Muscles. We have over 600 of them. They make up between 1/3 and 1/2 of our body weight, and along with connective tissue, they bind us together, hold us up, and help us move. And whether or not body building is your hobby, muscles need your constant attention because the way you treat them on a daily basis determines whether they will wither or grow. Say you're standing in front of a door, ready to pull it open. Your brain and muscles are perfectly poised to help you achieve this goal. First, your brain sends a signal to motor neurons inside your arm. When they receive this message, they fire, causing muscles to contract and relax, which pull on the bones in your arm and generate the needed movement. The bigger the challenge becomes, the bigger the brain's signal grows, and the more motor units it rallies to help you achieve your task. But what if the door is made of solid iron? At this point, your arm muscles alone won't be able to generate enough tension to pull it open, so your brain appeals to other muscles for help. You plant your feet, tighten your belly, and tense your back, generating enough force to yank it open. Your nervous system has just leveraged the resources you already have, other muscles, to meet the demand. While all this is happening, your muscle fibers undergo another kind of cellular change. As you expose them to stress, they experience microscopic damage, which, in this context, is a good thing. In response, the injured cells release inflammatory molecules called cytokines that activate the immune system to repair the injury. This is when the muscle-building magic happens. The greater the damage to the muscle tissue, the more your body will need to repair itself. The resulting cycle of damage and repair eventually makes muscles bigger and stronger as they adapt to progressively greater demands. Since our bodies have already adapted to most everyday activities, those generally don't produce enough stress to stimulate new muscle growth. So, to build new muscle, a process called hypertrophy, our cells need to be exposed to higher workloads than they are used to. In fact, if you don't continuously expose your muscles to some resistance, they will shrink, a process known as muscular atrophy. In contrast, exposing the muscle to a high-degree of tension, especially while the muscle is lengthening, also called an eccentric contraction, generates effective conditions for new growth. However, muscles rely on more than just activity to grow. Without proper nutrition, hormones, and rest, your body would never be able to repair damaged muscle fibers. Protein in our diet preserves muscle mass by providing the building blocks for new tissue in the form of amino acids. Adequate protein intake, along with naturally occurring hormones, like insulin-like growth factor and testosterone, help shift the body into a state where tissue is repaired and grown. This vital repair process mainly occurs when we're resting, especially at night while sleeping. Gender and age affect this repair mechanism, which is why young men with more testosterone have a leg up in the muscle building game. Genetic factors also play a role in one's ability to grow muscle. Some people have more robust immune reactions to muscle damage, and are better able to repair and replace damaged muscle fibers, increasing their muscle-building potential. The body responds to the demands you place on it. If you tear your muscles up, eat right, rest and repeat, you'll create the conditions to make your muscles as big and strong as possible. It is with muscles as it is with life: Meaningful growth requires challenge and stress.
Mišići. Imamo ih preko 600. Čine između jedne trećine i polovine mase naših tela, i zajedno sa vezivnim tkivima, povezuju nas, drže nas uspravnim i pomažu nam da se krećemo. Bez obzira da li je bodibilding vaš hobi, mišićima je potrebna vaša stalna pažnja jer način na koji se ophodite prema njima svakog dana određuje to da li će splasnuti ili će narasti. Recimo da stojite pred vratima, spremni da ih otvorite. Vaš mozak i mišići savršeno usklađeno vam pomažu da ovo ostvarite. Prvo, vaš mozak šalje signal motornim neuronima u vašoj ruci. Kada oni prime ovu poruku, pale se i mišići se skupljaju i opuštaju, što vuče kosti u vašoj ruci i stvara neophodni pokret. Što je izazov veći, to je jači signal u mozgu i veći je broj motornih jedinica u akciji koje vam pomažu da ostvarite zadatak. Ali šta ako su vrata od čistog gvožđa? Ovde sami mišići vaše ruke neće moći da stvore dovoljno pritiska da se ona otvore, tako da vaš mozak priziva ostale mišiće u pomoć. Namestite stopala, zategnete stomak i ukočite kičmu, stvarajući dovoljno sile da ih otvorite. Vaš nervni sistem je samo iskoristio ostale resurse koje već imate, druge mišiće, kako bi iznašao rešenje. Dok se ovo sve dešava, vlakna vaših mišića prolaze kroz drugu vrstu ćelijske promene. Kako ih izlažete naporu, dobijaju mikroskopska oštećenja, što je u ovom kontekstu dobra stvar. Kao odgovor na to, povređene ćelije ispuštaju upalne molekule, citokine, koji aktiviraju imuni sistem koji popravlja povredu. Ovde se dešava magija rasta mišića. Što je veća ozleda mišićnog tkiva, vašem telu će biti potrebno više da se oporavi. Posledični ciklus oštećenja i oporavljanja na kraju mišiće čini većim i jačim jer se prilagođavaju sve većim zahtevima. Pošto su naša tela već prilagođena većini svakodnevnih aktivnosti, one uglavnom ne proizvode dovoljno opterećenja da stimulišu novi rast mišića. Kako bi se izgradili novi mišići kroz proces zvani hipertrofija, naše ćelije moraju da se izlože većem naporu nego što je uobičajeno. Zapravo, ako stalno ne izlažete svoje mišiće nekom otporu, oni će se skupiti, što je poznato kao mišićna atrofija. Nasuprot tome, izlaganje mišića veoma visokom naponu, naročito dok se mišići istežu, što je poznato kao ekscentrično skupljanje, stvaraju se efektivni uslovi za novi rast. Ipak, mišići se oslanjaju na više od same aktivnosti kako bi rasli. Bez pravilne ishrane, hormona i odmaranja, vaše telo nikada ne bi moglo da popravi oštećena mišićna vlakna. Protein u našoj ishrani čuva mišićnu masu tako što daje gradivne materijale za novo tkivo u obliku aminokiselina. Adekvatno unošenje proteina, zajedno sa prirodnim hormonima, poput faktora za rast - insulina i testosterona, pomažu da se telo prebaci u stanje gde se tkivo popravlja i raste. Ovaj ključni proces popravke uglavnom se dešava kada odmaramo, naročito noću dok spavamo. Pol i godine utiču na ovaj mehanizam popravke, zbog čega mladi muškarci sa više testosterona imaju prednost u rastu mišića. Genetski faktori takođe imaju udela u sposobnosti rasta mišića. Neki ljudi imaju robusnije imune reakcije na oštećenja mišića i bolje popravljaju i zamenjuju oštećena mišićna tkiva, povećavajući svoj potencijal za rast mišića. Telo odgovara na zahteve koje pred njega stavite. Ukoliko mišiće pokidate, pravilno jedete, odmarate se i ovo ponovite, stvorićete uslove da vaši mišići narastu što je više moguće. Sa mišićima je kao sa životom: smislen rast zahteva izazove i napor.