1 導讀現代智能手錶功能繁多，但除了步數和心率，HRV（Heart-rate variability，心率變異性） 正在成為健康達人們最關注的指標。它不僅能反映心臟健康，更是衡量身體壓力和自主神經系統狀態的“晴雨表”。PS：HRV為什麼“反直覺”？ 通常我們認為規律是好事，但在心臟跳動上，高度規律意味著壓力。就像一個緊張的士兵只會機械執行命令（交感神經主導），而一個放鬆的人則能靈活調整節奏（副交感神經參與）。HRV高，說明你的身體調控系統極其靈敏。2 核心詞彙與表達總結重點詞彙 (Key Vocabulary)indicator [ˈɪndɪkeɪtə(r)] n. 指標；跡象unconsciously [ʌnˈkɒnʃəsli] adv. 無意識地neurotransmitter [ˌnjʊərəʊtrænzˈmɪtə(r)] n. 神經遞質precisely [prɪˈsaɪsli] adv. 精確地interpretation [ɪnˌtɜːprɪˈteɪʃn] n. 解讀；詮釋常用短語 (Common Phrases)all else being equal / other things being equal 在其他條件相同的情況下chug along 穩步推進，（引擎等）持續運轉fight-or-flight 戰鬥或逃跑（應激反應）rest-and-digest 休息與消化in response to 響應；針對struggle with 掙扎於；費力應對go easier 放鬆點，別那麼拼3 ｜原文｜翻譯｜字詞｜A most useful indicator of overall health一個非常有用的整體健康指標"Heart-rate variability" has been decades in the making“心率變異性”這一概念的形成歷經數十年Modern smart watches can measure all sorts of health indicators. Step counts and heart rates sit at the simpler end of the array, whereas VO2 max and blood-oxygen levels are of more interest to committed health nuts. But a category currently attracting particular attention is heart-rate variability (HRV).現代智能手錶可以測量各種健康指標。步數和心率處於這一系列指標中較基礎的一端，而最大攝氧量（VO2 max）和血氧水平則更受堅定的健康狂熱者關注。但目前引起特別關注的一個類別是心率變異性（HRV）。As its name suggests, HRV measures not how quickly the heart beats, but how regularly spaced those beats are. With heart rate a lower score is usually better, other things being equal, since it suggests a high level of cardiovascular fitness. When it comes to HRV, though, a higher number—that is, a more irregular pattern—is generally what you want.顧名思義，HRV 測量的不是心跳的速度，而是這些心跳之間的間隔是否規律。在其他條件相同的情況下，心率通常是分數越低越好，因為這表明心血管健康水平較高。然而，當涉及到 HRV 時，數值越高（即心跳模式越不規則）通常才是你想要的。HRV arises from the way the body regulates the heart. Left to its own devices, the heart will chug along at 100 beats per minute or so. That default rate is nudged up or down by the opposing halves of the autonomic nervous system (ANS), which acts unconsciously to control things like body temperature, breathing and digestion.HRV 產生於身體調節心臟的方式。如果不加干預，心臟會以每分鐘 100 次左右的速度持續跳動。這個默認速率由自主神經系統（ANS）的兩個對立部分向上或向下微調，該系統在無意識下運行，控制體溫、呼吸和消化等。variability /ˌveəriəˈbɪləti/ n.可變性；易變性；反覆不定committed /kə'mɪtɪd/ adj. 堅定的，盡職的cardiovascular /ˌkɑːdiəʊ'væskjələ/ adj. 心血管的irregular /ɪ'reɡjələ/ adj. 不規則的，無規律的left to its own devices 聽任其自然發展chug /tʃʌɡ/ v.咕嚕聲；(發動機緩慢運轉時)發出突突聲nudge /nʌdʒ/ v. 推進，微調，輕推unconsciously /ʌnˈkɒnʃəsli/ adv.不知不覺地；無意地One half is the sympathetic nervous system, often known as the “fight-or-flight” system. This revs up the heart in response to things like exercise or fear or excitement. Its control is mostly exerted through hormones in the blood and neurotransmitters in the brain. That makes it a blunt instrument, and as the heart rate rises, so the time between beats becomes steadier.其中一半是交感神經系統，通常被稱為“戰鬥或逃跑”系統。它在應對運動、恐懼或興奮時會加速心跳。其控制主要通過血液中的激素和大腦中的神經遞質來實現。這使其成為一種“鈍器”（調節不夠精細），隨著心率上升，心跳之間的時間間隔會變得更加穩定。