Search

Background: Correct mastering of a basic Ollie jump is essential for development of other jumps in skateboarding. In scientific literature we can find a lack of scientifically proved knowledge that describes the difference in muscular activity on various levels of this jump performance. Objective: The aim of this study was to characterize muscular activity in the basic skateboard Ollie jump and to compare this activity with a more difficult modification of the switchstance Ollie jump (the same jump but changed position of limbs). Methods: Ten men experienced in skateboarding for several years, aged 20.0 ± 4.6 years participated in the study (height 1.79 ± 0.05 m, body mass 71.5 ± 4.1 kg). All subjects performed 3 measured Ollie jumps and after that 3 switchstance Ollie jumps. In case of the last-mentioned front and back lower limbs are switched. The observation of muscular activity was carried out by the Delsys Trigno electromyography system. The jump was divided (after video records) into four phases: preparatory, take-off, flight-up and landing. Mean amplitude of muscle activity was measured in following muscles: tibialis anterior, gastrocnemius medialis, rectus femoris, semitendinosus and gluteus medius. Comparison of muscle activity during Ollie and switchstance Ollie was performed by the Wilcoxon test in Statistica. Results: Significantly greater activity (p

Background: A ballet dance routine places extreme functional demands on the musculoskeletal system and affects the motor behaviour of the dancers. An extreme ballet position places high stress on many segments of the dancer's body and can significantly influence the mobility of the lower limb joints. Objective: The aim of this study was to observe the differences in the gait pattern between ballet dancers and non-dancers. Methods:Thirteen professional ballet dancers (5 males, 8 females; age 24.1 ± 3.8 years; height 170.2 ± 8.5 cm; weight 58.3 ± 11.2 kg) participated in this research. We compared these subjects with twelve controls (3 males, 9 females; mean age 24.3 ± 2.75 years; height 173.3 ± 6.01 cm; weight 72.2 ± 12.73 kg). None of the participants had any history of serious musculoskeletal pathology or injury or surgery to the lower limbs. Control groups had no ballet experience. Each participant performed five trials of the gait at self-selected walking speed. Kinematic data was obtained using the Vicon MX optoelectronic system. The observed data was processed in the Vicon Nexus and Vicon Polygon programmes and statistically evaluated in Statistica. Non-parametric test (Mann-Whitney U test, p p p = .008) and hip abduction (-9.18 ± 5.89° vs. -6.08 ± 2.52°; p < .001) peaks together with increased pelvic tilt (3.33 ± 1.26° vs. 3.01 ± 1.46°; p = .020), pelvic obliquity (12.46 ± 3.05° vs. 10.34 ± 3.49°; p < .001) and pelvic rotation (14.29 ± 3.77° vs. 13.26 ± 4.91°; p = .029) were observed. Additionally, the dancers demonstrated greater knee flexion (65.67 ± 4.65° vs. 62.45 ± 5.24°; p = .002) and knee extension (3.80 ± 4.02° vs. -1.54 ± 5.65°; p < .001) peaks during the swing phase when compared to the controls. Decreased maximal ankle plantar flexion was observed during the loading response (-8.84 ± 3.74° vs. -10.50 ± 3.99°) and increased maximal ankle plantar flexion in terminal stance (-20.30 ± 4.93° vs. -17.00 ± 3.99°; p = .025) was observed for the dancers. Conclusions:The results confirm that long-term intensive ballet training affects the kinematic pattern of particular joints during gait performance. The findings suggest overloading in the lumbosacral region and dysfunction or weakness of several muscles in ballet dancers.