The purpose of the study was to compare the biomechanical analysis of hybrid swing on sidehill lies in professional golfers.
For this study, eight low handicap professional golfers who earn a living by playing golf were selected. And Kwon3D XP of motion analysis program and Ultium ESP for Electromyography(EMG) analysis were used. On the biomechanical variables, Displacement and Velocity from Center of Mass(COM), Body Joint Angle, Duration Time, Ground Reaction Force(GRF), Displacement of Center of Pressure(COP), Electromyography(EMG), Club and Ball etc. were analyzed.
The data were analyzed using the one-way analysis of variance(ANOVA) in the SPSS 26.0, and with statistical significance level at .05.

The results of this study are summarized as follows :

First, there was no statistically significant difference in the duration time for each swing phase on sidehill lies.

Second, there were significant differences in the left and right displacement from the center of mass(COM). The results of the post-hoc tests showed that uphill sidehill lie(USL) was lower than downhill sidehill lie(DSL) at E1 ? E6. And there were no significant differences in the anterior and posterior displacement from the center of mass(COM). Whereas, there were significant differences in the vertical displacement from the center of mass(COM). Post-hoc tests showed that DSL was higher than flat lie(FL) and DSL at E1 ? E6.

Third, there were no significant differences in the left and right velocity, in the anterior and posterior velocity, and in the vertical velocity from the center of mass(COM) when golfers swing the hybrid on sidehill lies.

Fourth, there were significant differences in body joint angles each for the hip joint, ankle joint, and knee joint when swinging a hybrid on sidehill lies. The right hip joint at E1, E2 and E4 had significant differences one-way ANOVA results. Post-hoc tests revealed that DSL was lower than FL and USL at E1, USL was higher than DSL at E2, DSL was lower than FL and USL at E4 in angle. The left hip joint at E1, E2, E4 and E5 had significant differences one-way ANOVA results. Post-hoc tests revealed that DSL was lower than FL and USL in angle.
There were significant differences in the right knee joint at E5/E6. Post-hoc tests revealed that FL was higher than DSL in angle. The left knee joint at E6, there was a significant difference. Post-hoc test revealed that DSL was lower than FL and USL in angle. In the right ankle joint, there were significant differences at E1, E2 and E3. Post-hoc tests showed that FL was a higher than USL, but lower than DSL at E1. And at E2, DSL was the most high, FL was the second, and USL was the most low, DSL was higher than FL and USL at E3 in angle. In the left ankle joint, there were significant differences at E1 - E6 all and post-hoc tests showed that DSL was higher than FL and USL at E1/E2. At E3, E4, E5 and E6, USL was lower than DSL in angle. In the trunk tilt angle, there were significant differences at E1 - E5 each, and Post-hoc tests showed that DSL was higher than FL and USL at E1/E2, DSL was higher than only USL at E3/E4. At E5 showed that DSL was higher than FL and USL in angle.

Fifth, there was a significant difference at E3 of the X-Factor, and post-hoc test showed the FL was higher than DSL in angle.

Sixth, there was a significant difference at E5 of the O-Factor, and post-hoc test showed DSL was higher than FL and USL in angle.

Seventh, there were significant differences in the ground reaction force y-axis(Fy) of the right foot at E1 ? E6 all. And post-hoc tests showed that DSL was higher than FL and USL at E1, E3, E4, E5 and E6, DSL was the most high at E2, FL was the second, and USL was the most low. There were significant differences in the ground reaction force y-axis(Fy) of the left foot at E1, E2, E4, E5 and E6, and post-hoc tests showed that DSL was higher than FL and USL at E1, E2, E5 and E6, USL was lower than DSL at E4.

Eighth, there were no significant differences in the left and right displacements and the anterior and posterior displacements of the center of pressure(COP).

Ninth, there were no significant differences in the activities of lower extremity muscles on electromyography(EMG) analysis in all phases during the hybrid swing on sidehill lies.

Tenth, there was a significant difference in the FACE ANGLE of the club kinematic variables at the impact of hybrid swing, and post-hoc test showed that DSL was higher than FL and USL. And there was a significant difference in the FACE TO PATH at the impact of hybrid swing, and post-hoc test revealed that DSL was higher than USL. Also, there was a significant difference in the SWING PLANE, and post-hoc test showed that DSL was higher than FL and USL. There were significant differences in the SPIN AXIS and SIDE of the ball kinematic variables, and post-hoc tests showed that DSL was higher than FL and USL.

In summary, it is shown that being stability of the forward and backward movements of the upper body is important to get an effective hybrid swing on sidehill lies.

Finally, it may be concluded that it was found that stability is important for the hybrid swing. And it is necessary to get the coordination of the body joints and the action of the ground reaction force(GRF) for a sidehill lie. When the movement of the center of mass(COM) and the center of pressure(COP) on sidehill lies are the same as the movement on flat ground, the effects of muscle action on lower extremities will be like when swinging a hybrid on flat ground. Also, strategic distance and direction can be improved.