Low-Jerk Isometric Tendon Rehab
Ramp into controlled holds that load injured tissue without sharp pain or jerk
- Difficulty
- Moderate
- Time to result
- ~weeks to results
- Steps
- 6
- Confidence
- 99%
Baar's model starts with stress shielding: stiffer, stronger regions take most of a rapid load, leaving weaker or scarred regions under-stimulated. A sustained isometric allows the strong regions to relax so tension spreads more evenly through the tendon. For a mature injury, he favors 30-second holds because isolated tendon tests showed roughly 85 percent of stress relaxation by that point, with diminishing returns afterward. An overcoming isometric—gradually pushing against an immovable resistance—also avoids the sudden catch required by a yielding hold. The working dose is four 30-second holds with about two minutes of rest, entering and leaving each hold slowly. Pain stays at two out of 10 or below, and point-specific “ice pick” pain means stop.
Origin
Baar connected engineered-ligament findings with the history of slow eccentric rehabilitation and concluded that low velocity, not eccentric motion itself, was the active mechanism.
Core principles
- 01Slow loading lets strong regions relax so force reaches shielded tissue
- 02Velocity and jerk matter more than whether a contraction is eccentric or concentric
- 03Thirty-second holds capture most stress relaxation in a chronically injured tendon
- 04Controlled tension matters more than maximal effort
- 05Specific sharp pain is a stop signal
How to run it
- 1
Map the painful function
Identify the movement directions and joint positions that load the affected muscle-tendon unit. Include multiple positions when the activity uses the tissue differently across its range.
Pro tip For tennis elbow, Baar discusses both wrist extension and forearm rotation.
Watch out Do not assume one exercise covers every contributing muscle and tendon.
- 2
Set an immovable resistance
Arrange an overcoming isometric so you can push gradually without the resistance moving.
Pro tip A racket, belt, door jamb, counter, or machine can provide resistance when positioned safely.
Watch out A yielding hold can introduce a sudden load as soon as you catch the weight.
- 3
Ramp the force
Develop tension over roughly three seconds instead of hitting the resistance abruptly. Use enough effort to feel tension without shaking or crushing yourself.
Pro tip Baar suggests that around half effort can be sufficient for a more established injury.
Watch out Keep pain at two out of 10 or below.
- 4
Hold through relaxation
Maintain the isometric for 30 seconds so the stronger regions relax and load distributes more evenly.
Pro tip Longer holds may be useful for larger tendons, but 30 seconds captures most of the measured relaxation.
Watch out Stop if pain feels point-specific, like an ice pick.
- 5
Release and recover
Let the force off slowly, then rest for about two minutes before the next hold.
Pro tip Rotate among relevant positions during the rest interval for one tissue.
Watch out Dropping the load abruptly reintroduces the rapid force change the protocol is designed to reduce.
- 6
Complete the dose
Perform four 30-second holds, producing roughly 10 minutes of total activity including rests. Progress load or duration only while the tissue tolerates the current dose.
Pro tip Track force when instrumented equipment is available so progress is measurable.
Watch out Do not use soreness or exhaustion as proof that the session worked.
In the wild
Ferriss describes placing a tennis racket beneath a kitchen ledge and trying to rotate it upward without movement. Baar recommends gradually developing force, holding for 30 seconds, and releasing slowly rather than catching a pan's weight abruptly.
→ The setup gives the elbow extensors and rotators a low-jerk loading stimulus with controllable effort.
For Ferriss's elbow symptoms, Baar suggests rotating 30-second holds with the elbow bent, straight, and overhead, plus an isometric for the triceps contribution.
→ The sequence loads the contributing tissue combinations across positions within one session.
Common mistakes
Chasing maximal effort
The objective is a controlled tissue signal, not an 80-to-90-percent effort or visible shaking.
Loading too quickly
Abrupt acceleration introduces jerk and routes force through the stiffest regions rather than patiently loading the whole tendon.
Ignoring sharp local pain
Baar distinguishes diffuse warm burning from a specific ice-pick sensation and says to stop for the latter.
Is it for you?
Best for
People rehabilitating a long-standing tendon problem under appropriate clinical guidance.
Not ideal for
Unassessed injuries, exercises that cause point-specific sharp pain, or situations where a clinician has prohibited loading.
From the transcript
“It had nothing to do with the eccentric. It had nothing to do with the concentric. It was the tempo. It had to do with…”
“And by about 30 seconds is about 85% of the way to the bottom.”
“What I like about the overcoming isometrics is I can have you now instead of going like hold the pan and you have to immediately…”
From the episode
#797: Dr. Keith Baar, UC Davis — Simple Exercises That Can Repair Tendons (Tennis Elbow, etc.), Collagen Fact vs. Fiction, Isometrics vs. Eccentrics, JAK Inhibitors, Growth Hormone vs. IGF-1, The Anti-RICE Protocol, and How to Use Load as an Anti-Inflammatory
Keith Baar