Test-Retest Reliability of a Static and Dynamic Motor Fatigability Protocol Using Grip and Pinch Strength in Children
Lieke Brauers1,2, Rob Smeets2, Peter Feys1
1REVAL - Rehabilitation Research Centre, Faculty of Rehabilitation Sciences, Hasselt University, Hasselt, Belgium.
Insights
New motor fatigability tests for grip and pinch strength show moderate to high reliability in children with unilateral cerebral palsy (UCP). These measures are useful for identifying motor fatigability, particularly in older children.
Area of Science:
- Pediatric Rehabilitation
- Neurology
- Motor Control
Background:
- Unilateral cerebral palsy (UCP) often impacts motor function, including grip and pinch strength.
- Assessing motor fatigability is crucial for understanding functional limitations in children with UCP.
- New outcome measures for motor fatigability require validation for reliability and interpretability.
Purpose of the Study:
- To evaluate the test-retest reliability of novel motor fatigability outcomes for grip and pinch strength.
- To determine the measurement error and interpretability of these new outcomes in children with UCP.
- To establish the clinical utility of these measures for assessing motor fatigability in pediatric UCP populations.
Main Methods:
- Fifty children with UCP (mean age 11 years) underwent two grip and pinch strength testing sessions within 48 hours.
- A 30-second static and dynamic maximum exertion protocol was used to measure motor fatigability.
- Static Fatigue Index (SFI), mean force (Fmean1, Fmean3), and peak counts were calculated for both hands.
Main Results:
- Static motor fatigability measures (Fmean1, Fmean3) demonstrated moderate to high reliability (ICC 0.56-0.88).
- Dynamic motor fatigability measures showed moderate to high reliability (ICC 0.54-0.91).
- Reliability was generally lower in younger children (6-11 years) compared to older children (12-18 years).
Conclusions:
- Most static and dynamic motor fatigability measures for grip and pinch strength are reliable in children with UCP.
- These tests are suitable for reliable investigation of motor fatigability, especially in older children.
- Measurement error necessitates cautious interpretation of changes in these outcome measures.
Objective:
The purpose of this study was to investigate the test-retest reliability, measurement error, and interpretability of new motor fatigability outcomes of grip and pinch strength for children with unilateral cerebral palsy (UCP).
Methods:
Motor fatigability during grip and pinch strength was measured twice (within 48 hours) in both hands of 50 children (mean age = 11 years 2 months; 14, 31, and 5 children with Manual Ability Classification System levels I, II, and III, respectively) using a 30-second static and dynamic maximum exertion protocol. For static motor fatigability, the Static Fatigue Index (SFI) and mean force (Fmean) in the first (Fmean1) and last (Fmean3) 10 seconds were calculated. For dynamic motor fatigability, Fmean1, Fmean3, and the number of peaks in the first and last 10 seconds were calculated.
Results:
For static motor fatigability, the intraclass correlation coefficients (ICCs) were moderate to high for Fmean1 and Fmean3 (0.56-0.88), and the SFI showed low to moderate reliability (ICC = 0.32-0.72). For dynamic motor fatigability, the ICCs were moderate to high for all outcomes (0.54-0.91). The standard error of measurement agreement and the smallest detectable difference agreement were large in all outcomes, except for the SFI in static motor fatigability. Details per age group are provided. In general, younger children (6-11 years old) showed lower reliability than older children (12-18 years old).
Conclusion:
Most outcome measures for static and dynamic motor fatigability of grip and pinch strength show moderate to high reliability in children with UCP, indicating that these tests can be used reliably to investigate the presence of motor fatigability in UCP, especially in older children. Standard error of measurement agreement and smallest detectable difference agreement indicated that these outcome measures should be interpreted with caution when evaluating change.
Impact:
Most of the proposed outcome measures for static and dynamic motor fatigability of grip and pinch are reliable in children with UCP and can be used for discriminative purposes.
