| Summary: | 碩士 === 國立彰化師範大學 === 運動學系 === 107 === The purpose of this study was to diagnose the isokinetic strength and the power of shoulder internal/external rotation and to compare the difference between the elite and the recreational volleyball players. This study was also to determine the correlation between the spike velocity of ball and the parameters of strength/power of shoulders. The volunteer participants were seven elite (19.9 ± 1.1 years old, 183.7 ± 4.2 cm, 77.7 ± 5.7 kg, and 9.5 ± 2.6 years of practice) and seven recreational (20.0 ± 0.9 years old, 177.7 ± 4.9 cm, 69.0 ± 5.3 kg, and 6.8 ± 4.7 years of practice) university volleyball players. The Biodex System 4 Pro was used to record the concentric strength and the power of shoulder internal/external rotation under the load conditions of 60, 270, and 400 deg/s. A speed gun (Doppler sensor, Jupiter BSG-1) was used to collect the ball velocity during standing spike. The independent t-tests were used to compare the statistical differences with an alpha level .05 between the elite and the recreational volleyball players. Pearson’s product moment correlation coefficient was used to determine the correlation between the ball velocity of spike and the shoulder internal/external strength or power. The results showed the peak strength of external rotation had no difference between the elite and the recreational volleyball players under the load conditions of 60, 270, and 400 deg/s (ps > .05). However, the average powers of internal rotation showed the elite players were higher than the recreational players in the all the load conditions (ps < .05). The peak internal strength in 60 deg/s and the ball velocity of spike showed the elite players were higher than the recreational players (ps < .05). Over 50% of the variability in the strength/power variable can be explained by variance in the ball velocity of spike. The ratio of internal/external of shoulder showed the elite players were lower than the recreational players (ps < .05).
Keywords: biomechanics, shoulder joint, muscle strength, internal rotation.
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