KIN 300 Test #2

Muscle Functions

-movements essential for basic survival

• breathing

• running away from danger

Types of Muscles

Skeletal Muscle

-regulates body temperature

-attach to bones to bones

• some attach one side to bone and another side to skin

  • muscles in face → bone to skin

-movement at joints

-voluntary control & involuntary control

-accounts for significant portion of body weight

Cardiac Muscle

-cardiac system

• heart (contractions)

-involuntary control

• can’t purposefully contract heart

Smooth Muscle

-digestive tract

-involuntary control

Muscle Properties

Electrical Excitability

-conducts electrical impulses

Contractility

-contraction

-generates tension within muscle

-generates force on whatever its attached to

Extensibility

-passive properties

-can extend

Elasticity

-passive properties

-can stretch

Levels of Organization in Human Body

-cell division & growth

Specialized Cell Types

-muscle

-neurons (nerve)

-connective tissue cells

• ligaments & tendons

-epithelial cells

• line blood vessels, overall structure of cells

Organ (Skeletal Muscle)

-muscle tissue

-connective tissue

-nervous tissue

-blood/vascular tissue (endothelial)

• endothelial under category of epithelial

-organ ends up in

• musculoskeletal system

• neuromuscular (nervous) system

-each muscle is an organ

• quads, biceps, triceps

Connective Tissue Components

Superficial Fascia

-holds everything in place

-in subcutaneous layer of skin

Deep Fascia

-beneath subcutaneous layer

-protect muscle

-conduit for nerves and muscles

Deep Connective Tissue Components

Tendons

-attaches muscle to attachment point (usually bone)

Aponeurosis

-type of tendon

Muscles Connect to Our Skeleton → Movement

-when a muscle contracts, it generates tension and exerts force on the skeleton to move our body

-muscle contracts to generate force to allow a movement

-muscle attachment is across a joint to allow for movement

muscle attachments have to cross the joint to cause movement at the joint → cannot attach the same bone

• concentric contraction, results in 2 bones moving closer to each other 

• bending the elbow, wrist, hip = concentric usually, but not all the time

Microscopic Anatomy of Muscles

-skeletal muscle → fascicle → muscle fibers (cells) → myofibrils

-muscle cell plasma membrane → sarcolemma

-muscle cell intracellular fluid/cytoplasm = sarcoplasm

-muscle cell contractile organelle = myofibrils

*muscle fiber = muscle cell

Sarcomere

-functional unit of muscles

• how contractions occur

• all sarcomeres contract simultaneously → whole muscle contraction

-filaments arranged in compartments

• thin & thick filaments

  • repeat in sequence

  • thin filament within thick filament

  • alternating within the sarcomere

  • slide along each other during contraction

    • don’t shorten or change length

  • thin filaments slide over thick filaments

-contractile unit of skeletal muscle

• gives striated appearance to muscle (feature of muscle cell)

  • striped look under microscope

Thick Filaments

-made of myosin proteins

• tail points towards center

• globular heads points outwards

Thin Filaments

-actin, troponin, tropomyosin proteins

Actin

-molecules in helical arrangement

Troponin

-secures the position of tropomyosin over actin

-holds everything together/keeps everything in place

-3 binding sites

• binds to calcium ions

  • released into sarcoplasm when muscle fiber is activated

  • when Ca binds to troponin → changes structure

    • loosens grip

• binds actin and myosin together

Tropomyosin

-when at rest, blocks actin from binding to myosin

Activated Filaments

-calcium is released from the sarcoplasmic reticulum into the sarcoplasm when muscle contracts

-cross-bridge forms when myosin binds to actin

Feature of Muscle Contraction

-how much tension is produced

• how much force generating power muscle has

-how quickly the tension rises (speed of contraction)

