wHAT ABOUT “IMPACT”?

We talk a lot about "impact" in running, often in a negative light – something to avoid, cushion, or minimize. It is understood that running is “high-impact” compared to other activities like swimming and cycling. Heck, running shoe companies have picked up on this and are making more and more ultra-cushioned maximalist shoes to absorb ground reaction forces before they reach the body. But what does "impact" truly mean for a runner's body, and is it really causing damage to our joints and connective tissues?

In essence, running is a continuous cycle of absorbing and generating force. Every stride is a mini-collision with the ground, a micro-event where your body has to skillfully manage the energy transmitted through your bones, muscles, and connective tissues. It's not about eliminating this impact, but rather about teaching your body to utilize it. Think of it this way: your body is an incredible adaptive machine. When exposed to appropriate levels of stress, it gets stronger. This is the fundamental principle behind all training. For runners, those ground reaction forces, the very "impact" we often try to soften, are the signals your body needs to build resilience. It’s what stimulates your body too build stronger bones and joints.

So, how can we make sure this impact is productive and not destructive on the body?

Controlled Exposure: The key, as always, is gradual progression. You wouldn't throw a beginner lifter under a max squat. Similarly, you wouldn't send a new runner out for a marathon without proper buildup. Introducing new or increased impact needs to be strategic. This means respecting your body's current capacity and slowly increasing the load. This could be increasing mileage, adding a short burst of speed, or incorporating some gentle downhill running (a fantastic way to build eccentric strength and impact tolerance).

Spring in Your Step: The Role of Elasticity: Beyond simply absorbing force, your body's tissues are designed to store and release elastic energy. Think of your tendons and ligaments as springs. When you land, this spring stretches and stores potential energy, then recoils to propel you forward with minimal muscular effort. A "stiffer" and more responsive muscle-tendon unit allows for a greater return of this stored elastic energy, reducing the metabolic cost of running (Arampatzis 2006). This means your muscles don't have to work as hard to generate force, which can lessen overall tissue fatigue and, by extension, impact-related stress. Training your body to optimize this spring-like action is paramount. This is where running form and mechanics come into the picture. The more economical a runner is, the better he or she is able to re-use ground forces to drive forward.

Imagine two cars driving at the same speed. One guzzles gas, the other sips it. The second car has better fuel economy. Running economy is the human equivalent: it's the amount of oxygen (or energy) your body uses to run at a given pace. A more economical runner uses less energy to maintain the same speed, making them more efficient and, critically, often more resilient.

Integrating Intentional Loading: This is where our previous discussion on plyometrics and power training comes back into play. These aren't just about getting faster; they're about enhancing your body's ability to interact with impact effectively. Exercises like pogo hops, bounding, and hill sprints specifically train your tissues to absorb and then rapidly re-apply force. They teach your body to become a more efficient shock absorber and a more powerful projector.

Impact is not a threat to the structure of the body. It is a training tool, and we can empower ourselves to build a more robust and resilient system by understanding this. It’s about teaching your body to be a master of force management, not just a passive recipient. So, the next time you hit the pavement, remember that every landing is an opportunity for your body to adapt, strengthen, and become even more ready for the miles ahead. Embrace the impact – it's making you stronger!

Arampatzis, A., Karamanidis, K., & Albracht, K. (2006). Adaptational responses of the human Achilles tendon and muscle to successive plyometric training. Journal of Applied Physiology, 101(6), 1735-1740.