Quiz 2 - Prep Flashcards
What are the types of resistance training?
Static (isometric)
Dynamic (isotonic)
Static resistance training
External load = not moveable
Velocity = 0
Dynamic resistance training
External load = constant
Velocity = variable
Define muscle strength
maximum force output of a muscle or muscle group
Define 1-RM
the maximum weight that an individual can lift at least once
Define multiple RM
Multiple repetition maximum (e.g. 4-6-RM)
the maximum weight that an individual can lift for a given number of repetitions
used to predict 1-RM
Training principles:
Individuality
Genetics, cellular growth rate, metabolism, cardiovascular and respiratory, and neural regulations
High responders vs. low responders
Training principles:
Specificity
Mode, intensity, duration, muscle group
A swimmer vs. a cyclist
Training principles:
Reversibility
Use it or lose it
Maintenance training program
Training principles:
Progressive overload
Muscle is loaded beyond the load that is normally used.
- Frequency (training sessions/week/muscle group)
- Load (amount of resistance used as the percentage of 1RM).
- Number of sets and repetitions
- Volume (sets x exercises x repetitions)
- Duration of the rest
What is sarcopenia?
Loss of skeletal muscle mass and strength that occurs in concert with biological aging
- Between 3% and 8% each decade after age 30 (~0.2kg of lean weight loss per year)
- Increases to 5% to 10% each decade after age 50 (~0.2kg of lean weight loss per year)
How can sarcopenia cause health issues?
Muscle tissue is the primary site for glucose and triglyceride disposal, so muscle loss specifically increases the risk of glucose intolerance and associated health issues
What are the contributing factors to sarcopenia?
decreased numbers of motoneurons
decreased physical activity,
altered hormonal status,
decreased total caloric and protein intake,
inflammatory mediators, and
factors leading to altered protein synthesis
Is sarcopenia preventable by exercise?
Yes
- High-volume RT can prevent sarcopenia in elderly individuals
Brief sessions including 12-20 total exercise sets of regular RT (2-3 days/week) can increase muscle mass in adults of all ages
Lean weight gains of about 1.4 kg following approximately 3 months of RT
What is the effect of resistance training on body fat?
RT reduces intra-abdominal fat in young and older individuals
RT stimulates increased muscle protein turnover and actually has a dual impact on RMR.
RT necessitates more energy at rest for ongoing tissue maintenance
1.0-kg increase in trained muscle tissue may raise RMR by about 20 cal/day
RT increases in RMR (approximately 7%) after several weeks of RT
RMR increases 5% to 9% for 3 d following a single session of RT
Reducing body fat
With respect to overall body fat, 12 weeks RT resulted in ~1.4 kg of lean weight gain and ~1.8 kg of fat weight loss
Research study: Increased resting metabolic rate would seem to be a major factor in fat loss
- A 2X 20-min circuit resistance training program/ Week (8 sessions/mo)
- Requires ~250 cal for every session
- 25% as many additional calories (~100cal) for recovery during the72h following the workout
- ~5000cal/month
What is the effect of resistance training on bone mineral density (BMD)?
RT programs prevent or reverse approximately 1% of bone loss per year
Young men increase BMD by 2.7% to 7.7% through RT
What is transient hypertrophy?
Transient (sarcoplasmic) hypertrophy
- Immediately after an exercise bout
- Increase the volume of sarcoplasmic fluid
- Fluid accumulation (edema) in the intracellular space
Swole after a workout
What is chronic hypertrophy?
Chronic (Myofibrillar) hypertrophy
- Structural changes due to long-term resistance training
- Increased the number of myofibrils in parallel (fibre hypertrophy)
- Increased number of muscle fibres (fibre hyperplasia)!!!
Muscle growth
Development of muscle mass, density and capacity
Eccentric exercise: muscle fibre protein remodelling
What is the effect of high-load vs. low-load resistance training on muscle hypertrophy and muscle strength?
