306 research outputs found
Manipulation of the kinematic chain using visual biofeedback
Feedback has been shown to be an influential component in skill development, yet this has not been assessed in movements involving an explosive proximal to distal sequencing pattern. Novices (n=14) were introduced to a lunge touch task. Visual biofeedback were given on the timing and magnitude of rear leg kinematics. Results showed that those who received feedback adapted their movement patterns by developing extension velocity magnitudes in a summative pattern (pre v post, mean ± SD peak ankle angular velocity: biofeedback; 479 ± 181 v 689 ± 117, control; 466 ± 106 v 477 ± 84 deg·sˉ¹), resulting in greater horizontal impulse (mean ± SD: biofeedback; 1.17 ± 0.60 v 1.7 ± 0.89, control; 1.33 ± 0.33 v 1.49 ± 0.33 N·s·kgˉ¹). The changes were retained after six weeks. These results demonstrate that knowledge of performance based biofeedback interventions alone are effective in developing whole limb contributions in an explosive task
Longitudinal manipulation of the kinematic chain using a reducing biofeedback schedule
Feedback has been shown to be an influential component in skill development, yet this has
not been assessed longitudinally in a complex motor skill. Novices (n=32) were introduced to
a lunge touch task. Visual biofeedback were given on the timing and magnitude of rear leg
kinematics. Results showed that those who received feedback adapted their movement
patterns by developing extension velocity magnitudes (40.0%, 24.8% and 28.9% increases
for the hip, knee and ankle respectively). The changes were retained across 26 weeks, with
a reducing visit schedule of feedback. These results demonstrate that knowledge of
performance based biofeedback interventions alone are effective in developing whole limb
contributions in an explosive task, and that a reducing visit schedule negates dependence on
feedback
Comparison of simple gravity based accelerometer calibration procedures
Accelerometers are commonly used, yet the process of calibrating them and the influence this has on recorded accelerations is rarely reported. The aim of this study was to compare the accuracy of three simple gravity based calibration methods of accelerometers. Using a custom made rig, 16 Delsys Trigno sensors were simultaneously calibrated by positioning the sensors in 9 positions throughout the full range of orientations across three axes. Three calibration methods were used spanning a range of 1g (1G), 2g (2G), and 2g with optimisation (2Gopt). Errors were greatest in 1G (RMSD=3.1%) and equally as good for the 2G and 2Gopt (2.1%). Gravity based calibration of accelerometers can be achieved quickly, and calibration over a larger range provides more accurate results. This work provides recommendations of accelerometer use which help the applied practitioner to collect more reliable and valid data. Further investigation of factors, including those affecting the frequency of calibration, is required
Abnormally high content of free glucosamine residues identified in a preparation of commercially available porcine intestinal heparan sulfate
Heparan sulfate (HS) polysaccharides are ubiquitous in animal tissues as components of proteoglycans, and they participate in many important biological processes. HS carbohydrate chains are complex and can contain rare structural components such as N-unsubstituted glucosamine (GlcN). Commercially available HS preparations have been invaluable in many types of research activities. In the course of preparing microarrays to include probes derived from HS oligosaccharides, we found an unusually high content of GlcN residue in a recently purchased batch of porcine intestinal mucosal HS. Composition and sequence analysis by mass spectrometry of the oligosaccharides obtained after heparin lyase III digestion of the polysaccharide indicated two and three GlcN in the tetrasaccharide and hexasaccharide fractions, respectively. (1)H NMR of the intact polysaccharide showed that this unusual batch differed strikingly from other HS preparations obtained from bovine kidney and porcine intestine. The very high content of GlcN (30%) and low content of GlcNAc (4.2%) determined by disaccharide composition analysis indicated that N-deacetylation and/or N-desulfation may have taken place. HS is widely used by the scientific community to investigate HS structures and activities. Great care has to be taken in drawing conclusions from investigations of structural features of HS and specificities of HS interaction with proteins when commercial HS is used without further analysis. Pending the availability of a validated commercial HS reference preparation, our data may be useful to members of the scientific community who have used the present preparation in their studies
