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Updated: Apr 19, 2026
Isometric and Eccentric Force Generation Assessment of Skeletal Muscles Isolated from Murine Models of Muscular Dystrophies
Published on: January 31, 2013
Isokinetic muscle strength differences in patients with mucopolysaccharidosis I, II, and VI
Natalie E Taylor1, Donald R Dengel2, Troy C Lund3
1School of Medicine and Public Health, University of Wisconsin, WI, USA.
Purpose:
To determine muscular strength differences in patients with MPS-I, II, and VI versus age- and sex-matched healthy controls.
Methods:
Dominant leg isokinetic knee extension strength was measured at 90 and 120 degrees per second (d/s) using a dynamometer in 30 subjects with MPS and 42 controls (5-16 yrs). MPS-I was further divided into MPS-IA (attenuated) and MPS-IH (severe). Strength measures analyzed were peak torque (PkT), peak torque per unit body weight (PkT/BW) and per unit lean body mass (PkT/LBM), and average power (AP).
Results:
Following adjusting strength measures for age, MPS-IH and MPS-II had significantly lower strength measures for all variables at both angular velocities. MPS-VI had significantly lower PkT, PkT/LBM, and AP compared to controls at 90 and 120d/s. In contrast, MPS-IA was not significantly different from controls for any strength variable at either angular velocity.
Conclusion:
The results of this study suggest that decrements in skeletal muscle strength depend on MPS diagnosis and severity of disease. Children with MPS-IH demonstrate the greatest difference in muscular strength compared to healthy controls.
Insights
Children with severe Mucopolysaccharidoses (MPS-IH) show significant muscle weakness compared to controls. Milder MPS-IA cases had strength comparable to healthy peers, indicating disease severity impacts muscular deficits.
Area of Science:
- Biomedical science
- Genetics
- Pediatric medicine
Background:
- Mucopolysaccharidoses (MPS) are rare genetic disorders.
- These conditions lead to the accumulation of glycosaminoglycans, affecting multiple organ systems.
- Skeletal muscle function can be impaired in individuals with MPS.
Purpose of the Study:
- To compare muscular strength between patients with Mucopolysaccharidoses types I, II, and VI and healthy controls.
- To identify differences in strength based on MPS subtype and disease severity.
- To assess isokinetic knee extension strength in pediatric patients.
Main Methods:
- Isokinetic knee extension strength was measured using a dynamometer in 30 patients with MPS and 42 healthy children (ages 5-16).
- Measurements included peak torque (PkT), PkT normalized to body weight (PkT/BW), and PkT normalized to lean body mass (PkT/LBM), along with average power (AP).
- MPS-I was subcategorized into attenuated (MPS-IA) and severe (MPS-IH) forms.
Main Results:
- Patients with severe MPS-I (MPS-IH) and MPS-II exhibited significantly lower strength measures across all variables and angular velocities compared to controls.
- Patients with MPS-VI also showed significantly reduced PkT, PkT/LBM, and AP at both 90 and 120 degrees per second.
- In contrast, patients with attenuated MPS-I (MPS-IA) did not show significant differences in strength compared to healthy controls.
Conclusions:
- Skeletal muscle strength deficits in MPS are dependent on the specific diagnosis and the severity of the disease.
- Children with the severe form of MPS-I (MPS-IH) display the most pronounced reduction in muscular strength.
- These findings highlight the variable impact of MPS on muscle function and underscore the importance of disease stratification.