High-intensity RT is usually recommended for hypertrophy or strength gains
high-load = muscle strength
low/high load = muscle hypertrophy
hypertrophy:
- load doesn’t matter
- volume & failure do
(low-load + high reps = high load + low reps)
*if load is constant, high volume is favoured over low volume
Muscle hypertrophy and strength:
High-load
Training with lower intensities but with higher volume (until muscle failure) can overcome the reduced intensity and promotes similar muscle gains as higher intensities
Muscle hypertrophy and strength:
Rest intervals
Longer rest intervals are a key variable in high-volume programs because it allows maintaining high intensity for a high volume
Muscle hypertrophy and strength:
Creatine
One of the main mechanisms by which creatine supplement improves resistance training adaptations is by allowing greater training volume and total work or maintenance of intense exercise for longer periods
The dose-response relationship between resistance training volume and muscle hypertrophy?
Substantial hypertrophic gains can be made using low-volume protocols (≤ 4 weekly sets per muscle group)
High-volume protocols produce significantly greater increases in muscle growth than low-volume
How many weekly sets per muscle group are necessary to maximize increases in muscle mass?
At least 10 weekly sets
- a threshold for volume beyond which hypertrophic adaptations plateau and perhaps even regress due to overtraining
What factors determine total energy expenditure?
- Thermic effect of feeding
- Obligatory thermogenesis
- Facultative thermogenesis - Thermic effect of physical activity
- duration and intensity - Resting metabolic rate
- FF BM, gender, thyroid hormones, protein turnover
Thermic Effect of feeding
Obligatory thermogenesis:
- Digesting and processing food
- Growth
- Pregnancy
Facultative thermogenesis:
- Superimposed on obligatory thermogenesis
- Control of thermoregulation
- E.g. shivering in muscles
What is ATP?
Adenosine triphosphate
- Energy for all bodily functions
- The currency of energy in our body
includes an adenine + a ribose + 3 inorganic phosphates
How is ATP resynthesized and broken down?
Hydrolysis:
- When ATP is combined with water (catalyzed with ATPase enzyme), the last phosphate group is separated and releases 7.3 kcal energy /mole of ATP.
The hydrolysis of ATP produces ADP +Pi
ATP includes an adenine + a ribose + 3 inorganic phosphates
How much energy does ATP produce per mol?
7.3 kcal/mol
What is substrate-level phosphorylation?
ATP generated independently of
oxygen
What is oxidative phosphorylation?
ATP-producing reactions with the use of oxygen
What are the main muscle functions that need ATP?
Mechanical work
- actomyosin cross-bridge cycling
Chemical work
- converting molecules
- e.x., glucose -> glycogen
Na/K channels
- pumps powered by ATP
Which muscle function uses the least and the most ATP?
Mechanical work uses the most ATP
Na/K channels use the least (?)
What is phosphorylative coupling efficiency?
~60%
The proportion of potential energy that is retained as ATP and is synthesized
An endergonic (requires the absorption of energy) reaction
What is mechanical coupling efficiency?
~50%
Proportion of total chemical energy that contributes to external work
What is Human overall efficiency?
Overall efficiency = ~30%
~70% is lost as heat!
How can we measure energy expenditure?
Since all energy eventually degrades to heat, the amount of energy released in a biological reaction can be measured from the amount of heat production or oxygen consumption
Direct calorimetry
Done in a sealed chamber
All metabolic processes within the body ultimately result in heat production
The coils absorb the heat produced and radiated by the participant.
Suit calorimeter, Air flow calorimeter
Indirect calorimetry
All energy reactions in humans ultimately depend on oxygen use.
Measuring O2 consumption provides an estimate of energy expenditure.
