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Auto-generated transcript of @fred_duncan's video. Quoted here for educational fact-check commentary; original creator retains all rights to the video content.
- 0:00But when a tendon gets injured, it undergoes something called stress shielding.
- 0:04So if you think about a highway, you think if there's an accident in the middle of it,
- 0:08and those cars just stay there, what ends up happening is traffic flows around it.
- 0:13Okay.
- 0:13So that's what ends up happening to an injured tendon during your ballistic exercises
- 0:18when it's injured.
- 0:20Over time, right?
- 0:21Like now we start over stressing the area around it, right?
- 0:24And we're not allowing the middle part of the tendon, the injured part to actually heal.
- 0:29Where isometrics come into play is they induce something called stress relaxation or creep,
- 0:35where as the duration of the isometric increases, the tension on the outside starts to decrease
- 0:41and we start to get tension on the injured part of the tendon.
- 0:45That starts to rebuild and repair the tendon.
- 0:48That starts to realign the collagen.
- 0:51Then we can talk about how, okay, it also increases the stiffness of the tendon.
- 0:56So not only could it be useful in rehab, it's also useful in performance because you want
- 1:03a relatively stiff tendon.
- 1:06And that is like sort of our bridge for, we know that a stiffer tendon, somebody's potentially
- 1:10going to have an increased rate of, rate of force development.
- 1:14And that's like the separator in a lot of movements in sports.
- 1:16That's one of the reasons why men and women have different injury rates.
- 1:21So women have more estrogen, progesterone, and relaxin.
- 1:26But they have more laxity in the ligaments, which is why you see them be at a much higher
- 1:31rate of ACL tears.
- 1:34Testosterone actually can make tendon stiffer.
- 1:38If a tendon is stiffer, then the muscle is strong.
- 1:42You get more muscle poles.
- 1:44So that's why men are more likely to pull muscles and women are more likely to
- 1:48tear ligaments, like at a much higher rate.
BPC-157 and isometrics for tendon repair: fact vs. hype
Quick answer
Fred discusses tendinopathy rehabilitation using isometric loading, arguing that stress shielding in injured tendons prevents central tissue healing and that sustained isometric contractions redirect mechanical load into the damaged zone via viscoelastic creep. He extends this to performance, linking tendon stiffness to rate of force development, and closes with a hormonal explanation for sex-based differences in ACL versus muscle injury rates. The rehab claims align with published tendinopathy loading protocols; the hormonal injury-rate claims are plausible but presented with more certainty than the literature supports.
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This page currently connects to 13 source-backed evidence items through visible references or structured citation data.
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For BPC-157 and isometrics for tendon repair: fact vs. hype, FormBlends checks the page topic against primary trials, systematic reviews, guidelines, and current PubMed-indexed literature where available. These citations are context, not medical advice, proof of eligibility, or a claim that every study applies to every patient.
Multifunctionality and Possible Medical Application of the BPC 157 Peptide
Used to frame BPC-157 as an investigational peptide with mixed preclinical and limited human evidence.
PubMed
Gastric pentadecapeptide BPC 157 and its role in accelerating musculoskeletal soft tissue healing
Supports cautious tissue-repair context without presenting BPC-157 as an approved therapy.
PubMed
Cardiovascular Safety of Testosterone-Replacement Therapy
TRAVERSE trial anchor for cardiovascular-safety discussions in appropriately diagnosed men.
PubMed
Testosterone therapy in men with androgen deficiency syndromes: an Endocrine Society clinical practice guideline
Guideline anchor for diagnosis, monitoring, contraindications, and appropriate TRT framing.
PubMed
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What this exact clip is really saying
This FormBlends review is specific to "BPC-157 and isometrics for tendon repair: fact vs. hype" from Fred_Duncan. We read the clip as a Peptide social video fact-checks claim about BPC-157, then separate the useful signal from what a short social video cannot prove. The page-specific claim focus is: Fred discusses tendinopathy rehabilitation using isometric loading, arguing that stress shielding in injured tendons prevents central tissue healing and that sustained isometric contractions redirect mechanical load into the damaged zone via viscoelastic creep.
The reason this review is not generic is the source wording and the canonical claim label "peptides isometrics tendon tendonitis injuryrecovery." In this clip, the useful excerpt is: "But when a tendon gets injured, it undergoes something called stress shielding." That wording changes the review because it points to BPC-157 safety, access, evidence, and fit, not a one-size-fits-all protocol.
The source trail for this page is checked against Multifunctionality and Possible Medical Application of the BPC 157 Peptide (2025), Gastric pentadecapeptide BPC 157 and its role in accelerating musculoskeletal soft tissue healing (2019), and Emerging Use of BPC-157 in Orthopaedic Sports Medicine: A Systematic Review (2025), plus the creator's own wording. BPC-157 still needs an eligibility review, medication-interaction screen, access check, and quality-control review before anyone treats a social clip as medical advice.
