When bending sideways, the center of gravity and the body weight lean towards the side and the body weight and pressure from the body weight bear down on the side of the foot. The center of gravity does fall on the center of the sole but aligns with the side of the foot. The outer muscle group that extends from the outer side of the heel to the little toe bears all the weight. If that group of muscles of the foot is tight or fatigued, it will hurt. If the arch is also tight, the weight imbalance will also “arch” the arch muscles and pain will be felt in the arch on the inside of the foot.
All of this indicates that the foot muscles are tight, i.e., the foot is tight. Relax the foot by soaking it in hot water, use vapor rub and pain relief gel to rub and massage the foot.
A good exercise to relax tension in the foot is to roll the foot on a golf ball.
The outer side of the foot may hurt when one bends sideways after standing for a very long period.