Tim FerrissSimple Exercises That Can Repair Tendons — Dr. Keith Baar
CHAPTERS
- 0:00 – 1:21
Why immobilization and boots can worsen tendon healing (stress shielding)
Dr. Keith Baar opens by arguing that common orthopedic approaches like immobilization boots reduce tension in injured tissue, which can promote scarring. He contrasts how outdated immobilization practices are with how medicine would treat other conditions if therapies hadn’t evolved.
- •A boot functions as a mechanical “stress shielder” that takes tension off the injured tissue
- •He says reduced tension promotes scar formation, so shielding can make the problem worse
- •He notes immobilization has been used for thousands of years and criticizes orthopedics for slow progress
- 1:21 – 3:41
How Tim found Baar’s work: climber hangboard protocol and surprising grip gains
Tim Ferriss describes discovering Baar’s work via a climber’s YouTube video and a study/review about engineered ligaments. He recounts a hangboard protocol using partial bodyweight isometric hangs that led to major improvements in grip performance.
- •Tim found Baar’s work while seeking remedies for tennis elbow in the context of rock climbing
- •He describes a climber using 10 seconds on/50 seconds off hangs for about 10 minutes daily
- •He reports dramatic grip improvements after 30 days and asks what adaptations explain it
- 3:41 – 6:01
Strength without size: force transfer, connective tissue adaptation, and the mTOR backdrop
Baar explains that strength isn’t only about bigger muscles and recounts his earlier work on mechanisms of hypertrophy. He describes how athletes can get stronger without gaining size by improving force transfer through tendons and connective tissue.
- •Baar identifies mTOR complex 1 as a key pathway involved in resistance-exercise hypertrophy
- •He describes encountering athletes getting stronger without getting bigger, prompting a rethink
- •He emphasizes force transmission from muscle to bone via connective tissue as a major limiter
- 6:01 – 10:19
Minimal effective dose for tendons and the 6–8 hour refractory period
Drawing from engineered ligament work, Baar describes finding that tendons and other connective tissues respond to surprisingly small amounts of loading. He explains the idea of a short signaling window and an 6–8 hour wait before connective tissues respond optimally again.
- •Engineered ligament experiments suggested connective tissue signaling saturates quickly
- •He describes a “minimal effective dose” of about 10 minutes to capture most adaptation signal
- •He introduces a refractory period: roughly 6–8 hours before another optimal loading session
- •He links this framework to the hangboard protocol performed twice per day
- 10:19 – 15:02
Rapamycin, mTOR, and trade-offs: muscle adaptation vs. inflammation control
Tim asks whether rapamycin use for longevity compromises training adaptations. Baar says low doses likely have minimal but still somewhat negative effects on skeletal muscle adaptation and may also reduce immune responsiveness.
- •Baar says longevity-style rapamycin dosing has minimal but not zero negative effect on muscle adaptation
- •He notes endurance exercise and metformin-like pathways can counteract mTORC1 signaling
- •He describes mTOR’s role in immune cell function and mentions a mild immunocompromised effect
- 15:02 – 20:28
Isometrics vs. eccentrics for tendon rehab: stress shielding, creep, and load distribution
Baar explains why isometrics can load more of a heterogeneous tendon compared to fast or dynamic loading. He introduces stress shielding—stronger regions taking more load—and describes how sustained holds redistribute load as stronger regions fatigue or relax.
- •Tendons are mechanically heterogeneous; load preferentially travels through stiffer/stronger regions
- •During sustained isometrics, strong regions fatigue/relax, shifting load to other regions
- •He uses a wall-sit example to explain tendon creep and increasing muscular effort during holds
- •He explains how stress shielding can protect weak regions until conditions change
- 20:28 – 24:48
Why eccentric rehab ‘worked’: velocity and jerk, not eccentricity itself
Baar recounts the origins of eccentric tendon protocols and reframes their effectiveness as a function of slow velocity rather than the eccentric phase per se. He introduces “jerk” (rate of change of acceleration) as a key driver of tendon injury risk.
