Chapter 9.5 Cheat Sheet (DRAFT) by jjovann

•Skeletal muscle
–Able to switch between low and high activity levels
•Low activity
–Relaxed and using a moderate amount of ATP
•High activity
–Contr­acting and using ATP at a rapid pace

•Creatine is a small, amino acid derived molecule that is synthe­sized in the liver, kidneys, and pancreas
–It is then transp­orted to muscle fibers
–Can also be obtained through milk, red meat, and some fish
•When relaxed, muscle fibers produce more ATP than is needed for resting metabolism
–The excess ATP is used to make creatine phosph­ate(CP)
–Creatine kinase (CK), an enzyme­,ca­talyzes the transfer of one of the high energy phosphates from ATP to creatine forming CP and ADP
•It does the reverse, too – CP and ADP to Creatine and ATP

•Lactic acid
–Diffuses through muscle transport proteins into the inters­titial fluid and then bloods­tream
–Can be used as fuel by liver, kidneys, and heart
–Can also be converted back into pyruvic acid or glucose by liver
•Anaerobic respir­ation yields only 5% as much ATP as aerobic respir­ation, but produces ATP 2½ times faster
–Rapidly provides fuel for ~30 – 40 seconds of strenuous exercise
–Drawback - uses huge amounts of glucose for relatively small amounts of ATP produced and creates lactic acid as byproduct

•Produces ~95% of ATP during rest and light to moderate exercise
–Slower process than anaerobic
•Series of chemical reactions that require oxygen
•Glyco­lysis is first step
–When oxygen is present in proper amounts, pyruvic acid is modified and sent to the mitoch­ondria
•Occurs in the mitoch­ondria in two steps (citric acid cycle and oxidative phosph­ory­lation)
–Breaks pyruvate down producing CO2 ,H2O, and a large amount of ATP
•Glyco­lysis breaks down the glucose into pyruvate (pyruvic acid)
•With enough oxygen present in the cytosol, pyruvate is modified and enters the mitoch­ondria where the breakdown of the modified pyruvate during the citric acid cycle produces molecules that are used in oxidative phosph­ory­lation to produce a lot of ATP
•Beta oxidation of fatty acids (lipids) and oxidative deamin­ation, followed by transa­min­ation, of amino acids provide substrates for aerobic respir­ation to produce ATP as well
•Fuels - stored glycogen, blood borne glucose, pyruvic acid from glycol­ysis, amino acids, and free fatty acids

•Oxygen Debt, or "­Excess Post-E­xercise Oxygen Consum­pti­on" (EPOC) is the amount of O2 repayment required after exercise in skeletal muscle to:
–Replenish ATP stores
–Replenish creatine phosphate and myoglobin stores
–Convert lactic acid back into pyruvate so it can be used in the mitoch­ondria to help replenish ATP
–Balance hormones
•Some studies have shown that high-i­nte­nsity exercise periods, such as interval training, may increase EPOC and thus allow you to increase post exercise metabolism
–EPOC is commonly referred to as the “after burn”
•The greater the EPOC, the more fat stores you may potent­ially use throughout the day to return muscle back to original state

•Spasm
–A sudden involu­ntary activation of a motor unit within whole muscle
– usually painless
•Cramp
–Invol­untary and often painful tetanic muscle contra­ctions
–Caused by:•in­ade­quate blood flow to muscles (such as in dehydr­ation or blood clot)
•nerve compre­ssion
•overuse
•Injury
•abnormal blood electr­olyte levels
–calcium and magnesium levels important
•Intra vs extrac­ellular Na and K also important

•Endurance (aerobic) training
–Leads to increased
•Muscle capill­aries (blood flow)
•Number of mitoch­ondria (ATP production when oxygen present)
•Myoglobin synthesis (more oxygen storage)
–Results in greater endurance, strength, and resistance to fatigue
•Greatest effect seen in SO fibers
–May cause the gradual transf­orm­ation of some FG fibers to FOG fibers
•The transf­ormed fibers show a slight decrease in size, but an increase in number of mitoch­ondria (aerobic ATP capacity) and blood supply
–Endurance training also results in cardio­vas­cular and respir­atory adapta­tions that increase the nutrient transport and waste removal for skeletal muscle cells
•VO2 max and lactate threshold come into play here

