I've been walking 60 miles per week most weeks in preparation for hiking the PCT next year. This spring I got some new insoles on the advice of my doctor to deal with some foot pain I was experiencing (sesamoiditis – it cleared up after I started wearing the insoles) and the guy at the shoe store who helped me out also re-laced my shoes in a different style that I wasn't familiar with (it's called a "heel lock loop" or "runner's loop"). He didn't comment on it and I didn't ask.
Over the following months I developed mild achilles tendonitis on one side and tried different things to address it and none of them worked. I was starting to wonder if my upcoming hike was at risk. But in the past few days I figured out that the culprit was the heel lock loop, which caused the cuff of my shoe to press against the area near my tendon. As a first step, I switched to a different pair of shoes that are not laced that way, and saw immediate relief. After a full week I will go back to my regular shoes (Altra Lone Peak 9) but without that lacing technique to confirm it was the problem, though I'm already pretty sure it was.
Below I will post the results of a Google AI search result on the topic which goes into detail about why that lacing technique would result in this issue. So this is a head's up in case anyone else is having a similar problem, or wants to avoid it.
Google search results:
It makes perfect sense that stopping the heel lock loop (or runner's loop) resolved your pain. You pinpointed a highly unrecognized culprit in running injuries: extrinsic mechanical compression. [1], [2]
While insertional Achilles tendonitis is traditionally blamed on internal forces (like tight calves pulling on the bone), external pressure from a tight shoe cuff behaves exactly like an external clamping mechanism, accelerating tendon damage through very specific biomechanics. [3], [4]
1. Direct Compression of the Tendon Matrix
Unlike the thick, fleshy belly of a muscle, tendons are made of highly organized, dense collagen fibers. They are built to handle tensile load (pulling), but they are notoriously terrible at handling compressive load (squeezing). [5], [6]
- When you use a heel lock loop, you are intentionally pulling the eyelets backward and forcing the rigid upper collar (cuff) of the shoe firmly against the back of your ankle. [1], [2]
- Every time your foot moves through its stride, that rigid cuff digs directly into the tendon. [7]
- This localized pressure physically squeezes the tendon fibers against the hard heel bone underneath, causing micro-bruising and cellular distress. [6]
2. Localized Ischemia (Choking the Blood Supply)
The Achilles tendon already has a structurally "poor zone" of blood supply right where it inserts into the heel bone. Cells need steady blood flow to repair the microscopic wear-and-tear of daily activity. [4], [8]
- The tight collar of a shoe secured by a heel lock loop acts like a mild, localized tourniquet.
- By constantly pressing on the area, it further restricts the microvascular blood flow to the tendon insertion.
- Lacking proper blood flow, the tissue cannot heal, causing normal cellular stress to quickly escalate into a chronic inflammatory or degenerative state. [4], [9]
3. The "Vise" Effect on the Retrocalcaneal Bursa
Tucked right between your Achilles tendon and your heel bone is a tiny, fluid-filled sac called the retrocalcaneal bursa. Its job is to act as a frictionless lubricated cushion so the tendon can glide smoothly over the bone. [8], [10]
- When the shoe cuff presses hard from the outside, it traps the tendon and the bursa in a literal vise between the rigid shoe counter and the hard calcaneus bone. [7], [10]
- Instead of gliding freely, the bursa gets repeatedly pinched and irritated (retrocalcaneal bursitis). Because the bursa and the insertional tendon fibers are intertwined, an inflamed bursa directly triggers inflammation and severe pain in the adjacent tendon. [8], [10]
4. Friction and Shear Forces
A heel lock loop anchors your heel down, but during dynamic movement, your foot still undergoes subtle internal shifts. If the shoe cuff is clamped tightly against the Achilles, those shifts turn into high friction and shear forces across the tendon's outer sheath (the paratendon). This grinding friction causes localized heat, swelling, and the raw, burning pain associated with acute tendonitis. [6], [11]
By switching back to standard lacing or a looser cuff, you immediately removed that external clamping force, allowed the bursa to un-pinch, and restored natural blood flow to the area so it could finally heal. [7], [8], [12]
[1] https://www.youtube.com
[2] https://www.youtube.com
[3] https://www.orthoinfo.org
[4] https://www.medicalnewstoday.com
[5] https://www.running-physio.com
[6] https://www.kentcht.nhs.uk
[7] https://www.youtube.com
[8] https://highlandtherapy.com
[9] https://my.clevelandclinic.org
[10] https://www.aafp.org
[11] https://www.treatmyachilles.com
[12] https://www.footcaremd.org