Lecture 33 - Physical Activity III Flashcards
Muscle cells are specialized for
contraction
What are the 4 properties all muscle cells share and describe them
1) Contractility - Ability of muscle cells to forcefully shorten
2) Excitability: Ability to respond to stimulus
3) Extensibility: Ability of muscle to be stretched
4) Elasticity: Ability of a muscle to return to its original length when relaxed
What are the 3 types of muscle tissue
1) Skeletal
2) Cardiac
3) Smooth
properties of Skeletal Tissue
Long cylindrical fiber, striated, with many peripheral nuclei that are found on bones and around entrance points to the body
properties of Cardiac Tissue
Short, branched, striated, single central nucleus, found in the heart
Smooth Tissue
Short, spindle-shaped, no striation with single nucleus in each fiber that is used for involuntary movement and control of respiration (eg. regulates blood flow and movement of food)
Sarcolemma
Plasma membrane of skeletal muscle
Sarcoplasmic Reticulum
Stores, releases and retrieves calcium ions and contains fibrils which give muscle fiber striated appearance
What is the functional unit of skeletal muscle?
the Sarcomere
the 2 filaments in Sarcomeres are
actin (thin filament) and myosin (thick filament)
Simple pathway of how a muscle contraction occurs across the neuromuscular junction (6 steps)
Where and what is the function of the neuromuscular junction
where the motor neuron’s terminal meets the muscle fiber
converts electrical impulses into electrical activity in the muscle fiber
when a sarcomere contracts, the z lines move ______ _______ and the I band becomes _______.
closer together, and the I band becomes smaller (A band stays the same width)
At full contraction
The thin and thick filaments overlap
What are the benefits of resistance training
What are two factors that strength training impacts to alter contractile strength
1) Muscle Size
2) Neural properties
When are neural adaptations involved in increased muscular strength with resistance training
Beginning - There are initial gains in muscular strength without an increase in the cross-sectional area
T or F: Muscle fibers with the greatest surface area produce the most force
T
what leads to Muscle Hypertrophy
- adaptation to overload
- increase in protein synthesis and decrease in protein breakdown
- increased sarcomeres = increased muscle size, and increased strength and power
Where does muscle growth typically occur
Muscle belly - Centrally in area of largest circumference where most activated during activity
Is momentary muscular failure important for hypertrophy?
Yes
T or F: There are similar increases in muscle thickness between no load and high-load training because all motor units are recruited regardless of load at muscular failure
T
What are the important factors of a training program to obtain hypertrophy (4)?
1) Training variation that targets mechanical and metabolic factors
2) Each muscle group is trained 2-3x/week
3) Range of intensities to elicit significant muscle growth (reps must be performed to or near failure)
4) Program varies in exercise selection and sequence, intensity, volume, volume load, contraction duration, rest intervals, velocity, set termination point, and frequency form
what are some exercise programs that target glycolysis?
- high volume, short rest intervals
- blood flow restriction
Hyperplasia occurs from
increased satellite cell proliferation following muscle damage
Hyperplasia results in what 3 structural changes to skeletal muscle
1) Increase in # of myofibrils, the density of the sarcoplasm, sarcoplasm reticulum, and T-tubules, and increased activity of sodium-potassium ATPase pump activity
2) Increased fascicle length and fiber orientation
3) Increased mitochondrial and capillary density
What are the 3 principles of individualized strength training
1) Progressive Overload
2) Variation
3) Specificity
Progressive overload
Manipulating program variables to impose a continued physical overload on systems being trained
What are 6 ways to manipulate progressive overload
1) Increase resistance or loading
2) change source of resistance (eg. bands, TR, weights)
3) Add more reps to current workload
4) Increase lifting velocity with submaximal loads (neural response)
5) Lengthen rest intervals (enable greater loading)
6) Increase training volume within reasonable limits or varied to accommodate heavier loads
Specificity
Determines outcome of a specific type of training program (eg. to strength chest muscles you want to incorporate heavier intensities and lower volume on bench press)
Variation
Variation in volume and intensity of exercise to cause bodily adaptations since the body adapts rapidly to stress
Benefits of closed-chain kinetic exercises (variation)
1) More function
2) Provides proprioceptive feedback
3) Less joint shear force
4) Different torque/ROM curves
5) Alter muscle recruitment patterns
What are 3 different types of resistance training: Describe them, their intensity and # of approximate reps
What is the recommended FITT for novice trainers vs experienced trainers
How much energy does 1 ATP produce
7.3 kcal
Breakdown of ATP to ADP and PI is called
Hydrolysis (produces water molecule)
T or F: Depleted ATP stores cannot be replenished
F, they can by the reverse process of joining ADP and Pi in recovery or lower-intensity bouts of exercise
What are the 2 energy pathways
1) Aerobic
2) Anaerobic
T or F: Anerobic exercise contributes immediately to maximal effort, while aerobic contributes to maximal effort later on
T
Phosphagen system
- is the most rapid form of generating ATP - - Comprised of ATP and creatine phosphate
- maximal rate capacity is 10 seconds
