Think sporting equipment and you're immediately thinking tennis racquets, cricket bats, or boxing gloves. But one piece of equipment almost every athlete requires is shoes. Different sports require different kinds of shoes, and a lot of research and careful scrutiny goes into selecting the right footwear.
Here's a look at some of the distinct footwear required for certain Olympic disciplines.
In fencing, movements such as the lunge can have an impact force of up to seven times the body weight on the heel of the lead foot, as the heel strikes the ground fast and at an extreme angle. In addition, there are many sudden changes in direction, forward and back as well as side-to-side, especially on the trailing foot.
Fencing shoes have good heel cushioning, set at an angle, to absorb those enormous impact forces.
The cushioning must not, however, be so much as to take away the fencer's feel for the strip. They are reinforced on the sides to cope with the changes in direction, and special attention is paid to ensure the medial (inner) side is durable. Their soles are designed to have good traction, to ensure stability on the strip, while the upper is made flexible and breathable.
Wrestlers' ankles are subject to immense stress, making them vulnerable to injuries. Their shoes must also have good grip, and be flexible and lightweight -- they must feel like the wearer is almost barefoot.
Wrestling shoes almost always go above the ankle -- the high-top design stabilises and protects the ankle from injury. A snug fit, as well as features like asymmetrical lacing and a strap across the ankle in some models, provides additional ankle support. They typically have rubber soles for superior traction on the mat, with circular tread patterns on the soles providing grip no matter the angle between the foot and the ground.
Some models have studded soles for increased purchase on the mat. A split sole shoe, which has the sole cut into a front piece and back piece, offers extreme flexibility and helps the wrestler be quick on their feet. A unisole shoe, which has a single, continuous sole, has a lower level of flexibility but offers better grip and is more durable.
Boxing shoes have similar requirements to the wrestling shoes: ankle support, lightweight, good grip and snug fit. However, the priorities of the traction required from the shoe differ between the two sports.
The tread pattern on boxing shoes are typically in a forward direction, maximising traction on forward and back movements, while decreasing resistance to lateral movements -- aiding boxers in making quick side to side movements to evade their opponents' punches.
In addition, boxing shoes are flat, unlike the elevated arch of wrestling shoes.
Good technique in the squat portion of a lift involves pushing one's weight down into the floor through the heel and then driving the body up through the lift in a powerful, fluid motion.
Weightlifting shoes have an elevated heel, typically half an inch to an inch in height -- to improve the biomechanics of the squat. It shifts the balance of the lifter's weight forward, which is compensated by a more upright torso, allowing for a deeper squat than that possible with flat-soled shoes. The elevated heel also allows greater mobility of the ankle joint, allowing one to lift more weight safely.
In addition, they have stiff, inflexible soles for stable, optimal transfer of force through the ground. A wide sole with good traction distributes the load and good grip ensures the foot doesn't slip. Some models come with what's called a metatarsal strap that goes across the middle of the shoe for increased support.
The criteria of shoes - weight, cushioning, spikes, fit, and shape, among others - vary based on the particular track-and-field discipline.
Broadly speaking, there are three categories for track-and-field shoes: for running events, jumping events and for throwing events.
Track running shoes differ from road running shoes -- they use spikes for better traction, have little to no cushioning and are lighter than road running shoes. There are three types of track running shoes -- for sprinting, middle distance and long distance.
Sprinting shoes are extremely lightweight, with virtually no cushioning, a minimal heel and midsole, and 7-8 spike pins or a spike plate.
Shoes for middle distances (800m to 3,000m) have some cushioning and a reduced number of spikes.
Shoes for long distances (3,000m to 10,000m) have the most flexibility and cushioning, and the smallest number of spike pins. As the distance increases, the cushioning increases and the number of spikes decrease to keep the weight in check.
Shoes for long jump and triple jump have an extra layer of cushioning for the impact and a flat heel for added power and stability.
High jump shoes have spikes for traction and a midfoot strap to keep the foot in place during the runup and takeoff.
Among the jumping shoes, pole vault shoes have the most rigid sole and the most padding in the heel.
Javelin shoes are bulky and have front and rear spikes, to help plant the thrower and bring them to a sudden stop.
Shoes for hammer, shot put and discus do not have spikes as they involve circular motions that do not require additional grip. Instead, they have a smooth but not slippery outsole for a fluid spinning motion. Some models, however, have a textured sole for grip.