Is it? The entire point of a placebo is that it does lead to measurable change that can be very significant.

> The change is real, even if it would be caused by something else.

... such as a placebo effect. Placebo can lead to real, significant change. To the extent that there has been serious discussion about harnessing the placebo effect (the primary issue being the ethics of lying to a patient).

> But, my primary point was meant to be that the results of the study don't imply placebo, through many comments here throw it around a lot. (I am not sure what kind of effect they would want to see through.)

The study doesn't imply placebo, but the issue is whether or not it rules it out. Part of the problem here is that designing a good placebo for cold showers is not straightforward. You could try to convince people of the positive health benefits of cold showers and try to convince a different group of the positive health benefits of a pill, but you'd still then not have blinded study, and you'd have a hard time demonstrating that any difference in effect isn't simply down to people finding the cold showers more convincing.

Note that this is not saying you shouldn't do cold showers if it works for you. If it works for you, it doesn't matter if it's a placebo effect or not. The issue of whether or not it is a placebo is more about mechanism. In other words: Is it actually something about the showers? Or is it something about the way you were convinced to think the showers had an effect? It matters because it may affect how this treatment works for others, and how consistently it works, and because a placebo mediated effect can change over time as cultural expectations change (e.g. placebo effect of sugar pills have gone up as people have become accustomed to using pills to solve medical problems).

But if the effect is there for you, that ought to be secondary to you. If it works without causing any harm, then awesome.