It is based on the same fundamental principle as the diet aspect: what is best for us is what we were doing for tens of thousands of years.
What makes the best fitness program? Something that mimics the types of movements and activities we needed to do while hunter-gatherers.
He points out we have been walking, lots and lots, sprinting in a few cases, and then lifting heavy things.
Most of that is pretty self-explanatory, but what types of exercise mimic the lifting heavy things?
"Humans have been squatting, horizontal pressing, vertical pressing, climbing, and using their torsos to resist pushing and pulling forces for millions of years."
(See A Fitness Plan So Easy A Caveman Did It.)
How all this should fit together is best summarised by Mark's Primal Blueprint Fitness Pyramid:
He explains this further:
Lift Heavy Things – Resistance training is the cornerstone of fitness. Stronger people live longer, survive hardships better, and are able to enjoy life more fully than weaker people. Two to three Lift Heavy Things workouts of 7-30 minutes each week, employing the Four Essential Movements.
Run Really Fast Every Once in Awhile – Sprinting is the biggest “bang for your buck” exercise. It’s brutally effective and highly efficient, promoting growth hormone release, fat burning, and lean mass building, but you know why I really like sprinting? It’s over in ten to fifteen minutes, and you only gotta do it once a week.
Move Frequently at a Slow Pace – Slow movement is the foundation of fitness. Walking, hiking, gentle cycling… these aren’t about burning calories, they’re about maintaining the movement and the ability to move. Three to five hours a week.
And that's the basics of his method.
The things I like about his fitness program:
1. It's pretty simple, you don't have to know much about exercise to be able to do most of it.
2. It's reasonably balanced with some weights, anaerobic and aerobic exercise.
3. The majority of the exercise being done is aerobic so as a fitness program shouldn't be too stress inducing for a beginner. It would be difficult to over-train following this program.
One thing against it is that it requires a lot more time than most people are prepared to give to exercise when they are first starting out. People find it difficult to exercise for 30mins 3 times a week, which only really covers the weights and the sprinting, and doesn't account for the large amount of time needed for the cardio work.
So optimistically I think it is a great program, but realistically I don't know if many beginners are actually going to spend that much time. Most people have trouble sticking to the couch to 5k program which really is only 30mins 3 times a week.
However, if you can start adding in the longer, slower cardio work as part of your everyday life (walk to work once or twice a week, go for a bike ride on the weekend), and then use your 'exercise' time for the weights and sprinting, then you could see real results.
I don't really see that many other downsides to the program. What do you think?