The Greek philosopher Socrates said, "When our feet hurt, we hurt all over." The largest and strongest tendon in the foot, located on the back of the ankle, is named the Achilles tendon after the Greek hero Achilles.
Leonardo da Vinci called the human foot a work of art and engineering. The human body has 206 bones, with 26 bones in each foot, a quarter of all the bones in the body. These 26 bones are held together by over 30 joints, 20 muscles, more than 100 ligaments, a complex network of muscles, thousands of nerve endings, and blood vessels that allow for movement.
Because feet carry the weight of the body throughout one's lifetime, they need to be strong and sensitive, sturdy yet flexible. Each time a person takes a step, the foot must bear a force of 1.5 to 2 times the person's weight. Running requires the foot to bear a force of 2 to 3 times one's weight.
The foot has 250,000 sweat glands and releases approximately 500 milliliters of sweat per day. About two-thirds of people have feet of different sizes.
Around 70% of foot problems are caused by improper footwear, with much of it due to incorrect footwear during childhood. In the United States, about 70% of people have had foot pain at some point in their lives. The treatment of foot problems for people over 60 years old costs approximately $30 million per year in the United States, with much of it being caused by improper footwear or incorrect footwear during childhood.