111. 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, published scientific conference contribution Keywords: šport, motorika, gibalna/športna aktivnost, predšolski otroci, testiranja, meritve
Published in RUP: 15.10.2013; Views: 7584; Downloads: 94
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112. Bilateral synergies in foot force production tasksNejc Šarabon, Goran Marković, Pavle Mikulić, Mark L. Latash, 2013, original scientific article Abstract: 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
Keywords: kinesiology, force, synergy, legs, bilateral deficit, symmetry
Published in RUP: 15.10.2013; Views: 5576; Downloads: 241
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115. The effects of aging on the rambling and trembling components of postural swayNejc Šarabon, Andrej Panjan, Mark L. Latash, 2013, original scientific article Abstract: 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
Keywords: postural control, aging, sway, rambling, trembling
Published in RUP: 15.10.2013; Views: 3283; Downloads: 79
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117. Effects of whole-body cryotherapy on recovery after hamstring damaging exerciseBorut Fonda, Nejc Šarabon, 2013, original scientific article Abstract: 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
Keywords: whole-body cryotherapy, damaging exercise, hamstring muscles, recovery
Published in RUP: 15.10.2013; Views: 4196; Downloads: 98
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120. Adjusted saddle position counteracts the modified muscle activation patterns during uphill cyclingBorut Fonda, Andrej Panjan, Goran Markovič, Nejc Šarabon, 2011, original scientific article Abstract: The main aim of this project was to study muscle activity patterns during steep uphill cycling (UC) (i.e., with a gradient of 20%) with (1) normal saddle geometry and (2) with adjusted saddle position ASP (i.e., moving the saddle forward and changing the tilt of the saddle by 20%). Based on our preliminary case study, we hypothesized that: (1) during 20% UC muscle activity patterns would be different from those of level cycling (LC) and (2) during 20% UC with ASP muscle activity patterns would resemble those of LC. Twelve trained male cyclists were tested on an electromagnetically braked cycle ergometer under three conditions with the same work rate (80% of maximal power output) and cadence (90 rpm): level (LC), 20% UC and 20% UC with ASP. Electromyographic signals were acquired from m. tibialis anterior (TA), m. soleus (SO), m. gastrocnemius (GC), m. vastus lateralis (VL), m. vastus medialis (VM), m. rectus femoris (RF), m. biceps femoris (BF) and m. gluteus maximus (GM). Compared to LC, 20% UC significantly modified both the timing and the intensity of activity of the selected muscles, while muscles that cross the hip joint were the most affected (RF later onset, earlier offset, shorter range of activity and decrease in peak amplitude of 34%; BF longer range of activity; GM increase in peak amplitude of 44%). These changes in EMG patterns during 20% UC were successfully counteracted by the use of ASP and it was interesting to observe that the use of ASP during 20% UC was perceived positively by all cyclists regarding both comfort and performance. These results could have a practical relevance in terms of improving performance during UC, together with reducing discomfort
Keywords: cycling, electromyography, bicycle geometry, muscular coordination
Published in RUP: 15.10.2013; Views: 4746; Downloads: 149
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