• depends on type of myosin protein in the muscle fiber type

  • how quickly myosin head can catalyze

• how long the contraction can be maintained

  • endurance/fatigability

-muscle contraction → generates tension → strength

• amount of tension directly related to number of cross-bridges formed

  • more cross bridges/bonding = more tension = stronger = more proteins

  • amount of bonds that can be made between myosin and actin

Muscle Contraction Cycle

-when muscle at rest → tropomyosin blocks actin from binding to myosin

-during neural stimulation → ATP & Ca present

• calcium is released into muscle cell from sarcoplasmic reticulum

• calcium binds to troponin and causes a change in troponin

• troponin shape change moves tropomyosin out of the way

• actin’s binding site is no longer blocked

• myosin heads from thick filaments can bind to actin in thin filaments

• myosin pulls actin inward and makes muscle contract

• second ATP attaches to myosin head → myosin is released from actin

  • binds to new actin if possible

-myosin head contains enzyme that breaks down ATP

-ATP provides energy for powerstroke & allows cycle to continue (new ATP each time)

• 2 ATP used

• a new ATP comes in → triggers and binds to new myosin

Muscle Metabolism

-ATP is fuel for cross bridge/contraction cycle

-how muscles generates the ATP necessary to power the contraction cycle

• anaerobic creatine phosphate (phosphocreatine)

• aerobic cellular respiration

• anaerobic glycolysis

Creatine Phosphate

-short burst of energy

-short amount of energy (~15s)

-anaerobic process (no oxygen involved)

• eg. 100 m dash (power output to do the sprint)

-body stores creatine phosphate to allow 15s of burst of energy

• quick and convenient way of manufacturing ATP in muscle

• fast acting system

-made from meat, dairy products

Glycolysis

-anaerobic process (no oxygen involved)

-breaking down glucose

• glycolysis

• 1 glucose molecule = 2 molecules of ATP

Cellular Respiration

-aerobic process (oxygen involved)

-mitochondria produces ATP

-oxygen from hemoglobin blood/from myoglobin in muscle fibers

-lots of ATP produced

-powers long term sustained activities

• powers endurance activities

Muscle Fiber Types

Type I

-slow oxidative (SO) fibers

-aerobic

-long distance/endurance

Type IIa

-fast oxidative-glycolytic (FOG) fibers

-aerobic/anaerobic

-short distance activities

Type IIx (IIb)

-fast glycolytic (FG) fibers

-intermediate

-anaerobic

Muscle Contraction Types

Tension

-determined by opportunity to form cross-bridges

-proportional to number of cross-bridges formed

-size factor

• muscle fibers differ in size, diameter

• large diameter = more filament proteins = more cross bridges

-other factors influence tension on contraction-by-contraction basis

• mechanical factor

  • amount of overlap between thick and thin filaments → length of muscle

  • neural factor: amount of calcium released into the sarcoplasm → depends on neural stimulation

Type I

-smallest diameter → less tension

-least powerful

-good for endurance (rich blood supply)

• lots of myoglobin

• lots of mitochondria → huge capacity for generating ATP

Type IIa

-largest diameter → more tension

-very powerful

-good for short distances

Type IIx

-intermediate muscle fiber diameter

-force output is greater than Type I, less than Type IIa

Fatigability

-determined by supply of ATP

Type I

-high capacity for aerobic cellular respiration

-fatigue-resistant (high endurance performance)

Type IIa

-relies on anaerobic processes for ATP

-fatigable (low endurance)

Type IIx

-relies on aerobic and anaerobic systems for ATP

-not as fatigable as Type IIa but less endurance than Type I

Speed of Contraction

-determined by speed of cross-bridge cycling

Type I

-ATPase enzyme activity in myosin heads relatively slow in Type I fibers myosin heavy chain isoform

-slow speed of contraction

Type IIa

-ATPase activity in myosin heads very fast

-fast contraction speed

Type IIx

-intermediate

-not as slow as Type I but not as fast as Type IIa

Energy Systems Over Time

Energy Continuum

-power athletes rely on anaerobic systems

• Type IIa fibers

• high % of FG fibers

• 100 m dash

• light lifting

-long endurance athletes rely on aerobic systems

• Type I fibers

• high % of SO fibers

• marathon runners

• heavy lifting

Length-Tension Relationship

-muscles for gripping

• originates in forearm and crosses your wrist to reach fingers

  • neutral wrist → optimal length of finger flexor muscles

  • flex wrist → shortens finger flexor muscles

  • extend wrist back → lengthens finger flexor muscles

-when muscles stretch → less overlap of thin and thick filaments

-muscles travel through forearm

-hand → bend downwards → muscle shorter

-hand → bend backwards → muscle longer

Sticking Point

-part of range of motion in a resistance exercise where there is a large increase in the difficulty level to continue the lift

