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

INTRA-LIMB JOINT COUPLING PATTERNS DURING THE USE OF THREE LOWER EXTREMITY EXERCISE MACHINES

The purpose of this study was to preliminarily describe sagittal plane joint coupling patterns for a spectrum of common lower extremity exercises. Each participant performed 3, 10 second sessions on a stationary bicycle, elliptical and treadmill. Intra-limb coupling angles of the hip and knee for two recreational athletes were quantified using vector coding techniques on randomly selected cycles from each movement. Variability patterns within the same movements were repeatable within and between each participant while each movement’s distinguishable variability pattern differed both spatially and temporally between pieces of exercise equipment. These findings suggest that each exercise machine studied is distinguishable characteristics in its variability pattern. Comparison of variability patterns might be a useful method in the design of functional training exercises to aid in optimally mimicking task kinematics

LANDING STRATEGY MODULATION IN BACKWARD ROTATING PIKED AND TUCKED SOMERSAULT DISMOUNTS FROM BEAM

The aim of this study was to develop understanding of the landing strategy modifications made when performing backward rotating piked (BP) and tucked (BT) dismounts from beam. Sagittal plane lower-body joint angular kinematic profiles were determined for four female gymnasts during the landing phase of BP and BT somersaulting dismounts. A common hip-biased landing strategy was employed by the four gymnasts in the dismounting skills. The more complex BP task was distinguished by the use of a more extended (3.7º) and flexed (5.0º) initial knee and hip joint configuration, respectively compared to the basic BT skill performed. Effective skill developments of backward rotating dismounts from beam may require modulation to the individual joint patterns defining the lower-body landing strategy

JOINT KINEMATIC VARIABILITY IN THE AERIAL AND LANDING PHASES OF BACKWARD ROTATING DISMOUNTS FROM BEAM

This study aimed to develop insight into the joint kinematic variability in backward rotating dismounts from beam. Two-dimensional lower-body coordinate data were obtained for ten backward piked (BP) and tucked (BT) dismounts performed by four gymnasts (N = 80 trials). The within-gymnast coefficient of variation (CV%) in the joint angle profiles was lower in the aerial-landing phase transition than the remaining dismount element. The CV% was consistently larger in the initial joint configurations of the BP aerial and landing phases than the more basic BT skill. Initial ankle and hip joint landing configurations produced the largest CV% difference between skills (ankle: 9.4 %, hip: 9.4 %). The development of complex dismounts from beam requires a pre-programmed control strategy allowing joint kinematic modulations at the onset of aerial and landing phases

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

EFFECTS OF INDEPENDENT CRANK ARMS AND SLOPE ON PEDALING MECHANICS

The aim of this study was to identify the effects of independent crank arms and slope on pedaling kinetics during an anaerobic maximal-effort cycling bout. After undergoing 6 weeks of training with independent crank arms, each of 6 male cyclists completed four 30 s Wingate tests under different cycling conditions of: fixed crank arms on level surface; fixed crank arms on a slope; independent crank arms on level, and; independent crank arms on a slope. Two-dimensional pedal forces recorded using instrumented pedals were used to derive pedaling effectiveness, work distribution and power output. The effects of the crank arms and the slope were minimal, but highly effective and consistent pedaling force (90% effectiveness, 70% work and effective force of 155±6 N) was observed between 45-135° of the crank cycle in all experimental conditions

A Bayesian spatio-temporal study of the association between meteorological factors and the spread of COVID-19

BACKGROUND: The spread of COVID-19 has brought challenges to health, social and economic systems around the world. With little to no prior immunity in the global population, transmission has been driven primarily by human interaction. However, as with common respiratory illnesses such as influenza some authors have suggested COVID-19 may become seasonal as immunity grows. Despite this, the effects of meteorological conditions on the spread of COVID-19 are poorly understood. Previous studies have produced contrasting results, due in part to limited and inconsistent study designs. METHODS: This study investigates the effects of meteorological conditions on COVID-19 infections in England using a Bayesian conditional auto-regressive spatio-temporal model. Our data consists of daily case counts from local authorities in England during the first lockdown from March-May 2020. During this period, legal restrictions limiting human interaction remained consistent, minimising the impact of changes in human interaction. We introduce a lag from weather conditions to daily cases to accommodate an incubation period and delays in obtaining test results. By modelling spatio-temporal random effects we account for the nature of a human transmissible virus, allowing the model to isolate meteorological effects. RESULTS: Our analysis considers cases across England's 312 local authorities for a 55-day period. We find relative humidity is negatively associated with COVID-19 cases, with a 1% increase in relative humidity corresponding to a reduction in relative risk of 0.2% [95% highest posterior density (HPD): 0.1-0.3%]. However, we find no evidence for temperature, wind speed, precipitation or solar radiation being associated with COVID-19 spread. The inclusion of weekdays highlights systematic under reporting of cases on weekends with between 27.2-43.7% fewer cases reported on Saturdays and 26.3-44.8% fewer cases on Sundays respectively (based on 95% HPDs). CONCLUSION: By applying a Bayesian conditional auto-regressive model to COVID-19 case data we capture the underlying spatio-temporal trends present in the data. This enables us to isolate the main meteorological effects and make robust claims about the association of weather variables to COVID-19 incidence. Overall, we find no strong association between meteorological factors and COVID-19 transmission

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