Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

This article is part of the PlexusDx Education Hub — your resource for evidence-based guidance on Genetics & Performance. Browse all Genetics & Performance education

The Achilles is the strongest tendon in the human body, yet it is also one of the most frequently injured. Some people tear it or develop chronic pain after years of activity that others handle without trouble. Part of the difference comes down to load, footwear, and training — and part comes down to the genes that build and maintain your connective tissue.

This article explains what happens in an Achilles injury, why collagen structure matters, and which gene variants research has linked to tendon injury risk, along with evidence-based prevention.

What actually happens in an Achilles injury

Achilles injuries fall on a spectrum. Tendinopathy is a chronic, overuse-related breakdown of the tendon’s collagen matrix, causing pain, stiffness, and thickening — often several centimeters above the heel. Acute rupture is a sudden, often complete tear, frequently during explosive push-off in sport, and it usually requires medical evaluation.

Both involve the tendon’s ability to absorb and transmit force. When repeated load outpaces the tissue’s capacity to repair itself, the collagen framework weakens — and that framework is genetically influenced.

Why collagen structure matters

Tendons are built mostly from type I collagen, organized into tightly aligned fibrils that give the tendon its tensile strength. Type V collagen acts as a regulator, controlling how those fibrils assemble and how thick they become. Small differences in the genes that encode these collagens can change tendon stiffness, elasticity, and resistance to microdamage.

This is why two athletes with identical training can have very different injury histories: their connective tissue is engineered slightly differently from the DNA up.

COL5A1 and tendon injury risk

The gene most studied in tendon injury is COL5A1, which encodes part of type V collagen. A variant in the COL5A1 gene, notably rs12722, has been associated in multiple studies with Achilles tendinopathy and, in some cohorts, rupture risk. The variant sits in a region that influences how the collagen message is regulated, which may affect tendon stiffness and how the tissue responds to mechanical strain.

As with all complex traits, the effect is probabilistic. Carrying a risk-associated COL5A1 genotype raises susceptibility; it does not make injury inevitable.

Other connective-tissue genes

COL5A1 is not the only player. MMP3 encodes a matrix metalloproteinase enzyme that helps remodel and break down collagen during repair; variants here have been linked to tendon pathology. TNC (tenascin-C) and GDF5 have also appeared in tendon and musculoskeletal injury research. Together these genes describe a connective-tissue profile rather than a single switch.

Evidence-based prevention

Genetics does not override the most reliable protection: sensible loading. Progressive strength work — particularly eccentric and heavy slow-resistance calf training — has strong evidence for building tendon capacity and reducing Achilles pain. Gradual increases in training volume, adequate recovery, appropriate footwear, and attention to calf flexibility all lower risk.

If you carry a higher-risk connective-tissue profile, these habits matter even more. None of this replaces professional care — persistent or sudden Achilles pain should be evaluated by a qualified clinician or physical therapist.

What genetic insight adds

Understanding your connective-tissue genetics gives context, not a prescription. The PlexusDx Precision Peptide Genetic Test analyzes 14 pathways, 49 peptides, 150+ genetic insights across pathways that influence tissue repair, recovery, and inflammation — the biological systems relevant to tendon health. It describes tendencies in your biology; it does not diagnose injury or predict whether you will be hurt.

Genetics is a guide, not a guarantee. Pairing pathway-level insight with smart training and provider guidance is the most practical way to use it.

Frequently Asked Questions

Can genetics really affect Achilles injury risk?

Yes, in part. Variants in collagen genes such as COL5A1 (including rs12722) have been associated with Achilles tendinopathy and rupture in several studies. Genes influence tendon structure and repair, but training load, footwear, age, and recovery remain major, modifiable contributors to overall risk.

What is the best way to prevent Achilles injuries?

Progressive calf strengthening — especially eccentric and heavy slow-resistance work — has the strongest evidence. Increase training volume gradually, allow adequate recovery, maintain calf mobility, and use appropriate footwear. These habits build tendon capacity regardless of your genetic profile and lower injury odds.

Does a genetic test tell me if I will tear my Achilles?

No. A genetic test describes pathway-level tendencies in connective tissue and repair biology. It cannot predict a specific injury, diagnose a condition, or replace clinical assessment. It offers context about your biology to inform prevention decisions with a qualified provider.

Should I stop running if I have a COL5A1 risk variant?

Not necessarily. A risk-associated variant raises susceptibility, it does not forbid activity. Many carriers train and compete without issue. Sensible load management, strength work, and prompt attention to symptoms matter more day to day than any single genotype. Discuss concerns with a provider.

Want to understand the tissue-repair pathways behind tendon health? Take the Precision Peptide Genetic Test.

This article is part of the PlexusDx Education Hub. Browse all Genetics & Performance education

The Precision Peptide Genetic Test analyzes how your genes influence peptide-related biological pathways. It does not recommend, prescribe, or determine which peptides you should use, and it does not diagnose, treat, cure, or prevent any disease. Consult a qualified healthcare provider before beginning any peptide protocol or making changes to your care.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.