• if exercise is performed to exhaustion → failure is experiences around vicinity of sticking point

-could be related to length-tension relationship

Neural Input to Skeletal Muscle

-motor neurons located in spinal cord

• transmits impulses from nervous system to muscle fibers

-nerve cells/neurons

• alpha-motor neurons

-electrical impulses gets transmitted to muscle fibers to release calcium

-neural firing → neuromuscular junction → release of calcium into sarcoplasm → contraction cycle

Neuromuscular Junction

-link (synapse) between motor neuron & skeletal muscle fibers

-cell to cell

• nerve cell connects to muscle cell

Motor Unit

-1 motor neuron + all the muscle fibers it innervates (connects to)

• each motor neuron is responsible for a given set of muscle fibers

-one motor unit has branches and connects to muscle fibers

-everytime a neuron fires an electrical impulse → generates response in muscle

• 1 nerve impulse → x amount of tension in muscle fiber

-no big or small nerve impulses

• all nerve impulses are identical and always the same

• amount of tension that gets generated is the same

Motor Units Have Different Sizes

-small motor units

• muscles for fine movements

• eyeball moving, singing

• made of Type I muscle fiber units

  • higher endurance

-large motor units

• muscles for powerful movements

• kicking a ball, lifting weights

• made of Type II muscle fiber units

  • more powerful

-orderly recruitment of motor units

• recruit from small motor units to large motor units

• as you need more power → go from Type I to Type II muscle fiber units

  • heavy lifting: Type I to Type IIa to Type IIx

-muscle fibers switch from Type IIx to Type IIa with training

• because Type IIx fatigue easily

-to increase muscle tension, nervous system can do 2 things

• increase number of motor units recruited

• increase firing rate (frequency) of motor neurons (motor units)

-large units may not be recruited

Motor Units are Active “At Rest”

-always background (low level) motor unit/neural activity

-gives us muscle tone

• otherwise muscles would be flaccid/hypotonic

-motor units are always firing steadily

Neural Contribution to Muscle Tension

-each muscle fiber is innervated by 1 motor neuron

-neuromuscular system can increase tension

• increase frequency of stimulation

• recruit more motor units (recruit more muscle fibers)

-small motor unit = small amount of muscle fibers connect to muscle neuron

-large motor unit = lots of muscle fibers can connect to muscle neuron

Effect of Firing Frequency (Frequency-Tension Relationship)

-faster the firing frequency, more tension can build up in the muscle fiber

-faster frequency = more tension that can build up

Muscle Twitch

-single stimulus contraction-relaxation sequence in one muscle fiber

-1 nerve impulse → 1 muscle twitch

Recruitment

-skeletal muscle contains 1000s of muscle fibers (cells)

-each muscle fiber is supplied by 1 motor neuron

• but each motor neuron supplies several muscle fibers

Initial Effects of Strength Training Program

-initial effects of training are neural adaptations

• first thing that adapts in body is neural adaptation

  • improvement of background tone of motor unit firing

• first thing enhances is neural input

  • allows you to keep going at baseline

• changes in actual muscle fibers (hypertrophy) after a few weeks

• more motor neurons at rest = burning more energy

• weight training important for weight loss

Fuel Utilization at Different Exercise Intensities

-exercise intensity drives carbohydrate use

-muscle glycogen rarely used at 65% VO₂ max (low intensity training)

• used more at 85% VO₂ max (high intensity training)

