Abstract
BackgroundThe aim of this study was to evaluate the usefulness of an ultrasound-based method of examining extensor muscle architecture, especially the parameters important for force development. This paper presents the combination of two non-invasive methods for studying the extensor muscle architecture using ultrasound simultaneously with finger extension force measurements.MethodsM. extensor digitorum communis (EDC) was examined in 40 healthy subjects, 20 women and 20 men, aged 35–73 years. Ultrasound measurements were made in a relaxed position of the hand as well as in full contraction. Muscle cross-sectional area (CSA), pennation angle and contraction patterns were measured with ultrasound, and muscle volume and fascicle length were also estimated. Finger extension force was measured using a newly developed finger force measurement device.ResultsThe following muscle parameters were determined: CSA, circumference, thickness, pennation angles and changes in shape of the muscle CSA. The mean EDC volume in men was 28.3 cm3 and in women 16.6 cm3. The mean CSA was 2.54 cm2 for men and 1.84 cm2 for women. The mean pennation angle for men was 6.5° and for women 5.5°. The mean muscle thickness for men was 1.2 cm and for women 0.76 cm. The mean fascicle length for men was 7.3 cm and for women 5.0 cm. Significant differences were found between men and women regarding EDC volume (p < 0.001), CSA (p < 0.001), pennation angle (p < 0.05), muscle thickness (p < 0.001), fascicle length (p < 0.001) and finger force (p < 0.001). Changes in the shape of muscle architecture during contraction were more pronounced in men than women (p < 0.01). The mean finger extension force for men was 96.7 N and for women 39.6 N. Muscle parameters related to the extension force differed between men and women. For men the muscle volume and muscle CSA were related to extension force, while for women muscle thickness was related to the extension force.ConclusionUltrasound is a useful tool for studying muscle architectures in EDC. Muscle parameters of importance for force development were identified. Knowledge concerning the correlation between muscle dynamics and force is of importance for the development of new hand training programmes and rehabilitation after surgery.
Highlights
The aim of this study was to evaluate the usefulness of an ultrasound-based method of examining extensor muscle architecture, especially the parameters important for force development
In previous US studies of the lower and upper extremities, parameters such as fascicle length, muscle cross-sectional area, shape changes, muscle thickness, muscle volume and pennation angles have been shown to affect the manner in which muscle force is transmitted to the tendons and bones [9,10,11]
No major difficulties were encountered in assessing the muscle circumference, muscle cross-sectional area (CSA), muscle thickness or pennation angles
Summary
The aim of this study was to evaluate the usefulness of an ultrasound-based method of examining extensor muscle architecture, especially the parameters important for force development. This paper presents the combination of two non-invasive methods for studying the extensor muscle architecture using ultrasound simultaneously with finger extension force measurements. Muscle architecture is mainly characterized by fascicle length, pennation angle and the thickness of the muscle [4,5,6]. Knowledge of human muscle architecture has until recently been based on the dissection of cadaver specimens or biopsies. Neither cadaver muscles nor biopsy specimens allow muscle fibre morphology and force development to be studied during contraction in the living human being [7]. Non-invasive methods on living subjects are required to study muscle contraction patterns and real-time muscle changes in architecture during force development. In previous US studies of the lower and upper extremities, parameters such as fascicle length, muscle cross-sectional area, shape changes, muscle thickness, muscle volume and pennation angles have been shown to affect the manner in which muscle force is transmitted to the tendons and bones [9,10,11]
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