Sports Engineering / Sports Biomechanics
Abbass Farjad Pezeshk; Heydar Sadeghi; Mohammad Shariatzadeh Joneidy; Zahra Safaie Pour
Volume 10, Issue 4 , January 2017, , Pages 315-324
Abstract
Background and Aim: The Stiffness of human could have the substantial effect on motion efficiency by the influence in Stretch-Shortening cycle. The purpose of this study was to investigate the relationship between mechanics of the negative and positive phases of hopping; to identify the effect of ...
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Background and Aim: The Stiffness of human could have the substantial effect on motion efficiency by the influence in Stretch-Shortening cycle. The purpose of this study was to investigate the relationship between mechanics of the negative and positive phases of hopping; to identify the effect of stiffness and stretch shortening cycle on the optimal performance of the cyclic movements. Materials and Methods: To calculate the leg stiffness, knee and ankle joint stiffness and also angular velocity of the 30 young male with the age range of 18-33 and weight range of 60-88 kg during hopping, we used motion analysis and force platform system. Results: the results of the Principle component analysis showed that all of the ankles related parameters were classified on the first PC. Pearson correlation coefficient also showed that there are a significant relationship between joint stiffness, negative and positive mechanical energy and angular velocity (P<0.05, P<0.01). Conclusion: Due to results of this study, it seems that during cyclic motions, the common mechanism for performing strength and power activity is not useful for having the maximum advantage from stretch shortening cycle, though the ankle joint stiffness reduction is an efficient way to decrease required energy for performing these activities.
Neuro-Muscular Engineering
Sohrab Barimani; Ali Maleki; Ali Fallah
Volume 8, Issue 1 , March 2014, , Pages 101-111
Abstract
FES based method used for rehabilitation of patients with spinal cord injury (SCI). One of these methods is FES cycling. FES cycling exercise has to be useful among SCI patients because of creating a periodic activity in the muscles of the lower extremities and stability of seating position. The major ...
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FES based method used for rehabilitation of patients with spinal cord injury (SCI). One of these methods is FES cycling. FES cycling exercise has to be useful among SCI patients because of creating a periodic activity in the muscles of the lower extremities and stability of seating position. The major challenge for application of FES in rehabilitation is early fatigue occurrence in electrically stimulated muscles. Motor control system selects a low-cost path among the infinite possible route to the body's movements. High efficiency and the minimum rate of muscle fatigue are main characteristics of the motor control system. This type of control system is called muscle synergy. In this study, the quantification of muscle synergy between the core muscles in cycling has been done by non-negative matrix factorization (NMF) method and considering the kinesiology basis. Four synergies were determined as appropriate and optimal synergies to describe the cycling in different mechanical terms. VAF criteria with regard to the four synergies to describe cycling in speeds of 40, 50 and 60 rpm are 92±4, 92±3 and 91±4% respectively and torques, 5, 7 and 9 Nm are 91±3, 92±5 and 92±4% respectively. Correlation between Synergies extracted at different mechanical terms is 98.4 percent in average.
Gait Analysis
Afsaneh Yavari; Mostafa Rostami; Ali Esteki; Ali Tanbakoosaz; Mehdi Yousefi Azar Khanian
Volume 7, Issue 1 , June 2013, , Pages 75-84
Abstract
Most of the recent biomechanical researches have been focused on the stability of people with disabilities and a few researches have been done on the athletes with high balance skill.The methods of elite athletes in keeping the balance can state valuable information about balance strategies and effective ...
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Most of the recent biomechanical researches have been focused on the stability of people with disabilities and a few researches have been done on the athletes with high balance skill.The methods of elite athletes in keeping the balance can state valuable information about balance strategies and effective parameters on balance. In this study we calculate local dynamical stability of musculoskeletal systems during a hard balance motion. Eight non elite athletes and six elite athletes in Wushu participatedin this study. Kinematic parameters for quantitative assessment of postural fluctuations were recorded by VICON ® Motion Analysis System. Using Lyapunov stability theory, stability and preparation of athletes were evaluated and the best model in performing the balance motion was shown to the coaches. Results from this study showed that motion pattern and preparation of athletes are effective in the displacements of center of mass and center of pressure and finally the stability of athletes.
