• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.199-206
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• 2015

Objective : The purpose of this study was to conduct a biomechanical analysis of a one-legged jump in a traditional Korean dance (Wae Bal Ddwigi) according to breathing method. Method : Participants for this study were 10 dancers with experience for at least 10 years in traditional Korean dance. Independent variables for this test were two different types of breathing methods. Dependent variables were ground reaction force and lower extremity kinematic variables. The jumping movement was divided into three separate stages, take off, flight, and landing. The subjects were asked a questionnaire regarding the degree of impact force and stability of landing posture after the experiment. The Kistler Force Plate (9281B, Switzerland) was used to measure ground reaction force. A digital camera was used to look into angles of each joint of the lower part of body. SPSS was used for statistical analysis via the dependent t-test(p<.05). Results : There were significant differences in jumping according to breathing method. The inhalation & exhalation method yielded significantly longer flight times combined with greater ground reaction force. The breath-holding method required more core flexion during landing, increasing movement at the hips and shoulders. Conclusion : Consequently, there was more flexion at the knee to compensate for this movement. As a result, landing time was significantly higher for breath-holding.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.175-182
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• 2015

Objective : The purpose of this study was to investigate difference in fascicle behavior of the medial gastrocnemius during the locomotion with varying intensities, such as gait and one-legged and two-legged vertical jumping. Methods : Six subjects (3 males and 3 females; age: $27.2{\pm}1.6yrs.$, body mass: $62.8{\pm}9.8kg$, height: $169.6{\pm}8.5cm$) performed normal gait (G) at preferred speed and maximum vertical jumping with one (OJ) and two (TJ) legs. While subjects were performing the given tasks, the hip, knee and ankle joint motion and ground reaction force was monitored using a 8-infrared camera motion analysis system with two forceplates. Simultaneously, electromyography of the triceps surae muscles, and the fascicle length of the medial gastrocnemius were recorded using a real-time ultrasound imaging machine. Results : Comparing to gait, the kinematic and kinetic parameters of TJ and OJ were found to be significantly different. Along with those parameters, change in the medial gastrocnemius (MG) muscle-tendon complex (MTC) length ($50.57{\pm}6.20mm$ for TJ and $44.14{\pm}5.39mm$ for OJ) and changes in the fascicle length of the MG ($18.97{\pm}3.58mm$ for TJ and $20.31{\pm}4.59mm$ for OJ) were observed. Although the total excursion of the MTC and the MG fascicle length during the two types of jump were not significantly different, however the pattern of length changes were found to be different. For TJ, the fascicle length maintained isometric longer during the propulsive phase than OJ. Conclusion : One-legged and two-legged vertical jumping use different muscle-tendon interaction strategies.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.3
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• pp.201-207
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• 2012

Jumping is considered as a suitable way for realizing fast locomotion on the ground. As for the issue of developing mobile robots that can jump up and forward enough for accomplishing useful missions, this paper first introduces two types of jumping principles that are found in biological animals or insects. We also present how the principles are applied to several jumping robot examples that include outcomes for the past a few years and also our recent one. Design ideas and features of the robots are explained and compared in order to discuss important issues and guidelines for the design of jumping robots.