By Dr. Moshe Richmond DPT, MS, ATC, CSCS

Concierge Physical Therapy & Wellness Five Towns

published February 9 2026

Read time: 6 minutes

In a previous blog, we discussed how collagen and vitamin C support tendon healing by supplying the raw materials needed for repair. But nutrition alone does not restore tendon health. Without the correct mechanical stimulus, collagen is laid down in a disorganized and mechanically weak manner.

Tendons don’t just need collagen.
They need direction.

That direction comes from slow, progressive loading.

Whether the condition involves the Achilles, patellar tendon, or elbow, effective tendinopathy rehabilitation follows the same principles. The specific tendon matters far less than how load is applied.

One of the most common mistakes in tendinopathy care is complete rest.

Prolonged unloading leads to:

• Poor collagen alignment
• Reduced tendon stiffness
• Decreased load tolerance

While rest may temporarily reduce pain, symptoms often return quickly once activity resumes. Tendons require graded mechanical stress to heal properly. Without it, the tendon becomes deconditioned rather than stronger.

The real question is not whether to load a tendon—but how.

The origin of eccentric training in tendon rehabilitation is often misunderstood. The story is best explained through Keith Barr, a leading researcher in tendon healing who frequently discusses how this discovery unfolded.

Barr recounts the work of Håkan Alfredson, who developed chronic Achilles tendinopathy that failed to improve with rest or conventional care. Frustrated and considering surgery, Alfredson attempted to intentionally overload his tendon in a way he believed would cause rupture.

He chose eccentric loading for a specific reason: humans are approximately 30–40% stronger eccentrically, allowing much heavier loads to be handled. By lowering the weight slowly and under control, he could expose the tendon to extremely high forces while maintaining movement control. His expectation was failure.

Instead, the tendon healed.

This experience led to the Alfredson Protocol and brought eccentric training into mainstream tendon rehabilitation. The critical conclusion—emphasized by Barr—is this:

It wasn’t the eccentric contraction that healed the tendon. It was the slow, controlled application of high load.

Eccentrics were simply the most practical way to achieve high tension at low speed.

Barr uses this story to highlight a fundamental concept in tendon injury: jerk.

In biomechanics, jerk refers to the rate of change of force over time—how quickly force is applied.

• Fast, explosive movements → high jerk
• Slow, controlled movements → low jerk

High jerk produces rapid spikes in tendon force, which is how tendons commonly fail. This is why sudden accelerations, decelerations, and uncontrolled lifts frequently lead to injury.

Slow loading—even with heavy weight—keeps jerk low while maintaining high mechanical tension, signaling adaptation rather than injury.

In addition to improving tendon capacity, isometric exercise provides a unique pain-modulating benefit.

Research led by Jill Cook, a world-recognized expert in tendinopathy, showed that a single bout of isometric contractions can:

• Reduce tendon pain immediately
• Maintain pain relief for at least 45 minutes
• Increase maximal voluntary isometric contraction (MVIC)
• Reduce cortical inhibition, suggesting a central nervous system mechanism

Importantly, pain reduction occurred without a loss of muscle strength.

In people with patellar tendinopathy, isometric contractions were often tolerated with little to no pain, making them an ideal early-stage intervention when dynamic loading is too provocative.

Cook’s work highlights an important distinction:

Pain in tendinopathy is not purely structural—it is also neurologically mediated.

Isometric loading appears to reduce pain by:

• Decreasing inhibitory signaling at the motor cortex
• Allowing force production with minimal tendon strain
• Maintaining high load with very low jerk

This reinforces a consistent message across tendon research:

Controlled load + controlled speed = improved capacity and reduced pain.

When these findings are viewed together, tendon rehab becomes clearer:

• Isometrics
  Load the tendon heavily with minimal movement and very low jerk—ideal early on.
• Slow eccentrics
  Teach force absorption while maintaining strict tempo control.
• Slow, heavy concentrics and heavy slow resistance
  Equally effective when performed deliberately, reinforcing that speed—not contraction type—is the key variable.

These methods work not because they are different exercises, but because they all control velocity while maintaining load.

Effective tendon healing requires alignment between biology and mechanics:

• Collagen and vitamin C provide the building blocks
• Slow, progressive loading tells the tendon how to organize them

Complete rest weakens tendons.
Fast loading injures them.
Slow, controlled strength rebuilds them.

For patients seeking evidence-based concierge physical therapy in the Five Towns, this principle guides everything we do in tendinopathy rehabilitation.

Healthy tendons are built by loading smarter—not resting longer.

About the Author

Dr. Moshe Richmond, DPT, MS, ATC, CSCS,

is a Doctor of Physical Therapy and performance specialist serving the Five Towns area. He specializes in concierge physical therapy, performance-based rehabilitation, and strength training for adults focused on recovery, resilience, and long-term health.