After enjoying all those holiday treats, you might be thinking about joining a gym. But ever wonder what's lurking on that equipment? Marketplace puts gyms to the ultimate test, swabbing all the popular surfaces to reveal how germy gyms can be, and how you can protect yourself when you work out.

Plus: Do you really need protein powder? For decades, consumers have believed a protein shake within one hour of their workout will make all those weights they're lifting worth it. But we're about to kill the buzz and break down how you can get the same protein you need from food instead.

And…Cold Plunging has taken our feeds by storm... but the science behind the benefits of ice baths is about as solid as the ice some people are swimming in. We kill...or should we say..chill...the buzz.