Feet muscles are one of the most important muscles to train in order to become more athletic in my opinion. Training the feet muscles is something overlooked by most athletes and coaches. In the judo community, "foot sweeps" require strong feet and some judo athletes train the feet but they are probably not realizing all the other benefits they get by this type of training. Training the feet muscles can improve speed, power and balance. Athletes that perform in the field are moving in various directions and this movement starts in the feet. In my opinion quality of movement and agility is linked with the performance of feet muscles.
One of the best ways to strengthen the feet is balance training on PVC pipes. This is something that is becoming more popular among the MMA community. This type of training rewires your nervous system, which I believe is a big part of the human performance puzzle. If you have not seen my article on this type of training and rewiring the nervous system, please check out my article titled: "Turkish Get Ups With Water Bottles and The Whole Puzzle Of The Athletic Game"
This type of training technically is proprioception training. Proprioception is basically one's awareness of their body in space based on the sensation received by proprioceptors which are sensors in limbs that provide information on joint angle, muscle length, and muscle tension.
Athletes generate force from the ground. Imagine if you were standing on ice and you were trying to push something. It would be very difficult since you do not have something to push off from. I hope this example gives you an idea of how important the feet are for force production. As someone once said "A chain is not stronger than it's weakest link." This applies to the body and all muscles must be strong for maximum performance. Strong feet are the foundation for athletes the generate strength.
When I first started balance training on PVC pipes, I noticed I was getting faster and more agile on the mat then when I was doing judo. My balance improved and I was not getting thrown as much. This gave me a sense of confidence and I was able to stay more relaxed during sparring seasons. Being able to be relaxed during sparring can help combat athletes conserve energy. I highly recommend this type of training for athletes that need to perform. Squats and deadlifts are great but they do not train the feet muscles as these exercises do. PVC pipe feet exercises are for elite athletes that are trying to get an edge. It can be very dangerous if it is not done right under supervision of a coach. I would not do this type of training on PVC pipes that are larger than 3 inches in diameter.