Scroll down for the English version
深蹲、衝刺、舉重、波比跳，每一個動作都從神經系統開始。肌肉動起來之前，訊號已經先送出去了。
神經系統是什麼
神經系統是身體的通訊網路。大腦和脊髓是中樞，負責接收資訊、做決定、下指令。從大腦和脊髓延伸到全身的神經，叫周邊神經系統，負責把身體的訊號送回中樞，再把指令送出去。
周邊神經系統又分幾個部分。其中兩個和運動最有關：體神經系統管你自己決定要做的動作，例如把槓鈴推過頭頂；自律神經系統管你不用想的事，例如心跳、呼吸和流汗。
一堂課裡它在做什麼
協調動作：同一個弓步，要有很多條肌肉照順序用力，不需要的肌肉要放鬆。這些都是神經系統在安排。
維持平衡和姿勢：單腳分腿蹲、棒式撐住的時候，身體一直在做很小的調整。
調整心跳、呼吸和體溫：運動越用力，心跳越快、呼吸越深，身體也開始流汗散熱。這是自律神經系統在配合你的強度。
兩個方向：加速和減速
自律神經系統有兩個分支。交感神經讓身體進入「準備行動」的狀態，心跳加快、人比較警醒，你衝最後一組的時候就是它在推。副交感神經的作用方向相反，會讓心跳慢下來。研究觀察到，這兩個分支平常多半一個上升、另一個就下降，像蹺蹺板。
對你的訓練有什麼用
第一，剛開始練重量，進步很快，不一定是肌肉變大了。美國運動醫學會（ACSM）的重量訓練立場聲明指出，沒有訓練基礎的人在訓練初期，神經方面的適應占主要部分，肌肥大要等到大約六週後才明顯。神經系統學會招募更多的肌肉，用得更協調，所以同樣的肌肉，你會用得比以前好。
第二，技術比重量重要。動作是神經系統學出來的，先用你能掌握的重量，把動作做穩，再慢慢加。同一份聲明也指出，要讓肌肉有持續的進步，需要漸進式增加負荷，也就是一次加一點重量或多做幾下，不要一次加太多。
第三，休息日要留。ACSM 的聲明提到，訓練計畫裡安排休息日，是為了讓身體恢復，並降低過度訓練的機率。
以上是一般的運動知識，每個人的狀況不同。有受傷、疼痛、慢性疾病，或是正在懷孕，請先問醫師；上課時覺得頭暈、胸悶、想吐或心跳不正常，請立刻停下來告訴教練，並且去看醫生。
參考資料
Ratamess NA, Alvar BA, Evetoch TK, Housh TJ, Kibler WB, Kraemer WJ, Triplett NT. American College of Sports Medicine position stand: Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687-708. https://pubmed.ncbi.nlm.nih.gov/19204579/
Murtazina A, Adameyko I. The peripheral nervous system. Development. 2023;150(9):dev201164. https://doi.org/10.1242/dev.201164
Weissman DG, Mendes WB. Correlation of sympathetic and parasympathetic nervous system activity during rest and acute stress tasks. Int J Psychophysiol. 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC7987796/
F45 Training 總部，What Is the Nervous System? 2026 年 9 月。https://f45training.com/article/what-is-the-nervous-system/
本文改寫自 F45 Training 總部的會員文章，內容已大幅精簡並依台灣的情況調整。
這是一般的運動資訊，不是醫療建議。調整訓練之前，請先問教練；健康方面的問題，請諮詢醫師。本文引用公開的學術資料，不代表任何機關或學會為 F45 背書。
Every squat, sprint, lift and burpee starts with your nervous system. The signal goes out before the muscle moves.
What the nervous system is
The nervous system is your body’s communication network. The brain and spinal cord are the centre: they take in information, decide, and send out instructions. The nerves that run from them to the rest of the body are the peripheral nervous system, which carries signals from the body back to the centre and instructions back out again.
The peripheral system has several parts. Two matter most for exercise. The somatic system handles movements you choose to make, such as pressing a barbell overhead. The autonomic system handles things you do not have to think about, such as heart rate, breathing and sweating.
What it does in a class
Coordinating movement: a single lunge needs many muscles to fire in order while the ones you do not need stay quiet. The nervous system arranges that.
Balance and posture: in a split squat or a plank your body is making small adjustments all the time.
Heart rate, breathing and temperature: the harder you work, the faster your heart beats, the deeper you breathe and the more you sweat. The autonomic system is matching the effort.
Two directions: speeding up and slowing down
The autonomic system has two branches. The sympathetic branch puts the body in a “get ready to act” state, with a faster heart rate and more alertness. It is what you feel on the last round. The parasympathetic branch works the other way and slows the heart. Research on the two branches finds that, in general, when one rises the other tends to fall, a bit like a seesaw.
What this means for your training
First, when you start lifting, progress can come quickly even though your muscles have not grown. The American College of Sports Medicine (ACSM) position stand on resistance training says neural adaptations predominate in the early stages of training for people new to it, and that muscle growth becomes evident from around six weeks. Your nervous system learns to use more of the muscle you already have, and to use it in a more coordinated way.
Second, technique comes before load. Movement is learned by the nervous system, so start with a weight you can control, make the movement steady, then add a little at a time. The same position stand says progressive overload is needed to keep muscle improving, meaning small increases in weight or a few more reps at a time.
Third, keep your rest days. The ACSM position stand notes that rest days are built into a training plan to allow recovery and to reduce the chance and size of overtraining.
This is general exercise information and everyone is different. If you have an injury, pain, a medical condition, or are pregnant, ask your doctor first. If you feel dizzy, short of breath, nauseous or notice an unusual heartbeat in class, stop, tell a coach and see a doctor.
References
Ratamess NA, Alvar BA, Evetoch TK, Housh TJ, Kibler WB, Kraemer WJ, Triplett NT. American College of Sports Medicine position stand: Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687-708. https://pubmed.ncbi.nlm.nih.gov/19204579/
Murtazina A, Adameyko I. The peripheral nervous system. Development. 2023;150(9):dev201164. https://doi.org/10.1242/dev.201164
Weissman DG, Mendes WB. Correlation of sympathetic and parasympathetic nervous system activity during rest and acute stress tasks. Int J Psychophysiol. 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC7987796/
F45 Training HQ, What Is the Nervous System? September 2026. https://f45training.com/article/what-is-the-nervous-system/
Adapted from an F45 Training HQ member article, substantially shortened and revised for Taiwan.
This is general information, not medical advice. Ask a coach before you change your training, and talk to a doctor about any health question. Citing published research does not imply endorsement of F45 by any organisation.
