High resolution ultrasound (HR-US) analysis of muscular pennation angle in track-and-fields athletes

Purpose: To evaluate the fascicle angles of pennation of lower limb muscles (vastus lateralis (VL) and medial head of gastrocnemius (MG)) using HR-US in highly trained track-and-field athletes, in order to investigate whether the fascicle arrangements of the muscles could be different according to their muscular activities (aerobic versus anaerobic).

Materials and methods: 36 track and field athletes trained in aerobic (marathon runners) and anaerobic (100 metres runners) were evaluated at the end of their training session. The evaluation was performed by a 7.5–13MHz probe on VL and MG of both limbs. The measurement of fascicle pennation angles were obtained by longitudinal scans along the major axis of the muscle belly.

Results: Anaerobic trained athletes (100 metres runners) showed greater fascicle angles than aerobic trained athletes (marathon runners). There is significant difference of the orientation of fibres between aerobic and anaerobic trained athletes.

Conclusion: Anaerobic athletes have greater pennation angle than anaerobic athletes as measured by ultrasound. HR-US evaluation of muscle fascicle pennation angles is a simple technique that can provide to achieve information about the muscle architectural characteristics.