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Updated: Apr 27, 2026
Measurements of Motor Function and Other Clinical Outcome Parameters in Ambulant Children with Duchenne Muscular Dystrophy
Published on: January 12, 2019
Longitudinal assessment of grip strength using bulb dynamometer in Duchenne Muscular Dystrophy
Tatiana M Pizzato1, Cyntia R J A Baptista1, Mariana A Souza1
1Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Faculty of Medicine of Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
Insights
Grip strength in boys with Duchenne Muscular Dystrophy (DMD) declines or stays stable, unlike healthy boys. A bulb dynamometer effectively tracks this muscular weakness progression.
Area of Science:
- Neuromuscular diseases
- Pediatric orthopedics
- Musculoskeletal research
Background:
- Grip strength is a key indicator of functional status, but its correlation with neuromuscular diseases is debated.
- Studies comparing grip strength in children with Duchenne Muscular Dystrophy (DMD) and healthy children using bulb dynamometers are scarce.
Purpose of the Study:
- To evaluate grip strength evolution and weakness magnitude in boys with DMD compared to healthy controls.
- To correlate functional data in DMD boys with their grip strength measurements.
Main Methods:
- Grip strength was measured using a bulb dynamometer in 18 ambulant boys with DMD (aged 4-13) and 150 age-matched healthy boys.
- The DMD group was followed for 6-33 months, with functional performance assessed using the Vignos scale.
Main Results:
- Grip strength did not differ between dominant and non-dominant hands in either group.
- Healthy children showed increased grip strength with age, while DMD boys' grip strength remained stable or decreased.
- Significant differences in grip strength were observed between groups, with healthy children exhibiting higher values that widened with age.
Conclusions:
- The bulb dynamometer accurately detected progressive muscular weakness in boys with DMD.
- Despite increasing weakness, functional performance (Vignos scale) remained largely unchanged in the DMD group.
- The amplitude of weakness in DMD boys increased with age.
Background:
Grip strength is used to infer functional status in several pathological conditions, and the hand dynamometer has been used to estimate performance in other areas. However, this relationship is controversial in neuromuscular diseases and studies with the bulb dynamometer comparing healthy children and children with Duchenne Muscular Dystrophy (DMD) are limited.
Objective:
The evolution of grip strength and the magnitude of weakness were examined in boys with DMD compared to healthy boys. The functional data of the DMD boys were correlated with grip strength.
Method:
Grip strength was recorded in 18 ambulant boys with DMD (Duchenne Group, DG) aged 4 to 13 years (mean 7.4 ± 2.1) and 150 healthy volunteers (Control Group, CG) age-matched using a bulb dynamometer (North Coast- NC70154). The follow-up of the DG was 6 to 33 months (3-12 sessions), and functional performance was verified using the Vignos scale.
Results:
There was no difference between grip strength obtained by the dominant and non-dominant side for both groups. Grip strength increased in the CG with chronological age while the DG remained stable or decreased. The comparison between groups showed significant difference in grip strength, with CG values higher than DG values (confidence interval of 95%). In summary, there was an increment in the differences between the groups with increasing age. Participants with 24 months or more of follow-up showed a progression of weakness as well as maintained Vignos scores.
Conclusions:
The amplitude of weakness increased with age in the DG. The bulb dynamometer detected the progression of muscular weakness. Functional performance remained virtually unchanged in spite of the increase in weakness.
