Livestrong.com is an authority site with PR7. It has tons of quality content related to health, fitness and lifestyle niche. Getting backlinks from this site would really help your site/blog ranking considering the link relevance. They are using a social media application called "Pluck Blog" which enables registered users to create a blog and post content. It also offers blogroll where you can add upto 10 links with anchor text. If you are a firm believer of link relevance, create a blog over there. Post content related to your niche and drop backlinks. Also make use of the blog roll. Use it as your "Buffer" site. Do SB/Xrumer blast and whatever you want!