Background: This study compared vertical jump phase identification using a three-dimensional motion capture system to three common force platform based methodologies. Methods: Thirty-two semi-professional male rugby league players (23.3 ± 4.1 years) volunteered to participate in the study. Participants completed six vertical jumps on a force plate with landmark body markers for the motion capture system analysis. The data from the motion capture system was then analysed against three common methods used in vertical jump analysis. Results: Eccentric phase time, concentric phase time, time to peak force and rate of force development for method one were significantly different (p<0.001) from motion capture system data. Method 2 was significantly different (p<0.05) for eccentric phase time identification compared to motion capture analysis. No significant differences were found among the three groups for maximum concentric force when compared with motion capture system data. Conclusion: While no differences were found in the maximum force values, differences were found in the eccentric and concentric phase times. The accurate identification of the start and ending of the phases is essential to correctly measure the time to peak force and rate of force development during the vertical jump. The rate of force development and time to peak force has been identified as key predictors of sports performance and therefore care must be taken in the methods chosen to measure these important variables.
International Journal of Physical Medicine & Rehabilitation / Vol. 4, No. 5, Article 1000369