{"schemaVersion":1,"id":"en-hub-adaptations","type":"hub","pillar":"adaptation","locale":"en","translationGroupId":"hub-adaptations","slugPath":"adaptations","title":"Adaptations: how the body changes","shortTitle":"Adaptation","summary":"The Adaptation pillar answers one question: how does the body change when it is trained? Three mechanisms and two videos describe muscle growth, the role of mechanical tension and the synthesis of proteins.","level":"intermediate","estimatedMinutes":4,"synonyms":["adaptation","hypertrophy","muscle growth","progressive overload","volume"],"blocks":[{"id":"b1","type":"paragraph","content":[{"kind":"text","value":"The Adaptation pillar answers the question: how does the body change when the same effort is asked of it regularly?"}]},{"id":"b2","type":"paragraph","content":[{"kind":"text","value":"A single session builds nothing on its own. It produces a signal. What we call adaptation is the response the body constructs afterwards, between sessions, over weeks and months. This pillar therefore separates three things every time: the stimulus, the immediate response, and the lasting change."}]},{"id":"b3","type":"heading","level":2,"text":"Three time scales","anchor":"three-time-scales"},{"id":"b4","type":"paragraph","content":[{"kind":"text","value":"The pages in this pillar keep coming back to the same distinction, because it is what makes research results readable."}]},{"id":"b5","type":"list","ordered":false,"items":[[{"kind":"strong","value":"During the session"},{"kind":"text","value":", the muscle produces force and accumulates fatigue. Nothing has been built yet."}],[{"kind":"strong","value":"In the hours that follow"},{"kind":"text","value":", the body launches chemical responses, among them the making of new proteins in the fibre."}],[{"kind":"strong","value":"Across several weeks"},{"kind":"text","value":", repeating those responses eventually alters the structure of the muscle."}]]},{"id":"b6","type":"paragraph","content":[{"kind":"text","value":"Confusing those scales leads to the most common misunderstandings: believing that a hard session equals an effective session, or that an absence of soreness signals an absence of progress."}]},{"id":"b7","type":"heading","level":2,"text":"What this pillar explains","anchor":"what-this-pillar-explains"},{"id":"b8","type":"list","ordered":false,"items":[[{"kind":"text","value":"What sets off a muscular adaptation, and what does not."}],[{"kind":"text","value":"How "},{"kind":"term","value":"mechanical tension","definition":"the force exerted on muscle fibres while they contract or resist being lengthened"},{"kind":"text","value":" differs from the simple sensation of effort."}],[{"kind":"text","value":"The role of training volume and accumulated fatigue, and why the two should not be conflated."}],[{"kind":"text","value":"What the body does with dietary protein after a session."}],[{"kind":"text","value":"What remains debated: optimal intensities, frequencies and durations are the subject of an evolving literature."}]]},{"id":"b9","type":"heading","level":2,"text":"How to work through the pillar","anchor":"how-to-work-through-the-pillar"},{"id":"b10","type":"paragraph","content":[{"kind":"text","value":"One reading order gives the clearest bearings."}]},{"id":"b11","type":"list","ordered":true,"items":[[{"kind":"strong","value":"How muscle grows"},{"kind":"text","value":" sets the general frame: signal, response, time scale."}],[{"kind":"strong","value":"Mechanical tension, fatigue and volume"},{"kind":"text","value":" details the variables training actually acts on."}],[{"kind":"strong","value":"Muscle protein synthesis"},{"kind":"text","value":" goes one level down, to the proteins that make up the fibre."}]]},{"id":"b12","type":"paragraph","content":[{"kind":"text","value":"The two videos in the pillar cover the same content in animated form. They do not replace the written pages: the sources, the levels of certainty and the limits sit in the text."}]},{"id":"b13","type":"callout","tone":"insight","title":"What to keep in mind before reading","content":[[{"kind":"text","value":"Adaptation is measured in weeks, not in sessions. What you feel during or just after a session — heat, pump, soreness — tells you about the effort you put in, not about the change that will follow."}],[{"kind":"text","value":"No page in this pillar makes it possible to predict the result of a programme for any given person. The response to training varies widely between individuals on an identical protocol."}]]},{"id":"b14","type":"heading","level":2,"text":"What this pillar does not do","anchor":"what-this-pillar-does-not-do"},{"id":"b15","type":"paragraph","content":[{"kind":"text","value":"Body Lab explains mechanisms. It offers no programme, no load and no personalised training frequency, and it sets no numerical goal. Where a practical action exists, it is flagged by an explicit link to Shapier, never by an instruction slipped into the text."}]},{"id":"b16","type":"paragraph","content":[{"kind":"text","value":"The figures quoted on the detailed pages always come with their context: the population studied, the duration, the training conditions. A single study is never presented there as a general certainty."}]},{"id":"b17","type":"shapierAction","actionId":"dossier-hypertrophie-progression","label":"Putting hypertrophy and progression into practice","description":"Planning how loads and volumes progress across the weeks is done in Shapier; Body Lab only explains why these variables matter.","webTarget":"https://shapier.app/en/dossiers/hypertrophie-progression","appTarget":"shapier://dossiers/hypertrophie-progression"},{"id":"b18","type":"heading","level":2,"text":"The pages in the pillar","anchor":"the-pages-in-the-pillar"},{"id":"b19","type":"relatedContent","title":"The whole Adaptation pillar","targetIds":["en-mechanism-motor-command","en-mechanism-motor-learning","en-mechanism-how-muscle-grows","en-mechanism-tension-fatigue-volume","en-mechanism-muscle-protein-synthesis","en-mechanism-dietary-protein","en-video-muscle-growth","en-video-protein-synthesis"]}],"relations":[],"authors":["equipe-editoriale-shapier"],"reviewers":["Thanh Chau"],"references":[],"review":{"publishedAt":"2026-08-02","reviewedAt":"2026-08-02","reviewDueAt":"2027-08-02"},"limitations":["This entry page describes how the pillar is organised; the mechanisms, their levels of certainty and their sources are set out on the detailed pages."],"seo":{"title":"Adaptation — how muscle changes when you train it","description":"The entry point to the Adaptation pillar of Body Lab: muscle growth, mechanical tension, fatigue, volume and protein synthesis, and how to work through them.","canonicalPath":"/en/adaptations","image":"/og/en/hub-adaptations.png"},"app":{"offlineEligible":true},"version":1}