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.
肌肉 我們有超過600塊肌肉 佔身體重量的三分之一到二分之一 與結締組織 將身體連結在一起, 讓我們站,讓我們動 無論健身是不是你的興趣愛好 肌肉都需要你的持續關注 因為你每日使用的方式 可決定肌肉的消長 比如說你站在門前面,準備拉開門 你的大腦和肌肉會 完美協調幫你達成目標 首先,你的大腦會給手臂 的運動神經元發送信號 當它們接到信號,它們就會啟動 造成肌肉收縮和放鬆 拉動手臂的骨骼作出相應的行動 動作的挑戰越大, 大腦發送的信號就越強 越多的運動單位會聚集幫助你達成任務 但是如果這扇門是鐵門呢? 現在,單憑你手臂的肌肉 是不可能產生足夠的拉力來開門的 所以你的大腦會叫其他肌肉來幫忙 你站穩腳,收腹,挺直腰 產生足夠的力量使勁拉開門 你的神經系統剛剛挪用身體現成的資源 其它肌肉 來滿足需求 當這一切發生時 肌肉纖維進行另一種細胞改變 當肌肉承受拉伸,會發生微細的損傷 在這種狀況下,是一件好事 對此反應,損傷的細胞釋放出 稱為“細胞因子”的發炎分子 用來激活免疫系統和修復損傷 這就是增長肌肉的魔法 肌肉組織的損傷越大 身體就會進行越多的自我修復 損傷和修復導致的循環 最終使肌肉更大更強壯 以便可以適應逐漸更大的需求 因為我們的身體已經 適應大多數的日常活動 通常日常活動就無法產生足夠的壓力 來刺激新的肌肉生長 所以,增長新的肌肉, 所謂“肥厚增生”的過程 必須承受比平常更高的工作負荷 事實上,如果你不持續讓肌肉承受一些阻抗 肌肉會縮小 這個過程稱為“肌肉萎縮” 相對的,讓肌肉承受高強度張力 特別是肌肉拉伸時 也被稱為“離心性收縮” 可為新的肌肉生長產生有效的條件 然而,肌肉增長不只是 依賴助長生長的活動 沒有合適的營養、賀爾蒙,和休息 身體永遠不能修復受損的肌肉纖維 飲食中的蛋白質能維持肌肉的質量 藉著以氨基酸的形式,提供 組成單位給新生肌肉組織 藉著以氨基酸的形式,提供 組成單位給新生肌肉組織 足量的蛋白質攝入, 再加上天生的荷爾蒙, 比如類胰島素生長因子和睾固酮 可協助身體進入組織已 修復和生長的狀態 這個重要的修復過程 主要發生在休息的時候 尤其是晚上睡眠時 性別和年齡也會影響修復機制 這就是為什麼有較多睾固酮的年青人 在肌肉增長有優勢 基因因素也會影響一個人增長肌肉的能力 有些人對肌肉損傷有更加強大的免疫反應 而且對損傷的肌肉纖維 有較佳修復和替換的能力 增大增長肌肉的潛能 身體會對你的需求做出反應 如果你撕裂肌肉,補充營養, 好好休息,持之以恆 你將創造使肌肉儘可能 變大變強壯的條件 肌肉增長就和生命一樣 有意義的成長需要挑戰和壓力