Types of Carbohydrates to Increase Carbohydrate Oxidation

-figure out which sugar is best for exercise

Oxidation of Infused Carbohydrate

-infusing glucose → bypassing GI tract

• straight to bloodstream instead of waiting for absorption

-if you infuse glucose instead of consuming glucose

• higher rate of blood glucose oxidation

-glucose & fructose have 2 transporters

• GLUT5

• higher carbohydrate oxidation

-glucose & fructose gives best results

• glucose + fructose → 56 minutes for athletes to complete cycling

• glucose → 60 minutes for athletes to complete cycling

• placebo → 67 minutes to complete cycling

Sport Drinks

-moderate concentration of glucose : fructose

-what sports drinks athletes should choose

• sports drink/gel practiced with & adapted to

• same drink available on race day

• sports drink that still tastes good after practicing

  • flavour that athlete won’t be tired of

    • if strawberry & banana only available → won’t be wanting the exact same flavour after race

Individual CHO “Sweet Spot”

-increased intake = increased oxidation = increased performance

-sweet spot ~ 70 g CHO/hr

• varies amongst athletes

-GI problems at 120 g CHO/hr

-every athlete is accustomed to a different amount of CHO

• impaired performance

• too much carbohydrate & fluid intake

• leads to GI disorders

• throw up

Practice Fueling & Hydration Sweat Rate Tracking during Long Runs

-practice rule of 15

• ~15-25 g CHO every ~15-25 min

• ~150-200 mL of fluids

-practice fueling & hydration in long sessions

-practice with different amounts of fluids & fuels

• mimic timing of intake in race

Know & Practice Race Course

-practice at race intensities, durations, exercise mode, projected weather conditions & wind conditions

-different locations have different inclines

• Boston - flat

• NYC - hilly

• Paris - hilly

-weather conditions affect run

• heat affects GI tract more

-practice when/where in course you’ll be able to fuel & hydrate

• know how long into race should fuel → where breaks/tents will be

Resistance Training

-act of repeated voluntary muscle contractions against a resistance greater than those normally encountered in activities of daily living

-voluntary contractions on purpose

• lifting a load greater than normal activities

• could be any type of resistance → heavy enough that muscle is putting in work

  • barbell, resistance bands, dumbbells

-to get stronger/bigger/better at doing things

-good for bone health

-makes us healthier

-improvement in quality of life and aging benefits

Effects of Resistance Training

-more you lift → stronger you get

-when you start to lift

• neural adaptations (neurons) occurs first

  • better at turning muscles on

  • “newbie” gains

• muscle undergoes hypertrophy

  • muscle grows

  • takes longer for muscles to grow

Resistance Training Program Variables

-load

• heavy load

  • lift less times

• light load

  • lift more times

-volume

• sets & reps

-exercise sections

-frequency

• how often you train

• how many times you rest during exercise

-type of exercise

-range of motion

-effort

• how hard you are trying

• lifting a load very heavy that can only be lifted once → high effort

• lifting a load you can lift 15x but only lifting it 10x → low effort

• maximize hypertrophy → 8-12

• maximize strength → 2-6

• muscular endurance → 13 - 20+

Strength

-maximal ability to generate force regardless of speed

-high load = close to peak strength

-low load = far from peak strength

• need to do more reps

-lift heavy → neural adaptations most important

Hypertrophy

-increase in size of muscle fibers

Absolute Endurance

-lifting a certain amount of weight and keeping it up for a certain time

• ex: if you have the same load for 2 people pre or post training, who can lift the most times. This is more important, bigger stronger people have bigger absolute endurance

-total work which can be completed with same absolute load

-moving → 2 people carrying couch up the stairs

• whoever can hold it longer has higher absolute endurance

-to build endurance for heavy load: getting stronger is better

-to build endurance for light load: more reps is better 

-to be better at muscle endurance: getting stronger is better

Relative Endurance

-figuring out how many reps one can do with for example 30% of their 1 RM. Stronger people can lift harder. This is not as helpful, if someone gets stronger and they test at the same % RM, they will be lifting a greater absolute load

-total work that can be completed with same relative load (%1RM)

Quadriceps Hypertrophy

-doesn’t matter if you lift light load or heavy load

• load isn’t important for hypertrophy

-as long as you build to the point where you can’t go anmore

-volume is important for hypertrophy → doing more → better for growing muscles

Metabolic Rate

-rate at which body expends energy or burns calorie

-anabolism, catabolism

Anabolism

-growth

-set of metabolic reactions that require energy to synthesize new molecules from simple precursors

