I am excited that muscle is nowrecognized as being important for every-one, not just bodybuilders and other ath-letes. You’ve probably seen medical re-ports on the news showing 80 and 90year-olds lifting weights. Even in ad-vanced age, resistance exercise makesmuscles stronger and improves quality oflife. It allows people to be more activeand self-sufficient, and it reduces injuries(such as falls) as well. Muscle atrophy(when muscles get smaller and weaker)is so common that it is considered a nor-mal part of aging. In actuality, disuse isprobably the main culprit.
Resistancetraining can certainly slow down, andeven reverse, many of the signs of physi-cal decline usually attributed to aging.Strength training is also becom-ing more popular among young people,including women. People have found thatthey cannot achieve the lean, muscular,shapely body they desire by aerobic exer-cise alone. All of the Ms. Fitness com-petitors I work with include weight train-ing as part of their program. If your goalis to be lean and firm with good muscletone, but not to get big muscles, remem-ber that muscles are the place where bodyfat is burned. So if you want to lose yourfat, you’ve got to work your muscles.Resistance exercise increases lean bodymass and thus metabolic rate, causing yourbody to burn more fat 24 hours a day. Itincreases growth hormone, improves glu-cose tolerance, and lowers cholesterol lev-els. Simply put, it makes you look better,feel better, have more energy, and livelonger. The fountain of youth has beendiscovered, and it’s in the gym.This series of articles will explorethe structure, function, physiology, bio-chemistry, and metabolism of muscle. Iwill explain basic scientific concepts ofmuscle as well as training strategies forincreasing muscle size and performance.Bodybuilders, of course, are pri-marily concerned with increasingmuscular size. Power lifters careabout muscular strength. Cy-clists and runners train to im-prove muscular endurance.Other athletes, such as bas-ketball and football play-ers, are concerned mainlywith muscular powerand speed.
Each ofthese concerns de-scribe a different pa-rameter relating tomuscular perfor-mance. The firstpractical trainingstrategy we’ll men-tion is a principleof muscle physi-ology known astraining speci-ficity (1,2,3).It simplymeans that amuscle willspecificallyadapt to thetype oftrainingstimulus thatis applied toit. The sec-ond practicalprinciple tolearn is theconcept ofintensity. Inorder tocause amuscle to change, or adapt, it must bechallenged by an exercise stimulus whichexceeds some threshold of intensity.The reason exercise causesmuscles to get bigger and stronger is thatthe exercise load places a physical andmetabolic demand on the muscle. In or-der to elicit an adaptive response (i.e., toget the muscle to grow) the exercisestimulus must be intense enough to rep-resent a challenge to the muscle. Duringthe next few days after the training ses-sion, if adequate nutrients are supplied,the muscle responds by getting strongerso that next time it will be better able tomeet that exercise challenge. The most effective exercise stimuli tax the muscleby pushing it to the limit of its perfor-mance abilities.
After a very intense train-ing session it can take as long as two weeksfor the muscle to completely recover andadapt. Of course, optimum nutrition andsupplementation can speed up the processover what can be achieved with merelyadequate nutrition, and that’s where ourNutrition Program comes in.The training specificity principlestates that a muscle will adapt structur-ally and functionally in a manner appro-priate to the type of stimulus applied, pro-vided that the stimulus is intense enoughto elicit an adaptive response at all (inten-sity threshold). To illustrate this con-cept, compare the legs of a bodybuilderwith the legs of a marathon runner. Bothof them train their legs hard, pushingthemselves to the limit. The bodybuildertrains his legs with squats, and over timedevelops huge muscles. The marathonertrains his legs by running long distances,and over time improves his speed andendurance, but he never develops hugeleg muscles. Can the runner squat asmuch weight as the bodybuilder? Ofcourse not. He hasn’t trained his legsto lift heavy weights. Can the body-builder run a marathon? Of course not.
He hasn’t trained his legs to do that. Toillustrate the concept of the intensitythreshold, consider someone who wantsto build massive biceps by curling onepound dumbbells. Consider the sprinterwho trains by walking the 100 yard dash.I think you can see intuitively that theseathletes will not significantly improve inperformance because the training stimu-lus is not intense enough to challenge themuscles to grow.So the first thing to do when de-signing an exercise program is to decidewhat your goals are. Do you want tomaximize muscle size, strength, power,speed, or endurance? These goals are notthe same, and different training programsare appropriate for each. We’ll describehow to train effectively for each of theseparameters as we go along. For now, let’sstart off with some definitions. Increasesin muscle size come about by increasesin muscle cross sectional diameter (1,2,3).We’ll get into the cellular and molecularbasis of this later. Muscle strength is de-fined as the maximum load (weight) thata muscle can lift one time (1,2,3). Thus,the one rep maximum (1RM) is a mea-sure of muscle strength. Someone whocan curl a maximum of 100 pounds onetime is twice as strong as someone whocan curl a maximum of 50 pounds onetime. Speed describes how fast a musclecan contract, and how fast it can move aload. Endurance describes how long amuscle can perform a given task beforefailing. Someone who can curl 50 pounds20 times before failing has biceps withtwice the endurance of someone who cancurl 50 pounds 10 times before failing.
