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Bulletin #32 – Parrillo Performance Guide to Muscle, Part 5

In the previous bulletin I introducedthe “all or nothing” principle of musclecontraction, which states that a givenmotor unit either contracts maximally ornot at all. I also explained the pattern ofmuscle fiber recruitment. For low inten-sity activities, such as fine finger move-ments or precise movement of the eyes,small motor units are recruited. Smallmotor units allow precise muscular con-trol and are primarily composed of slowtwitch fibers, which generate low forcesand are fatigue resistant. As progressivelymore force is required for an activity, morefast twitch motor units are called into play.These have more muscle fibers connectedto each nerve cell (that is, they are largermotor units) and are capable or generat-ing high forces although they fatigue moreeasily.

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In this bulletin I would like to talk aboutdifferent types of muscle contraction, andwhy these are important in bodybuilding.Concentric muscle actions occur when amuscle is shortening. This happens whenforce generated within the muscle is suf-ficient to overcome the resistance toshortening (1).  An example is the liftingphase of a biceps dumbbell curl.  Duringthis phase of contraction, action poten-tials are arriving at the neuromuscularjunction, causing a release of the neu-rotransmitter acetylcholine at the synap-tic cleft.  This causes an influx of cal-cium into the muscle cell, as well as arelease of calcium from the sarcoplasmicreticulum.  (Review previous articles inthis series in these concepts are fuzzy.)The rising calcium concentration sets offa series of events resulting in activationof the actin-myosin cross-bridges.  ATPis consumed as the sarcomeres shorten,bringing the Z lines at the ends of the sar-comere closer together.  

Thus when amuscle fiber contracts, each of the indi-vidual sarcomeres contract, and ATP isconsumed.  Concentric muscle actions arereally the only true muscular contractions,because contraction literally means “toshorten.”Isometric muscle actions refer to thesituation where the force generated by themuscle is sufficient to exactly balance theresistance.  An example is at the top of abiceps curl at the moment of peak con-traction, or any time when you pause dur-ing the curl and the weight remains sta-tionary.  “Isometric” means “the samelength,” and thus describes any time amuscle is working but is not changing inlength.  Eccentric muscle actions refer tosituations when the muscle is generatingforce but that force is less than the resis-tance on the muscle.  An example is thelowering phase of a biceps curl.  Here,the muscle is still working and generatingforce, but the muscle is actually gettinglonger.  Gravity is the force pulling thedumbbell downward, and this force istransmitted to the forearm and then to thebiceps tendon.  If this force is greater thanthe internal force generated by the bicepsmuscle, then the muscle will lengthen in-stead of contracting, even though it is stillworking and generating force.“Isokinetic” means “the same velocity” anddescribes muscle actions that occur atconstant velocity.  

An isokinetic contrac-tion is simply a concentric muscle actionthat occurs at constant velocity.It is important to realize that duringisometric and eccentric muscle actions westill have nerve impulses (action poten-tials) arriving at the muscle, triggeringcalcium release and activation of the ac-tin-myosin cross-bridges, just like we doduring concentric actions.  The differenceis that the force generated by the muscleis no longer sufficient to overcome theresistance.  During isometric actions thesarcomeres remain the same length, andduring eccentric actions the sarcomeresactually get longer.  During eccentric ac-tions the actin-myosin cross-bridges arestill trying to pull the Z lines together toshorten the sarcomere, but they’re justnot strong enough.  As you might imag-ine, this causes quite a bit of damage tothe cross-bridges and to the whole sar-comere.  The sarcomere is working tocontract, but is being overcome by ex-ternal forces which are forcing it tolengthen while it is trying to contract.This is the main source of microtrauma(microscopic damage) to the muscle thatoccurs when you work out.