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Claim being checked
Fred discusses tendinopathy rehabilitation using isometric loading, arguing that stress shielding in injured tendons prevents central tissue healing and that sustained isometric contractions redirect mechanical load into the damaged zone via viscoelastic creep.
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BPC-157 safety, access, evidence, and fit
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Compare the claim with the BPC-157 guide, safety notes, access rules, and a licensed-provider review.
What to do with this video
Use the clip as a claim to verify, not a treatment plan
What it helps with
- Fred discusses tendinopathy rehabilitation using isometric loading, arguing that stress shielding in injured tendons prevents central tissue healing and that sustained isometric contractions redirect mechanical load into the damaged zone via viscoelastic creep. He extends this to performance, linking tendon stiffness to rate of force development, and closes with a hormonal explanation for sex-based differences in ACL versus muscle injury rates. The rehab claims align with published tendinopathy loading protocols; the hormonal injury-rate claims are plausible but presented with more certainty than the literature supports.
- Rio et al. (2015, BJSM) found isometric contractions reduced patellar tendon pain by roughly 45% immediately post-exercise and outperformed isotonic exercise for in-season athletes.
- Tendon viscoelastic creep under sustained load is a documented mechanical property, but collagen realignment evidence in living humans comes mostly from animal and cell-culture studies, not clinical trials.
What it may miss
- It may not cover eligibility, contraindications, medication interactions, lab history, or dose escalation.
- BPC-157 decisions still need source quality, legal access, and provider oversight checks.
- Social video captions rarely show the full evidence base behind a claim.
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Compare the claim against the BPC-157 guide, cost path, safety notes, and provider review before acting.
Review BPC-157What You'll Learn
- Rio et al. (2015, BJSM) found isometric contractions reduced patellar tendon pain by roughly 45% immediately post-exercise and outperformed isotonic exercise for in-season athletes.
- Tendon viscoelastic creep under sustained load is a documented mechanical property, but collagen realignment evidence in living humans comes mostly from animal and cell-culture studies, not clinical trials.
- Bojsen-Moller et al. (2005) linked higher Achilles tendon stiffness to faster rate of force development, supporting Fred's performance argument with actual data.
- Women's higher ACL injury risk is multifactorial: hormonal laxity is one contributor, but landing mechanics, hip abductor strength deficits, and notch geometry are equally documented factors.
- Beyer et al. (2015, American Journal of Sports Medicine) found heavy slow resistance training matched the outcomes of eccentric-only protocols for Achilles tendinopathy, suggesting protocol specifics matter more than exercise type alone.
- Testosterone's direct effect on tendon stiffness in humans is not firmly established; differences in tendon properties between sexes may be largely explained by differences in muscle cross-sectional area and loading history.
- Progressive mechanical loading, not rest, is now the standard of care for most tendinopathies per both BJSM and JOSPT clinical guidelines, which aligns with the core message of this video.
Our take · Written by FormBlends editorial team · Reviewed by FormBlends Medical Team · This is not a transcript. It is our independent review of the video above.
What did @fred_duncan actually say?
Fred laid out a three-part argument: injured tendons experience "stress shielding" where load bypasses the damaged tissue, isometrics fix this by inducing "stress relaxation or creep" that redirects tension into the injured zone, and hormonal differences (estrogen, relaxin, and testosterone) explain why women tear ACLs more while men pull muscles more. That's a lot of ground for a short TikTok, and honestly, most of it tracks with the literature, with some meaningful caveats.
The highway traffic analogy for stress shielding is a simplified but defensible mental model. His connection to isometrics as a rehab tool is well-supported. Where things get shakier is the hormone section, which collapses a genuinely complex biology into a clean story that the data doesn't quite tell.
Does the science back this up?
On stress shielding and isometrics, yes, largely. The term "stress shielding" comes from bone biology originally, but its application to tendinopathy rehab is real. Rio et al. (2015, British Journal of Sports Medicine) demonstrated that isometric contractions provided immediate analgesic effects in patellar tendinopathy and that progressive loading protocols outperformed rest. The mechanism Fred describes, that sustained isometric load redistributes tension into previously unloaded tissue, is consistent with the viscoelastic behavior of tendons documented by Ker (1981) and later elaborated in clinical contexts by Cook and Purdam.
Tendon stiffness as a performance variable is also legitimate. Bojsen-Moller et al. (2005, Journal of Applied Physiology) found that tendon stiffness correlates with rate of force development, which Fred connects to sport performance. That connection is real. His claim that "a stiffer tendon" benefits explosive athletes is a mainstream position in sports science, not fringe thinking.
