Final Flashcards
Muscle hypertrophy
2 types
Muscle growth and size
Transient (sarcoplasmic) hypertrophy - immediate, fluid accumulation
Chronic (myofibrillar) hypertrophy - structural changes, fiber hypertrophy, fiber hyperplasia
Eccentric exercise
muscle fiber protein remodeling
What is usually recommended for hypertrophy or strength gains
Lower intensities…
Key variable
High-intensity resistance training
higher volume promotes similar muscle gains as higher intensities
Longer rest intervals
Dose-response relationship between RT
volume and muscle hypertrophy
Low-volume protocols - less than 4 sets per muscle group per week
10 weekly sets per muscle to maximize
The effects of RT on LBM in older men and
women
-After 20.5 weeks there was a 1.1kg increase in Lean body mass (LBM)
-RT is effective for promoting gains in lean body mass among aging adults, particularly with higher-volume programs
Signals for muscle hypertrophy
mechanical tension, muscle damage, metabolic stress
Mechanical tension
force and stretch, leads to pathway activation, eccentric contractions may provide greatest benefit
Muscle damage
Muscle damage decreases over time with working out
Initial protein synthesis does not correlate with muscle hypertrophy but it does with less damage later on
Metabolic stress
5 mechanisms
many mechanisms have been linked to metabolic stress with muscle atrophy
Increased fiber recruitment, elevated hormonal response, altered myokine production, accumulation of ROS (reactive oxygen species) and cellular swelling
Blood flow restriction training and muscle hypertrophy
Bicep
significant increases in leg size have been reported following walking with BFR (put on prior to exercise)
Yet, applying BFR cuffs to biceps immediately following resistance have been shown to impair hypertrophy (trapping metabolites doesn’t work as well with no tension)
Do acute hormonal alterations impact muscle adaptations?
mixed and limited evidence
If hormones did play a role, it is probably minor
Homeostasis
A stressor
Stress-response
Adaptation
The way an organism maintains internal stability while experiencing an external change
Anything that disrupts internal stability
Re-establishes internal stability
modification to fit conditions of new environment
Progressive overload vs accommodation vs overtraining
Gives you maximal gains and adaptation
Still gives you some adaptation but not maximal
Causes maladaptation
Dose-response concept in training
the magnitude of response (adaptation) to a given stimulus (training period)
Minimum effect dose and diminishing returns
Smallest amount of input required to acquire desired result
a decrease in output for a given increase of input
Avenues for exercise progression, regression and variation
-Load
* Placement of load
* Type of implement
* Tempo
* Other technique modifications such as grip or stance,
etc
* Range of motion
Range of motion
Training at relatively longer muscles lengths (i.e., full ROM) has commonly been seen to create greater hypertrophy than smaller ROM
Energy is extracted from food incrementally
Photosynthesis: chemical reactions in plants convert light from the sun to stored chemical energy, humans obtain energy by eating plants and animals, energy substrates from food are broken down in our body to release energy, chemical pathways convert substrates to energy through step-wise metabolic reactions
Metabolism
the chemical reactions in the body collectively
Chemical bonds in macro nutrients in our food are a form of potential energy and then…
our body needs to convert these to high-energy compounds to be usable
ATP (Adenosine triphosphate)
Substrate-level phosphorylation:
Oxidative phosphorylation:
Unfortunately
Breaking of the high energy bonds of ATP releases 7.3kcal free energy
ATP generated independently of oxygen
ATP producing reactions with the use of oxygen
the store of ATP is enough for only about 2-3 seconds of maximal effort
Hydrolysis and condensation
Using water to split something up
Getting rid of water to add 2 things together
First law of thermodynamics
energy can not be created or destroyed ex. potential energy is transferred to electricity, potential energy is transferred to ATP
Biological work
cellular respiration, mechanical work, chemical work, transport work
Second law of thermodynamics
spontaneous transfer of potential energy decreased capacity to perform work (entropy always increases which is non-usable energy) - as macronutrients are oxidized, products have less potential energy than reactants
Humans are inefficient; how much of the energy we get is converted to mechanical work?
Phosphorylative coupling efficiency ~60%
Proportion of energy that is converted into ATP
Mechanical coupling efficiency ~50%
Proportion of chemical energy stored in ATP that is converted to mechanical work when using ATP
Overall efficiency ~30%
Work and power equations
Review this!!!
How can we measure energy expenditure
Direct vs indirect calorimetry
Amount of energy release can be measured from amount of heat production or oxygen consumption
Heat production, sealed chamber
vs
o2 and co2 production, typically open circuit (5.0kcal/L of oxygen consumed)
Indirect calorimetry closed circuit
Pros?
Cons?
Douglas bags - one way breathing valves collect mixed gases over a timed period and are analyzed
Pros - error rate is only about 1.5%, pretty accurate
Cons - leakages, rapid changes in ventilation and oxygen uptake cannot be measured, collected time points, time consuming to set up
Indirect calorimetry open circuit
Pros?
Cons?
