Weather 
A new trend is spreading. Well, a new trend that involves a very old pastime.
Introducing: the “churn and burn,” a viral challenge that gives all new meaning to the phrase “grocery run.”
It started when a couple of Oregon-based trail runners decided to test out how easily they could make butter in their vests during a run. The answer, they discovered, is that it’s actually a pretty smooth process.
It was earlier this year that Libby Cope and her boyfriend Jacob Arnold, both 30, were first inspired to make a batch of hands-free dairy.
Cope had poured some decadent cream-top milk into her morning coffee, naturally prompting Arnold to ask: “Do you think if we ran with this it would turn into butter?”
“And then we went to the store, got a real heavy cream, and went for a run,” Cope tells The Post.
The actual technique was only slightly more involved: First, the pair poured their heavy cream into a Ziploc bag — a total of 32 ounces, which, they told Runner’s World, was a bit over the top in retrospect. They then added a good shake of sea salt. That bag went inside another Ziploc bag, and they were ready to hit the trails.
Their hypothesis was that the jostling of their bodies during their roughly hour-long run would transform the heavy cream into a solid. The proof, in this case, wasn’t in the pudding, but in the yellowish gunk they managed to spread on a piece of bread at the end of their workout.
Cope, who’s also a professional content creator, was sure to capture every step of the butter creation on video for her channels.
And the experiment was an instant hit with the culture, whipping up over 11 million views on Instagram.
While footage of another runner’s proprietary trail-run chocolate ice cream and frosted lemonade have also shaken up the running community, Cope and Arnold weren’t able to find examples of anyone who had made butter this way before.
But since Cope’s initial post, several other runners have attempted to recreate the magic. One documented her run-concocted corn juice honey butter, while another attempted the churn-and-burn in a snowstorm.
But the ideal conditions for run butter are actually a bit warmer. Cold cream will have a harder time turning into butter because the liquid molecules will be moving slower than if they were at room temperature. (And if you add ice to the bag, you might wind up with ice cream.)
Too hot, however, and the cream will stay runny.
Based on her experience, when it comes to the length of the run, Cope says the five to six mile range “is definitely the sweet spot.”
But the type of run is an equally important consideration, too. “I think being on a trail is really helpful because of the higher impact. I don’t think pace really matters as long as it’s shaking.” She and Arnold kept to a 10-minute pace, she estimates.
The couple has since enjoyed their butter on pasta at home, and they’re working on a batch of homemade sourdough that they’re excited to smother.
If nothing else, the promise of a delicious snack seems to be enough to convert some newbies into bona fide running fanatics.
“I’ve received so many comments saying ‘I guess this is what gets me into running,’ which I love,” Cope says.
Maybe other sports could benefit, too, from this kind of smear campaign.
