Resistance Training

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  1. Endocrine System and Resistance Training CHAPTER 6

  2. Objectives • Understand hormones and target tissue • Explain anabolic and catabolic hormones • Describe hormone responses to strength training • Design training programs to stimulate hormone secretion

  3. Endocrine Glands • Secrete substances (hormones) into blood or body fluid • Promotes homeostasis • Based on Selye’s General Adaptation Syndrome • Tissue adaptations are related to endocrine responses to exercise

  4. Hormones- chemical messengers synthesized and released by endocrine glands Nervous system- fast and short acting Endocrine system- slow and longer lasting Target tissue- the tissue the hormone effects

  5. Peptide hormones (protein)- indirectly effects cell function by binding to a hormone receptor Steroid hormones (fat)- directly effect the DNA in the nucleus of a cell Hormones function in reproduction; growth and development; energy production, utilization, and storage; immunity

  6. Hypothalamus Pituitary Thyroid Parathyroid Heart Liver Adrenal cortex Adrenal medulla Pancreas Ovaries/testes Major Endocrine Glands

  7. Endocrine Function in Muscle • Muscle tissue is “remodeled” with exercise • Muscle is multinucleated with one nucleus controlling a “nuclear domain” • Increase in actin and myosin • Conversion of IIx to IIa fibers • Increase in size • Type I, decrease in protein degradation • Type II, increase in protein synthesis

  8. Build up Protein synthesis Hypertrophy Occurs more in type II muscle fibers Break down Protein degradation Atrophy Occurs more in type I muscle fibers Hormones:Anabolic vs. Catabolic

  9. Hormonal Mechanisms • Lock and key mechanism- hormone is the key • Cross reactivity- a receptor partially interacts with another hormone • Allosteric binding sites- non-hormone substances can bind to the cell membrane to enhance or reduce the cellular response to the hormone • Down regulation - a receptor can become less sensitive to a hormone

  10. Lock and Key

  11. Lipid- fat soluble Forms hormone-receptor complex Direct effect on nucleus EX: testosterone Protein- water soluble Uses “second messengers” as signals to nucleus EX: growth hormone HormoneSteroid VS Peptide

  12. Hormonal Response to Heavy Resistance Training • Hormonal secretions related to • Amount and type of stress • Metabolic demands of exercise • Changes in resting metabolism • Hormonal response occurs only in tissue exercised

  13. Mechanisms of Hormone Interaction • Increased concentration of hormones facilitates interaction • Recovery from anaerobic exercise promotes cell growth (anabolism) • Inappropriate exercise prescriptions can result in a net catabolic effect

  14. Hormonal Changes in Peripheral Blood • Blood levels may not be an indicator of specifically what is happening in the target tissue • Increase- increases probability of hormone/receptor interaction • Decrease- cellular uptake, degradation of hormone, decreased secretion of the hormone

  15. Mechanisms Related to Blood Concentrations of Hormones • Fluid volume shifts • Tissue clearance rates • Hormonal degradation • Venous pooling of blood • Binding with proteins in the blood • Receptor interaction potential

  16. Adaptations in the Endocrine System • Synthesis and storage of hormones • Transport of hormones via binding hormones • Time for hormone to clear liver and other tissues • Rate of hormone degradation

  17. Blood to tissue fluid shift during exercise How tightly hormone binds to receptor Number of receptors in the tissue Magnitude of signal sent to cell nucleus Degree of interaction with cell nucleus

  18. 1. Testosterone • Primary male sex hormone, does have an effect in females • Growth • Protein anabolism • Male secondary sex characteristics

  19. Secondary Sex Characteristics

  20. Testosterone • Direct effects- • Interacts directly with muscle tissue • Indirect effects- • Promotes the action of GH from the pituitary • Interacts with the NS to increase production of neurotransmitters

  21. Increasing Serum Testosterone • Large muscle-mass exercises • Heavy resistance (80-95% 1RM) • Moderate to high volume • Short rest intervals • 2 or more years training experience

  22. Testosterone in Women • Secreted from ovary and adrenal gland • 15-20 times lower concentration in women than in men • Training increases testosterone in women very little or not at all

  23. 2. Growth Hormone • Secreted by anterior pituitary • Enhances cellular uptake of amino acids and protein synthesis in type I and type II muscle fibers • Has both direct and indirect (through IGF-1) effects on muscle • Injections of GH stimulate muscle hypertrophy (with decreased ability to produce force)

  24. Main Effects of GH • Decreases glucose utilization • Decreases glycogen synthesis • Increases protein synthesis • Increases utilization of fatty acids • Increases lipolysis • Increases availability of glucose and amino acids

  25. Increases collagen synthesis Stimulates cartilage growth Increases retention of nitrogen, sodium, potassium, phosphorus Increases renal plasma flow and filtration Promotes renal hypertrophy Enhances immune function

  26. 3. Insulin-like Growth Factors (IGF-1) • Polypeptide hormones secreted from the liver • Mediate some effects of GH • Stimulate protein synthesis • Variable changes with resistance training in males • Little or no change with resistance training in females

  27. 4. Cortisol • Glucocorticoid from the adrenal cortex • “Stress hormone” • Converts amino acids to CHO • Increases proteolytic enzymes • Inhibits protein synthesis • Short term increases related to tissue remodeling • Long term increases related to overtraining

  28. 5. Catecholemines • Epinephrine, norepinephrine, • Increase force production in muscle • Increase muscle contraction rate • Increase blood pressure • Increase blood flow • Increase secretion rates of other hormones

  29. Summary: Resistance Training and the Endocrine System • Remodeling occurs only in the muscle fibers used during training, including hormonal adaptations • Recruiting more muscle fibers increases the potential for adaptation

  30. To Increase Serum Testosterone… • Use large muscle mass exercises • Use heavy resistance • Use multiple sets or exercises • Use short rest intervals (60-90 s)

  31. To Increase Growth Hormone… • Use protocols that stimulate high lactic acid production (high intensity, 10RM, short rest periods) • Use carbohydrate and protein supplements before and after the workout

  32. To Optimize Adrenal Responses… • Use high volume, large muscle mass exercises with short rest periods • Vary the training program to allow the adrenal response to promote recovery • Monitor for overtraining

  33. Next Class • Chapter 5 Bioenergetics

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