What are your thoughts or some good resources on barefoot sports/training/running? I have ran barefoot for the past three years and have increasingly recommended it to those that I train or that train with me. I also see that many of the trainees go sans shoes. Is this for a purpose or just their preference?
For most of the guys who train barefoot it's a crossover from jiu-jitsu or MMA. Those sports are done barefoot so those athletes often train in the gym barefoot to maintain foot strength, sensitivity, callouses, etc.
Others wear shoes in the gym because it's what they are used or the movements are safer with shoes on (box jumps, rowing, etc). Unfortunately most of these shoes have some foam cushioning underfoot that places the heel higher than the toe. When doing the DL or OHS where detailed awareness of weight distribution is needed most will go barefoot. For many movements weight should be on the heels so if the construction of the shoes shift weight forward it's a mechanical barrier. Also, foam cushioning compresses unevenly with use and time, which can affect tracking of the knees and the load on connective tissue in all weight-bearing joints. Going barefoot can improve alignment, and proprioception.
The rule of thumb we use is to go barefoot when lifting a high percentage 1RM, or when doing any technical practice (Oly lifts, DL, OHS, etc). For circuits or movements without heavy loading Rob wears flat, hard-soled wrestling shoes. Some others wear Chuck Taylors or their normal "running" shoes for these workouts.
I used to spend most of the winter in climbing boots or ski boots so each spring I had go through a period of walking and running barefoot (on grass) to rebuild the foot musculature I lost over during the previous months. Any footwear that provides "too much" support, i.e. ski boots, cycling shoes, ice climbing boots, ice and inline skates, etc. reduces the use of the stabilizing muscles in the feet, which can have an overall negative effect on posture. As you have learned, the body is mechanically designed to go barefoot, and the advent and use of shoes contradictory to this. I think we can get away with, and benefit from lighter, more flexible footwear in many situations, as long as the period of reintroduction isn't too quick or the loading too radical.