In general, you want to train with heavyweights and low repetitions (3-6) to in-crease in strength, and with lighter weightand more reps (say 15-30) to increase inendurance. This is a result of the trainingspecificity principle. In both cases, youwant to train to muscular failure on thatset. Training for strength in the 5 reprange means picking a weight which isso heavy that you can perform 5 repeti-tions, but no more. Performing a set of 5reps with a weight which you could havelifted 20 times will do you no good. Theintensity is too low. In weight training,intensity describes a level of effort wherethe set is carried to the point of momen-tary muscular failure – keep doing repsuntil you couldn’t get another even ifsomebody was holding a gun to yourhead. If you’re just trying to tone andfirm your muscles, you don’t have to takeit that far. But if you’re going for sizeand strength, that’s what it takes.Muscle power is a little morecomplicated to define. From physics wehave three mathematical equations forpower. Strictly speaking, power is de-fined as work performed per unit time, orpower = (work/time). Since work isequal to (force X distance), power =(force X distance)/time. And finally, sincespeed is equal to (distance/time), power= (force X speed). Muscle power thenis the product of the force of contrac-tion and the speed of contraction (1,2,3).A person who can squat 300 pounds isstronger than a person who can squatonly 200 pounds. However, if the per-son squatting 200 pounds can do it twiceas fast, he will generate more power thanthe guy squatting 300 pounds.
We alsoknow from physics that kinetic energyequals (1/2) X (mass) X (velocitysquared), or KE = (m X v2)/2. Let’ssay you’re a football player and youwant to tackle someone (hopefully an-other football player). What matters inknocking that person over is how muchkinetic energy you can transfer to hisbody. This depends on the mass of yourbody and how fast you’re moving whenyou hit him. Since kinetic energy is pro-portional to velocity squared, a small in-crease in velocity can result in a large in-crease in energy. The same is true of hit-ting a baseball, a tennis ball, in boxing,and many other sports. This is why poweris the most important parameter of mus-cular performance in sports like football,baseball, basketball, tennis, and sprinting:because performance depends on bothforce and speed. It’s not just how hardyou hit the baseball (force) but also howfast you hit the baseball (speed) that willdetermine how much kinetic energy istransferred from the bat to the ball, andthus how far the ball will go.Training for size, strength, power,speed, and endurance are all different. Bodybuilders, power lifters and Olympicstyle weight lifters all train with weights.They perform largely the same exercisesand train at maximum intensity.
However,while the bodybuilders have biggermuscles, the power lifters can lift moreweight. This paradox is explained by thefact that when you lift weights you’re notonly training your muscles, you’re alsotraining your nervous system. In gen-eral, the bigger a muscle’s size (the largerits cross sectional diameter), the strongerit is. However, power lifters have trainedtheir nervous systems to recruit moremuscle fibers to fire at the same time.We’ll cover how to train for size versushow to train for strength in a future ar-ticle. Training for power includes somestrength training, but also includes somework with lighter weights that are accel-erated very rapidly to train the speed com-ponent. The branch of exercise physiol-ogy concerned specifically with trainingfor muscle power is called plyometrics(3,4), and we’ll get into that toward theend of the series. Training for size,strength, and power are similar, and allresult in bigger, stronger muscles.Training for endurance is verydifferent, results in a totally different adap-tive response, and does not make musclesget bigger or stronger (1-4). This is acomplex issue and is still an area of activeinvestigation. We’ll get into the specificslater. For now, let’s just say you can ei-ther have legs like Tom Platz, or you canrun a marathon, but probably not both. Ihave no doubt that Tom Platz could run amarathon, if he trained for it.
But by thetime he trained long enough to be able torun a marathon, his legs would be half asbig as they are now. A note to bodybuild-ers: don’t stop doing your aerobics! Youstill need aerobics to burn fat and pro-mote cardiovascular health. But remem-ber, you’re doing aerobics to burn fat, notto become an endurance athlete. Forbodybuilders, 30-45 minutes of aerobicsa day should be enough. If it’s not, you’renot following the diet. Our bodybuildersdo go up to one to two hours of aerobicsa day, but that’s only for a few weeksbefore a contest. It’s far better just notParrillo Performace Guide to Muscle, Part Ito get fat in the first place, then you won’thave to do too much aerobics and run therisk of losing muscle.Next month we’ll pick up withthe microscopic anatomy of muscle, andexplain the cellular and molecular basis ofmuscle contraction. After we understandthe structure of muscles and how theywork, we will discuss how they adapt tovarious training stimuli. This leads rightinto how to design training protocols toachieve your particular goals. Until then,keep pumping!
1. Wilmore JH and Costill DL. Physiol-ogy of Sport and Exercise. Human Kinet-ics, Champaign, IL, 1994.
2. McArdle WD, Katch FI, and Katch VL.Exercise Physiology – Energy, Nutrition,and Human Performance. Lea & Febiger,Malvern, PA, 1991.
3. Baechle TR. Essentials of StrengthTraining and Conditioning. Human Kinet-ics, Champaign, IL, 1994.
4. Komi PV. Strength and Power in Sport.Blackwell Scientific Publications, Oxford,1992.