Spring into Action: How the Stretch-Shortening Cycle Boosts Your Run.

Have you ever marveled at a runner who seems to glide effortlessly, their stride brimming with power and efficiency?  Behind that fluid motion lies a hidden powerhouse - the Stretch Shortening Cycle (SSC).  Not only is this mechanism critical to running success, but the good news is that it’s highly trainable.  

What is the Stretch Shortening Cycle?

The stretch-shortening cycle (SSC) is a muscle action that involves stretching and immediately shortening it.  The SSC combines eccentric and concentric muscle contractions, which are essential to nearly every movement we make.  Now I will admit that this concept of sports science has been difficult for me to grasp conceptually in how it operates, but quite simply it can be thought of as a spring like mechanism where the muscle undergoes an eccentric contraction, followed by a transitional period prior to the concentric action.  The compressing of the coil causes the rebound  or jump off which propels us in our intended direction whether that be forward (running), upward (jumping), or in any other direction.  Essentially in the running stride we have our landing where the muscles undergo an eccentric contraction (stretching), which stores energy that is rapidly released during the push off which is our concentric contraction (shortening) phase of our stride.  This stretch shortening cycle allows for runners to generate more force than a simple muscle contraction without the initial stretch and allows the runner to effectively improve running economy.

Why Does the SSC Matter for Runners?

Now that we’ve covered the basics of what the stretch-shortening cycle consists of, let’s dive into why this is important in endurance athletes, particularly distance runners.  The innate ability of this SSC provides runners with increased efficiency in their stride mechanics.  Since we have already compared the SSC to a spring it’s no mistake that we talk about having an extra spring in your step or a pop in your stride.  Think of how a spring works in that the more force that can be applied to the spring the faster and more powerful the recoil or bounce back.  This also applies to the running stride, and a powerful stride is one that can handle higher input forces or loading rates during the initial eccentric phase to get that more efficient and powerful stride in the concentric phase.  Quite simply, the higher the loading rate, the greater the running performance.  Elite athletes from both power and endurance based sports have demonstrated to possess a superior ability to store elastic energy. (Walker)  In aerobic long-distance running, higher SSC abilities have been shown to enhance running economy - suggesting that athletes with a better SSC capacity can conserve more energy while running. (Walker, 2024)

How to Train the SSC  

How can this quality be trained outside of running more volume or at faster paces?  To improve our stretch-shortening cycle we need to work on loading rates during the initial eccentric phase of the cycle.  More load during the active phase, the better the recoil during the propulsion phase.  With that you can train eccentrically.  Eccentric training comes at a lower energy cost.  Think tempo squats with longer durations loading the eccentric phase of the exercise.  Plyometric training is probably the most effective way to train to enhance the stretch-shortening cycle since it produces maximal force in the shortest time within the muscles.  Plyometrics speed up all three phases of the SSC and  results in improvements in efficiency and explosiveness in the running stride overall.  

Plyometric Training Guidelines

Incorporating plyometrics into your training is not as challenging as it seems.  Generally plyometric exercises are safe to add into your existing training plan, but you will want to keep in mind that volume is the most critical factor in managing injury risk unless you are incorporating weighted jumps into your plan which is only recommended for athletes with a solid training history with plyometrics.  For any low intensity jumps such as base pogos or line hops total volume per session should stay between 150-300 contacts.  For short bounds and jumps such as split jumps or lateral bounds the total volume per session should be between 30-60 contacts.  Start on the low end of these contact totals, and work your way up during base building.  During your competition phase or when building toward your goal race, be sure to account for your overall running volume in order to ensure you don’t over train and open yourself up to increased injury risk. 

Training the stretch-shortening cycle, and having the ability to load more into the eccentric phase directly translates to a more powerful and efficient stride pattern.  If you’re looking for that spring in your step for every run, this is where you can focus some effort and get some big gains.  Ready to power your next run? Start by adding just one plyometric session per week, and watch your efficiency and speed improve over time!  Here’s to powering that next run with a little training of the stretch-shortening cycle.   

References:

Walker, O. (2024, April 29). Stretch-shortening cycle (SSC). Science for Sport. https://www.scienceforsport.com/stretch-shortening-cycle/