Cold showers are unlikely to cool the body sufficiently to interfere with muscle-building processes.

“It's hard for me to imagine that taking a brief cold shower after a strength or hypertrophy training session would completely reverse or short circuit the effects of that strength and hypertrophy training. But again, if you're neurotically attached to getting every last bit of strength and hypertrophy out of your training sessions, then by all means, err on the side of caution and wait four hours or more to do your cold shower just as you would wait four hours or more to do your cold water immersion.”