Author(s): SOLOMONS, T., HAJAT, A., GREEN, A., Institution: UNIVERSITY OF JOHANNESBURG, Country: SOUTH AFRICA, Abstract-ID: 2408

INTRODUCTION:
Muscle architecture is central to skeletal muscle function, with muscle thickness (MT) reflecting morphological size and pennation angle (PA) indicating fibre orientation and packing capacity [1]. These features influence force production during both dynamic and static tasks. Isokinetic dynamometry provides controlled measures while hand-held dynamometry (HHD) provides a portable assessment method. Despite their importance, the extent to which muscle architectural features predicts functional outputs in the tibialis anterior (TA) and gastrocnemius remains unclear. This study examined relationships between MT and PA with isokinetic and isometric strength measures.
METHODS:
Twenty-six physical active participants (19 male, 7 female) were assessed. Stature (66.3 plus/minus 9.8) and body mass (168.9 plus/minus 9.5) were recorded. Isokinetic dynamometry was used to assess peak torque, total work and peak power; HHD assessed maximal force, mean force and RFD during dorsiflexion and plantarflexion. Ultrasonography quantified MT and PA of the right and left TA and gastrocnemius (lateral and medial). Correlations determined associations between architectural and strength variables (p<0.05).
RESULTS:
Right TA MT showed a positive correlation with isokinetic total work (p=0.004) and isometric mean dorsiflexion force (p=0.004), while the left TA MT was significantly correlated with isokinetic peak torque (p=0.003), total work (p=0.012) and peak power (p=0.003), with no significant PA and isometric associations found. Left medial gastrocnemius MT correlated with isokinetic peak torque (p=0.018), total work (p=0.017). No significant correlations were reported for the right gastrocnemius MT or PAs.
CONCLUSION:
MT rather than PA showed consistent moderate associations with isokinetic performance in the TA and left medial gastrocnemius while isometric strength measures showed limited relationships. This suggests that greater muscle size improves force generation during dorsiflexion and plantarflexion. In contrast, isometric measures showed limited relationships with architecture as static contractions depend more neural drive, joint-specific positioning and voluntary activation rather than structural size alone [2],[3]. Overall, MT appears to be a meaningful morphological indicator of dynamic lower-limb performance.
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2. Hedayatpour, N (2025). Acute and chronic neural adaptations to different types of muscle contractions. Sports Science for Health, 21:1223-1232.
3. McMahon, G and Onambele-Pearson. G. (2024). Joint angle-specific neuromuscular time course of recovery after isometric resistance exercise at shorter and longer muscle lengths. Journal of Applied Physiology, 136(4):889-900.