•Length of use and doses required to produce desired results can be dangerous
–Cause many cells in the body to grow, including cancerous cells
•Liver damage and various types of cancer is common with oral and injected steroids
–Kidney damage
–Stunted growth for those still growing
–Mood swings in long-term users from affected neurot­ran­smitter release in the brain
•Increased irrita­bility and aggres­sion... Roid Rage!
•Depre­ssion
–Increased blood pressure and risk of heart disease
–Increased LDL levels... these are the bad kind
–Increased sebaceous gland secretion
•Pimple Party!!!
•...Backne and trapne
–Users often combine different types of steroid and non-st­eroid drugs when undergoing a cycle
– stacking

•Muscle cells undergo atrophy in response to lack of use
–Decrease in size/d­iameter due to decrease in the things listed under hypert­rophy slide
•Muscle strength can decline around ~5% per day
–Atrophy can occur from simply not using them (disuse atrophy) or damage to the nerves that cause them to contract (dener­vation atrophy)
–If atrophy persists for extended periods, 6 months to over 2 years, muscle fibers can be irreve­rsibly replaced by fibrous connective tissue

•Claimed benefits of most supple­ments not well supported by quality scientific evidence
–ACSM Discussion of vitamins and supple­ments
–Wikipedia article on BB supple­ments
•Some info may be incomplete or incorrect, usual Wikipedia risk
–NIH resource on supple­ments
–Consumer medical watchdog group (scien­ce-­based medicine)
•Some products may contain unlisted ingred­ients that may be harmful or banned by athletic organi­zations

•Strenuous exercise produces stress and damage to muscle fibers
–Torn sarcol­emmas in some muscle fibers
–Damaged myofibrils
–Disrupted Z-discs
•Blood analysis post exercise shows the presence of proteins that are normally confined to muscle cells
–Myoglobin
–Creatine Kinase

•Within a particular motor unit, all the skeletal muscle fibers are of the same type
–The different motor units in a muscle are recruited in a specific order depending on the task being performed
•Weak contra­ctions usually require SO motor units only•If more force is required, FOG motor units are recruited
•If maximal force is required, the big FG fibers are recruited!

•Claimed benefits of most supple­ments not well supported by quality scientific evidence
–ACSM Discussion of vitamins and supple­ments
–Wikipedia article on BB supple­ments
•Some info may be incomplete or incorrect, usual Wikipedia risk
–NIH resource on supple­ments
–Consumer medical watchdog group (scien­ce-­based medicine)
•Some products may contain unlisted ingred­ients that may be harmful or banned by athletic organi­zations

•Claimed benefits of most supple­ments not well supported by quality scientific evidence
–ACSM Discussion of vitamins and supple­ments
–Wikipedia article on BB supple­ments
•Some info may be incomplete or incorrect, usual Wikipedia risk
–NIH resource on supple­ments
–Consumer medical watchdog group (scien­ce-­based medicine)
•Some products may contain unlisted ingred­ients that may be harmful or banned by athletic organi­zations

•By Function
–Slow oxidative fibers (SO)(Type I)
•Small, appear dark red, are the least powerful type.
•Myosin heads hydrolyze ATP slowly leading to a lower rate of contra­cti­on... hence slow
•They are very fatigue resistant
•Low amount of glycogen stores compared to FOG and FG
•Highly vascul­arized
•Have a lot of mitoch­ondria
–Generate ATP mainly through aerobic respir­ation, hence oxidative
•High myoglobin
•Used for endurance activities where big, powerful contra­ctions are not needed
–Ex: postural mainte­nance, long distance activities in running, swimming, and cycling

•ATP is the only source used directly for contra­ctile activities
–Move and detach cross bridges, power calcium pumps in SR and sarcol­emma, and power the return of Na+ & K+to normal levels after excitation
–Available muscle stores of ATP depleted in 3–6 seconds from the onset of contra­ction
•In order to maintain activity, the muscles must make more ATP

–CP is 3-6 times more plentiful than ATP in the sarcoplasm of a relaxed muscle fiber
•When contra­ction begins, muscles quickly use ATP stores
–Leads to increase in ADP in sarcoplasm
–CK takes a phosphate back from CP and adds it to ADP forming ATP
•CP catalyzed regene­ration of ATP allow muscles to contract for roughly 15 seconds

