VKTRY Performance Insoles Opinion Paper
VKTRY Performance Insoles (aka “VKs”) were designed to 1) Improve performance by increasing the amount of ground force that a human can generate, and 2) Reduce the chance of lower extremity injury.
Improved Performance Benefits of the VK:
The VK Performance Insole improves performance by increasing the amount of elastic (potential) energy in the eccentric phase of movement and releasing that energy by reducing the time between dorsiflexion and plantarflexion in the concentric phase. VKs create no energy of their own. The insoles simply use the energy that an athlete produces and focuses it directly back into the ground resulting in more efficient movement, less energy dissipation and increased athletic performance.
In plyometric terms, during the eccentric phase of the SSC, VKs reduce the force load on the joints by absorbing the load created eccentrically and assisting the preload of elastic energy by storing it at dorsiflexion. The unique arched shape of VKTRY Insoles assists in the eccentric phase by preloading energy at midstance. During the concentric phase, VKs rapidly releases the energy stored during the eccentric phase during plantarflexion. This release of energy in the sagittal plane, propels the athlete efficiently forward, upward or laterally.
On a more granular level, VKTRY Performance Insole reduce the transition between the eccentric and concentric phases (amortization), by increasing elastic tension, thereby exploding through amortization, encouraging a smooth, rapid transition to the concentric phase, allowing for improved plyometrics. By storing more energy eccentrically, this energy is released more explosively and at a faster rate thereby reducing amortization by minimizing ground contact time.
In addition, the increased rate of the plantarflexion moment encourages optimal COM (center of mass) weight distribution, Posterior/Lateral to Anterior/Medial, by attenuation of shock at heel strike, progressing smoothly through mid-stance (preloading the VKs), advancing through the loading phase (heel off) and progressing to the explosive phase (toe-off).
This smooth transition reduces joint loading by increasing elastic (potential energy) and assisting in the concentric phase, thereby negating the necessity of the joints to take all of the load.
- The Dynamic support structures of the foot and lower leg, such as the tibialis posterior, tibialis anterior and flexor hallucis longus are assisted due to VKs’ response to deflection in the sagittal plane.
- The Passive support structures, of the foot, plantar aponeurosis, plantar calacaneonavicular ligament, long and short plantar ligaments are supported by the VKs’ stability in the frontal plane.
Due to the unique carbon fiber orientation and biasing of VKTRY Insoles, energy return in the sagittal plane is optimized but stability in the transverse and frontal planes are maintained. VKs are designed to flex sagittally but remain rigid in inversion/eversion. If VKs flexed during medial or lateral movements, stability would be compromised. Unlike traditional insoles that offer one product for all body weights, VKs are available in 5 flexibility ratios (“Pro” levels) based on a proprietary algorithm specifically designed for the athlete. Depending on the athlete’s weight, foot size and sport, an appropriate “Pro” level is determined. The “Pro” level is based on how much deflection force an athlete can comfortably exert on VKs – this force is stored and released back to the athlete, as shown in the graph below as a percentage of athlete weight.
For example, a 40 yard combine sprint would require a maximum amount of propulsive power because the athlete only has about 4-5 seconds, (18-22 steps) to perform and indeed the difference between winning and losing is often determined in the first 10 yards. A decrease of .03 seconds can mean the difference between a gold medal and not even placing. Conversely, during longer events, lower Pro levels (i.e. – more product flexibility) are recommended for more consistent energy return and greater comfort.
This cycle of eccentric-amortization-concentric forces in rapid succession, each one focused by the VK, can result in a cumulative effect that is material.
Injury Protection Benefits of the VKTRY Insole:
Along with its considerable performance benefits, VKs also provides protection against a number of injuries common to athletes. With the advent of artificial turf fields and athletic shoes with very flexible soles, metatarsophalangeal sprains otherwise known as turf toe, have become more commonplace. Serious athletes want to return to training and competition as soon as possible, sometimes ignoring the possible consequences.
Carbon fiber plates, also known as turf toe plates, have been used for many years to manage the symptoms of MPJ sprains and accompanying damage to the plantar ligaments and sesamoid apparatus. Because of the anatomy of the distal foot and the unique use of the foot to push off at a mechanically disadvantaged position, it is often impossible to properly tape or brace the joint. VKs limit dorsiflexion and plantarflexion of the MPJ prophylactically, in order to keep it within the acceptable functional range both in hyperextension and hyperflexion.
As a result of damage to the 1st metatarsalphalangeal joint, not only is normal ROM (range of motion) impaired but the ability of the 1st ray to provide any meaningful push is limited. Because of its propulsive properties, VKs can, help a recovering athlete replace some of the lost ground force. A great majority of these athletes will develop hallux limitus or rigidus and VKs can be beneficial by keeping the joint supported.
Many studies have shown the maximum safe dorsiflexion angles of the 1st MPJ are somewhere within the range of 52°- 60° of dorsiflexion, deemed the most mechanically advantageous angles allowed for proper joint function. Above these dorsiflexion limits, the condyloid complex with its articulations are at a mechanical disadvantage because of the extreme angle. As shown in the graph above, VKs provide a preventative deflection force at dorsiflexion angles over 60°, thereby reducing the chance of MTP injury.
The human foot does not react well to torsional forces. Inversion of the rear foot combined with eversion of the forefoot or vice versa can result in calcanealnavicular–calcanealcuboid joint sprains or fractures. (Lisfranc). VKs’ carbon fiber layer biasing provides torsional control between the rearfoot/midfoot as well as the midfoot/forefoot. By providing a kind of “sway bar” for the foot, VKs can limit the chance of midfoot sprains common in today’s increasingly competitive sports.
Most athletic trainers have used traditional, flat, carbon fiber plates after a lower extremity injury has already occurred. VKTRY Performance Insoles have been specifically developed and designed to be comfortably worn prior to an injury. In this case, the athlete will experience: 1) Improved performance benefits, 2) Decreased loading of the joints, and 3) Reduced chance of injury.