What are the fast acting hormones?
Catecholamines (epinephrine, norepinephrine), Insulin, Glucagon
What are the slow acting hormones?
Cortisol, Growth Hormone
Where do Catecholamines come from and what is their role?
They are released by Adrenal Medulla and they are responsible for:
- increase CO2
- Vasoconstriction of non-exercising muscle and increase in SBP to help shunt blood to where it’s most needed
- Vasodilation of heart and skeletal muscle
Describe the change in Plasma Catecholamines during exercise
Norepinephrine- steady increase until about 50% VO2 max
Epinephrine- sharp increase at about 60%
What is the role of Epinephrine
- dilate respiratory passages
- decrease digestive/bladder activity
- mobilize fats & carbs
- break down triglycerides in adipose tissue
- increase lipolysis
- Glycogenolysis in liver/Skeletal muscle
What is the role of Insulin and how does one acute exercise bout affect it
Glucose, FA, and AA storage, stimulated by high BG
*Even after one acute bout of exercise, muscles increase insulin sensitivity to uptake/use Glucose more efficiently
What is the role of Glucagon and when does it kick in
mobilizes Glucose in the liver, stimulated by low BG, and it works later during exercise as activity increases and Glycogen stores deplete
What are the slow acting hormones and why do we nee them?
Cortisol, Growth Hormone
*Important for Carb, Fat, and Protein metabolism
What is the role of Cortisol?
- Is a glucocorticoid made in the Adrenal Cortex that stimulates:
1. FFA mobilization from the tissues
2. mobilizes glucose synthesis in the liver
3. decrease rate of glucose utilization by cells (remember fast-acting hormones will usually deal with glucose/FFA mobilization)
What are the negative implications of elevated plasma Cortisol?
protein breakdown, tissue wasting, negative nitrogen balance, abdominal obesity
What is Ketosis?
increased ketoacid concentrations in extracellular fluid, can lead to prolonged/elevated Cortisol
What is Growth Hormone?
Made in the pituitary gland
1. plays a major role in protein synthesis
2. supports the actions of cortisol
3.
How are hormones released and what are their major roles during exercise?
They are released into circulation generally, bind to specific receptors in order to:
- regulate cellular metabolism
- Facilitate CV response to exercise
- Facilitate transport across cell membranes
- Induce secretory activity
- Modulate protein synthesis
What is the female athlete triad and what causes it?
- osteoporosis
- disordered eating
- Amenorrhea
* Caused by low body weight/excessive exercise which leads to low estrogen
How can resistance training increase Testosterone levels (both during exercise and over time)?
85-95% 1-RM or moderate/high intensity volume, multiple sets, less than 1 min rest
What hormones are released by the Pituitary gland and what are their roles?
- Vasopressin (aka Aldosterone), decreases urinary excretion of water (increases w/ dehydration to prevent fluid loss)
- Oxytocin, contracts uterus/intestines
- FSH & LH, tells Gonads to release sex hormones (decreases w/ endurance due to less stress, increases w/ resistance)
- TSH- tells Thyroid to release Thyroid hormones
- ACTH (Adrenocorticotopic), tells Adrenals to release glucocorticoids
- GH- general/skeletal growth, increases metabolic function
- Prolactin- inititiates/maintains breast milk production
What hormones are released by the Thyroid gland and what are their roles?
- Thyroxine- increases O2 consumption and heat production w/ exercise
- Triiodothyronine (same role as Thyroxine)
- Calcitonin- decrease blood calcium and phosphate levels
What hormones are released by the Parathyroid gland and what are their roles?
- Parathyroid hormone, increase blood calcium and phosphate levels
What hormones are released by the Adrenals and what are their roles?
- Epinephrine (Medulla)- muscular vasodilation, visceral vasoconstriction, promotes Hyperglycemia (epi is responsible for rise in HR just before exercise)
- Norepinephrine (Medulla)- increase HR, force, vasoconstriction of many blood vessels
- Mineralcorticoids/Aldosterone- reapsorption of NA+ and excretion of K+ in kidneys, made in Adrenal Cortex
- Glucocorticoids- aka Cortisol, Protein and triglyceride breakdown
What happens to Catecholamine output w/ chronic exercise?
Within the first several weeks, output declines significantly (as seen by lowered resting HR and smaller rise in BP during exercise)
What hormones are released by the Pancreas (islets of Langerhorns) and what are their roles?
- Insulin (Alpha cells) tells liver/muscle to store glycogen, exercise increases insulin sensitivity (decreases production linearly w/ training)
- Glucagon (beta cells) tells liver to release glucose from glycogen in liver, smaller increases in glucose levels during exercise
