Appendix B. Coefficients of variation for every subject, describing within subject variance for every variable that was presently measured in the laboratory. These coefficients of variation are quite comparable to previously reported coefficients of variation describing intrasubject variability for forehands performed on an indoor tennis court (Knudson & Blackwell, 2005). HA = Head Angle; VT = Vertical Trajectory Vertical Trajectory; HV = Horizontal Velocity; VV = Vertical Velocity; BI = Before Impact

Subject	Hitting Zone Length	Racquet HA at Impact (Ëš)	Racquet VT BI (Ëš)	Racquet HV BI (m/s)	Racquet VV BI (m/s)	Ball Spin Rate (RPM)
1	15.9	3.8	18.4	5.0	13.2	9.9
2	19.7	2.5	7.7	9.0	9.7	21.6
3	3.7	2.3	14.2	10.7	21.5	18.5
4	21.9	4.8	14.3	10.8	8.9	21.4
5	16.2	3.2	16.6	7.7	11.3	17.4
6	34.9	2.3	9.8	4.2	7.8	12.1
7	3.6	1.9	7.0	4.1	7.0	22.8
8	10.3	2.8	28.8	6.8	20.8	11.2
9	22.1	2.5	22.3	7.3	25.0	20.6
10	38.0	2.9	14.3	7.0	26.9	7.2
11	34.8	2.5	11.9	6.1	10.0	11.6
12	18.5	3.2	9.6	3.7	6.4	11.5
13	36.1	2.3	18.9	4.8	22.4	7.8
Mean	21.2	2.8	14.9	6.7	14.7	14.9
St Dev	11.8	0.8	6.2	2.4	7.5	5.6