An insole comprising an upper foot contacting substrate, a lower substrate, and a shock absorbing flexible substrate with a plurality of cylinders and a plurality of carrying strips. The strips are trapped between the upper and lower substrates.

A jumping assist system to be mounted in conjunction with each lower leg and foot of a human which will cause the imparting of additional energy during the jumping movement which will result in the individual being able to jump higher, especially in a succession of jumps, as well as having greater endurance in jumping. When the lower leg moves forwardly into the jump-ready position, a pulling force is applied from the lower leg to a tension brace which extends substantially parallel to the back of the leg to under the heel of the foot causing a forward rotational force at the ankle joint. This force will assist the individual in the jumping action. There is also a separate strap connection over the dorsum of the foot which extends along the bottom of the foot and under the heel, anchoring in the achilles area. This dorsum strap further assists in achieving an increased level of upward support and some rotational force that assists the individual in the jumping motion.

A shoe having a resilient strap running from under the forefoot to a rigid heal counter is provided. The shoe is constructed such that a fulcrum is provided under the strap so as to create a windlass effect during the normal walking cycle. This effect results in providing added support for the longitudinal medial arch of the wearer of the shoe.

An adjustable shoe heel spring and stabilizer device provides the wearer of a shoe the ability to adjust the energy absorption and return characteristics of the shoe to suit their particular needs. An operable adjustment device is located on an exterior surface of the shoe. The wearer operates the adjustment device to selectively position a fulcrum at a desired location relative to upper and lower members of a spring mechanism disposed within the mid-sole of the shoe. The position of the fulcrum defines the energy absorption and return characteristics for the shoe. An indicator is provided for displaying to the wearer the relative position of the fulcrum, and hence the energy absorption and return setting for the shoe.

A replaceable shoe heel spring assembly allows the wearer of a shoe to selectively change the energy absorption and return characteristics of the heel portion of the shoe by changing shoe heel spring cartridges. The wearer activates a release mechanism located on an exterior surface of the shoe and a cartridge containing a shoe heel spring is ejected from a location in the mid-sole of the shoe. Another shoe heel spring cartridge having different energy absorption and return characteristics can then be inserted into the mid-sole. The cartridge is securely held in the mid-sole by a locking mechanism connected to the release mechanism. The shoe heel spring is provided with a cover which matches the material of the mid-sole. The cover assists in preventing debris from entering the mid-sole. The selectable range of energy absorption and return characteristics is limited only by the number of cartridges available.