--- title: How Much Exercise Do I Need: Researcher Walks Back Running Claim description: A health researcher is walking back his claim that strenuous exercise places runners at equal risk of death as people who don't exercise. canonical: https://time.com/3809117/strenuous-exercise-study/ author: Justin Worland article:opinion: false article:content_tier: free article:published_time: 2015-04-08T14:09:52.000Z article:modified_time: 2026-08-04T08:05:16.589Z article:section: Health og:title: Strenuous Exercise May Not Be That Bad for You After All og:description: A researcher is changing his tune about his findings og:url: https://time.com/3809117/strenuous-exercise-study/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production og:image:width: 1200 og:image:height: 675 og:image:alt: TIME og:type: article twitter:card: summary_large_image twitter:title: Strenuous Exercise May Not Be That Bad for You After All twitter:description: A researcher is changing his tune about his findings twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production --- # Strenuous Exercise May Not Be That Bad for You After All > Sponsored content. 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A total body workout while you hang from a hammock._  by [Justin Worland](https://time.com/author/justin-worland/)  ## Justin Worland Senior Correspondent Apr 8, 2015 2:09 PM UTC  by [Justin Worland](https://time.com/author/justin-worland/)  ## Justin Worland Senior Correspondent Apr 8, 2015 2:09 PM UTC A health researcher is walking back his claim that strenuous exercise places runners at equal risk of death as people who don’t exercise at all, after the study received widespread media attention. The researchers should have presented the result as a possibility rather than a concrete finding, study lead author Peter Schnohr told the [BBC](http://www.bbc.com/news/magazine-32160231). “We should have said we suspect that it is so, but we can’t say for sure. Everybody makes some mistakes in papers,” he said. The study concluded that “strenuous joggers have a mortality rate not statistically different from that of the sedentary group.” Schnohr’s research, which received attention across many media outlets, including [TIME](http://time.com/3692668/when-exercise-does-more-harm-than-good/), looked at data on the health of thousands of runners and non-runners over a 12-year period. But its conclusions on strenuous exercise were drawn from a sample of only 36 people. The study reported the small sample size, something that Schnohr said sophisticated readers should have noticed. “It shouldn’t have been misunderstood,” he told the BBC. “If you normally read papers you could say ‘Ah!'” Strenuous exercise was defined as running at a speed of more than 7 mph for at least four hours per week. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/3809117/strenuous-exercise-study/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/3809117/strenuous-exercise-study/"},"headline":"Strenuous Exercise May Not Be That Bad for You After All","datePublished":"2015-04-08T14:09:52.000Z","dateModified":"2026-08-04T08:05:16.589Z","description":"A researcher is changing his tune about his findings","url":"https://time.com/3809117/strenuous-exercise-study/","keywords":["Exercise & Fitness","fitness"],"thumbnailUrl":"","author":[{"@type":"Person","name":"Justin Worland","jobTitle":"Senior Correspondent","url":"https://time.com/author/justin-worland/"}],"articleSection":"Health","image":[],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/exercisefitness/","name":"Exercise & Fitness"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/3809117/strenuous-exercise-study/","name":"Strenuous Exercise May Not Be That Bad for You After All"}}]},{"@context":"https://schema.org","@type":"VideoObject","name":"We Tried This: Aerial Vinyasa Yoga","description":"A total body workout while you hang from a hammock.","thumbnailUrl":"https://cdn.jwplayer.com/v2/media/68PN7sJl/poster.jpg?width=720","uploadDate":"2012-08-20T20:55:26.000Z","contentUrl":"https://cdn.jwplayer.com/manifests/68PN7sJl.m3u8","embedUrl":"https://time.com/3809117/strenuous-exercise-study/","duration":"PT1M28S","potentialAction":{"@type":"SeekToAction","target":"https://time.com/3809117/strenuous-exercise-study/?jw_start={seek_to_second_number}","startOffset-input":"required name=seek_to_second_number"}}] ```