The other half of the ANS is the parasympathetic, or “rest-and-digest” system. This slows the heart down when it is time to relax. It communicates with electrical signals sent via the vagus nerve. That allows precise control from moment to moment, which makes the time between heartbeats more variable. (Your heart rate speeds up slightly when you breathe in, for instance, and slows down as you breathe out.)自主神經系統的另一半是副交感神經系統，即“休息和消化”系統。當需要放鬆時，它會減慢心率。它通過迷走神經傳送的電訊號進行通訊。這允許時刻進行精確控制，使得心跳之間的時間更加多變。（例如，當你吸氣時心率會略微加快，呼氣時則會減慢。）All else being equal, stress on the body boosts the sympathetic nervous system, decreasing HRV. All sorts of stress count, whether psychological or physical. A hard workout will cause HRV to fall for hours (or sometimes days) as your system recovers. So will lack of sleep, a cold, a failing marriage or worries about money.在其他條件相同的情況下，身體壓力會增強交感神經系統，從而降低 HRV。各種壓力都算在內，無論是心理上的還是生理上的。一次高強度鍛鍊會導致 HRV 在系統恢復期間下降數小時（有時是數天）。睡眠不足、感冒、婚姻失敗或對金錢的擔憂也會產生同樣的結果。sympathetic /ˌsɪmpəˈθetɪk/ adj.同情的；支援的；有同情心的；n.交感神經系rev /rev/ v.(使)快速運轉hormone /'hɔːməʊn/ n. 激素，荷爾蒙neurotransmitter /ˌnjʊərəʊtrænz'mɪtə/ n. 神經遞質parasympathetic /ˌpærəsɪmpə'θetɪk/ adj. 副交感神經的vagus nerve 迷走神經variable /'veəriəbl/ adj. 多變的，易變的psychological /ˌsaɪkə'lɒdʒɪkl/ adj. 心理的At a population level, higher HRV is a sign of an ANS that is in good nick, and a body that can adapt itself to the stresses of life. It is associated with a lower risk of heart attacks, and a higher chance of survival if you do have one. (It was in cardiology wards that HRV first proved its usefulness.) It is also associated with slower progression of dementia, less inflammation, a lower chance of suffering depression, and more.在群體水平上，較高的 HRV 是自主神經系統狀態良好、身體能夠適應生活壓力的標誌。它與較低的心臟病發作風險以及一旦發作後更高的生存機率有關。（HRV 最初正是在心臟病病房證明了其用途。）它還與痴呆症進展減慢、炎症減少、抑鬱風險降低等有關。Most people will be more interested in what HRV can tell them about their personal lives. The best way to think of it is as an “accumulated stress” score. For sporty types a low HRV may be a signal that the body is struggling with too much training, and a hint to go easier in the gym for a while. But the numbers need careful interpretation. A big day out on the bike will cause a low HRV in the morning. But so will beers at the pub afterwards (alcohol suppresses HRV), or an unexpected tax bill waiting at home.大多數人會更感興趣 HRV 能告訴他們關於個人生活的什麼。看待它的最佳方式是將其視為“累積壓力”評分。對於運動型人士來說，低 HRV 可能是一個訊號，表明身體正在應對過度訓練，並暗示應在健身房放鬆一段時間。但這些資料需要仔細解讀。騎自行車出遊一天會導致第二天早上 HRV 偏低。但在酒吧喝酒（酒精會抑制 HRV）或家裡等著的一張意想不到的稅單也會導致同樣的結果。Those nerdy enough to track HRV may therefore want to keep a journal to refer to alongside the charts. Knowing what the numbers are telling you, after all, is the difference between mere data and its much more valuable cousin—useful information.因此，那些痴迷於追蹤 HRV 的人可能希望在查看圖表的同時記錄日誌。畢竟，瞭解這些數字背後的含義，才是區分單純的資料和更有價值的資訊的關鍵。 (Chris的外刊閱讀筆記)in good nick 狀態良好（英國俚語）dementia /dɪ'menʃə/ n. 痴呆inflammation /ˌɪnflə'meɪʃn/ n. 炎症interpretation /ɪnˌtɜːprɪ'teɪʃn/ n. 解讀，解釋suppress /sə'pres/ v. 抑制，鎮壓nerdy /'nɜːdi/ adj. 書呆子氣的，痴迷技術的mere /mɪə/ adj. 僅僅的，只不過的