Why are isometrics often more effective than eccentrics for tendon healing?

Eccentric training was thought to work due to the negative movement, but research shows it's actually the slow tempo and reduction of velocity that is beneficial. Isometrics maximally reduce velocity (to zero), allowing for more even distribution of load across the entire tendon, including weaker parts that are usually stress-shielded.

How soon after a tendon injury or surgery should I start loading the tissue?

Contrary to traditional advice, early loading is crucial. Studies show that starting low-jerk isometric loads as early as two days post-injury or surgery can significantly accelerate return to activity (up to 25% faster). The key is to ensure zero pain and slowly build force.

What is the recommended collagen and Vitamin C protocol for tendon health?

Consume about 15 grams of hydrolyzed collagen peptide powder (from a skin source like bovine hide to avoid heavy metals) along with 200-250 milligrams of Vitamin C. Take this mixture approximately 30 minutes to one hour before your exercise session to ensure peak amino acid availability when the tendon is being loaded.

Do orthobiologic treatments like PRP or BPC-157 work for tendon injuries?

For lower body tendon injuries, there's no strong evidence that orthobiologics like PRP, Prolotherapy, or stem cells provide a benefit over saline injections, as the injected substances tend to dissipate quickly. BPC-157 has shown no direct impact on engineered tendon cells' mechanics or collagen content. In some cases, these treatments might cause transient benefit by damaging other parts of the tissue which temporarily makes it more sensitive to load.

Are certain medications known to increase the risk of tendon rupture?

Yes, fluoroquinolone antibiotics (e.g., Ciprofloxacin) are associated with a 3.5-fold increased risk of tendon rupture. Even more significantly, AT-1 receptor drugs (Angiotensin Receptor Inhibitors, like sartans, commonly used for blood pressure) carry a 7.6-fold increased risk. It's important to be aware of these risks, especially if engaging in physical activity.

How do estrogen and testosterone affect tendon stiffness and injury risk?

Estrogen, particularly its monthly fluctuations in women, decreases tendon stiffness by inhibiting an enzyme that cross-links collagen, making ligaments stretchier. This contributes to women being 4-8 times more likely to rupture their ACL. Testosterone, conversely, activates an enzyme that decreases collagen, leading to stiffer but more brittle tendons, making them prone to rupture from strong muscles.

Can inflammation be beneficial, and how should it be managed after exercise or injury?

Inflammation is essential for adaptation and tissue repair. Aggressively suppressing it with pharmaceuticals or ice can blunt this process. Instead, use light, low-jerk isometric loading as an "anti-inflammatory" to gently squeeze out fluid from sore areas. For example, after an ankle sprain, performing alphabets with the foot can help manage swelling and promote healing.

What are the effects of a ketogenic diet on muscle, longevity, and bone health?

A ketogenic diet, by reducing carbohydrate intake and thus insulin, functions to lower MTOR activity, similar to rapamycin, and has been shown to increase longevity (e.g., 13% in mice) and improved mitochondrial quality. However, it can negatively impact bone mass, leading to fragility, which is a significant concern, especially in children.

Simple Exercises That Can Repair Tendons, Isometrics vs. Eccentrics, and More — Dr. Keith Baar

Tim Ferriss

Howto & Style4 min read108 min video

Feb 27, 2025|215,542 views|5,464|360

tim ferriss 4 hour body timothy ferriss tim ferriss blog Tim Ferriss Podcast dr. keith baar tendons exercises for tendons tendon repair collagen vitamin c supplements

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Key Moments

TL;DR

Dr. Keith Baar discusses isometrics, tendon repair, and optimizing exercise for strength and longevity.

Key Insights

Tendons and ligaments adapt most effectively to mechanical load through specific loading protocols, not prolonged inactivity or excessive stress.

Isometrics, particularly 'overcoming isometrics' with a controlled tempo, are highly effective for tendon repair and strengthening by engaging the entire tissue.

Eccentric loading's benefits for tendon issues may stem from reduced velocity rather than the eccentric nature itself; isometrics achieve maximal velocity reduction.

Early and appropriate loading after injury or surgery, even just the day after for some procedures like Achilles tendon repair, can significantly accelerate recovery.

The timing and type of collagen supplementation, combined with Vitamin C and exercise, can support connective tissue synthesis.

Hormonal differences, particularly estrogen's effect on collagen cross-linking, contribute to sex-based differences in connective tissue stiffness, injury risk, and athletic performance.

THE FUNDAMENTAL PRINCIPLES OF TISSUE ADAPTATION

Dr. Keith Baar emphasizes that connective tissues like tendons and ligaments require mechanical stimulation to adapt and strengthen. Contrary to traditional approaches like immobilization in boots after an ankle sprain, which causes "stress shielding" and leads to scarring, consistent and appropriate loading is crucial. He likens tendon cells to a teenager who needs brief, impactful messages; prolonged or excessive stress leads to wear and tear rather than beneficial adaptation. This principle applies across various tissues, including bone, suggesting a need for optimized loading protocols rather than just duration.