- •He says classic eccentric protocols centered on slow eccentrics; the key variable was low velocity
- •He defines jerk and links it to injuries during rapid direction changes or impact (e.g., catching a bar, racket-ball contact)
- •He argues making velocity zero (isometrics) can produce a strong tendon stimulus with less injury-provoking jerk
- 24:48 – 27:06
Programming isometrics: 10–30 second holds, rest intervals, and tendon size considerations
Tim asks about optimal work/rest timing, and Baar explains how hold duration changes based on injury status. He argues longer holds are needed for chronic injuries because shielding is stronger, and he explains why different tendons may require different hold durations.
- •For healthy tendons, shorter holds (1–10 seconds) can be sufficient
- •For more mature or chronic injuries, Baar favors ~30-second holds to overcome shielding via relaxation
- •He notes stress relaxation curves: big gains by ~30 seconds, diminishing returns beyond
- •He says larger tendons (e.g., Achilles) may need longer holds than smaller finger flexor tendons
- 27:06 – 41:16
Tim’s tennis elbow case: load selection, pain rules, and why overcoming isometrics reduce jerk
Tim describes his history of elbow issues and current protocol (including collagen plus vitamin C timing and various isometric setups). Baar critiques load management and introduces practical cues: keep pain low and prioritize controlled loading that minimizes jerk.
- •Tim describes chronic lateral elbow pain recurring with climbing and various home isometric experiments
- •Baar recommends keeping pain around 2/10 or less and focusing on tension without excessive load
- •He distinguishes point-specific “ice pick” pain (stop) from diffuse warm soreness (acceptable)
- •He explains overcoming isometrics allow gradual force ramp-up and reduced jerk compared to yielding setups
- 41:16 – 45:52
Practical rehab prescriptions: multi-angle elbow isometrics and adding related tissues
Baar gives specific movement categories for tennis elbow and explains why changing joint angles recruits different contributors. He recommends rotating through positions and adding related muscle-tendon units (including triceps work) when symptoms suggest broader involvement.
- •For tennis elbow, he says to train both extension and rotational components
- •He endorses rotating positions (bent elbow, straight arm, overhead variations) within a session
- •He suggests adding an overhead triceps extension isometric when triceps involvement is suspected
- •He compares this approach to rotator cuff programming across multiple positions to cover the system
- 45:52 – 51:09
Early loading after surgery and why RICE/boots can be counterproductive
Tim asks when to load after surgery, and Baar argues for loading very early—often the next day—using low-jerk, pain-free isometrics. He critiques RICE and routine immobilization as drivers of stress shielding and scarring, while acknowledging full loading immediately after repair isn’t appropriate.
- •Baar says early loading can begin the next day in some contexts, and discusses faster return timelines with earlier loading
- •He criticizes RICE and immobilization boots as promoting stress shielding and scar-like remodeling
- •He proposes brief, controlled, pain-free isometrics even while otherwise using a boot
- •He emphasizes slow force development, 30-second holds, and slow release to minimize jerk
- 51:09 – 1:01:11
Post-surgical Achilles rehab: suture choices, loading positions, and avoiding stress shielding of native tissue
Baar explains why reinforced non-resorbable sutures can divert load away from the healing tendon, risking native tissue weakening. He describes safer early isometrics in shortened positions and argues resorbable sutures may better enable loading the native tissue over time.
- •He says strong sutures can take most load, preventing native tissue from being loaded and adapting
- •He recommends early loading in plantarflexed (shortened) positions to avoid stressing the repair excessively
- •He advocates developing tension over 3–5 seconds, holding ~30 seconds, then slowly releasing
- •He argues resorbable sutures can enable better native tissue restoration without increased lengthening in the discussed animal work
- 1:01:11 – 1:06:44
Collagen + vitamin C: what matters, what doesn’t, and why pre-loading timing helps low-blood-supply tissues
Baar outlines what he looks for in collagen supplements and why vitamin C is paired with collagen. He explains that timing before loading may matter more for tendons/ligaments/cartilage due to limited blood supply and nutrient delivery via compression/stretch cycles.
