Account Deleted By User So it's been going through news that marathons cause kidney damage.  It's bullshit, and because you just fucking know that fat shits are going to use it as yet another excuse not to exercise I'll do a little explaining why for you shitfolk. First of all, the study cited was tiny.  As in 22 athletes.  Which basically means that any results from it fall into the category of "hey, that's kinda sort of interesting but there's not nearly enough evidence to prove anything definitively without a lot more research. Second, the study didn't actually show any kidney damage at all.  What it showed is that immediately after a marathon, a runner's creatinine levels spike.  Which, if you know anything about creatinine, is about as surprising as the statement that "water is wet." In case you don't know, creatinine is one of the main measures of kidney function.  It's a breakdown product of creatine, which is an important part of cellular respiration and is concentrated heavily in the muscles.  Which means that creatine (and therefor creatinine) fluctuates from person to person based on your muscle mass.  Men have more than women, and athletes have more than non-athletes.  And, as I'm sure you know, a lot of athletes also supplement creatine, which makes the levels of both molecules even higher in those individuals.  Some body builders might generate so much creatinine that their blood test looks abnormal, even with pristine kidneys. The breakdown from Creatine to creatinine happens at a pretty constant rate, based on the amount of creatine present.  So athletes/runners/lifters normally have more creatinine generated than non-athletes.  This isn't really that big of a deal, creatinine is mostly inert biologically and it just gets filtered out by your kidneys.  This is why we use creatinine as a marker for the kidney; If your kidney starts filtering your blood slower then your creatinine levels start to shoot up. But just because your kidneys slow down doesn't actually mean they're in trouble or damaged.  In fact, you expect to see this in response to dehydration and heavy sweating.  Like what happens when you exercise for an extended period of time. Such as, for example, in a marathon. Even if you're drinking and staying hydrated you're still going to be losing a significant amount of water and salt through your skin.  Which means that your kidneys need to switch to water conservation mode.  So your kidneys slow down a little bit, and your creatinine levels spike. And, as we already established, Creatinine production is higher in athletes.  So while your kidneys slow down your creatinine spike faster and higher than you'd see in a dehydrated non-athlete over the same time frame. But then the marathon ends.  You rehydrate and your kidneys pick up the pace again and your creatinine levels return to normal after a while.  Which is exactly what this study showed. Honestly, this study pisses me off.  Not the study itself, the science behind it sounds fairly solid.  It probably only cost a few hundred bucks to perform, and its results are entirely consistent with what we already knew about the human body.  But the interpretation being applied to it is so fucking far off base that it borders on malpractice. Running is not bad for your kidneys. Being a fat, worthless shit and drinking liters of soda every day, however, is a one way trip to dialysis town. Sorry that this is only tangentially related to FPH, but I thought you guys would find it interesting and hopefully it will help some of you smack down some excuses from the swine you can't avoid. (minor grammatical/clarification edits)