What would be the suitable source of content for health fitness articles for my blog?

Well, I have booked a domain name to begin a blog on health care and fitness. I’m looking at outsourced content. It may be from the freelance writer, any other kind of contributor or online sources etc. The health fitness articles should be well researched and properly written. What would be the suitable source of content for Health fitness articles for my blog? I want real, accurate, useful information of 500 plus words per article. I need expert articles on health and fitness, especially weight training and power lifting. please suggest me something.