I recently discovered this series of videos by this company called EAS. In this one they talk about core strength and how important it is for weight training and all physical activity.
Core strength is one of the most neglected facets of martial arts training and yet everything depends on it.
We love to train our upper torso and our legs but sometimes we forget about the middle of the body. If the core is not powerful we cannot execute techniques correctly.
This video talks about alignment and how to keep your core in the optimal position for performance.