Breath-by-breath, gas samples by mouth piece
Pros - automated (no math), generates time series and measures variabilities in each breath
Cons - less accurate at higher breathing frequencies, artificial breathing resistance because of masks on face
Carbohydrates
how much is used during exercise depends on carb availability and development of carb metabolism in muscles
All carbs eventually converted to a 6-carbon sugar (glucose transported through blood to muscles
At rest, carbs are stored in muscle and live as glycogen
Fat
Main source of energy during prolonged and low-intensity exercise
Adult with more body fat stores would be twice as large while carbs would be the same
Fats yield more energy (9.4 kcal/g vs. 4.1 kcal/g for carb)
Non energy producing fats - phospholipids and steroids
Protein
Minor energy source
Only usable under certain conditions - severe energy depletion, starvation
before used, protein converted into glucose or FFA
Produces 4.1kcal/g
Per litre of oxygen you get more
Carbs
Respiratory exchange ratio (RER)
Carbon dioxide produced/ oxygen consumes
RER = VCO2/VO2
RER equations Lecture 13
ATP use in muscles
Myosin ATPase - 75% - dissociating actin-myosin cross-bridges
Sarco-endoplasmic reticulum ATPase (SERCA) - 25% - CA2+ reuptake
NA+/k+ ATPase - 5% - rebalancing ions across cell membrane
Sources of ATP
Immediate system - ADP and PCr
Anaerobic/glycolytic system - glycogenolysis and glycolysis, lactate production
Aerobic/Oxidative system - carbs, lipids, protein, lactate, oxidative phosphorylation
Immediate system (ATP-PCr system)
Stores ATP and phosphocreatine (equations)
- fastest and simplest energy system
-PCR breakdown releases 10.3 kcal/mol
-PCR storage is only enough for 8-13s of maximal effort
PCR depends on…
The higher the intensity…
Exercise intensity
The lower the PCR and the higher the ATP
PCR sacrifices itself for ATP
Anaerobic glycolytic system
Limitations
Lactate is a…
-early stages of high-intensity exercise
- does not require oxygen
- carbs are the only nutrient that can generate ATP anaerobically
Limitations: Does not produce large amounts of ATP, produces h+ ions (reason for fatigue not lactate)
Lactate is a fuel - it can convert to glucose (gluconeogenesis) and produce energy
Aerobic/oxidative system (in mitochondria)
3 processes
What is required?
Occurs inside
Aerobic glycolysis, krebs cycle, electron transport chain (produce ATP to replace ATP in immediate cycle)
Oxygen required
Mitochondria - number and density of mitochondria determine aerobic capacity of that muscle - denser near capillaries to optimize O2 delivery
Lipolysis (also day to day activities)
Fat molecules
Longer exercise
Goes to beta oxidation and then to krebs cycle
Review 4 exercises contribution of energy systems (end of lecture 14)
True or false all of the 4 systems are active in all forms of exercise, however the amount and intensity of exercised determines which system is most active
True
Lipolysis involves the break down of
Triglycerides
exercise - adipose tissue cells - triglyceride - glycerol will enter glycolysis - free fatty acid - albumin - beta oxidation
Beta oxidation schematic
Yield from fat oxidation
Fatty acyl-CoA - beta oxidation (converts fatty acyl coA to Acyl CoA - krebs cycle - ETC
Glycerol: enters glycolysis = 16 ATP
B oxidation: 3 x 18C FFA = 360ATP
Total = 376 ATP
More ___ is needed to get the same amount of ATP from lipids compared to carbohydrates
Oxygen
(carb is more efficient with oxygen)
RER = VCO2/VO2
IF Respiratory exchange ratio (RER) is 1.0…..
IF Respiratory exchange ratio (RER) is 0.71….
If 1.0 > RER 0.71…
carbs are the fuel
lipid is the fuel
the fuel is a mix of carbs and fats
What influences fuel selection?
- Exercise intensity
- Exercise duration
- Substrate availability
- Diet
- Sex
- Training status
If at high exercise intensity what is being broken down?
At lower - longer exercise intensity what is being broken down?
Carb, fat
After, before and during doing low or medium exercise, don’t eat __ if you want to burn fat
Carbs
There is a __ fat oxidation during exercise in females at the whole-body level
Higher
True or False, RER is way higher in non-trained people at the same speed
True
Non-trained people rely much more on carbohydrates
Cardiac output = HR x SV
Resting cardiac output…
Maximal cardiac output ranges from…
about 4.5L/min
about 20-40L/min
Oxygen is carried in 2 forms
- dissolved in fluid of blood (~4% of O2 at rest)
- bound to hemoblobin (~96% of O2 at rest) - each hemoglobin can bind to 4 O2 (1.34 ml o2/g oxygen capacity of hemoglobin)
- more exercise gives your more hemoglobin to carry oxygen
Mitochondria density is
Increased by training
How do we assess cardiorespiratory fitness?
