What Do We “Know” About Running Injuries?
What do we “know” about running injuries? If we reduce the question down to its core elements, it is conversation about managing forces. It’s a conversation about tissues being able to dampen external forces and use them to produce internal forces to act back upon the ground. It’s about them being able to handle these demands with forces at given magnitudes over a certain accumulated volumes both acute and chronic.
So what are these forces at play? Vertical ground reaction forces (vGRF) are the highest magnitude (and thus most studied) forces we are succumbed to during running. These forces can be broken down into 2 smaller elements, the impact peak and the active peak. First is the impact peak, which is the initial “shock” of braking. The body taking the punch from the earth as we return from our brief moment of floating. Many studies show that the rate at which this initial loading occurs may be as important or more important than the absolute magnitude for risk of certain common injuries. ( see work by Willie, Dicharry etc..)
This rate of loading is broken down into instantaneous and average. A lower loading rate is akin to “riding with the punch”. The high forces can be dispersed over a longer time reducing impact peak. When we are watching runners and see a smooth glide versus choppy stomper this is the quantification of that aesthetic visual.
Vertical Ground Reaction Forces (vGRF) are the highest magnitude (and most studied!) forces acting on the body during running. These forces can be broken into several components and qualities as seen in the figure above
The stomper takes the punch by ramming his head into it, while the glider patiently rides the wave.
Characteristic profile of the “stomper”. The impact peak designates a braking shock to the system.
Second, there is the active peak. This is the moment the rubber band is released. Potential energy being converted into kinetic. Occurring right around mid stance, this is the moment of maximum propulsion. The forces are internal tissue compressing and acting on each other to allow a punch to be delivered to the ground.
Characteristic profile of the “glider”. A more gradual rate of loading smooths out the forces and removes the harsh impact peak.
With force, it’s all in how we manage it. How efficient we can be. The difference between graph one with the choppy peak and graph two with the smooth peak are all in the movement profile of the individual. Central to this is the long debate over striking patterns. Conventional wisdom may tell you that the high impact peak directly relates to the heel strike while the smooth slope is related to the forefoot striker. While these are correlated they are not directly linked.
The interplay between the forces at play and the risk of injury is certainly complex. The force profile that works for some may be poison for another. Understanding the large scale averages of how humans adapt and manage certain characteristics of force and what qualities may increase our risk of certain injuries is paramount in decision making.
– Dr. Anthony Iannarino, Rehab 2 Perform – Bethesda
- This episode features two amazing questioners and thinkers, Adam Grant and Malcolm Gladwell rethinking each other’s ideas live on stage. These two openly challenge each other’s work and opinions while discussing where they have been wrong, how they changed their mind, and where they believe they are correct. This is a beautiful exercise in collegial sparring to battle test your ideas and prune your thinking.
- This article is an excellent overview of the shortcomings of only tracking weekly distance in runners and suggestions for more efficacious strategies to monitor load. The article discusses new technology and strategies for coupling internal and external load parameters into monitoring and decision making.
- Paquette MR, Napier C, Willy RW, Stellingwerff T. Moving beyond weekly “distance”: optimizing quantification of training load in runners. J Orthop Sports Phys Ther. 2020;50(10):564-569.
- Dietz and Peterson offer a succinct yet dense look at strength and power development by dissecting the stretch shortening cycle into three phases. A practical road map for oiptimizing the magnitude and rate of force production is laid out throughout the book in an approachable and applicable manner. This is a must read for physical therapists and performance coaches working with individuals looking to maximize force production capabilities.
- Rufus Blackbone is one of the most experienced coaches in our industry with 40+ year of experience in a wide number of sports and scenarios. Coupled with this, he is one of the most passionate learners you will ever meet. Rufus has taken his passion for learning and channeled it into a podcast clip show featuring some of the world’s leaders in physical performance. It’s casual conversations of “coaches talkin’ to coaches” with some major gems in each segment.