the most common problems that I see in my office during sandal and flip flop season are tired feet, arch cramps, muscle spasms, calluses on the heel and ball of the foot, blisters on the toes and lower leg pain such as shin splints.
Shopping all day or standing on your feet for hours wears you out and results in tired feet, arch cramps, muscle spasms and shin splints. This can be lumped into one cause, abnormal pronation where the arch excessively collapses during the normal gait cycle. This leads to the muscles in the arch of the foot and lower leg to fatigue and tire because of the increased stress resulting in an overuse phenomenon causing foot and lower leg pain. The trigger is wearing non supportive sandals or flips flops.
Biomechanically speaking the foot is unstable and slides around when walking in those types of shoe wear. Toes will curl downward and try to grab the ground because of the instability in the joints of the foot. The muscles in the front of the lower leg will fire continuously and eventually fatigue and become tight and sore.
Dr Comfort orthopaedic sandals.