Achilles Ruptures: They’re Not Just Bad Luck
Are we missing the picture on training?
Achilles ruptures aren’t random or bad luck. Training science hasn’t fully adapted to reflect this reality, mainly because many of our current models are centered around different limiting constraints.
Thanks to Soviet and Bulgarian training systems, we now understand that neurological output is often the primary constraint in performance. However, the prevailing strategies, like deloading, fail to consider other critical factors.
Why deloading isn’t the solution
Let’s start by defining reactive strength.
Reactive strength is traditionally understood as the ability to utilize the stretch-shortening cycle, a key quality often equated with athleticism. It’s what gives an athlete that “pop” or their ability to change direction, accelerate, and get off the ground quickly.
Rate of force development (RFD) eccentrically equally as important as RFD concentrically
More specifically, it’s the capacity to transition rapidly from eccentric (lengthening) to concentric (shortening) contractions—to absorb force and then produce maximal force in another direction within a short time window.
This is often measured through a reactive strength index or RSI. This is calculated by dividing the height jumped with ground contact time. This can be improved by increasing jump height or decreased ground contact time. However, RSI testing requires specialized equipment, which becomes a barrier for many coaches seeking to understand or train reactive strength effectively.
Reactive strength is directly related to a term called rate of force development. What we see as explosiveness is the simultaneous output of your CNS to recruit the muscular tissue via CT tissue.
Rate of force developement is generally understood by many as a purely concentric action. This however is only one component of reactive strength.
In reality, reactive strength depends on the rapid transition between eccentric and concentric phases, meaning both the lengthening and shortening of tissue must occur at a high rate of force (application).
Explosive strength, therefore is the result of both CNS output and tissue-specific function.
Take for example an NBA player undergoing load management. The athlete is rested, allowing their CNS to recover. As a result, their RSI improves. But here's the issue: their connective tissue which is highly sensitive to mechanical load also gets deloaded.
This tissue is highly sensitive to mechanical load as a stimulus. The output of strength and afferent information of reactive strength work on different timelines in terms of an optimal strategy for progressing reactive strength.
CNS recovery 1-3 days
Connective tissue recovery 5-7 hours post stimulus
So when an athlete comes back their nervous system has recovered but their connective has regressed further from where it needs to be. This mismatch of neuro and biology creates a big asymmetry which is why the strategy is failing.
The NBA in particular has a reactive strength problem. According to their return to play data, 36.8% either retired or play fewer than 10 games post injury in their career.
What is the Deloading Strategy?
What’s the logic behind it?
Fatigue is a big RSI risk factor that is highly monitored.
When the number drops below a mean, a player is rested.
A huge caveat here is that I don’t presume to know what every protocol looks like, as each organization operates differently. This is only looking at one facet of injuries, the mechanical load and neurological demand. But these are things to consider:
Just because your favorite athlete is “available’ doesn’t mean they aren’t battling through other stuff.
It’s their job, do you always feel 100% at your job? Just because they play a game for a living, doesn’t negate the fact that they likely have numerous demands from their sponsors and other endorsement relationships outside of their “work” on court.
It’s not the shoes. If it were, soccer players would have the same problem (they don’t).
The million things that don’t get announced by sports reporters.
What’s the solution?
We don’t need deloading strategies, we need better programming.
Output of RSI - Also measuring tissue-tension to identify CT abnormalities in addition to RSI measurements.
Stimulation of CT tissue more frequently - High frequency input for the CT, allowing the tissue to keep working and moving towards balance with the CNS.
Loading continuum - Using treatment and training concurrently, allowing optimal frequency of tension or load without fatiguing the nervous system.
Movement is Feedback
Movement provides feedback that directly impacts CNS output. The argument can be made that RSI alone is not going to provide an NBA staff enough information to manage CT injuries. Discerning the length-tension changes provides the missing information to base decisions on how to proceed.