•The metabolite (break down product) of creatine is creatinine
–Creat­inine is filtered by the kidneys into the urine
–Adults require about 2 grams of creatine a day through synthesis or dietary means to replace the urinary loss.
•Some studies have shown that creatine supple­men­tation can increase explosive movements such as sprinting or resistance training
•Others have shown no perfor­mance enhanc­ement
•Some murine (mouse) studies have shown that ingesting excess creatine can cause the body to produce less endogenous (self produced) creatine
–The mechanisms of how this works are still not entirely understood
–The long term effects of creatine supple­men­tation have yet to be determined

•~40% of energy released in muscle activity used for work
•Remaining energy (60%) is converted to heat
–Heat is a byproduct of many chemical reactions in the body
•Dangerous build up of heat levels prevented by radiation of heat from skin
–Sweating increases rate of heat removal from skin surface
•Shivering - result of involu­ntary skeletal muscle contra­ctions to increase muscle metabolism
–Increases skeletal muscle heat production to offset a dangerous decrease in core body temper­ature

•Skeletal muscle fibers are not all alike in appearance and function. By appear­ance:
–Red muscle fibers (the dark meat) have a high myoglobin content, many mitoch­ondria, and rich vascul­ari­zation (blood supply)
–White muscle fibers (the white meat) have high amounts of glycolytic enzymes, low myoglobin content, fewer mitoch­ondria, and less vascul­ari­zation vs. red fibers

•Strength training (anaerobic activity) increases the size and tension production of FG fibers
–Increase in size and strength due to increase in number of myofil­aments in muscle fiber.
•Overall result is hypert­rophy
–Bulging muscles
–Increased number of mitoch­ondria
•Quicker ATP replen­ishment during rest when blood flow is restored
–Increased glycogen stores­•In­creased glucose availa­bility for glycolysis during contra­ction
–Increase in number of glycolytic enzymes
•results in greater ATP production capacity during contra­ction
–May cause the gradual transf­orm­ation of some FOG fibers to FG fibers

•Ratio of FG to SO fibers in each muscle is most likely geneti­cally determined
–This provides a partial explan­ation for why some people may be better at particular activities than others
•People with higher propor­tions of FG fibers may excel in activities involving short, powerful, intense activities
–Weight lifting and sprinting
•People with a higher percentage of SO fibers may excel in endurance activities
–Long distance cycling, running, swimming

•Delayed Onset Muscle Soreness (DOMS)
–Muscles become sore 12-48 hours post exercise
•Due to inflam­mation from damage to muscle
•Accom­panied by stiffness, tender­ness, and swelling
•Greatest effects felt 24-72 hours post activity
–Causes of DOMS not completely unders­tood. but studies reveal that micros­copic muscle damage (micro­trauma) may be a major contri­buting factor
•Damage to sarcomeres (z-discs, thin, and thick filaments can tear or become dislod­ged), calcium homeos­tasis in muscle cell disrupted, ATP production may slow, possible increase in sarcomere protein breakdown by the proteases
–Inter­est­ingly, muscle become more damaged, and sore, from eccentric contra­ctions (the negative rep) than from concentric or isometric contra­ctions
•Mecha­nisms not entirely understood
–Not caused by lactic acid build-up
•Conce­ntric contra­ctions produce lactic acid and do not cause DOMS
•Studies show lactic acid levels in blood return to normal within 1 hour after exercise

•Aging
–By age 30, loss of muscle mass (sarco­penia) begins
•In part,due to decreased levels of physical activity
•With aging,­humans undergo a slow, progre­ssive loss of skeletal muscle mass that is replaced largely by fibrous connective tissue and adipose tissue
–Muscle strength at 85 is roughly 40%of what it was at age 25
–Regular exercise can slow the rate of loss
–Exercise in the elderly can still produce signif­icant adaptation
•Aerobic training is of particular importance due to it’s cardio­vas­cular effects
•Strength training, even a modest amount, can partially prevent the loss of muscle tissue that occurs with aging
–Also helps reduce bone density loss and loss of ROM in joints