summarize Glycolysis
10-step reaction that catalyzes 1 glucose into 2 pyruvate
Phase 1 of glycolysis is called the
Energy Investment phase
Phase 2 of glycolysis is called the
Energy Generation phase
Describe the energy investment phase of glycolysis
Glucose is converted into 2 x Glyceraldehyde 3-phosphate and requires an investment of 2 ATP (glycogen requires 1 ATP)
Describe the energy generation phase of glycolysis
2 pyruvate molecules are formed, 4 ATP are generated for a net yield of 2 ATP when the substrate is glucose
what is the net yield of ATP produced in glycolysis if the initial substrate is glycogen
3 ATP
NADH produced from glycolysis are used in
the electron transport chain to produce ATP
Differentiate between a steady-state (aerobic) vs non-steady (anaerobic) state of exercise during glycolysis
Aerobic: Hydrogen ions and electrons from NADH are passed into the mitochondria to produce ATP
Anaerobic: Hydrogen ions and electrons from NADH are passed back to pyruvate to form lactate OR can be transferred to the mitochondria to produce ATP (requires O2)
Why do we need a constant production of lactate
Because red blood cells lack mitochondria and need to generate energy through anaerobic pathways
T or F: In the rest and steady-state of exercise, the body maintains a balance between lactate production and removal of lactate
T
Lactate produced in the skeletal muscle is then
Shuttled out of muscle cell and is transported by the blood to the liver where it is converted back to glucose (gluconeogenesis)
Lactate being transported to the liver from the muscle to take part in gluconeogenesis is called
The Cori Cycle
What are the 3 aerobic pathways (3 fuel types) and explain them
1) Glucose/Glycogen is broken down to pyruvate where it is converted to Acetyl-CoA that enters mitochondrial respiration
2) Triglycerides (FFAs and glycerol) enter pathway via beta-oxidation and glycolysis
3) Amino acids (proteins) enter through ketogenic pathways as Acetyl-CoA or other intermediates of the krebs cycle and are converted to pyruvate (glucogenic)
After glycolysis occurs what are the next two steps of the pathway
1) Krebs Cycle
2) Electron Transport Chain
1 molecule of glucose generates how many turns of the Krebs cycle
2 (one from each acetyl-CoA from two pyruvate)
What 2 molecules from glycolysis and krebs cycle donate protons and electrons to the electron transport chain
FADH2 and NADH
How many ATP does each NADH generate in ETC
3 ATP
How many ATP does each FADH molecule generate in ETC
2 ATP
Compare the glucose and glycogen number of ATP produced in the muscle vs either the liver, kidney and cardiac cells
When does lipid oxidation occur
When the body is under stress the sympathetic nervous system releases epinephrine (mod-to-vig exercise), which activates hormone-sensitive lipase to break down triglycerides stored in fat or muscle
Each cycle of lipid beta-oxidation produces
1x Acetyl-CoA
1x FADH2
1 x NADH
When we break down palmitate (most common fatty acid), what is the result?
8 x Acetyl CoA
7 x FADH2
7 x NADH
In total produces 406 ATP which is best for low-to-mod exercise
When does protein oxidation occur
It only occurs during short-duration high intensity or sustain exercise in which glycogen depletion is a significant concern. Overall it only contributes to 5-10% total ATP production during exercise
What is the cycle called for protein oxidation
Glucose-Alanine Cycle
Steady-state exercise refers to
Conditions where ATP demand is supplied exclusively with ATP generated from mitochondrial respiration (aerobic)
When does a second wind in exercise occur
45 seconds to 4 minutes after (steady-state reached)
T or F: The energy provision is simply the product of a series of energy systems turning on and off
F, it is a blending and overlapping of all 3 energy systems (carbs, fats, and proteins)
Describe the adaptations with training between high intensity and submaximal endurance training for phosphagen, glycolysis and mitochondrial respiration
What are 4 changes that occur in energy pathways as a result of aging
1) Type I and II muscle fibers decline (Type II more)
2) Gradual decline in power and strength because type II produce ATP via phosphagen and glycolysis
3) Decrease in GLUT-4 so less glucose is available to fuel glycolysis
4) Decreased mitochondrial volume and enzymatic activity resulting in reduce generation of ATP in mitochondrial respiration (decline in cardioresp fitness)
Explain what 3 effects exercise has on the cardiovascular response
1) Heart changes structurally - LV get larger and left atrium increases its volume - goal is to increase oxygen delivery to muscles (SV)
2) Heart rate decreases at rest due to increased vagal tone and increased parasympathetic nervous system. Max heart rate also decreases. Overall increases LV filling times and preserves large end-diastolic and SV
3) Increases the perfusion of arteries throughout the musculoskeletal system causing increased arterial diameter and reduced wall thickness to increase blood volume carrying capacity
Explain the effects aerobic exercise has on musculoskeletal adaptations
Increase muscle growth by promoting hypertrophy, enhancing muscle protein synthesis, and dampening catabolic protein pathways
T or F: the sliding filament model of contraction states that the thick and thin filament interaction upon release of calcium from the SR causes muscle contraction
true
what are 3 influencing factors of muscle hypertrophy?
- training program
- metabolic stress
- hyperplasia
T or F: aerobic exercise can only enhance muscle protein synthesis in young individuals
false, aerobic exercise can enhance muscle protein synthesis, irrespective of age
