Podcast #24: Healing Tendons with Dr. Keith Baar

Tendon Viscoelasticity

“If I move quickly, the water doesn’t have time to move out as I pull on my tendon.”

“If I move slowly, as I pull it, the water slowly seeps out of the collagen and now there’s less resistance, so there’s less stiffness.”


“If I’m really inactive… I’m gonna get both the increase in cross-links and I’m gonna get less collagen in the tissue. And that’s when the tissues get brittle.”

“As we load, we’re gonna increase the production of collagen. And as we’re inactive, we decrease the production of collagen. So our tendons and ligaments get smaller.”

Increasing Tendon Stiffness

Does heavy lifting increase tendon stiffness? “If you take people and you do only heavy, slow lifting… they’ll be slower. Their rate of force development goes down. Every single study shows that. And so if tendon stiffness is going up. You’d actually expect that their CMJ goes up… all of these things that actually go down.”

Age and tendon stiffness: “I would say that we get stiffer as we get older. But the research looking at tendon stiffness actually says that our tendon stiffness goes down as we get older. I can’t figure out any other way to explain that other than this is a measurement error.”

Stress Shielding

“When we understand what causes the hole, we can come up with a strategy to fix the hole.”

“The scar itself is a result from this process of stress shielding and if we can figure out a way to overcome the stress shielding, we can completely reverse the scar.”

Stress Relaxation

“If I take a whole tendon and I pull it, I can see about a 60% decrease in the load from when I initially pull it to when I measure 30 seconds later.”

Isometrics: “As I pull and I hold on my tendons, they’re gonna begin to relax, they can’t shield the injured area, now the injured area feels the load… and so it starts making collagen and making it directionally oriented.”

National Level Discus Thrower

Bilateral Patellar Tendinopathy. Unable to train. 5-days per week isometrics with nutritional components. Leg extension machine. Put the pin at the bottom. One leg at a time, push as hard as possible for 30 seconds.

7-weeks later. Hole in MRI completely gone. Collagen thicker and more aligned.

Other Notes

“We’ve got whole teams now that have had really good success about almost completely eliminating Patellar and Quad Tendinopathies from teams that historically have had rates of between 40 and 70% of their athletes.”

“There’s this idea that tendons and ligaments are really inert tissues, they don’t turnover very much. And what we’re finding out is, that’s completely not true.”

“If you’re gonna do Nordics, you better do a Spanish Squat… If you don’t, you’re gonna have stiffness differentials between the hamstrings and the quads, which are gonna accelerate ACL ruptures.”

In a tendinopathic tendon: “If we do dynamic loading (running, jumping).. we actually make the problem worse… we get more compression on the center part of the Patellar Tendon than we do get tension.”

Keith Baar on Twitter: https://twitter.com/musclescience?lang=en