- •He prefers collagen sourced from skin/hide rather than bone broth due to heavy metal concerns in bones
- •He says type labels and specialty peptides matter less than providing amino acids like glycine and proline
- •He recommends taking collagen and vitamin C together; vitamin C is essential for collagen synthesis machinery
- •He says taking it ~30–60 minutes before targeted tendon loading can improve delivery to low-blood-supply tissues
- 1:06:44 – 1:16:24
Peptides and orthobiologics skepticism: why injections may seem to help (pithing/debridement) and limits in lower body
Baar critiques BPC-157/156 based on results in engineered ligament models and offers a mechanism for perceived benefits unrelated to direct tendon effects. He also explains why many orthobiologic injections struggle especially in the lower body due to fluid being squeezed out during walking.
- •He says BPC-157/156 showed no direct effect in their engineered human ligament system
- •He suggests needling/debridement effects may come from weakening strong regions, reducing stress shielding so weak regions get loaded
- •He argues lower-body injections often don’t stay localized because walking squeezes fluid out
- •He references the view that randomized trials often show no benefit for PRP vs saline in certain tendons
- 1:16:24 – 1:30:02
Drug effects on tendons: JAK-STAT inhibitors, rupture-risk medications, and sex hormones’ opposite impacts
Baar discusses an FDA-approved drug class that affected engineered tendon properties and then shifts to medications associated with higher tendon rupture risk. He also explains how estrogen and testosterone influence connective tissue stiffness through collagen cross-linking, linking this to injury patterns and performance differences.
- •He describes developmental tendon growth signals associated with JAK-STAT inhibition and says JAK inhibitors increased engineered tendon size/strength
- •He reports a study finding certain antibiotics increased Achilles rupture risk and says AT1 receptor (sartan) drugs were associated with even higher rupture risk in that registry work
- •He explains estrogen reduces stiffness by inhibiting a collagen cross-linking enzyme, increasing ligament laxity and ACL risk in women
- •He says testosterone has opposite effects: stiffer but lower-collagen (more brittle) tendons, contributing to rupture risk alongside muscle gains
- 1:30:02 – 1:40:56
Protein, ketogenic diet, rapamycin parallels, mitochondria, and when to avoid keto
Baar and Tim move into nutrition, covering protein totals and timing, then connect ketogenic diet, low protein diets, and low-dose rapamycin through mTOR suppression. Baar explains mitochondrial roles, potential longevity effects in their work, and trade-offs including limitations for athletic speed and concerns about bone mass.
- •He says total daily protein matters more than rigid 4-hour dosing rules, and gives daily grams-per-kg targets
- •He frames keto/low-protein/rapamycin as different ways to reduce mTOR activity
- •He links keto to improved mitochondrial reliance and mitophagy, and describes improved strength/brain function in older animals in their work
- •He says ketogenic diets are not ideal for athletes needing sprint capacity and mentions bone mass as a downside (notably in pediatric epilepsy use)
- 1:40:56 – 1:47:57
Inflammation and recovery: load as an anti-inflammatory, plus ice bath timing around training
Baar argues inflammation is required for adaptation and that blanket suppression can impair gains. He proposes using brief isometric loading to “pump” fluid out as a way to manage soreness and swelling, and he suggests separating cold exposure from key training windows.
- •He says inflammatory processes support adaptation; suppressing them can blunt hypertrophy or aerobic adaptation
- •He proposes short isometrics to squeeze fluid out and reduce soreness without shutting down adaptation globally
- •He describes doing ankle “alphabets” after a sprain as early controlled loading
- •He suggests ice baths can be used away from key training (e.g., cold in the morning, strength later) to reduce interference
