I am running this sport site http://www.ifithd.com/ and in my mind training for mixed martial arts, lifting weights and eating healthy and even do Yoga is not in different niches. You have to do it all. But what Google think? Is this site for 1 niche or 3-4 different? Or it is more general like "Sport related niche"? Is it better to focus only on one of those things or I can write about them all and don't get any penalty for too wide topic?
if you throw your domain through the google keyword tool - itll tell you the keywords it thinks are relevant to your site... google - keyword ideas and put your url in...
I don't think this is what I need. But I'll take that I am in SPORT. So I can write about everything sport related. And getting backlinks from sport related sites is good for me.