Fig. 2
From: Muscle architecture of the medial gastrocnemius during growth
Relationships between the maturity index and chronological age and the relative muscle thickness, pennation angle, and fascicle length of the medial gastrocnemius (maturity index: muscle thickness (a), pennation angle (b), fascicle length (c); chronological age: muscle thickness (d), pennation angle (e), fascicle length (f)). PHV: peak height velocity