Today, I went out to do a metabolic conditioning workout. I didn't really have a plan, so I just made it up as I went along. I did a number of short sprints with brief rests, and then a few other sprints with long rest periods.
As I went back home and thought about things more, I realized that this type of variety in metcon workouts is crucial. In a Paleolithic environment, there were not any workouts (hunts) with standardized times and rest periods. The hunting situation dictated the physical demands, and these demands would be slightly different each time. For example, if a person trains to do 20-second sprints with 10 second rest periods, but then is called upon to do a 60 second sprint, they will have trouble. Therefore, I think the first principle of doing Paleo-based metcons is to have lots of variety from workout to workout. For example, Crossfit Endurance prescribes a lot of interval workouts, but there is plenty of variety. In a Paleolithic setting, there would be a need to be more of a generalist in terms of metabolic fitness.
The second principle would be to remember that Paleo metcons are all about locomotion. This means the focus should be on covering ground by foot and not by bicycling, swimming, or other substitutes. This could lead to a MovNat-style workout where a person is moving through obstacles to cover ground.
The third principle of Paleo metcons would be a natural surface. If at all possible, do the movements on grass or dirt to save wear-and-tear on the joints.
The fourth principle of Paleo metcons would be carrying loads. The reason a hunter-gatherer would do something resembling a metcon is to achieve a successful hunt. A successful hunt means carrying the load back to camp.
The fifth principle of a Paleo metcon would be celebration. After a successful hunt, a big meal and possibly a dance would ensue.
To summarize, a Paleo metcon would have the following components:
Repeated sprints with variation in intensity, duration, and rest periods
Focus on covering ground and moving through obstacles