Clinical Assessment of Trunk Flexor Muscle Strength in Healthy Girls ...

Fig. 5. Frequency of muscle grades by age group.
against gravity, the trunk flexor muscle test may be more
difficult for the younger age groups.
We excluded from this study children who did not have
full neck flexion strength against gravity. Therefore, the reported
values of trunk flexor muscle grades may be higher
than those of many children, especially the younger age
groups.
The assignment of a criterion-based muscle grade did not
account for the quality of movement. Although the younger
children often completed the requirements for a specific muscle
grade, they did not exhibit the same quality of movement
as older children who received the same muscle grade. We
observed that, in general, younger children took more time
to complete the tests, attempted to use more trunk rotation
instead of pure trunk flexion, and lacked the smoothness of
movement that was present in the older children.
Further study needs to be conducted on a larger, randomly
selected group of both sexes to establish normative trunk
flexor muscle grades in children. Such research should include
testing a wider age range including older children and adolescents.
Muscle strength testing in children under 3 years of age
may not be feasible because of their inability to follow instructions.
Measure of isometric trunk flexor muscle strength,
including duration of contraction, may also be useful in
assessing trunk flexor muscle strength in children. In addition,
simultaneous EMG recordings from the abdominal and hip
flexor muscles would be useful in determining the relative Fig. 6. Regression line for muscle grade vs subject age.
RESEARCH
Volume 64 / Number 8, August 1984 1207
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