 If you takea muscle biopsy (a small tissue sample)from a muscle after a workout and lookat it in the electron microscope, you willsee that the normal structure of the musclehas been disrupted.  The amount of dam-age to the muscle is far greater followingeccentric actions than for concentric orisometric actions, as you might guess.  Inconcentric actions under heavy resistance,the microscopic structures of the musclefiber literally get ripped apart as the musclefiber is forced to lengthen while it is try-ing to contract.Following intense training sessions wesee a phenomenon called “Z band steam-ing,” which describes the Z band struc-ture being disrupted and myofilamentsstreaming out from the normal sarcom-ere structure.  Under extreme conditionsyou can even see rupture (breakage) the sarcoplasmic membrane (the cell mem-brane of muscle cells) and leakage of cel-lular contents from the cell.  Some of thesecan be measured in routine lab tests in ahospital.  Creatine phosphokinase (CPK)is an enzyme in muscle cells which formscreatine phosphate, the short-term energyreserve in muscle cells which is respon-sible for immediately replenishing ATP(refer back to our series on cellular en-ergy metabolism).  When muscle cells aredamaged and the cell membrane startsleaking, CPK is released into the blood andcan be measured in the laboratory.  Inhospitals CPK levels are used as an initialscreen to tell if someone has had a heartattack or not, since during a heart attacksome of the heart muscle cells die andrelease CPK.  

Skeletal muscle cells alsorelease CPK when they are damaged.Using tests like muscle biopsy and CPK,scientists have determined that mostmuscle damage occurs during eccentricmuscle actions, when external forces ripthe myofibers apart.  This is also the maincause of muscle soreness 24-48 hoursafter a workout, and is called “delayedonset muscle soreness,” or DOMS.  Trya few sets of heavy forced negativessometime to prove it to yourself.  It iswell known to bodybuilders that negativescause the most muscle soreness, and nowyou know why.Why is all of this important to body-builders?  Because it is at the very heartof muscle growth.  You see, the micro-scopic tissue damage that occurs afterweight training serves as the stimulus forinflammation.  Inflammation is a processthat occurs in damaged or infected tis-sues that signals the immune system tocome into play.  White blood cells, mainlylymphocytes, neutrophils, and macroph-ages, are called in to clean up the mess ofthe damaged and leaking muscle cells.  Thewhite blood cells release immune media-tors such as histamine, bradykinin,cytokines, and interleukins, which helpbring about the repair process.  Bradyki-nin is one of the immune mediators that isparticularly famous for causing pain, andimmune mediators like bradykinin andprostaglandins are the reason muscles getsore after a workout.  

During the inflam-mation process, damaged cells and re-paired and the tissue is returned to its origi-nal state.  The body doesn’t like this in-flammation and repair process however,and overcompensates a bit during the re-pair process.  The body makes the musclesa little bit bigger and stronger than theywere before the workout, so that nexttime you hit the weights hopefully themuscles can take it and not get damaged.The body’s ability to overcompensate isvery limited however, and estimates arethat with each good workout yourmuscles increase in size only about 0.1%.This is why it takes years of consistenttraining to get really big muscles.There are two basic principles of body-building training that are more importantthan all the others put together.  The firstis the principle of intensity.  A workoutmust exceed some threshold of intensityin order to stimulate growth.  The secondis the principle of progressive resistance.This means that as you get stronger, youhave to keep progressively increasing theresistance to overload the muscle.  In otherwords, as the muscle gets stronger theintensity threshold required to stimulatefurther growth increases.  