-food intake sparks anabolism through biosynthetic pathways

Catabolism

-set of destructive metabolic reactions that transforms fuels into cellular (chemical) energy

• glycolysis — breakdown of glucose/glycogen to pyruvate

• glycogenolysis — breakdown of glycogen to glucose

Energy Extraction from Food

Digestion, Absorption and Transportation of Energy Yielding Nutrients

-carbohydrates — appear in body as simple sugars (glucose)

-fats — appear in body as fatty acids & glycerol

-proteins — appear in body as amino acids

-majority of foods we eat have carbohydrates, fats, proteins

-absorbed through the digestive tract and transported via the bloodstream to cells for energy use or storage

Production of Metabolites

-metabolites play key roles in cell’s energy production processes

-nutrients are further broken down in cells through metabolic pathways like glycolysis, beta-oxidation and protein catabolism

Cellular Energy Production (ATP Synthesis)

-metabolites are processed in mitochondria to produce ATP

• primary energy currency of cell

-ATP produced through oxidative phosphorylation in electron transport chain and citric acid cycle

-ATP used by cells for various metabolic processes

• including muscle contraction, active transport, biosynthesis

-ATP enables all of the cell’s energy-dependent activities to occur efficiently

Glycogen

-blood (4g glucose)

• for a healthy individual (no diabetes)

-storage form of glucose = glycogen

• body stores around 500g of glycogen in body

• skeletal muscle (300-400g)

• liver (75-100g)

-every 1g of glycogen is stored with approximately 3g of water

-glycogen stores will support moderate intensity exercise for 90 minutes or higher intensity exercise for ~30-45 minutes

-to eat before exercising?

• depends on how long you exercise for

  • moderate intensity at 90 minutes → probably not

  • high intensity at 30-45 minutes → probably should

    • ATP decreases → not as high of intensity after 45 minutes

    • body burning through glycogen stores and need to replenish the stores

Fat

-good fat

• avocados, fish, nuts, seeds, vegetable oils

-bad fat

-1g of glycogen = 4 kcal

• 500g of glycogen = 2000 calories

-fat is hydrophobic; can store a lot of fat (energy reserves)

• storage of fat is unlimited

-fat not a good fuel for high intensity athletes

Protein Recommendations for Athletes

-1.2-2g/kg/day

-consume 0.25 – 0.3 g protein/kg/eating occasion approx. every 3 hours

-consume 0.25 – 0.3 g protein/kg shortly after exercise

-consume ~30g casein protein source before bed

-high protein diet

• ~20 g of protein equal to

  • 3 oz meat

  • 2 eggs

  • 1.5 cup milk

  • ½ can tuna

  • ¾ cup beans or lentils

  • ½ cup cottage cheese

  • 1 cup yogurt

  • 1/3 pack tofu

Nutritional Supplementation

-athletes were using supplements to help with their performance

-supplements are not drugs nor stimulants

-have a natural health product (NHP) number

Why Nutritional Supplements are Problematic

-supplements not heavily regulated like drugs

• not under the same scrutiny as drugs

• not governed the same as drugs

-supplement companies don’t have to prove their claims up front

-doses of some ingredients may not be specified

-quality and composition may vary

Anabolic Steroids and Nutritional Supplements Study

-634 non-hormonal nutritional supplements from 13 countries purchased and tested

• 289 from prohormone selling companies

• 345 from companies that didn’t sell prohormones

-results

• 11 anabolic, androgenic steroids

• 15% contained prohormones when none of the products should have prohormones

• 10% couldn’t be analyzed

→ supplements not properly governed

Supplements in Sport

-food first, supplements second

-athletes subject to anti-doping and WADA code

-athletes responsible for what they take

-athletes may use supplements for justifiable reasons beyond a direct impact on sports performance such as in case of illness, travel or high volume training

-nutritional supplements pose a high risk for banned subs

-small number of supplements with good evidence behind them that athletes can trial with right guidance

-small number of supplements are beneficial to athletes and must carry these endorsements

• manufacturers can send their products to these companies and see if their products contain any banned substances

• if approved then these companies will endorse/allow the labels to be put on their packaging

World Anti-Doping Agency (WADA)

