2015, Volume 11, Issue 1
Selected kinematics characteristic during bench press by disabled powerlifting athletes
Wojciech Seidel1, Rafał Szafraniec1, Krystyna Chromik2
1Faculty of Sport Science, Department of Disability Sport, University School of Physical Education in Wroclaw, Wroclaw, Poland
2Faculty of Sport Science, Department of Athletes Motor Skills, University School of Physical Education in Wrocław, Wroclaw, Poland
Author for correspondence: Krystyna Chromik; Faculty of Sport Science, Department of Athletes Motor Skills, University School of Physical Education in Wrocław, Wroclaw, Poland; email: krystynachromik[at]gmail.com
Background and Study Aim. The aim of the study was to evaluate the effect of the weight of the barbell on the behavior of some kinematic parameters recorded during the bench press by disabled powerlifters.
Material and methods. 29 disabled weightlifters (23.9±6.1 years) from Disabled Sport Association were examined. Each subject performed a bench press, respecting all rules and regulations, 4 times. The subjects lay supine on the powerlifting bench, afterwards they took the bar from the racks, lowered it down to the chest and pressed upwards till full extension of the elbows. Following loads were used: 40%1RM, 60%1RM, 80%1RM and 95%1RM (1RM–one repetition maximum). A potentiometer was used to register time of movement and distance. Empiric distribution of analyzed characteristics didn’t differ from normal distribution, what was evaluated with the Shapiro-Wilk test. Distribution comparison at different loads analysis were calculated with the t-test for dependent samples (p<0,05). Spearman’s rank correlation coefficient for parameters in upwards and downwards movement was calculated.
Results. Time, velocity and acceleration of downward movement towards the chest were similar for all loads in all examined athletes. During upward movement the time increased from the load 60%1RM or more, whereas velocity and acceleration decreased with the bar load increase. Velocities were correlated in upward and downward movement, which means that the faster the athletes lowered the bar, the faster they also pressed it up. In 95%1RM trial the maximal acceleration didn’t differ statistically significant. Correlations between maximal acceleration in upward and downward movement were significant up to 80%1RM.
Conclusions. Bar load increase didn’t cause significant changes of kinematic parameters during downward movements, during upward movement the bar load influenced the parameters’ changes significantly. The time of movement increased, while velocity and acceleration values decreased.
Key words: kinematic parameters, muscle strength, sports, upper extremity, weight lifting