This is a directconsequence of the over-compensationprocess I described above.  During theinflammation and repair process, tissueremodeling occurs to help the muscleadapt to the stresses imposed on it.  Ini-tially, a 30 pound dumbbell curl maybe intense enough to cause muscledamage and set into play the pro-cess of muscle growth.  Musclegrowth is really just an adaptiveresponse that occurs so that thenext time you curl a 30 pounddumbbell it doesn’t cause somuch damage to the muscle.After a while, you will be able tocurl the 30 pound dumbbell eas-ily, without much strain or dam-age to the muscle.  At that point,the muscle and it’s associatedconnective structures have ad-equately adapted to the stressimposed by a 30 pound dumb-bell.  You can keep workingout with 30 pound dumbbells for the restof your life and little, if any, additionalgrowth will occur.  The muscle has grownand adapted to that level of stress.  If youstick to the 30 pound dumbbells you willfind that over time you will be able to domore and more reps with 30 pounds, butthat will do little to increase muscle size.Any time you’re doing more than 12-15reps with a weight you’re primarily train-ing muscle endurance, not musclestrength.  

Training for muscle enduranceis just fine, but does very little to increasemuscle size.  To increase muscle size youhave to increase strength, which meanslifting a heavier weight.  So you go up tothe 35 pound dumbbells and get maybe 6reps before your biceps fails.  This repre-sents a new level of stress, a higher levelof intensity, and the adaptation processbegins again.  After a few weeks ormonths you will be able to curl the 35pound dumbbells for 12 reps and yourbiceps will be bigger and stronger than itwas when you could only curl 30 poundsfor 12 reps.  This is the principle of pro-gressive resistance.For maximal gains in strength, youwant to train with a heavy weight at lowreps, say 3-6 reps.  For maximal gains inmuscle size, you want to train with aweight you can handle for 6-10 reps.  Asthe muscle adapts and gets stronger, youwill need to increase the weight in smallincrements (about 5-10% per jump) tokeep yourself in the proper rep range.  Themost effective training strategies over thelong haul involve some work in the 3-6rep range and some work in the 6-10 reprange.  This helps train the nervous sys-tem and well as the muscle and helps en-sure the high threshold pathways are re-cruited.  For purposes of increasingmuscle size and strength, by the time youcan perform 12 reps with a given weightthis means it’s time to increase the load.Just how does this process of musclegrowth and adaptation occur?  There aretwo basic mechanisms that come into play:hypertrophy and hyperplasia.  

Musclehypertrophy means that an individualmuscle cell gets bigger.  This occurs as itbuilds more myofibrils by adding moreactin and myosin (and other associatedstructures).  In other words, an individualmuscle cell builds more contractile pro-teins inside it, making it increase in diam-eter.  This of course also makes it stron-ger and able to generate more force whenit contracts.  Muscle hyperplasia describesthe situation of adding more muscle cells.Hypertrophy is an increase in muscle cellsize, and hyperplasia is an increase inmuscle cell number.  The overwhelmingbody of scientific evidence indicates thatmost muscle growth is the result of hy-pertrophy (2,3).  If you take biopsysamples of muscle before and after a train-ing program, you will see that after train-ing there are still about the same numberof muscle fibers (muscle cells), but thateach muscle fiber is bigger in diameter.This indicates that hypertrophy is a moreimportant adaptive response to exercisetraining that is hyperplasia.  Several stud-ies with bodybuilders do indicate howeverthat muscle hyperplasia can occur.  Inthese studies it was found that bodybuild-ers had more muscle fibers (cells) percross-sectional area than untrained con-trols (2,3).  

One experiment with catsdemonstrated a 9% increase in fiber num-ber following 101 weeks of resistance legtraining (2,3).  To reconcile these obser-vations with the body of data suggestingthat most muscle growth occurs by fiberhypertrophy, it was suggested that in or-der for muscle cell hyperplasia to occurthe training stimulus must be of high in-tensity, with heavy resistance and lowrepetitions (2,3).  Most studies in exer-cise physiology use untrained subjects,with moderate to low resistance and higherrepetitions.  While both growth mecha-nisms are probably at play in bodybuild-ers, most experts agree that most musclegrowth occurs by hypertrophy of exist-ing muscle fibers.When muscle cells do undergo hyper-plasia, what is the source of the newmuscle cells and the stimulus for theirgrowth?  This question is of course ofgreat interest to bodybuilders, since it isthe door to almost unlimited musclegrowth.  New muscle cells are believedto derive from differentiation and prolif-eration of satellite cells.  Satellite cells arelittle tiny cells not much bigger than nu-clei, and are found along the periphery ofmuscle fibers.  Satellite cells seem to bemost active during the growth of the fe-tus, while it is rapidly forming new muscletissue.  During adult life, satellite cells canbe induced to turn into new muscle cellsby factors released from damaged musclecells (4).  