-prohibited list is updated every year

-signatories to code include (groups that sign onto the code)

• Olympic & Paralympic Sports and committees

• events (commonwealth games)

  • ex: netball not part of Olympics but it is a commonwealth game

• FIFA, cheerleading, MMA, karate, rugby, australian football

• exceptions: MLB, NBA, NFL

  • internal drug policies

The Prohibited List

-drug has to meet 2/3 criterias to be banned

1. taking it must enhance or potentially enhance performance

2. place an athlete’s health at risk

3. violate the spirit of sport

   • ex: swimmers used special compression suits to make them swim faster

*masking agents/not approved for human use → also prohibited

1. substances prohibited at all times

   • non approved substances, anabolic agents; peptide hormones, growth factors; related substances and mimetics; beta-2 agonists; hormone & metabolic modulators; diuretics and masking agents

   • diuretics — allow people to make a weight class

   • hormones — helps with growth of bones & muscles

   • testosterone -- builds muscle mass

2. prohibited methods

   • manipulation of blood, chemical and physical manipulation (including IV infusions), gene and cell doping

3. substances & methods prohibited in competition

   • stimulants: narcotics, cannabinoids

     • CBD removed from list in 2018

   • immediate test on athletes to see if substance is in athlete’s system

4. substances prohibited in particular sports

   • beta-blockers — helps with precision & heart rate (makes you more calm

     • high skill with low intensity

       • golf, archery, darts

Caffeine

-not a diuretic

• increased liquid is the main contributor to increased urine

-crosses blood brain barrier

• fat-soluble

• passes quickly into brain

• affects central nervous system

-adenosine receptor antagonist

• blocks adenosine receptors

  • binds to adenosine receptor itself so that adenosine can’t bind to the adenosine receptor

• adenosine promotes sleepiness & relaxation

• blocked receptors = feeling alert & energized

-increases neural activity

• stimulates release of dopamine & norepinephrine

  • increases focus, concentration and wakefulness

• impacts serotonin

  • improves mood & motivation

-peak levels

• 45 minutes after consumption

-half-life

• 5 hours

  • large range — caffeine can affect your body for several hours

-genetic variability

• in activity of CYP1A2 among individuals

• use CYP1A2 well → fast metabolizers of caffeine

  • drink coffee 30 minutes before sleeping → able to sleep → fast metabolizers of caffeine

• don’t use CYP1A2 well → slow metabolizers of caffeine

  • drink coffee 30 minutes before sleeping → unable to sleep → slow metabolizers of caffeine

Caffeine Intake

-Health Canada

• shouldn’t exceed 400 mg of caffeine per day on a regular basis

• including energy drinks

Energy Drinks

-beverages containing stimulants (caffeine) marked as products that enhance mental and physical performance

• often include ingredients like ginseng, taurine, herbal extracts

• regular use may mask poor nutritional practice or underlying health concerns (issues with sleep)

-lots of additives, sugar

Protein Intake

-Canada RDA for protein is 0.8 g/kg/day

-1.6 g/kg/day to maximize protein when lifting

• 2x the RDA

• or 20+ g per meal/snack

-not everyone get benefits of protein

• some people get big with carbohydrates

-protein intake has a moderate effect on muscle gains following resistance training

-protein intake has a small effect on strength gains following resistance training

Essential Amino Acid Content

-plant proteins are lower in quality

-proteins high in leucine are better

• quality & leucine content is important

-casein is digested slowly

-whey has good amino acid profile

• faster than casein

• more muscle protein synthesis

• gets amino acids quickly into body

Anabolic Window for Proteins

-right after workout/close in proximity to workout

• lose out on gains if you wait

-real food works better than proteins from supplements

• better for muscles & body

-don’t need protein supplements to get big & strong

• but they’re not bad if you do take it

Muscle Full Effect

-infusing amino acids at a custom rate. Muscle protein synthesis increases with increased amino acids. As they kept infusing amino acids, participants had high amino acids but muscle protein synthesis went down to baseline after ~ 2-3 hours (muscle full effect). This is why can't eat protein all the time to get bigger muscles; we need exercise to increase muscle size (lifting/resistance exercise) and periods when we do not eat for a while