Resistance training in genetically confirmed classic EDS
One of the most common clinical messages given to patients with Ehlers-Danlos syndrome is to be careful with exercise — particularly with resistance training, which loads joints and connective tissue under high mechanical stress. For a condition defined by structurally compromised connective tissue, this caution has intuitive logic. It is also, in many patients, leading to under-treatment through avoidance of an intervention that the evidence supports. A 2014 study by Møller and colleagues in the Journal of Musculoskeletal and Neuronal Interactions provides direct evidence in the population with the highest stakes: patients with genetically confirmed classic EDS carrying verified COL5A1 or COL5A2 mutations. These are not patients with hypermobility spectrum disorder or the non-genetic hEDS phenotype. They are patients in whom a known mutation has structurally compromised collagen throughout the body. And in these patients, structured progressive resistance training was not just safe — it improved tendon mechanical properties, muscle strength, and functional performance within 12 weeks.
The Study: Genetic Confirmation, Not Clinical Diagnosis
The distinction between genetic and clinical EDS diagnosis matters for interpreting this paper. Classic EDS is caused by mutations in the COL5A1 or COL5A2 genes, which encode type V collagen — a collagen type that regulates the fibril diameter of type I collagen, which forms the structural backbone of tendons, ligaments, and skin. Verified mutations in these genes produce connective tissue that is biomechanically compromised by a known structural mechanism, not simply by clinical assessment of joint mobility and skin extensibility.
Møller and colleagues confirmed genetic diagnosis in all three patients before including them in the study. This is methodologically significant because it means the intervention was applied to tissue with verified collagen structural compromise — the strongest possible version of the concern about resistance training in EDS. If resistance training produces mechanical benefits even in genetically confirmed collagen-deficient connective tissue, the evidence for its application in hEDS (which has no confirmed structural collagen mutation and typically shows less severe biomechanical compromise) is considerably strengthened.
The Protocol: Progressive Loading With Joint Protection
The 12-week resistance training program was supervised and progressively loaded. Exercises targeted major muscle groups with progressive increases in resistance over the training period. Protocol modifications were made as needed for joint protection — the program was not a generic gym routine applied without consideration of the patients' connective tissue limitations. A qualified trainer or therapist supervised the sessions and adjusted loading and exercise selection based on patient tolerance and joint stability.
Progressive loading is the key principle that distinguishes therapeutic resistance training from recreational gym training for this population. The mechanical stimulus needs to be sufficient to stimulate tendon remodeling and muscle strength adaptation, but not so excessive that it overloads structurally compromised tissue beyond its tolerance. Starting with low loads and progressing conservatively over weeks to months allows the tissue to adapt incrementally. This is the principle that makes resistance training manageable in EDS, and it requires supervision and protocol modification that generic exercise prescriptions do not provide.
The Findings: Tendons, Strength, and Function All Improved
Pre- and post-measurements included maximal muscle strength using isometric and isokinetic testing, tendon mechanical properties assessed by ultrasonography, and functional performance tests. All three patients showed measurable improvements across all three domains. Tendon stiffness increased — the tendons became mechanically stiffer after 12 weeks of progressive loading. Maximal isometric strength improved across the muscle groups targeted by the training. Functional test scores — the kind of real-world physical performance assessments that reflect daily life capacity — improved alongside the structural and strength measurements.
No catastrophic joint or tissue injuries occurred during the program. This is not a trivial finding. The clinical concern about resistance training in EDS centers on the possibility of tendon rupture, ligament tears, or joint subluxation under high mechanical load. In three patients with genetically confirmed structural collagen compromise, 12 weeks of progressive resistance training produced biomechanical improvement without catastrophic adverse events. The concern is not groundless — appropriate caution and supervision are required — but this study demonstrates that the feared catastrophic outcome is not an inevitable consequence of appropriately designed and supervised loading.
Why Increased Tendon Stiffness Matters in EDS
The tendon stiffness finding is mechanically significant and deserves specific attention. Tendons in classic EDS are biomechanically compromised by the collagen mutation. The abnormal collagen fibril structure makes the tendon more extensible and less efficient at force transmission. A muscle contraction of given magnitude produces less effective joint movement because the energy that should be transmitted directly to the joint is instead absorbed by deforming the compliant tendon. This is why EDS patients often feel like their muscles are working but their body is not responding — the transmission mechanism is lossy in ways that normal connective tissue is not.
Tendon stiffness also directly affects proprioceptive feedback quality. Mechanoreceptors in tendons and ligaments detect the rate and magnitude of deformation and send that information to the spinal cord and brain. When tendons are overly compliant, the mechanoreceptor signal is delayed and distorted relative to actual joint movement — the nervous system receives degraded positional information. Increasing tendon stiffness through mechanical loading improves the precision of proprioceptive feedback, which has downstream effects on motor control and joint stability that extend beyond the direct mechanical improvement.
Resistance training does not fix the genetic mutation. It does not repair the structural collagen abnormality that makes the tissue compromised. What it does is apply a mechanical stimulus that drives tendon remodeling — collagen synthesis and reorganization — within the tissue that the mutation has already formed. The response to mechanical loading is preserved even in structurally abnormal connective tissue. The tissue cannot produce normal collagen, but it can produce more of what it has, organized more functionally, when it receives the mechanical signal that loading provides.
Implications for hEDS and Hypermobility Spectrum Disorder
Møller's classic EDS findings have direct implications for the larger and more clinically common hEDS and hypermobility spectrum disorder populations. hEDS has no confirmed genetic mutation — its connective tissue compromise is clinically diagnosed by hypermobility criteria and associated features rather than by identified structural collagen abnormality. The biomechanical deficits in hEDS are real but typically less severe than in classic EDS. If progressive resistance training is safe and effective in patients with genetically confirmed classic EDS, the evidence for its application in hEDS is strong.
This matters because a substantial proportion of hEDS patients have been counseled, either explicitly or implicitly, to limit physical loading. The result is deconditioning on top of connective tissue compromise — the worst combination for functional capacity. Rombaut and colleagues' research on muscle strength in EDS-HT established that the primary functional deficit is neuromuscular control and strength production, not muscle mass. Appropriately designed resistance training addresses exactly that deficit. Møller's work establishes that even the most severe genetic form of EDS tolerates and benefits from that training. The clinical message — for hEDS and hypermobility spectrum disorder patients — is that avoidance of resistance training is not protecting the tissue. It is leaving the most modifiable contributor to functional capacity unaddressed.