When satellite cells were placedin culture dishes it was found that theycould be induced to differentiate (turn intonew muscle cells) by adding an extractfrom minced or ground up muscle tissue(4).  An extract from undamaged muscleor from some other tissue could not dothe trick.  Thus it appears that muscle cellscontain some substance that can leak outwhen the cell membrane is damaged, andthis substance acts as a signal to causethe satellite cells to grow.  The idea is thatsatellite cells represent a reserve sourceof precursor cells that can be called uponfollowing muscle damage, to make newmuscle cells and repair the damagedmuscle.This all makes sense if you think aboutit.  We know that most muscle cell hy-perplasia comes about as a result of highresistance training with heavy weight (2).We also now that high resistance train-ing, especially the eccentric phase of themuscle action, results in the most muscledamage (1,2,3).  Finally, we also knowthat high resistance training is the mosteffective stimulus for increasing musclesize and strength (1,2,3).  So it all fitstogether.  And this is why it’s vitally im-portant for bodybuilders to pay specialattention to the lowering phase of eachrep – it’s the most important part of therep for stimulating muscle growth.  Youshould always lower the weight slowlyand resist the weight on the way down.

This type of training will make you sore,but it’s the best stimulus for musclegrowth.  I don’t recommend negative-onlytraining, however.  You still need the posi-tive (lifting) part of the rep to fully workthe muscle and to exhaust its ATP stores.Since the muscle requires ATP to relax aswell as to contract, if you use up the ATPin the positive phase of the movement,this will result in greater microtraumaduring the eccentric phase.  And this, pre-sumably, will trigger a greater adaptiveresponse and more muscle growth.The Parrillo program is founded on thebasics to help this process work at peakefficiency.  I’m sorry, but there really areno tricks or secrets.  It takes dedication,consistency, and hard work.  What do youdo?  First, you have to make every work-out count.  Every workout must be in-tense enough to stimulate muscle growth,or you’re just wasting your time in thegym.  You have to attack each workout.Think of the weights as enemies to beconquered – to be slaughtered.  Walk intothe gym with a feeling of overwhelmingpower.  The weights simply are not strongenough to resist you.  You WILL lift heavyweights today.  Get in there, kill theweights, and get out.  

That’s your job.Second, supply your body with morethan adequate amounts of every nutrientit needs to build muscle.  Protein, carbo-hydrate, vitamins, minerals, branchedchain amino acids – and most importantly, a foundation of solid nutritious food.  Startwith a solid bodybuilding diet and addsupplements to boost cellular nutrient lev-els even higher.  Don’t compromise onnutrition.  Can you imagine going to allthat work of busting your butt in the gymand then not growing because of sub-op-timal nutrition?  The optimal bodybuild-ing diet is laid out in detail in the ParrilloPerformance Nutrition Manual.  Whichfoods to eat ,which foods to avoid, howmuch protein, carbs, and fat, how manycalories, how many meals, and everythingelse you need to know.  It even comeswith a food scale and a food compositionguide, so you can precisely structure eachmeal for optimal results.  After the foun-dation is laid with the right foods, thenadd in supplements to boost nutrient lev-els even higher.  Start with the basics: Hi-Protein Powder™, Pro-Carb™, , Vitamins,and Minerals.  Add in Muscle Amino™,  forextra branched chain amino acids — theprimary structural amino acids in muscleprotein.  If you’re a hard gainer or wantfaster results, add in CapTri®.  

