Probably just placebo. There is really nothing you can do to get rid of DOMS (Delayed Onsett Muscle Soreness), after a hard day. I'm not saying this to be pessimistic, it's pretty much just a fact. To understand why your muscles are sore, there's one thing you gotta know...
DOMS = torn microfibres. Torn microfibres heal within 24-48 hours, approx. The only way to heal microtears faster (note the word 'faster', not completely), is through proper nutrition (like a scoop of whey mixed with water or milk, taken before bed time) and by restitutional activities, like...
1. A light massage (deep tissue massage will actually make the DOMS worse), followed by a cold bath
2. A hot bath, followed by a cold bath
3. Sauna, followed by a cold bath
Depending on your muscular conditioning, you will STILL have DOMS in the morning, as microfibres don't just heal over night. But(!), you'll rid yourself of the lactic acid you've built up in your muscles. The lactic acid is the real sinner here (note that built-up lactic acid and DOMS have no connection to each other, what so ever). So, you while you will still be sore no matter what, your muscles will definetely not feel just as tired and "used", as it would otherwise be the case. Try it!