ISOMETRICS VS. ECCENTRICS: REDISCOVERING LOAD VELOCITY

The conversation challenges the dogma around eccentric loading for tendon injuries, suggesting that the primary benefit comes from the slow velocity of movement, not the eccentric action itself. Isometrics, by definition, involve zero velocity, offering maximal control and minimal "jerk"—the rapid change in acceleration that can induce injury. Dr. Baar highlights that "overcoming isometrics," where you actively push against resistance, allow for controlled force development and maintenance, proving more effective for tendon repair than "yielding isometrics" or simply performing slow eccentrics without this controlled application of force.

OPTIMAL LOADING PROTOCOLS FOR TENDON REPAIR

Effective tendon loading requires a specific duration and rest period. For healthy tissues, short isometrics of 1-10 seconds may suffice, while injured tissues, which develop "creep" and require more time for load distribution, benefit from longer holds, typically around 30 seconds. The recommended rest interval between sets is approximately eight hours, allowing the tissue to recover. This approach, demonstrated by climbers improving grip strength with brief isometric hangs, applies to various injuries, including tennis elbow and Achilles tendon issues, emphasizing a minimum effective dose to stimulate repair without causing further damage.

EARLY LOADING AND INNOVATIVE SURGICAL APPROACHES

Dr. Baar advocates for aggressive early loading post-injury or surgery, often starting as early as the next day, which can significantly accelerate recovery times. He contrasts this with outdated medical practices like prolonged immobilization. Furthermore, he discusses advancements in surgical techniques, suggesting the use of resorbable sutures for tendon repairs. This allows for earlier loading of the native tissue, preventing the excessive reliance on non-resorbable sutures that can lead to stress shielding and delayed healing, ultimately promoting better long-term tissue integrity and function.

COLLAGEN SYNTHESIS AND NUTRITIONAL SUPPORT

Supplementation with hydrolyzed collagen peptides, particularly from skin sources like fish or bovine, combined with Vitamin C, can support connective tissue synthesis. The timing of consumption is important; taking collagen and Vitamin C 30-60 minutes before exercise allows peak delivery of amino acids to the working tissues during loading. While collagen provides essential building blocks like glycine and proline, it's crucial to remember that exercise remains the primary stimulus for collagen production, with supplements offering a supportive role of 2-5% compared to the loading stimulus.

HORMONAL INFLUENCES AND CONNECTIVE TISSUE DIFFERENCES

Hormonal differences significantly impact connective tissue properties. Estrogen, particularly during the menstrual cycle, can decrease collagen cross-linking, leading to reduced stiffness and increased ligament laxity in women, contributing to a higher injury risk. Conversely, testosterone tends to increase collagen cross-linking, potentially leading to stiffer, more brittle tendons. These hormonal fluctuations are implicated in performance differences between sexes and are a significant evolutionary adaptation related to childbearing, highlighting the complex interplay between hormones, tissue mechanics, and injury susceptibility.

THE ROLE OF LOAD, NOT JUST MEDICATION, IN HEALING

Dr. Baar critiques the overuse of anti-inflammatories and orthobiologics like PRP for lower-body injuries, explaining that injected substances are quickly squeezed out due to movement. He emphasizes that load is the primary driver of adaptation and healing. Whileceptation for inflammation because it signals adaptation, it should not be suppressed with medication when aiming for tissue repair. Instead, targeted loading, even for acute injuries like sprains, can help manage swelling and promote recovery by effectively "squeezing" out excess fluid and signaling the tissue to adapt.

NUTRITION, LONGEVITY, AND MITOCHONDRIAL HEALTH

Dietary strategies like ketogenic diets and intermittent fasting can influence longevity and metabolic health by modulating mTOR activity, similar to rapamycin. Ketogenic diets, by reducing carbohydrate intake, force the body to use fat for energy, promoting the development of high-quality mitochondria. However, they may not be optimal for high-intensity performance requiring rapid energy bursts. For athletes, total daily protein intake is more critical than precise meal timing, focusing on overall grams per kilogram of body weight, reinforcing that nutritional support complements, but does not replace, the fundamental stimulus of mechanical loading.

Mentioned in This Episode

●Supplements

●Products

●Software & Apps

●Tools

●Companies

●Organizations

●Concepts

●People Referenced

Tendon Health & Injury Recovery Protocols

Practical takeaways from this episode

Do This

Engage in isometric holds (30 seconds for injured tendons, 10 seconds for healthy) with 2-minute rests, for 4 rounds per session.

Implement overcoming isometrics (pushing against an immovable object) for injured tendons, gradually building force over 3 seconds and releasing slowly to minimize jerk.

Rotate through different joint positions during isometric exercises to target the various muscle and tendon contributions to pain (e.g., bent arm, straight arm, overhead positions for elbow/shoulder).

