The timing of this weekend exercise conversation is interesting.  I
conversed with Dr. Cordain via email on this very subject.

I started the conversation by stating how wierd it is that the two "health
heresies" that I follow, paleo eating and high intensity weight training,
found significant help from Colorado State University, Dr. Cordain's
academic home for the last 21 years and where I went to college my freshman
year.  Arthur Jones, the founder of Nautilus and a high intensity weight
training pioneer, did a great deal of experimentation (or marketing,
depending on how you want to look at the science involved) at CSU in the
late 70's.

Jim: "... from an anthropological standpoint, what is your view on [Jones'
recommendation of] direct, single set, high intensity exercise?"

Dr Cordain:  "...our research group has studied the activity patterns of
hunter gatherers & they tended to be similar to modern day cross trainers
in that they did both aerobic and strength activities regularly.
Additionally, periods of intense activity were followed by relatively long
periods of rest."

Jim:  "Although they have been largely ignored by the mainstream both then
and now, I believe that the reason Jones' workout recommendations work so
well is because they might very well closely model the ideal
hunter/gatherer exercise pattern. Intense but brief work every two or three
days followed by periods of rest. Move quickly between exercises to
maintain heart rate.  Concentrate on the major muscle groups.

I happen to be in excellent physical condition.  Although I am not a runner
and never train prior to the event, I run the eight-mile Turkey Trot every
Thanksgiving here in Dallas.  I'm not trying to brag here, but would like
to point out that the aerobic capacity that makes it possible for me to run
eight miles without training is a direct result of the kind of weight
training I am doing.  Strength and aerobics in one.  Sort of a single
package cross training, if you will."

Dr. Cordain: "Yes, many others also believe that short burst of high
intensity training closely mimick those for which our genome as been
previously conditioned via natural selection. I think you may be on to
something!"