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Reliability and Structural and Construct Validity of the Functional Strength Measurement in Children Aged 4 to 10
Wendy F M Aertssen1, Gillian D Ferguson2, Bouwien C M Smits-Engelsman3
1W.F.M. Aertssen, MPPT, AvansPlus, University for Professionals, Heerbaan 14-40, Breda, the Netherlands. wendyverhoef@live.nl.
Insights
The Functional Strength Measurement (FSM) is a reliable tool for assessing children's functional strength. This study confirms its good test-retest reliability and construct validity in children aged 4 to 10 years.
Area of Science:
- Pediatric physical function assessment
- Child motor development
- Musculoskeletal health in pediatrics
Background:
- Adequate muscle strength, power, and endurance are crucial for children's daily activities and sports.
- Existing instruments for muscle function assessment measure different aspects.
- The Functional Strength Measurement (FSM) was developed to evaluate performance in strength-requiring activities.
Purpose of the Study:
- To establish the test-retest reliability of the FSM.
- To determine the structural and construct validity of the FSM in children.
- To provide a reliable measure for assessing functional strength in pediatric populations.
Main Methods:
- A cross-sectional descriptive study involving 474 typically developing children.
- Test-retest reliability assessed using the intraclass correlation coefficient (ICC).
- Structural validity examined via exploratory factor analysis; construct validity evaluated using handheld dynamometry (HHD) and Movement Assessment Battery for Children-2 (MABC-2).
Main Results:
- High test-retest reliability for the FSM total score (ICC .91–.94).
- Structural validity indicated a single dimension encompassing all 8 FSM items.
- Convergent validity with HHD ranged from .42–.74; discriminant validity with MABC-2 was generally low (<.39).
Conclusions:
- The FSM demonstrates good test-retest reliability and construct validity for children aged 4 to 10 years.
- The FSM is a norm-referenced test suitable for measuring functional strength in children.
- Further research may be needed to fully explore discriminant validity across all age groups.
Background:
Adequate muscle strength, power, and endurance are important in children's daily activities and sports. Various instruments have been developed for the assessment of muscle function; each measures different aspects. The Functional Strength Measurement (FSM) was developed to measure performance in activities in which strength is required.
Objective:
The study objective was to establish the test-retest reliability and structural and construct validity of the FSM.
Design:
A cross-sectional descriptive study was conducted.
Methods:
The performance of 474 children with typical development on the FSM was examined. Test-retest reliability (n=47) was calculated with the intraclass correlation coefficient (2.1A) for agreement. Structural validity was examined with exploratory factor analysis, and internal consistency was established with the Cronbach alpha. Construct validity was determined by calculating correlations between FSM scores and scores obtained with a handheld dynamometer (HHD) (n=252) (convergent validity) and between FSM scores and scores on the Movement Assessment Battery for Children-2 (MABC-2) (n=77) (discriminant validity).
Results:
The test-retest reliability of the FSM total score ranged from .91 to .94. The structural validity revealed one dimension, containing all 8 FSM items. The Cronbach alpha was .74. The convergent validity with the HHD ranged from .42 to .74. The discriminant validity with MABC-2 items revealed correlations that were generally lower than .39, and most of the correlations were not significant. Exploratory factor analysis of a combined data set (FSM, HHD, and MABC-2; n=77) revealed 2 factors: muscle strength/power and muscle endurance with an agility component.
Limitations:
Discriminant validity was measured only in children aged 4 to 6 years.
Conclusions:
The FSM, a norm-referenced test for measuring functional strength in children aged 4 to 10 years, has good test-retest reliability and good construct validity.
