Unit 3 - Lecture 20 Flashcards
Three Stimulus for Hypertrophy Adaptation
- Nutrition
- Stress
- Hormones
Nutrition for Hypertrophy
- Energy Balance
- Protein Consumption
- Sedentary = 0.8 g/kg
- Athletes = 1.2-1.5 g/kg
- Endurance = 1.2 g/kg
- Resistance = 1.5 g/kg
- Older Individuals = > 1.6 g/kg
Stress for Hypertrophy
- Load
- Mechanical Tension
- Muscle Damage
- Metabolic Stress
Hormones for Hypertrophy
- IGF-1
- Testosterone
Note:
*Insulin is better for preventing muscle protein breakdown
Changes in Baseline mRNA, Protein, Performance vs. Time
In the short term, there are oscillatory changes in mRNA, while protein and performance are unchanged. As time continues, there are increases in each category.
Muscle Fibers:
Type I = _____
Type IIa = _____
Type IIx = _____
Slow
Intermediate/Adaptable
Fast
Physiologic Process for Hypertrophy:
- IGF-1 targets the cellular protein AKT.
- AKT stimulates mTOR.
- Key protein sensor for protein synthesis in tissue.
- mTOR stimulates protein synthesis.
Physiologic Process for Atrophy:
- Cortisol inhibits AKT (which will also inhibit mTOR).
- With limitations in AKT, the transcriptional factor FOXO upregulates.
-
FOXO enhances protein degradation.
- Increase ubiquitin ligases.
Note:
- Cortisol increases proteolysis.
- During long-duration exercise, cortisol will increase in order to stimulate protein oxidation to create glucose via gluconeogenesis in the liver.
- Same idea for an overnight fast.
- However, with too much stress in our lives, we will inhibit pathways that promote protein synthesis and stimulate pathways that up-regulate proteins like FOXO to promote protein oxidation.
Recruitment of muscle fibers is key for optimal adaptation.
To recruit the muscle fiber you want to adapt, you need to train in the proper intensity range. Higher intensities stimulate Type IIx fibers, and lower intensities stimulate Type I muscle fibers.
*Muscle fibers have different profiles (cumulative final type question).
The ability to produce maximal force is _______.
Strength
How do we gain strength?
Increase demand of the system and create an overload. (Progressive Overload)
What are the loads/reps that can achieve strength?
- Strength
- __ - __ reps
- Load (% 1RM) - ~ ___ %
- Power
- __ - __ reps
- Load (% 1RM) - ~ ___ %
- Endurance
- __ - __ reps
- Load (% 1RM) - ~ ___ %
- Strength
- 1- 4 reps
- Load (% 1RM) - ~ 100%
- Power
- 1-6 reps
- Load (% 1RM) - ~ 70%
- Endurance
- 12-16+ reps (*AMRAP - Failure)
- Load (% 1RM) - ~ 50%
Strength and Power will target Type IIx. Endurance will target Type I fibers.
Testosterone and Growth Hormone
- Both activate mTOR
- Stimulated by Acidosis (Increased H+)
- Longer duration working sets will stimulate anaerobic glycolysis.
Steroid hormones are synthesized by _________.
Cholesterol
- Clinical blood cholesterol < 200 mg/dL.
- Dietary intake < 300 mg/day.
- This is highly debated. There is a debate that eating higher cholesterol levels are good for hypertrophy because it will synthesize more steroid hormones. Evidence suggests potentially closer to 800mg/day for hypertrophy.
The greater the intensity of exercise, the ______ the stimulus we see in hormones.
Greater
- Lower limbs in particular most likely due to muscle activation (largest muscle groups in the body).
_______ is a contributor to male characteristics.
_____ characteristics are anabolic.
_____ characteristics are androgenic.
Testosterone
Muscular
Masculine
Two conversions of testosterone.
- Estradiol
- Female sex characteristics.
- DHT (5-reductase enzyme)
- Secondary sex characteristics
- Contains three times the androgenic properties, but only 50% anabolic.
It is worth mentioning that there are sex characteristics to these hormones.
Anabolic Steroids are designed to mimic _______ via ______ actions.
Testosterone; Anabolic
Two types of anabolic steroids.
- Oral
- Injectable
Oral Steroid Characteristics
- Broken down fast.
- High frequency of dosing.
Injectable Steroid Characteristics
- Longer half-lives (than oral steroids) - up to 30 days.
- Large doses.
- Contain a methylated group
- Help prevent breakdown in the liver.
*Injectable steroids are associated with liver dysfunction.
Testosterone is easy to detect in the blood. What do athletes take as a workaround?
Pro-Hormone supplements
The idea is that pro-hormone raw materials are going to provide precursor molecules to the body in order for the body to develop testosterone.
What are two popular prohormones?
- DHEA (dehydroepiandrosterone)
- Androstenedione
- In theory, will increase testosterone.
The evidence is not there that these work (in untrained populations). However, there is evidence that these can increase FFM and strength in trained people.
Should steroid and prohormone users be concerned about side effects?
- Yes, due to the negative biofeedback mechanisms.
- Hypothalamus > Gonadotropin-Releasing/Inhibiting Hormone (GnRH/GnIH) > Anterior Pituitary > FSH + LH > Testes > Testosterone
Exogenous androgen supplementation will stimulate testosterone and inhibit the anterior pituitary gland and the hypothalamus.
Taking steroids can reduce your body’s ability to produce endogenous testosterone.
Steroid effects > Pro-hormone - much greater.
Vitamin D precursor is located in the ____.
Skin
What is the mechanism of action for the production of Vitamin D3?
Skin > Vitamin D3 > Liver > 25-Hydroxy-Vitamin D3 (25(OH)D3 > Kidney > 1,25 Dihydroxyvitamin D3 (Active Form)
- Need 10-15 minutes of sun exposure to activate this process.
- Due to latitude in the United States, from November to February Vitamin D is very hard to make.
- Clothing
Low serum levels of Vitamin D (< 25 nM)
- Weakness
- Functional declines
- Higher fracture rates/falls.
How does Vitamin D relate to hypertrophy?
- Myogenesis
- Increase Satellite Cell Activation
- Increase Myoblast Proliferation
- Muscle Protein Synthesis Increase
- C2C12 Muscle Cells (Rodent derived muscle cells)
- Increase AKT; Increase mTOR
- Decrease Myostatin
- Inhibits mTOR (inhibits protein synthesis).
- C2C12 Muscle Cells (Rodent derived muscle cells)
Evidence is accumulating in humans, but it is very limited.
“Anabolic Resistance”
*% FSR = Fractional Synthesis Rate
In younger people, resistance training will cause a rise in the fractional synthesis rate of muscle, practically muscle protein synthesis.
In older adults, the response is blunted.
As you age, you may not derive the same response to exercise as a younger adult.
Is it aging? Obesity? Insulin Resistance? Physical Activity?
Some suggest that higher doses of exercise will work (Intensity? Volume?)
The first adaptation to resistance exercise is neural, followed by strength and then hypertrophy.