Application of high speed cameras in performance and injury prevention
High speed cameras have actively been used in sport science for a considerable time, particularly since the origins of modern sports biomechanics. With this technology now readily available and accessible even on mobile phone devices, this presentation was to demonstrate the application of IDT NX3 cameras, capable of filming at 18,000 frames per second, and how they have been incorporated in support of performance athletes and injury prevention through the theoretical construct of Sports Biomechanics. As one of 5 specialist technology hubs in the Lincolnshire region, this presentation was to demonstrate work conducted over a one year period while also identifying common issues with camera uses in human movement analysis
Kinematics of Women’s Sprint Canoeing Technique
Little is known about the biomechanics of sprint canoeing, especially for women’s canoeing, and a quantitative kinematic description of the motion would help coaches to develop valid technique coaching models. Five highly-trained female canoeists were filmed at 150 Hz while undertaking a 50 s maximal effort on a canoe ergometer, whose trolley motions were taken to represent those of the boat. Selected boat, body and paddle kinematics were evaluated at three key stroke cycle events (Contact, Paddle Vertical, and End of Drive) and their patterns monitored across the stroke cycle. While no clear trends between the kinematics and power output emerged, a range of strategies were identified and the data represent an initial step in the construction of detailed technique models that can be used to evaluate and monitor individual athletes
Kinematics of women's sprint canoeing technique
Little is known about the biomechanics of sprint canoeing, especially for women’s
canoeing, and a quantitative kinematic description of the motion would help coaches to
develop valid technique coaching models. Five highly-trained female canoeists were
filmed at 150 Hz while undertaking a 50 s maximal effort on a canoe ergometer, whose
trolley motions were taken to represent those of the boat. Selected boat, body and paddle
kinematics were evaluated at three key stroke cycle events (Contact, Paddle Vertical, and
End of Drive) and their patterns monitored across the stroke cycle. While no clear trends
between the kinematics and power output emerged, a range of strategies were identified
and the data represent an initial step in the construction of detailed technique models that
can be used to evaluate and monitor individual athletes
Coordination variability associated with attendance to a longitudinal reducing biofeedback schedule
The aim of this paper was to assess skill exploration via coordinated variability (CoordVar) during attendance to a longitudinal, reducing biofeedback (BFb) intervention. Novices (n=15 BFb; n=15 Control) were introduced to a lunge touch task. Visual BFb were given on the timing and magnitude of rear leg kinematics. A modified CI2 method (CI2area) was used to quantify CoordVar for rear leg joint couplings. Coefficient of variability was used to quantify CoM horizontal velocity as performance variability (PerfVar). Linear regression 95% confidence intervals were compared between groups to assess changes over time. The BFb group demonstrated increasing CoordVar as a response to the BFb, with all participants showing no change in PerfVar. This highlights the potential for CoordVar to identify the effectiveness of BFb provision by practitioners
Experimental study of the image of their future profession of students of psychology at initial stages of education
В статье рассматривается экспериментальное исследование образа профессии у студентов-психологов на начальном этапе обучения
Leg dominance effects on knee kinematics in unilateral and bilateral squats
Squatting movements are often used to assess known risk factors of injury such as knee valgus angle. This study aims to investigate the knee kinematics during unilateral and bilateral squats in relation to the dominant and non-dominant leg. Five uninjured participants completed three squats in three conditions; dominant unilateral, non-dominant unilateral and bilateral. Knee extension and valgus angles were calculated. Maximum knee valgus angle was higher in the non-dominant unilateral trial than the same leg during the bilateral squat (unilateral = 10.6°, bilateral = 8.4°; p < 0.05). Knee extension angles were significantly lower during bilateral squats (unilateral = 111.9° & 109.2°, bilateral = 97.5° & 98.2°; p < 0.05). Limb dominance effects knee valgus during squatting, and should therefore be taken into account during injury risk assessments
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