•Male side effects
–Decreased endogenous testos­terone production
–Conve­rsion of excess testos­terone to estradiol
•Causes gyneco­mastia – female­-like breast tissue in males
–Testi­cular atrophy from decreased sperm production
–Sterility
–Baldness
– increased develo­pment of androgenic alopecia for those with the affected
•Female side effects
–Atrophy of breasts and uterus
–Menstrual irregu­lar­ities
–Sterility
–Increased male-p­attern growth of body and facial hair (hirsu­tism)
–Permanent deepening of voice
–Clitoral enlarg­ement
•Adole­scent side effects
–stunted growth due to premature skeletal maturation and accele­rated puberty changes
–risk of not reaching expected height if steroid use precedes the typical adolescent growth spurt

•By function cont.
–Fast oxidat­ive­-gl­yco­lytic fibers (FOG) (Type IIa)
•Inter­mediate in size, appear red to pink
•More myofil­aments than SO
•As much to slightly less vascul­arized vs. SO
•Moder­ately resistant to fatigue
•Myosin heads hydrolyze ATP 3-5x faster than SO which make them contract faster
–Twitches reach peak tension faster than SO and are briefer in duration
– less than 100 msec
•Have the most mitoch­ondria of the different types
–Generate consid­erable ATP through aerobic (oxida­tive) respir­ation to power the greater number of myofil­aments vs. SO
•High myoglobin
•Have a moderate amount of intrac­ellular glycogen and can use anaerobic pathway (ferme­nta­tion) effici­ently when oxygen drops
•Contr­ibute to exercises such as walking and sprinting

•Muscle fibers regenerate ATP by:
–Direct Phosph­ory­lation (adding a phosphate) of ADP using creatine phosphate (CP)
•Espec­ially important in muscle fibers
–95% of the body’s creatine is found in skeletal muscle
–Anaerobic pathway (glyco­lysis  lactic acid)
•No O2 requir­ed•If Anaerobic, glycolysis is followed by fermen­tation
–Aerobic respir­ation
•glyco­lysis O2 and modified glycolysis products into mitoch­ondria

•Glyco­lysis
– does not require oxygen
–1st step in both aerobic and anaerobic pathway
–In the cytosol, glucose is degraded to 2 pyruvic acid molecules via enzyme catalyzed reactions
–Produces 2 ATP per glucose molecule
•At 70% of maximum contra­ctile activity
–Bulging muscles compress blood vessels
–oxygen delivery impaired
–W/o oxygen, pyruvic acid converted to lactic acid in order to regenerate specific molecules needed for glycolysis to continue making ATP•Fe­rme­ntation

Aerobic endurance
–Length of time muscle is capable of contra­ction using ATP primarily produced from aerobic pathway
•Anaerobic threshold
–Point at which muscle metabolism converts to primarily anaerobic ATP production

•Physi­olo­gical inability to contract despite continued stimul­ation
•Occurs when
–Ionic imbalances (K+, Ca2+, Pi) interfere with E‑C coupling
–Prolonged exercise may damage SR and interfere with Ca2+re­gul­ation and release
–Inhib­ition of Cross-­bridge cycling
•Build up of ADP and Pi in muscle fibers during activity may directly inhibit cross-­bridge cycling
•Lactic acid build-up not necess­arily a cause
–Elevated H+ ion concen­tration (acidi­fic­ation) in sarcoplasm may affect muscle fiber function
•Thought to be caused by release of H+ during ATP hydrolysis by contra­ctile proteins, not lactic acid production
–Recent studies show that increasing acidity in muscle fibers does not directly hinder contra­ctile proteins.
•It does directly create dysfun­ction in Ca regulation and release which affects contra­ctility and relaxation
•Total lack of ATP rarely occurs during states of continuous contra­ction, and would cause contra­ctures (conti­nuous contra­ctions)

•Class­ified functi­onally according to two charac­ter­istics
–Speed of contra­ction:
•slow or fast fibers according to
–Speed at which myosin ATPases split ATP
–Pattern of electrical activity of motor neurons
–Primary Metabolic pathways used for ATP synthesis while contra­cting
•Oxidative fibers—use aerobic pathways
•Glyco­lytic fibers—use anaerobic glycolysis

•Total number of muscle fibers typically does not increase
–Most people have roughly the same amount of muscle cells regardless of difference in body size
•Although, the charac­ter­istics of the fibers can change
–Different types of activity induce changes in muscle fibers
•Endurance vs. Strength

