Fig. 3. Postnatal time-course of whole body mass (A), three architectural parameters: muscle mass (B), fiber length (C) and physiological cross-sectional area (PCSA; D), and postnatal time-course of isometric stress (E). Muscle mass (F) and fiber length (G) were positively correlated with contractile function (mass: P<0.001, R²=0.52; fiber length: P<0.0001, R²=0.82), but PCSA (H) was uncorrelated (P>0.1, R²=0.06). ^*P<0.05 relative to the previous time-point.