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http://www.seomoz.org/blog/the-beginners-checklist-for-small-business-seo

This is a complex issue because if, for example, you decide to include more informative textual content, the consequent increase in rank and traffic may not off-set the drop in conversion rate that a 'new informative' layout might result in.  That said, I think you can find creative ways to move in the direction of informative without sacrificing conversion.  You may even find conversion improving, but you'll only figure this out through experimentation. I would introduce new textual elements- articles (targeted text) to compliment your already successful homepage- and also fill in the basic 'holes' in your strategy outlined above. A side note: fitness has a huge internet presence.  Get social and take advantage of the many bloggers who are happy to host a good colorful article or video about such 'unconventional' training.