Related Experiment Video
Updated: Aug 24, 2026
Lower Limb Biomechanical Analysis of Healthy Participants
Published on: April 15, 2020
Walking ability and its relationship to lower-extremity muscle strength in children with idiopathic inflammatory
Karen Lohmann Siegel1, Jeanne E Hicks, Deloris E Koziol
1Rehabilitation Medicine Department, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA. karen_siegel@nih.gov
Insights
Muscle weakness in children with juvenile idiopathic inflammatory myopathies (IIM) significantly impacts gait. Lower-extremity muscle strength directly predicts walking speed and stride length, highlighting the importance of strength assessment in managing IIM-related mobility issues.
Area of Science:
- Pediatric Rheumatology
- Movement Science
- Clinical Biomechanics
Background:
- Juvenile idiopathic inflammatory myopathies (IIM) are rare autoimmune diseases affecting muscles in children.
- Gait disturbances are common in IIM, impacting mobility and quality of life.
- Understanding the relationship between muscle strength and gait is crucial for effective management.
Purpose of the Study:
- To investigate gait deficits in children with juvenile IIM.
- To determine the association between lower-extremity muscle strength and specific gait parameters.
Main Methods:
- A cross-sectional study involving 25 ambulatory children with juvenile IIM.
- Manual muscle testing (MMT) assessed strength in key lower-extremity muscle groups.
- Video-based movement analysis quantified gait parameters like walking speed and stride length.
Main Results:
- Reduced walking speed was primarily due to shorter stride lengths.
- Walking speed strongly correlated with the number of weak muscle groups (MMT grade < 7/10) and hip flexor strength.
- Specific gait parameters were significantly impaired in children with juvenile IIM.
Conclusions:
- Lower-extremity muscle strength is a key predictor of gait limitations in children with juvenile IIM.
- MMT scores and the number of weak muscle groups effectively predict gait deficits.
- These findings underscore the importance of strength assessment in the comprehensive care of pediatric IIM patients.
Objective:
To describe gait deficits and their association with lower-extremity muscle strength in children with juvenile idiopathic inflammatory myopathies (IIM).
Design:
Cross-sectional, descriptive study.
Setting:
Clinical research center.
Participants:
Consecutive sample of 25 ambulatory children diagnosed with juvenile IIM.
Interventions:
Not applicable.
Main Outcome Measures:
Manual muscle test (MMT) of bilateral hip flexor, extensor, and abductor; knee extensor; and ankle plantarflexor strength, all measured on a 0- to 10-point scale and summary strength measures. Video-based movement analysis to determine walking speed; gait cycle time; right and left step time; stride length; right and left step length; and stance, swing, and double-limb support phase durations.
Results:
Walking speed (1.03+/-0.27 m/s) was reduced because of shortened stride lengths (1.03+/-0.21 m) more than prolonged gait cycle times (1.05+/-0.22s). Walking speed highly correlated with the number of muscle groups weaker than grade 7 out of 10 (r=-.89) and the strength of the hip flexors (r=.85).
Conclusions:
Lower-extremity strength measures, including MMT scores of individual muscle groups and the number of weak muscle groups, were predictive of gait limitations in children with juvenile IIM.
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