Table 4. GRFs in pivot and stride leg difference between adolescent and collegiate pitchers. Values are expressed as mean (±SD).

Variable	Adolescent pitcher (n = 32)	Collegiate pitcher (n = 30)	ES	Adolescent pitcher (n = 32)	Collegiate pitcher (n = 30)	ES
GRFs	Force Fx			Force Fz
Force on pivot leg at MKH (N/kg)	-.2 (.3)	-.3 (.3)	.14	8.0 (1.5)	6.8 (1.8)**	.69
Force on pivot leg at MAP (N/kg)	-.3 (.7)	-.3 (.7)	.08	10.5 (1.9)	10.8 (2.4)	.16
Force on stride leg at MER (N/kg)	.6 (.9)	.4 (1.0)	.28	18.4 (1.8)	18.4 (1.7)	.00
Force on stride leg at REL (N/kg)	.9 (.7)	1.2 (.9)	.39	16.6 (2.5)	17.7 (2.2)	.47
	Force Fy			Resultant forces
Force on pivot leg at MKH (N/kg)	.7 (.4)	.8 (.5)	.25	8.1 (1.5)	7.0 (1.7)**	.69
Force on pivot leg at MAP (N/kg)	7.2 (1.3)	8.4 (1.7)**	.74	12.8 (2.2)	13.8 (2.7)	.40
Force on stride leg at MER (N/kg)	-10.2 (1.6)	-10.9 (1.7)	.43	21.1 (2.1)	21.5 (2.1)	.16
Force on stride leg at REL (N/kg)	-7.9 (2.0)	-9.3 (1.8)**	.70	18.4 (3.0)	20.1 (2.6)*	.57
Maxima and minima of GRFs	Pivot leg			Stride leg
Maximum Fx (N/kg)	1.4 (.6)	1.3 (.6)	.18	1.2	1.4 (.7)	.23
Maximum Fy (N/kg)	7.2 (1.3)	8.4 (1.7) **	.74
Maximum Fz (N/kg)	12.5 (1.7)	12.9 (2.1)	.23	19.5 (2.0)	19.2 (1.7)	.16
Maximum Resultant forces (N/kg)	14.0 (2.2)	14.9 (2.6)	.37	22.2 (2.5)	22.2 (2.0)	.03
Minimum Fx (N/kg)	-.7 (.5)	-.7 (.5)	.06	-1.3 (.8)	-1.1 (.7)	.22
Minimum Fy (N/kg)				-10.9 (1.8)	-11.1 (1.7)	.11

ES; Effect Size value. MKH; Maximal stride knee height. MAP; Maximal anterior push-off force. SFC; Stride foot contacts ground. MER; Maximum shoulder external rotation. REL; Ball release.* p < 0.05, Significant difference between adolescent and collegiate pitchers.** p < 0.01, Significant difference between adolescent and collegiate pitchers