Rest & The Reactive Strength Doom-Loop: Christian McCaffrey Achilles Tendonitis Case

How Rest is Impacting Christian McCaffrey's Return to Performance.

McCaffrey suffered a mild calf strain in Week 17 of the 2023 Season. Credit: Getty

Rest: An Amplifier of the Lack of Reactive Strength Doom-Loop

As the NFL's Reactive Strength Problem continues to amplify, it's evident that many NFL organizations are still relying on outdated and ineffective strategies, with rest being a prime example—an approach that, as we are currently witnessing with the ongoing Christian McCaffrey case, will only exacerbate the reactive strength problem, creating a Lack of Reactive Strength Doom-Loop.

“When the prescription was rest…he sought out other opinions.”—Ed McCaffrey

Don’t just take our word for it—listen to McCaffrey’s father, who stated that the solution to his son's reactive strength injury was rest. It’s as if the 49ers are operating within a 2000s treatment and training paradigm, with their consensus being that McCaffrey’s best course of action was rest.¹ It’s no wonder McCaffrey fled the building and the country to seek out a facility with staff that understands connective tissue as biologically responsive to stress and capable of development.

Rest-to-Feel-Good = Amplifying the Doom Loop

Readers of Absolute who have embraced our Bulgarian Connective Tissue Loading strategy understand that the rest-to-feel-good cycle perpetuates reactive strength injury risks and limits an athlete’s return to consistent high performance.² This is because rest fails to address the root cause: an inadequate preparation of the bottom-up elements of connective tissue architecture to handle the top-down neuromuscular system outputs required for the explosive change-of-direction force transmission demands of the game.

Timeline of what a reactive strength doom-loop looks like: As you can see, the 49ers currently have no coherent strategy for McCaffrey—likely relying on more rest, though that is speculation on our part. Source

The Reactive Strength Doom-Loop Explained: The McCaffrey Case

A Doom-Loop³ generally refers to a negative, self-perpetuating cycle in which actions or strategies intended to solve a problem actually make it worse, creating a continuous loop of worsening conditions. In the context of sports performance and the NFL's Reactive Strength Problem, the Lack of Reactive Strength Doom-Loop works as follows:

1. Initial Injury (Athlete Not at Reactive Strength Point B):

   Christian McCaffrey, in this case, is not at Point B—he is missing the bottom-up biological component of reactive strength. This deficiency leads to maladaptive reactive strength generation⁴, which compromises his ability to rapidly transition from eccentric (muscle-lengthening) to concentric (muscle-shortening) contractions—movements essential for explosive actions like rapid changes of direction. The abnormal force transmission of these movements degrades the connective tissue.

   1. Specifically, his connective tissue architecture (CTA) is unable to handle dynamic force transmission scenarios, resulting in maladaptive changes to the structure of his Achilles tendon and creating a local tissue-specific biological feedback loop that manifests as Achilles tendonitis.

2. Outdated and Ineffective Strategy (Rest):
   In response to this reactive strength problem—referred to by the media by its pathology: Achilles tendonitis—teams, particularly the clinical personnel⁵ of the teams, often prescribe rest. While rest can alleviate central nervous system (CNS) fatigue⁶, it fails to normalize the connective tissue architecture. As a result, the neurological-biological asymmetry gains more inertia, and the doom-loop continues with momentum into the next phase.

3. Short-Term Pain Relief, Long-Term Problem (Feels Better but Not Ready):
   Rest may provide temporary pain relief⁷, making the athlete "feel better," but it does not resolve the root issue: the need to stimulate the development of the connective tissue infrastructure necessary to support McCaffrey’s scaled-up CNS outputs. This short-term pain relief creates the illusion of improvement⁸, while the underlying deficiency in CTA remains unresolved.

4. Increased Risk of Injury and Performance Decline (Returns Feeling Better, Further Away from Point B):