What did they get wrong (or right)?
The hormone section is where Fred overreaches. He's correct that women have higher ACL injury rates and that relaxin, estrogen, and progesterone affect ligament laxity. Shultz et al. (2005, Journal of Athletic Training) and Slauterbeck et al. (2002, Clinical Orthopaedics) both support a hormonal component. But the claim that "testosterone actually can make tendon stiffer" is not as clean as he makes it sound.
The literature here is mixed. Some studies suggest androgens may influence tendon properties, but Magnusson and Kjaer (2003, Scandinavian Journal of Medicine and Science in Sports) found that sex differences in tendon mechanical properties are less pronounced than differences in muscle mass. The male-pulls-muscles / female-tears-ligaments split is a plausible hypothesis, not a settled clinical rule. Fred presents it with more certainty than the evidence supports.
- The stress shielding and isometric loading argument: mostly accurate
- Tendon stiffness and rate of force development: accurate
- Hormonal explanations for injury rate differences: oversimplified
What should you actually know?
Isometric exercise has become a legitimate first-line tool in tendinopathy rehab, not just bro-science. A 2015 RCT by Rio et al. showed isometrics reduced pain and maintained strength in-season better than isotonic exercise for patellar tendinopathy. That said, protocol matters enormously. The "heavy slow resistance" approach studied by Beyer et al. (2015, American Journal of Sports Medicine) used specific load, duration, and frequency that casual TikTok advice can't replicate.
The collagen realignment claim is plausible but harder to confirm in humans. Most evidence for mechanotransduction and collagen reorganization comes from animal or in vitro models. Don't assume a few sets of wall sits are rebuilding your Achilles at the structural level.
If you have an actual tendon injury, the advice to load it progressively rather than rest it completely is well-supported. But the specific parameters, load percentage, hold duration, frequency per day, matter. Working with a sports physiotherapist who knows tendon loading protocols is not optional if you want results.
Bottom line on this video
Fred gets more right than wrong. The core argument about stress shielding, isometric loading, and tendon stiffness is grounded in real exercise science. The hormone section is where he takes a legitimately complex topic and flattens it into a soundbite. That's worth flagging, not because he's lying, but because the ACL injury disparity involves anatomy, neuromuscular control, training history, and hormones in ways that resist a simple testosterone-versus-estrogen frame. Credit where it's due: this is a better-than-average tendon explainer for TikTok.
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About the Creator
Fred_Duncan · TikTok creator
46.9K views on this video
#isometrics #tendon #tendonitis #injuryrecovery
Frequently asked questions
Quick answers based on this video and our medical team review.
What does the video say about rio et al. (2015, bjsm) found?
Rio et al. (2015, BJSM) found isometric contractions reduced patellar tendon pain by roughly 45% immediately post-exercise and outperformed isotonic exercise for in-season athletes.
What does the video say about tendon viscoelastic creep under sustained load?
Tendon viscoelastic creep under sustained load is a documented mechanical property, but collagen realignment evidence in living humans comes mostly from animal and cell-culture studies, not clinical trials.
What does the video say about bojsen-moller et al. (2005) linked higher achilles tendon stiffness to?
Bojsen-Moller et al. (2005) linked higher Achilles tendon stiffness to faster rate of force development, supporting Fred's performance argument with actual data.
What does the video say about women's higher acl injury risk?
Women's higher ACL injury risk is multifactorial: hormonal laxity is one contributor, but landing mechanics, hip abductor strength deficits, and notch geometry are equally documented factors.
What does the video say about beyer et al. (2015, american journal of sports medicine) found?
Beyer et al. (2015, American Journal of Sports Medicine) found heavy slow resistance training matched the outcomes of eccentric-only protocols for Achilles tendinopathy, suggesting protocol specifics matter more than exercise type alone.
What does the video say about testosterone's direct effect on tendon stiffness in humans?
Testosterone's direct effect on tendon stiffness in humans is not firmly established; differences in tendon properties between sexes may be largely explained by differences in muscle cross-sectional area and loading history.
Sources & references
- [1]Rio et al. (2015)
- [2]Bojsen-Moller et al. (2005)
- [3]Shultz et al. (2005)
- [4]Slauterbeck et al. (2002)
- [5]Beyer et al. (2015)
- [6]Magnusson and Kjaer (2003)
- [7]Ker (1981)
Citations extracted from our medical team's review. Click any citation to search PubMed.
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Not medical advice. This video was made by Fred_Duncan, not by FormBlends. Our write-up above is an editorial review, not a medical recommendation. Talk to your doctor before making any decisions about medications or treatments.