— Graded exercise tests (GXTs)
§ Laboratory or clinical tests
§ Field test
Grade exercise test - VO2 max
Parameters determining VO2 max
- maximal ability for CV system to deliver oxygen to muscles during dynamic exercise
- Heart rate
-stroke volume
-amount of oxygen removed by blood (arterial-venous oxygen difference)
there is a decreased risk of ___ based on the weekly volume of PA and aerobic fitness
Cardiovascular disease
Cardiorespiratory (CR) fitness is the
measure of an individual’s peak/maximal
capacity to perform aerobic work
Factors contributing to increased VO2max
— Elevated cardiac output,
— Augmented blood volume (both plasma and hemoglobin content)
— Increased skeletal muscle mitochondrial volume density as well as function,
— A shift in skeletal muscle fiber distribution toward more oxidative fibers
Heart and CV fitness with aging
VO2 can improve at any age with regular endurance training by approximately
15-20%
Heart rate reserve (HRR)
HRR = maximum heart rate - resting heart rate
REP borg scale starts at 6 because
Heart rate
Exercise prescription guidelines
- key component is intensity
-The most commonly used endurance exercise intensity prescription approach
utilizes a percentage of maximal values to assign intensity.
- major limitation is that it ignores the existence of individual exercise thresholds
V>O2 max ramp incremental test and
determination of exercise thresholds (2)
- gas exchange threshold (GET) -first change
- respiratory compensation point (RCP) - second increase, body breathes as hard as possible
Why do we perform ramp incremental test (RIT)?
what is significant about these 2 reasons?
- determine exercise capacity
- identify cardiorespiratory response thresholds
-find starting point
- tailor exercise plans to specific people
Pathways for producing ATP in each phase
1 - fat oxidation
2- fat oxidation, aerobic glycolysis and glycogenesis
3 - anaerobic glycolysis and glycogenolysis
Thresholds are highly individual
- GET/LT
- 40-80% of VO2 max
- RCP (MLSS)
- 65-95% of VO2 max
- Even at the same
percentage of VO2max,
individuals are not
necessarily experiencing
the same metabolic stress!
Creating exercise endurance prescription depends on
FITT-VP principle
Health, fitness or performance goals
Frequency - intensity - time - type - volume - progression
Stages of program progression
Initial conditioning
Improvement
Maintenance
lasts 1-6 weeks, develop basic techniques and habits of exercising
Progression towards goal, 4-8 months, starting manipulation of intensity, duration and frequency
Building on and maintaining fitness, add variety and activities of interest to the client
Frequency of exercise
- depends on client characteristics, goals and health
-combination of MIPA and VIPA for 3-5 days per week recommended
Intensity
CSEP guidelines
Look at finding heart rate reserve method
Time
- inversely related to intensity
- 20- 60 minutes per day recommended
- 30-60min MIPA benefits cardiorespiratory function
Type
Different kinds of aerobic activities
Progression of exercise
Need to challenge body to keep adapting
Write down goals of all 3 stages!
Effects of HIIT on healthy, young individuals
— Increased skeletal muscle oxidative capacity
— Increased resting glycogen content,
— Reduced rate of glycogen utilization and lactate production
— Increased capacity for whole-body and skeletal muscle lipid oxidation,
— Enhanced peripheral vascular structure and function,
— Improved exercise performance as measured by time-to-exhaustion tests
— Increased maximal oxygen uptake
Different types of stretching
§ Static stretching (SS)
§ Dynamic stretching (DS)
§ Ballistic (bouncing) stretching (BS)
§ Proprioceptive Neuromuscular Facilitation (PNF)
Muscle spindle vs golgi tendon organ
Static stretching
Does it increase flexibility?
mechanisms of short-term flexibility
- lengthening muscle until stretch sensation or point of discomfort is reached
yes
-Viscoelastic deformation of muscle
- increased tolerance to uncomfortable stretch sensation
- decline muscle spindle activation
Static stretching improves flexibility via
- Reduced viscosity (i.e., reduced
resistance) of connective tissue
components to a change in shape or
movement - Increased pain tolerance
-Reduced activation of muscle
spindles when a muscle is stretched
beyond the normal length
Dynamic stretching
Does it increase flexibility?
- controlled stretch through the ROM of the joint
yes (less than SS)
Ballistic stretching as a subgroup of DS
- attempt to exceed normal ROM by bouncing
- research evidence shows that bouncing does not improve flexibility
Proprioceptive Neuromuscular Facilitation (PNF)
Limitations:
Does it improve flexibility?
Isometric contraction followed by SS
Stretch - contract - stretch (SCS)
Limitations:
§ Requirement for partner assistant
§ Uncomfortable and painful
§ Increases risk of muscle strain
yes more than SS
Flexibility main thing
Muscle spindles are most important thing and the more you stretch the less they are fired
PNF sequence
1st Stretch: deactivates muscle spindles, improves viscoelastic deformation,
and increases pain tolerance
Contraction: activates GTOs and reduces tension in the muscle
2nd stretch: further deactivates muscle spindles, improves viscoelastic
deformation, and increases pain tolerance