While mixed nutritional factors are burned, 5.0 kcal / L of oxygen consumed
Advantages and limitations of direct calorimetry
Advantages
- accurate
Limitations
- have to be in a sealed chamber for 24 hours
- expensive
Advantages and limitations of indirect calorimetry:
Close-circuit method
Douglas bags
- One-way breathing valves collect mixed gasses in a Douglas bag over a timed period and are analyzed
Advantages:
- The most accurate method to measure oxygen consumption (error rate is ~1.5%)
- Low cost
Limitations:
- Wear and tear of the bag
- Leakages contribute to sources of measurement error
- Rapid changes in ventilation and oxygen uptake cannot be measured
- Can only analyze during collected time points
- Time-consuming to setup
Advantages and limitations of indirect calorimetry:
Open-circuit method
Breath-by-breath method
- Collection and analysis of gases
- The concentrations of gases are continuously measured directly from samples drawn from the mouthpiece
Advantages:
- Automated gas collection and analyses
- Generates discrete time series and measures variabilities in each breath
Limitations:
- Less accurate oxygen and carbon dioxide analysis at higher breathing frequencies, e.g. during maximal exercise testing
- Mouthpiece or ventilation valve adds artificial breathing resistance, increasing the required work for breathing
Stored and mobilized forms of carbohydrates
All carbs are eventually converted to a six-carbon sugar (glucose) transported through the blood to muscles
In resting conditions, carbs are stored in muscle and liver in the form of glycogen
- The stored glycogen is limited
- This glycogen is converted back to glucose as needed during muscle contraction
Stored and mobilized forms of fat
The main source of energy during prolonged and low-intensity exercise
In an adult with more body fat, the fat stores would be 2X as large while the carb stores would be the same.
Fat metabolism yields more energy (9.4 kcal/g vs. 4.1 kcal/g for carbs)
- However, fat metabolism is slower than carb because it should be reduced from its complex form (i.e. triglyceride) to free fatty acids (FFA) and then further processed in the Beta-oxidation system
FFA is the only form of fat that could be used by the mitochondria.
What is the respiratory exchange ratio (RER)?
RER is used to estimate the amount of carbohydrates and fats being used to fuel activity
Carbon dioxide produced / Oxygen consumed
- RER = V̇CO2 / V̇O2
Oxygen uptake: V̇O2
- A rate (L/min or mL/min)
Carbon dioxide production: V̇CO2
- A rate (L/min or mL/min)
As energy expenditure increases, we use less fat & more carbs
RER of carbohydrate and fat?
If RER = 1.0, carbohydrate is the fuel
If RER = 0.71, lipid is the fuel
If 1.0 > RER > 0.71, the fuel is a mix of carbohydrate and lipid
Cellular metabolism from three fuel substrates:
Step 1
Fat -> FFA + Glycerol
Carbs -> Glucose
Protein -> Amino acids
Cellular metabolism from three fuel substrates:
Step 2
FFA + Glycerol -> FFA <-> stored fat
Glucose -> Glucose <-> Glycogen
Amino acids -> Amino acid <-> body protein
Cellular metabolism from three fuel substrates:
Step 3
FFA -> lipolysis -> Metabolisms
FFA -> lipogenesis -> stored fat
Glucose -> glycogenolysis -> metabolisms
Glycogen -> glycogenesis -> metabolisms
Amino acid -> gluconeogenesis -> Glucose
What is the input, sequence of reactions and output of each energy pathway:
Lipolysis
FFA -> fatty Acyl-CoA
(occurs in cytosol)
Fatty Acyl-CoA -> Beta oxidation -> produces Acetyl-CoA
(occurs in cell - mitochondria)
Beta oxidation - breakdown of fatty acids in the mitochondria to make Acetyl-CoA that helps make aerobic ATP
- removes 2 carbons from fatty Acyl-CoA to create Acetyl-CoA that can enter the krebs cycle
What is the input, sequence of reactions and output of each energy pathway:
Glycolysis
Glucose -> Glucose 6 - P -> Pyruvate
(occurs in cytosol)
Pyruvate -> Acetyl-CoA -> Krebs cycle -> ETC
(occurs in cell - mitochondria)
What is the input, sequence of reactions and output of each energy pathway:
Glycolysis - output of Krebs cycle and ETC
Krebs cycle (TCA)
- ATP
- NADH
- FADH2
- CO2
ETC (electron transport chain)
- NAD
- FAD2
- CO2
What is the importance and contribution of energy pathways in each exercise intensity
Higher intensity exercise over a short time period the bodies reliance for energy will be placed on the anaerobic energy systems (ATP-PC system / anaerobic glycolytic system)
Lower intensity exercise over a longer time places greater reliance on the aerobic energy systems
Aerobic glycolytic pathway (oxidative system)
Also called aerobic glycolysis
Involves cellular respiration because oxygen is required in this pathway.
