111. The effect of vision elimination during quiet stance tasks with different feet positionsNejc Šarabon, Jernej Rošker, Stefan Loefler, Helmut Kern, 2013, izvirni znanstveni članek Opis: Literature confirms the effects of vision and stance on body sway and indicates possible interactions between the two. However, no attempts have been made to systematically compare the effect of vision on the different types of stance which are frequently used in clinical and research practice. The biomechanical changes that occur after changing shape and size of the support surface suggest possible sensory re-weighting might take place. The purpose of this study was to assess the effect of vision on body sway in relation to different stance configurations and width. Thirty-eight volunteers performed four quiet stance configurations (parallel, semi-tandem, tandem and single leg), repeating them with open and closed eyes. Traditional parameters, recurrence quantification analysis and sample entropy were analyzed from the CoP trajectory signal. Traditional and recurrence quantification analysis parameters were affected by vision removal and stance type. Exceptions were frequency of oscillation, entropy and trapping time. The most prominent effect of vision elimination on traditional parameters was observed for narrower stances. A significant interaction effect between vision removal and stance type was present for most of the parameters observed (p < 0.05). The interaction effect between medio-lateral and antero-posterior traditional parameters differed in linearity between stances. The results confirm the effect of vision removal on the body sway. However, for the medio-lateral traditional parameters, the effects did not increase linearly with the change in width and stance type. This suggests that removal of vision could be more effectively compensated by other sensory systems in semi-tandem stance, tandem and single legged stance
Ključne besede: balance, Body sway, Sensory manipulation, vision
Objavljeno v RUP: 15.10.2013; Ogledov: 3539; Prenosov: 146
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112. Fundamental motor patterns in children aged 4-7 yearsRado Pišot, Nejc Šarabon, Giuliana Jelovčan, Matej Plevnik, Saša Pišot, Urška Čeklić, Tadeja Volmut, Petra Dolenc, Mitja Gerževič, Nina Mohorko, Katja Koren, Boštjan Šimunič, 2010, objavljeni znanstveni prispevek na konferenci Ključne besede: šport, motorika, gibalna/športna aktivnost, predšolski otroci, testiranja, meritve
Objavljeno v RUP: 15.10.2013; Ogledov: 7709; Prenosov: 94
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113. Bilateral synergies in foot force production tasksNejc Šarabon, Goran Marković, Pavle Mikulić, Mark L. Latash, 2013, izvirni znanstveni članek Opis: We analysed the effects of task symmetry during bilateral accurate force production tasks performed by the two feet. In particular, we tested a hypothesis that bilateral deficit would lead to higher indices of synergies defined as co-varied adjustments in the two forces across trials that reduced total force variability. The subjects produced steady-state force followed by a quick force pulse into the target. The two feet could be acting both into plantar flexion and into dorsiflexion (symmetrical tasks), or in opposite directions (asymmetrical task). We used the framework of the uncontrolled manifold hypothesis to quantify two variance components, one of which did not change total force (VUCM), while the other did (VORT). Synergy indices during the asymmetrical task were higher than in either symmetrical task. The difference was due to higher VUCM (compared to the symmetrical plantar flexion task) or lower VORT (compared to the symmetrical dorsiflexion task). The synergy index showed a drop (anticipatory synergy adjustment, ASA) starting 100150 ms prior to the force pulse initiation. The ASA tended to be shorter and of a smaller magnitude for the asymmetrical task. This is the first demonstration of bilateral synergies during accurate force production by the legs. We conclude that bilateral deficit has no or weak effects on two-leg synergies. The results fit the earlier introduced scheme with two groups of neural variables defining average performance of a redundant system and patterns of co-variation among its elemental variables, respectively
Ključne besede: kinesiology, force, synergy, legs, bilateral deficit, symmetry
Objavljeno v RUP: 15.10.2013; Ogledov: 5728; Prenosov: 241
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116. The effects of aging on the rambling and trembling components of postural swayNejc Šarabon, Andrej Panjan, Mark L. Latash, 2013, izvirni znanstveni članek Opis: The effects of healthy aging on postural sway and its rambling and trembling components were studied. Young and elderly subjects stood quietly for 1 min in different postures, and with eyes open and closed. We found that age-related changes in postural sway and its components were similar to those observed in young participants in challenging conditions. These changes may therefore be viewed as secondary to the increased subjective perception of the complexity of postural tasks. Contrary to our expectations, stronger effects of age were seen in characteristics of rambling, not trembling. The commonly accepted hypothesis that older persons rely on vision more was not supported by this study: we found no significant interaction effects of age and vision on any of the sway characteristics. It was concluded that the reported higher reliance on vision in older persons may be task-specific. The results are compatible with the ideas that much of the age-related changes in postural sway emerge at the level of exploring the limits of stability and using the drift-and-act strategy. Our results suggest that the dominant view on rambling and trembling as reflecting supraspinal and peripheral mechanisms, respectively, may be too simplistic
Ključne besede: postural control, aging, sway, rambling, trembling
Objavljeno v RUP: 15.10.2013; Ogledov: 3322; Prenosov: 79
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118. Effects of whole-body cryotherapy on recovery after hamstring damaging exerciseBorut Fonda, Nejc Šarabon, 2013, izvirni znanstveni članek Opis: The purpose of this study was to examine the effects of whole-body cryotherapy (WBC) on biochemical, pain, and performance parameters during the 5-day recovery period after damaging exercise for hamstrings. Participants completed a bout of damaging exercise for the hamstring muscles on two separate occasions (control and experimental condition) separated by 10 weeks. During the control condition, subjects received no treatment after the damaging exercise. The experimental condition consisted of WBC everyday during the recovery period. WBC included single 3-min daily exposures to low temperatures (-140 to -195 °C) in the cryo-cabin. During the recovery period, subjects were tested for biochemical markers, perceived pain sensation, and physical performance (squat jump, counter movement jump, maximal isometric torque production, and maximally explosive isometric torque production). Majority of the observed variables showed statistically significant time effects (P < 0.05) in control group, which indicates the presence of muscle damage. Significant interaction between the control and WBC condition was evident for the rate of torque development (P < 0.05). Pain measures substantially differed between the WBC and the control condition after the exercise. Results of this study are not completely supportive of the use of WBC for recovery enhancement after strenuous training
Ključne besede: whole-body cryotherapy, damaging exercise, hamstring muscles, recovery
Objavljeno v RUP: 15.10.2013; Ogledov: 4245; Prenosov: 98
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