The split second effect is a model of how a tight calf muscle affects the foot an was given that name by Dr James Amis, MD from the Department of Orthopaedic Surgery at the University of Cincinnati in Cincinnati, OH in a 2016 paper in Frontiers in Surgery.
“Thus, the mere concept that equinus has anything to do with foot pathology is generally unknown or disregarded. The split second effect, described here, defines exactly how the silent equinus contracture creates incremental and significant damage and injury to the human foot and ankle resulting in a wide variety of pathological conditions.”
“We are awakening to a new era of understanding the mechanics and function of the human foot and ankle. There is a simple, singular, usually silent, and remote cause for the majority of non-traumatic acquired foot and ankle pathology, and mechanically, it creates cumulative damage to the foot and ankle through leveraged forces. In short and in this author’s opinion, equinus is the primary mechanical common denominator that leads to the majority of acquired non-traumatic foot and ankle problems by indirect leveraged means as well as direct forces along the posterior/plantar chain. There can be no more room for the standard thinking that these resultant foot and ankle problems arise just because we are getting older or we are obese or they are just random, or that an equinus contracture is only a part of the equation. Equinus is the equation.”
Illustration of the Split Second Effect from Amis (2016)
Amis described the effect of an equinus or tight gastrocenemius occurring in the last half of midstance when the swing phase foot starts to pass the stance phase foot and ends as the stance heel lifts just before the 3rd rocker is beginning. This lasts approximately 120ms (1/10th second) – the split second effect. It is during this split second that he considered the most destructive impacts of the grastronemius tightening occured.
Video from Dr Amis on the Split Second Effect:
This crucial concept must be vetted and passed on to as many people as possible and as fast as possible. We have already waited over a century since first described by Nutt; let us not wait too much longer. Better yet, going forward, we must promote prevention in the form of proactive daily calf stretching before the damage occurs.
Commentary:
- The video above and the images in figure 4 from Amis’s paper which are still shots from a video that he claims represent the split second effect from a gastrocnemius tightness look exactly like the images one would expect to see in a functional hallux limitus.
- Dr Amis has a financial interest in this concept or model as he markets a device to help stretch the calf muscles (One Stretch) and the promotion of daily calf muscle stretching.
Related Topics:
Equinus
External Links:
‘Equinus Is The Root Of All Foot Evils’ (Podiatry Arena)
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