CH 1: structure and function of exercising muscle
CH 3: neural control of exercising muscle
CH 2: bioenergetics and muscle metabolism
CH 5: energy expenditure
EXTRA
100

Muscle-Fascicle-Muscle fiber-Myofibril

Muscle: made up of bundles of fascicles; surrounded by epimysium

Fascicles: made up of muscle fibers; surrounded by perimysium

Muscle fiber: made up of myofibrils; surrounded by endomysium

Myofibril: made up of actin and myosin; divided into sarcomeres

100

6 steps of an action potential

1. -70 RMP

2. Na channels open, Na moves into the cell

3. Depolarized to 30 mV, Na channels close

4. Repolarized. K= channels open allowing K+ into the cell

5. Hyperpolarization

6. Back to -70 RMP

100

ATP-PCr fuel/enzymes/rate/energy produced

fuel: Phosphocreatine

Enzymes: creatine kinase

rate: 10 ATP/ second

Energy produced: 1 mol ATP/ 1 mol PCr

100

EPOC

Excess Post exercise Oxygen Consumption: occurs when O2 consumed> O2 demand in early recovery

Replenishes ATP/PCr stores, converts lactate to glycogen, replenishes hemo/myoglobin, Clears CO2

100

Role of Ca/Ach in muscle contraction/action potential

Ca: Binds to troponin and enables actin-myosin contraction

Ach: Binds to Ach receptors which opens up sodium channels, allowing Na+ into the cell which triggers an action potential

200

6 steps of a muscle contraction

1. AP starts in the brain

2. AP arrives at axon terminal, releases Ach

3. Ach crosses synapse and binds to receptors

4. AP travels down T-tubules

5. Ca is released from the sarcoplasmic reticulum

6. Ca enables actin-myosin contraction

200

Motor unit

A muscle neuron and the fibers that innervates it

200

Glycolysis fuel/enzymes/rate/energy produced

fuel: Glucose or glycogen

Enzymes: Phosphofructokinase

Rate: 5 ATP/ second

Energy produced: 2 mol (glucose) or 3 mol (glycogen)/ 1 mol substrate

200

Direct vs Indirect calorimetry

Direct: Estimates total body expenditure based on heat production- substrate metabolism efficiency

Indirect: Estimates total body expenditure based on O2 used and CO2 produced * main method used in lab settings* 

200

Role of ATP in cross-bridging

Binds to myosin, allowing it to release from the actin filament
300

Thin and Thick filaments

Thin: Actin: I band: anchored at z disk; contains 3 proteins: Actin, troponin, and tropomyosin

Thick: Myosin: H zone: titan is stabilizer (prevents overstretching); Globular heads: Protrude 360 degrees from thick filament heads, and interacts with actin filaments for contraction 

300

Size Principle

The order of recruitment is directly related to the size of a motor neuron

300

Oxidative (carbs) fuel/enzymes/rate/energy produced/steps

fuel: glucose or glycogen

enzymes: Isocitrate Dehydrogenase

Rate: 2.5 ATP/ second

Energy produced: 32 (glucose) or 33 (glycogen)/ 1 mol substrate; NADH and FADH2 is also produced

Steps: Glycolysis, Krebs cycle, Electron transport chain

300

RER and training

RER: Respiratory Exchange Ratio: ratio between rates of CO2 production and O2 usage; predicts substrate use, kilocalories/ O2 efficiency; O2 usage during metabolism depends on the fuel being oxidized ( more carbon atoms in molecules= more O2 needed)

RER CHO=1.0; Fats=0.70

Training allows for: High VO2 max, High lactate threshold (% VO2 max), high economy of effort, high % type 1 fibers- more training allows athlete to compete at a higher percentage of their VO2 max

300

Na/K pump

When K+ channels open and K+ leaves the cell, it is offset by the Na/K pump; Resting membrane potential is created by the Na/K pump

400

Role of Actin, Myosin, Troponin, Tropomyosin 

Actin: Contains myosin binding site

Myosin: Interacts with actin filaments for contraction

Troponin: Moves tropomyosin; binds to Ca+

Tropomyosin: Covers active site at rest

400

Golgi Tendon Organs and Muscle Spindles

GTO: Sensitive to tension; initiate relaxation

Muscle Spindles: Sensitive to stretch; initiate contraction

400

Oxidative (fats) fuel/enzymes/rate/energy produced/steps

Fuel: triglycerides or Free fatty acids (FFAs)

Enzyme: lipase, Acetyl-CoA

rate: 1.5 ATP/ second

Energy produced: 100+ ATP/ 1 FFA

Steps: dependent on how many carbons on FFA- beta oxidation, krebs cycle, electron transport chain

400

Kcal- O2L conversion

(Kcal/min)/5= (VO2L/min)

400

Muscle fiber types 

Type 1: slow-twitch; high oxidative capacity; fatigue resistant; high aerobic endurance; Recruited for low intensity aerobic exercise and daily activities

Type 11a: fast-twitch; poor aerobic endurance; fatigue quickly; used for short/intense endurance; produce more force than T1

Type 11x: fast-twitch; poor aerobic endurance; fatigue quickly; seldom used for daily activities; used for short/explosive sprints; produce more force than T1

500

Steps of cross bridge/ power stroke

1. Ca binds to troponin

2. Troponin pulls tropomyosin off binding site 

3.  Myosin heads pivot and power stroke

4. Myosin binds to actin

500

Sympathetic vs Parasympathetic

Sympathetic: Fight or flight; predominate during exercise

Parasympathetic: rest and digest; oppose the effects of the sympathetic nervous system

500

Time/Duration/ overlap of systems

Time- ATP-PCr: 3-15 seconds; Glycolysis: 15 seconds - 2 minutes; Oxidation (carbs) : 90 minutes; Oxidation (fats) : days

All 3 systems interact for all activities; no one system contributes 100%, but 1 system dominates for a given task

Low intensity exercise (below 60% VO2 max): lipids are primary substrate

High intensity exercise (above 75% VO2 max): Carbs are primary substrate 

500

VO2, Lactate threshold with training and effects on performance 

Lactate threshold: Point at which blood lactate accumulation increases markedly- lactate production cannot be cleared fast enough- good indicator of potential for endurance athlete

Usually expressed as percentage of VO2 max

Higher lactate threshold=better endurance performance 

For 2 athletes with the same VO2 max, the one with the higher lactate threshold will have better performance

500

The amount of force exerted during a muscular contraction is dependent on...

Type of motor unit recruited, initial length of the muscle, and the neural stimulation

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