| Summary: | 碩士 === 中國文化大學 === 運動教練研究所 === 85 === Biomechanical behaviors such as muscle strength and power in
controlling tennis player''s shoulder movement is critical
important. To tennis player, the performance of forehand and
backhand of racket swings are fundamental skill which requires
powerful upper extremity muscles. Based on this concept, many
investigations have been done with respect to shoulder muscles
in term of abductor-adductor, and internal-external rotators.
However, the components of forehand and ba ckhand of racket
swings are multi-joints movements. In addition, these movement
patterns require integration of upper extremity muscles in
direction of diagonal flexion and extension. As such the study
of muscle isokinetic behaviors in multi-joint movement to tennis
player is important . Therefore, The purposes of this study were
to (1) investigate isokinetic upper extremity muscle strength
and power in direction of diagonal flexion and extension (2)
compare the difference of isokinetic behaviors among three
levels of tennis players. Thirty female and non-injured tennis
players were voluntarily participated in this study. Subjects
were categorized into three groups, based on their previous
performance. Kin Com dynamometer was used as loading device in
this study. The speeds of each motion were 60, 120 and 180 °/
sec. One-way ANOVA was used in statistical comparison among
dependent variables which isokinetic values from different
groups and isokinetic values from different muscle groups.
Tukey''s multiple comparison tests were used to distinguish the
trend among each group. The analysis revealed the following
results: (A). With respect to the maximal muscle strength: a. At
all three angle velocity (i.e., 60, 120, and 180 °/sec) the
maximal muscle strength of shoulder adduction-flexion movement
for the advanced college players is bigger, compare to the
college less advanced and high school players. b. The angle
velocity of 180 °/sec is the velocity that close to a normal
swing at the current study. The advanced college players are
characterized by not showing reduced maximal muscle strength
when the angle velocity increased. c. All three groups showed
greater maximal muscle strength of shoulder adduction-flexion
movement than their shoulder abduction-extension movement. (B).
With respect to the power a. The advanced college players have
the greatest power of shoulder adduction-flexion movement and
shoulder abduction-extension movement, the less advanced college
players follow, and the high school players showed the smallest
power. Further more, all three groups showed greater power of
shoulder adduction-flexion movement than their shoulder
abduction-extension movement. b. The advanced college players
showed great power at the initiation stage of the swing. The
power peak at the ball contact stage, and the power can be
maintained to the completion of the movement. c. The power of
shoulder abduction-extension movement is greatest at the
initiation stage of the swing movement for all three groups.
Then the power decline along the course of the swing movement.
As such, maintaining great power to the completion of swing
movement is a key issue for the future. d. All three group
showed greatest power at the highest swing velocity (i.e.,180°/
sec). (C). With respect to the muscle strength ratio a. The
muscle strength ratio is 2:3 for all three groups of players.
However, the muscle strength ratio for the advanced college
players revealed a trend of decline with the increase of
velocity, while the less advanced college players showed no
change of the muscle strength ratio with the increase of swing
velocity. Key words: Tennis, isokinetic, forehand, backhand,
digonal flexion and extension.
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