•Training programs should reflect the type of activity an athlete wishes to perform
–High weight/low rep resistance training will have little effect on a marath­oner’s ability to run long distance
–Endurance type activi­ties, like half marathons and three mile swims, will not lead to the strength and size gains desired by weight lifters
–However, most successful long-term fitness regimens include both endurance and resistance training
•Changes in muscle in response to repeated periods of exercise occur over a period of weeks to months
–Speed of recovery, growth, and adaptation of muscle to exercise depends on many factor­s•G­ene­tics, age, hormones, nutrition, Satellite cells
•If regular exercise ceases, the muscle revert to their unexer­cised state

•Muscle fibers undergo repair and adaptation in response to damage
–Muscles become more resilient to type of activity that induced damage thus decreasing damage and soreness from future activities of similar type
•New regions of sarcolemma are formed to replace damaged areas
•More muscle proteins, such as myofib­rils, and organelles are formed
–Allow for greater contra­ctile strength and support
•Better able to resist, or buffer, the effects of the build up of metabo­lites such as acid

•The regularity of muscle use, as well as the duration and intensity of activity, affect the properties of muscle
•Exercise can produce an increase in size as well as changes in a muscle cell’s capacity for ATP production
•Muscle cells undergo hypert­rophy in response to stress
–Increase in size/d­iam­eter, not in number
•Enlar­gement of existing fibers due to increase in the number of:
–Myofi­brils
»More contra­ctile organelles = more tension generated
–Mitoc­hondria
»Bigger muscle cells with more contra­ctile organelles need more ATP to power them
–Sarco­plasmic reticula
»Need more Ca storage and release for new myofibrils
–Other organelles and proteins necessary for increased metabolic capacity

•Anabo­lic­-An­dro­genic Steroids
–Mimics the effects of testos­terone and DHT in the body
–Cause an increase in muscle size and thus strength
–Cause increase in lean muscle mass
•With proper diet
–Cause increased bone growth and remodeling
–Stimu­lates red bone marrow­•In­crease in RBCs

•Most whole skeletal muscles are a mixture of all three types of skeletal muscle fibers
–About half the fibers in a "­typ­ica­l"sk­eletal muscle are slow oxidative (SO) fibers
–Ratio of the three types in a whole muscle can vary depending on:
•The action of the muscle
•Training program
•Genetic factors
–Neck and back muscles often contain a higher proportion of SO fibers
•Primarily used for postural support
–Shoulder and arm muscles contain higher proportion of FG fibers
•Not used all the time
•Used briefly to produce large amounts of tension for activities like lifting or throwing
–Leg and thigh muscles contain large numbers of both SO and FOG fibers
•Used for support, walking, and running

•Vitamins
–Most Americans do not require vitamin supple­ments
–Much of the vitamins needed are obtained from a healthy diet
–Vitamin supple­ments can be useful in those with nutrit­ional defici­encies and profes­sional athletes
•Protein supple­ments
–Daily protein requir­ement for an adult human is about 0.8 grams per 2.2 lbs of body weight
•Can be higher in growing children, pregnant women, postsu­rgical patients, and athletes.
–Excess protein intake (over 200 g/day) may lead to kidney damage over time
–High protein diets can lead to fat gain if total caloric intake greater than expend­iture
•Pre-, during, and post workout supple­ments
–Many contain high amounts of various stimulants
•May cause increases in blood pressure
•May cause concen­tration issues
•May increase rate of dehydr­ation during activity
–Typically contain low amounts of advertised ingred­ients
•below amounts needed for physio­log­ically relevant levels as based on scientific studies quoted by the supplement company

•By function cont... cont
–Fast Glycolytic fibers (FG)
–Type IIx (or IId) in humans, or Type IIb in small mammals
•largest, white in color, and powerful
–Many myofib­rils, very low myoglobin content
•Low amount of mitoch­ondria compared to types I (SO) and IIa (FOG)
•Have a lot of glycolytic enzymes in the sarcoplasm for glycolysis
–Primarily use anaerobic pathway in generating ATP during contra­ction
–Suited to intense, powerful activity of short duration
•Contain large amounts of glycogen
–Blood glucose and oxygen delivery severely decreased when contra­cting
–Glyco­lysis and fermen­tation use a lot of glucose to make small amounts of ATP compared to aerobic
•Myosin heads hydrolyze ATP very quickly
–Fast and powerful contra­cti­ons­•Used in short, powerful activities
–resis­tance training programs
– lifting weights