Consume 15g of hydrolyzed collagen peptide powder (from skin source) and 200-250mg of Vitamin C an hour before doing brief, targeted exercise to optimize collagen synthesis.

Begin early loading (low-jerk isometrics) as soon as 2 days post-injury or surgery, ensuring zero pain and gradually increasing load/tension.

For Achilles tendon rehab, perform plantar-flexed isometrics (toes pointing away, pushing against a wall) in a shortened position or even in a boot, carefully avoiding pain.

Use load as an anti-inflammatory for muscle soreness and twisted ankles by performing short-duration (e.g., 5-second) isometric holds to "squeeze out" fluid. For ankle sprains, tracing alphabets with the foot can be beneficial.

If utilizing ice baths for mood elevation, time them in the morning, performing strength training later in the day to prevent interference with MTOR activation and muscle adaptations.

Avoid This

Avoid prolonged immobilization after injury or surgery, as it leads to stress shielding and scar tissue formation.

Do not rely solely on eccentric loading for tendon injuries; isometrics are superior due to maximal velocity reduction.

Don't consume bone broth as a primary collagen source due to potential heavy metal contamination; opt for skin-derived collagen.

Do not use BPC-157 for tendon healing, as studies show no direct benefit to tendon cells.

Avoid orthobiologic injections (PRP, Prolotherapy, stem cells) for lower body tendon injuries due to lack of proven efficacy and rapid dissipation.

Be cautious with fluoroquinolone antibiotics (e.g., Cipro) and AT-1 receptor drugs (e.g., sartans) due to significantly increased tendon rupture risk.

Don't over-rely on supplements; 95% or more of tendon and muscle strength comes from proper loading.

Do not take high levels of anti-inflammatory drugs (e.g., ibuprofen) or use excessive ice baths immediately post-exercise if seeking maximal muscle hypertrophy, as they can blunt adaptation.

Common Questions

For healthy tendons, 10-second isometric holds are effective. For injured or chronically problematic tendons, 30-second holds are recommended. These should be performed in 4 rounds, with 2 minutes of rest between each, accumulating to about 10 minutes of total activity. You can repeat sessions after 8 hours.

Topics

Tendon Health Isometric Exercise Eccentric Loading Connective Tissue Collagen Synthesis Orthobiologics ACL Injury Anti-inflammatory Strategies

Mentioned in this video

personNavdeep Chandelle

Researcher interviewed by the host about metformin.

organizationAspetar

Medical institution in Qatar where Rob Whitley, a leading physical therapist, works.

conceptProlotherapy

Injection-based treatment where a needle is used to repeatedly jab a tendon, potentially damaging healthy tissue to disrupt stress shielding.

personRob Whitley

One of the best physical therapists in the world, based at Aspetar in Qatar, who critiques orthobiologic injections and emphasizes the importance of loading for tendon healing.

drugNandrolone

Anabolic steroid mentioned as part of a cocktail of performance-enhancing drugs.

mediaEgyptian hieroglyphs

Ancient Egyptian pictorial writing system, cited as the first recorded instance of an ankle or leg immobilizer 4,500 years ago.

personEmil Abrahamsson

High-level climber, YouTube creator, and teacher whose video on hangboard training referenced Dr. Baar's work and showed significant grip strength improvements.

organizationEnglish Institute of Sport

Organization that invited Dr. Baar to their Cycling Center, where he observed athletes gaining strength without increasing muscle mass, contrary to his previous understanding.

personHjalmar Henderson

The Scandinavian scientist who developed the eccentric loading protocol for tendon injuries, originally intending to rupture his own Achilles tendon but instead fixed it.

supplementHydrolyzed Collagen Peptide Powder

Supplement taken by the host with Vitamin C before isometrics, recommended to be sourced from skin (e.g., bovine hide) to avoid heavy metals found in bone broth.

drugAT-1 Receptor Drugs (Angiotensin Receptor Inhibitors)

Class of drugs, like sartans (e.g., Losartan), taken by over 15 million Americans daily, that increase the rate of tendon rupture by 7.6 fold.

personMichael Kjaer

World's best sports medicine doctor for musculoskeletal injuries, based in Copenhagen. His work showed that heavy strength training without eccentric movement had the same effect, and his study on early loading post-injury found faster recovery.

drugFluoroquinolone antibiotics

Class of antibiotics that increase the rate of tendon rupture by about 3.5 fold.

locationEaster Island (Rapanui)

Location where the host interviewed David Sabatini and Navdeep Chandelle.

toolShockwave Therapy

Treatment method mentioned in the context of orthobiologics.

conceptPGC-1 Alpha

Coactivator involved in mitochondrial biogenesis.

organizationUniversity of Illinois Chicago

Former university of Dr. Baar, where a study showed that knocking out inflammatory cells prevented muscle hypertrophy.

productFlexBar

A churro-shaped device used for eccentric loading, which the host has for tennis elbow.