It occurs inside the mitochondria
Mitochondria is scatted throughout the sarcoplasm
The total number and density of mitochondria are factors determining the aerobic capacity of the muscle
Mitochondrial density is higher near capillaries
- To optimize oxygen delivery at a high metabolic rate
Unlike anaerobic pathway, aerobic glycolysis has a large-energy production capacity
Aerobic Glycolysis processes
Involves 3 processes:
Glycolysis
Citric acid cycle (CAC), also known as the TCA cycle (tricarboxylic acid cycle) or the Krebs cycle
The electron transport chain (ETC)
Input and output of:
Tricarboxylic acid cycle (TCA)
Input:
Acetyl-CoA
Output:
ATP
NADH
FADH2
CO2
Krebs:
Pyruvate enters the mitochondria and is converted to Acetyl-CoA
Acetyl-CoA enters TCA cycle
The TCA cycle combined with two coenzymes NAD+ and FAD produces ATP, NADH, and FADH2
Input and output of:
ETC
Input:
NADH
FADH2
Output:
NAD
FAD2
ETC:
- NAD+ and FAD gain electrons and are converted to NADH and FADH2.
- These coenzymes carry the electrons to the ETC
- As electrons are passed along to ETC, ATP synthase converts ADP to ATP
Input and output of:
Beta oxidation
Input:
Fatty Acyl-CoA, FAD, NAD+
Output:
Acetyl-CoA, NADH, FADH2
Acetyl-CoA enters TCA cycle
Anaerobic glycolysis
The 2nd method of ATP reproduction
Involves breakdown of glucose or glycogen
Involves glycolytic enzymes
Glycolysis produces 2ATPs and Glycogenolysis produces 3 ATPs
Predominates during early stages (e.g. 1-2 minutes) of high-intensity exercise
Does not require oxygen
The amount (grams) of glycogen and glucose in the liver, muscle and blood
Liver glycogen - 110g
Muscle glycogen - 500g
Glucose in the blood and cell - 15g
Substrate availability and substrate utilization during fast and fed state?
Energy is released from chemical compounds at a controlled rate based on:
1) Availability of the substrate
- Cells rely more on the available substrate
- Carbohydrate loading before exercise increases carbohydrate oxidation
What are the reactions of lipolysis?
Lipolysis involves break down of triglycerides
Releases the attached FFA from the Glycerol backbone
- Albumin -> ATP
The conditions and hormones contribute to FFA mobilization and FFA storage
Concentrations of free fatty acids (FFA) in the bloodstream are determined by the combined rates at which they are mobilized/released into circulation and uptaken from circulation.
Fatty acid mobilization typically increases when the body enters into a hypoglycemic state due to fasting or an increase in physical activity
Catecholamines (epinephrine and norepinephrine) and Glucagon stimulate fatty acid mobilization from adipocytes
FFA is released in the bloodstream and carried by albumin.
What is the total energy production per gram of carbohydrate and fat
Carbohydrate oxidation (glucose)
- 32 ATP/12 O = 2.67 P/O ratio
Free fatty acid oxidation (stearic acid)
- 120 ATP/ 52 0 = 2.31 P/O ratio
More oxygen is needed to get the same amount of ATP from lipids compared to carbohydrates!
Balance of Fat and Carbohydrate Oxidation during Exercise.
The exercise intensity where cross-over of carbohydrate and fat occurs?
There is a major shift in the balance of substrates used for oxidation during exercise grossly around 50% of the maximal aerobic capacity.
At the crossover point, carbohydrates represent more than 70% of the sources of energy for the exercising body
Note that the ordinates for % of fat oxidation and % of CHO oxidation are not symmetric, in order to better visualize the crossover
