Chris - check out the American Heart Association site at
www.americanheart.org as they have several key fact sheets.  As well,
the
Ottawa Heart Institute has guidelines tha closely follow the American
College of Sports Medicine ones (largely accepted as the international
standard).

Your local HSFO chapter can also link you with the Heart to Heart
support
group module that relates this to your question.  One of the video
modules
addressed it.

As well, the Centre for Activity and Aging through UWO in London, ON has
some data on their recommendations in this regard.  Speak to Gareth
Jones
there.

Hope this is useful -


Nancy Dubois
Community Facilitator- Southern Ontario
Active Living Community Action Project
(a project of OPHEA)