CapTri®supplies calories which are preferentiallyused for energy, sparing amino acids sothey can be used to build protein insteadof being burned as fuel.  The special thingabout CapTri® is that excess calories fromCapTri® are readily burned as body heatinstead of being converted to body fat.This makes CapTri® THE BEST way toadd calories to your diet in a way that willminimize body fat.  It’s a hard gainer’sdream come true.Third, get adequate rest to allowmuscles to recover between workouts.This is a must.  Remember, muscles don’tgrow in the gym – they get damaged inthe gym.  The growth phase occurs dur-ing the next couple of days following aworkout while the muscles are recover-ing.  You have to get adequate rest forthis recovery process to occur optimally.There’s no simple answer to the questionsof how often should you train eachmuscle, or how many days a week shouldyou train.  Trainers and muscle physiolo-gists have been studying this for years,and still don’t know the answer.  The rea-son is that the optimal training protocol isdifferent for different people.  Hard gain-ers do better with less work and moretime for recovery – say, training three daysa week on a one on — one off schedule.People who are naturally muscular andgain muscle easily often can train more,three on and one off, for example.  Somepeople even do well training every day,training one muscle group each day.  Someprofessionals train twice a day.  

The opti-mal schedule for you depends or your ownbody’s recovery ability as well as howmany other stressors you have in yourlife.  If you work 60 hours a week, forexample, this takes a big toll on your re-covery ability, and you probably won’t beable to recover from daily workouts.  Pro-fessional bodybuilders don’t have anyother job to worry about, so they are atan advantage in terms of recovery.  Youwill have to experiment to find the bestroutine for your body.  There are somebasics however, that are true for every-body.  You have to train hard.  You haveto give each workout everything you’vegot.  You have to keep slowly increasingthe resistance and getting stronger.  TheParrillo Performance Training Manualdescribes all the best exercises for body-builders, with descriptions of proper ex-ercise performance and sample routines.There’s enough in there to take you fromthe beginning level all the way through theprofessional ranks.Start off with the Nutrition and Train-ing Manuals, which are where you get theinformation you need to reach your body-building goals.  At any time, feel free tocall or write with questions or for per-sonal counseling.  We support our pro-gram all the way – we don’t just sell yousomething and then turn you loose.  Whatsets us apart is that Parrillo is a compre-hensive package, a total program of train-ing and nutrition, which is supported allthe way.  We supply information, not justsupplements.

 We actually teach you whatyou need to know to become the best youcan be.  Who else does that?  Who elsesends out a free magazine to customerswith scientific information about body-building endocrinology, cellular energymetabolism, and muscle physiology justParrillo Performace Guide to Muscle, Part Vto educate customers so they can get themost out of the workouts?  Nobody else.A lot of people sell supplements, but no-body else does what we do.  We’re forreal.  We’re here for the few people outthere who are really serious about reach-ing their goals.  We believe that peoplewho are dedicated and work hard in thegym deserve results.  When you buysupplements from somebody else, that’sall you get.  But when you buy supple-ments or a manual from Parrillo, that’sjust the beginning of a relationship.  That’sour commitment to you.  To supply notonly the products, but more importantlythe support and information you need toget results.  That’s why the serious peopleend up with Parrillo.


1. Baechle TR. Essentials of StrengthTraining and Conditioning. Human Kinet-ics, Champaign, IL, 1994.

2. Wilmore JH and Costill DL. Physi-ology of Sport and Exercise. Human Ki-netics, Champaign, IL, 1994.

3. McArdle WD, Katch FI, and KatchVL. Exercise Physiology – Energy, Nutri-tion, and Human Performance. Lea &Febiger, Malvern, PA, 1991.

4. Lieber RL. Skeletal Muscle Structureand Function. Williams and Wilkins,Baltimore, MD, 1992.

2018-03-13T11:10:37-04:00 May 20th, 2009|Technical Supplement Bulletins|

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