Abstract:
The objectives of this study were to investigate and compare the characteristics
of linear and angular momentum transfer patterns from trunk and upper extremity
segment to the racket during tennis double-handed backhand strokes of skilled and
non-skilled tennis players. The subjects were 19 males from the College of Sports
Science and Technology, Mahidol University. They were divided into two groups. The
first group was 6 skilled players who had participated in competitive tennis for 6-7
years and trained 3-5 days per week regularly. The second group was non-skilled
players who had been in a tennis class for at least 6 months with no history of tennis
competition prior to this experiment. All subjects were right-handed, not injured in the
trunk and upper extremities or recovering from any injury at the time of testing. The
linear and angular velocity and the linear and angular momentum were established by
2-dimension motion analysis using a camera operating at 4000 frames per second. The
statistical variables of this study were mean and standard deviation of linear and
angular velocity, linear and angular momentum of trunk, upper arm, forearm and hand.
The mean value of peak linear velocity of right forearm in vertical direction at impact
of the skilled players (3.729 m/s) was significantly greater than that of the non-skilled
players (2.029 m/s)(p<0.05). The mean values of peak resultant linear momentum and
peak linear momentum in the vertical direction of the left upper arm at impact of the
skilled players (6.679kg-m-s-1,9.393kg-m-s-1respectively) were significantly greater
than those of the non-skilled players (4.549 kg-m-s-1,6.502kg-m-s-1)(p<0.05).The peak
linear momentums in horizontal direction of the right forearm, left forearm and left
hand of the skilled players at impact (4.035kg-m-s-1,2.586kg-m-s-1and0.72 kg-m-s-
1respectively) were significantly greater than those of the non skilled players (2.122kgm-
s-1,1.913kg-m-s-1and0.561kg-m-s-1)(p<0.05). The mean values of peak resultant
angular velocity of right forearm at impact of the non-skilled players (10.8263m/s-1)
were significantly greater than those of the skilled players (9.1782m/s-1). However, the
mean values of peak resultant angular momentum of each segment at impact of the
skilled players and non-skilled players were not significantly different. It can be
concluded that the double-handed backhand stroke of the skilled players had greater
linear velocity and linear momentum than that of the non-skilled player. The trunk is
clearly the most important segment in generating linear and angular momentum in the
tennis double-handed backhand stroke, followed by the upper arm, forearm, and hand
respectively.