<story><title>Exercise Tied to Lower Risk for Some Types of Cancer</title><url>http://well.blogs.nytimes.com/2016/05/18/exercise-tied-to-lower-risk-for-13-types-of-cancer/?rref=collection%2Fsectioncollection%2Fhealth&amp;action=click&amp;contentCollection=health&amp;region=rank&amp;module=package&amp;version=highlights&amp;contentPlacement=1&amp;pgtype=sectionfront&amp;_r=0</url></story><parent_chain><item><author>jimrandomh</author><text>No. This study is confounded and provides no evidence of anything.&lt;p&gt;The problem is that people&amp;#x27;s willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can&amp;#x27;t distinguish between exercise causing reduced cancer risk, or a third variable affecting both.</text></item></parent_chain><comment><author>agumonkey</author><text>I can attest to that. I had weaker health a few years ago (lack of activity mainly) but I could kick a regular schedule of activity to get back on track. An accident broke my health below the self help threshold. When you&amp;#x27;re worried you can&amp;#x27;t jog, even walk, it&amp;#x27;s hard to bootstrap the exercice-health cycle again.</text></comment>
<story><title>Exercise Tied to Lower Risk for Some Types of Cancer</title><url>http://well.blogs.nytimes.com/2016/05/18/exercise-tied-to-lower-risk-for-13-types-of-cancer/?rref=collection%2Fsectioncollection%2Fhealth&amp;action=click&amp;contentCollection=health&amp;region=rank&amp;module=package&amp;version=highlights&amp;contentPlacement=1&amp;pgtype=sectionfront&amp;_r=0</url></story><parent_chain><item><author>jimrandomh</author><text>No. This study is confounded and provides no evidence of anything.&lt;p&gt;The problem is that people&amp;#x27;s willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can&amp;#x27;t distinguish between exercise causing reduced cancer risk, or a third variable affecting both.</text></item></parent_chain><comment><author>Someone1234</author><text>The same could be said of almost any study that tried to show this. It is unethical to design the study in the way you&amp;#x27;re suggesting (i.e. stop people exercising to see if they get cancer).&lt;p&gt;They did however:&lt;p&gt;&amp;gt;  Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment.&lt;p&gt;So even for two thin people, exercise seems to have helped. I legitimately don&amp;#x27;t see how you could design a study that you&amp;#x27;d be satisfied with.</text></comment>