Author(s): BALINT, K., HEGYI, A., PÉTER, A., KÓBOR, I., GU, Y., TIHANYI, J., GYEBNÁR, G., Institution: HUNGARIAN UNIVERSITY OF SPORT SCIENCE, Country: HUNGARY, Abstract-ID: 898

INTRODUCTION:
The ability of skeletal muscles to generate force is related to their architectural properties. Plantar flexor muscles are important for running propulsion. In propulsion, sprinters have a shorter time to produce larger forces as compared to distance runners, which may be associated with different muscle architecture in sprinters and distance runners. Although some studies examined plantar flexor architecture in these populations using 2-D ultrasonography, it is likely that more advanced 3-D methods such as diffusion tensor imaging (DTI) allow further insights into architectural differences between these groups.
METHODS:
In this study, we recruited 15 sprinters and 15 distance runners. To date, data from 9 sprint runners (IAAF score: 977±109, 5 males) and 13 distance runners (IAAF score: 958±125, 10 males) have been processed. 3-D muscle architecture of the plantar flexor muscles was reconstructed by scanning the right leg using T1 and DTI MRI sequences. Muscle segmentation was performed based on the T1 images to establish muscle boundaries and to generate the 3D mesh of the muscles. DTI tractography was used to reconstruct the architecture of the plantar flexor muscles. Muscle volume, fascicle length, pennation angle, and physiological cross-sectional area were estimated for each of the medial and lateral gastrocnemii as well as for four compartments of the soleus muscle. Because data collection is ongoing, statistical analysis has not yet been performed.
RESULTS:
In medial gastrocnemius, muscle volume (268±52 vs. 273±58 cm3), fascicle length (80.41±13.12 vs. 84.51±14.20 mm), pennation angle (26.27±2.33 vs. 25.34±1.45⁰) and physiological cross-sectional area (36.3±9.3 vs. 35.8±11.3 cm2) were similar between sprint and distance runners. Similarly, no difference between groups were evident in lateral gastrocnemius muscle volume (161±35 vs. 170±31 cm3), fascicle length (72.31±11.85 vs. 73.31±7.79 mm), pennation angle (27.93±3.04 vs. 27.93±3.23⁰) or physiological cross-sectional area (22.4±5.8 vs. 23±3.6 cm2). The total soleus muscle volume (455±118 vs. 456±82 cm3) and average fascicle length (43.8±4.7 vs. 47.6±5.9 mm), pennation angle (32.7±3.9 vs. 31.7±2⁰) and the physiological cross-sectional area (104.9±29.5 vs. 100.3±24.4) were also similar between groups.
CONCLUSION:
Compared to data on non-trained individuals using DTI MRI(1), gastriconemii fascicles were longer in sprinters and soleus fascicles were shorter in distance runners. Seemingly, there is no obvious difference between sprinters and distance runners in the volume or architecture of plantar flexor muscles. After completing our dataset, further analysis will be performed using statistical shape modeling to test for group effects on regional differences in muscle shape and architecture.
REFERENCES:
1) Bolsterlee et al., J. Biomech, 2019