What is Primal running?
Primal running is running in a shoe that has no cushioning, a very thin flexible sole, the same height at the front and back. It is similar to barefoot running, but with a little extra protection from abrasion.
Options for Primal footwear
Vibram FiveFingers (VFF)
The VFF range of shoes is very popular for Primal Running. They are a thin sole combined with just enough material to hold them to your foot. Each toe has a separate pocket, hence the name FiveFingers.
VFFs were created for boating, not running, but they have become hugely popular for many sports. In fact, it can be hard to get some of the VFF shoes as demand outstrips supply. I would recommend either the KSO (Keep Stuff Out) or the KSO Treks. The Trek version has a leather upper and a thicker sole, with a tread pattern.
It's been known for a long time that running barefoot is more efficient than running with shoes. It's been assumed that this is because of the weight of the shoes, but a recent study has shown running in FiveFingers is more efficient than traditional running shoes .
I have not used Feelmax shoes, but they have a very good reputation in primal runners. Feelmax shoes have a very thin (1mm, 0.04 inch) sole made of a Kevlar composite. This sole is very flexible and provides great feel. It also provides very good puncture resistance, which protects the foot. The shoes are also very light at about 4 oz.
Huarache Racing Sandals
I have no experience of these, but Barefoot Ted sells running sandals inspired by the Tarahumara Indians
Some people have been running in moccasins, especially in colder weather.
Options for near-Primal footwear (minimalistic)
The Nike Free are running shoes that are light weight, with very flexible soles. The sole is not thin, but is made flexible by deep groves in the sole. The Nike Free is a great minimalist running shoe and a half way house to Primal running. There is no outer sole (the hard rubber that meets the road), just a robust midsole (the cushioning part). The deep groves cut into the midsole allow the shoe to flex more than is possible with a traditional shoe. There are lots of different models of Nike Free, each with a number that indicates how flexible they are. The scale of the number is based on 10.0 as a traditional shoe and a 1.0 a barefoot. I would recommend using the Free 3.0, which is not as close to barefoot as the number suggest. A more realistic rating might be 6 or 7. I have been running in Nike Free for about 5 years and I believe they have helped me stay injury free in that time.
The biggest downside of the Nike Free from a Primal running standpoint is that it has a heel that is higher than forefoot. (Most shoes have 12mm high forefoot and 22mm high heel.) I take a knife and cut the heel down so it is roughly level with the forefoot. The Nike Free is ideal for this as it does not have a separate outsole. The midsole (the cushioning bit) is designed to be tough enough to withstand contact with the ground. It is relatively easy to cut the heel of the Nike Free away to produce a flat shoe. I find this is much closer to primal than the unmodified Free.
Some racing flats are popular as minimalist shoes. I have used the Nike Mayfly and I know that the Mizuno Universe is also recommended by the POSE method. I think the Nike Free offers better value for money, but these shoes are worth considering.
Modify your old shoes
Another cheap option is to take an old pair of running shoes and modify them. To do this, you would need to cut off the heel of the shoe to be level with the forefoot. This may work if your existing shoes are reasonably lightweight and flexible anyway, but not all shoes are suitable.
Some people have got on well with Converse style canvas sneakers, which are cheap and easy to find. Note: this is not the same as cheap running shoes. These canvas sneakers have very little sole.
Running barefoot is different to Primal running, but both fit under the general concept of 'natural running'. There are advantages and disadvantages to barefoot running. The biggest advantage is that it is cheap and easy. It is a great way of finding out what it's like to run without traditional shoes. Even if you don’t intend to do much in the way of barefoot or primal running, this is an easy thing to test out the idea without having to spend any money. Just try running for a short distance on a treadmill or on a grassy area. This should give you a sense of how different this style of running is.
A shoe to avoid - The Newton
Newton shoes focus on forefoot running by adding extra height to the forefoot of the shoe. I purchased a pair thinking they would move me closer to barefoot running. The result of the high forefoot is an unstable shoe. What I found was the Newton takes a bad idea (the traditional running shoe) and makes it worse. I hated running in the Newton shoes, but I think they are a valuable lesson. Natural running requires a minimalist shoe, not a more complex one. You can get a better alternative to the Newton just by hacking the sole off an old pair of running shoes. I would advise you to avoid these shoes.
 FiveFingers footwear is more efficient for runners than conventional running shoes