**3. Results**

The PHV age and the growth age were 13.3 ± 0.9 and 0.3 ± 1.5 years, respectively. A significant linear regression was obtained between the peak torque and growth age (*p* < 0.001, *R*<sup>2</sup> = 0.40) (Figure 1). A significant cubic regression was obtained between optimum angle and growth age (*p* = 0.01, *R*<sup>2</sup> = 0.14) (Figure 2). Coordinates of the minimal local value and maximal local value were (−1.0, 67.6) and (2.3, 74.6), respectively.

**Figure 1.** Relationships between maximal torque of knee extension and growth age.

**Figure 2.** Relationships between optimum angle of the knee extension and growth age.
