We investigated a general theory accounting for the guidance of ongoing movements in an interceptive reaching task. The aim was to assess the premise of tau-coupling that the coupling constant k, the ratio of taus (τs) of motion gaps between hand and object, reflects the kinematics of the on-going movement. The spatial and temporal constraints of the interceptive action were manipulated in three task conditions. While the time dependent counterpart of k, K(t) exhibited task effects, k itself could not distinguish between task manipulations. K(t) showed large variability during the initial acceleration phase, small variability during the rest of the movement, and task dependent changes during the final deceleration phase of interception. The findings highlight the importance of clarifying what constitutes as t-coupling.
Joanne Smith, Madeleine Grealy and Gert-Jan Pepping
Melanie Wade, Amity Campbell, Anne Smith, Joanne Norcott and Peter O’Sullivan
The link between static and dynamic landing lumbar postures, when gymnasts are exposed to large ground reaction forces, has not been established. This investigation aimed to (a) determine if a relationship exists between sagittal static and dynamic landing lumbar spine angles at peak ground reaction force (GRF) and (b) quantify how close to end-range postures the gymnasts were at landing peak GRF. Twenty-one female gymnasts’ upper and lower lumbar spine angles were recorded: statically in sitting and standing, during landing of three gymnastic skills, and during active end-range lumbar flexion. Pearson’s correlations were used to investigate relationships between the angles in different postures. Significant correlations (r = .77–.89, p < .01) were found between all the static/dynamic postures in the lower lumbar spine angle, while fewer and less significant upper lumbar spine correlations were reported. Thirty percent of gymnasts landed a backsault with their lower lumbar spine flexed beyond their active end-range while experiencing GRF 6.8–13.3 times their body weight. These results inform low back pain prevention and management strategies in this population and highlight areas for future research.
Anneke G. van der Niet, Joanne Smith, Jaap Oosterlaan, Erik J.A. Scherder, Esther Hartman and Chris Visscher
The objective of this study was to analyze the effects of a physical activity program including both aerobic exercise and cognitively engaging physical activities on children’s physical fitness and executive functions. Children from 3 primary schools (aged 8–12 years) were recruited. A quasi-experimental design was used. Children in the intervention group (n = 53; 19 boys, 34 girls) participated in a 22-week physical activity program for 30 min during lunch recess, twice a week. Children in the control group (n = 52; 32 boys, 20 girls) followed their normal lunch routine. Aerobic fitness, speed and agility, and muscle strength were assessed using the Eurofit test battery. Executive functions were assessed using tasks measuring inhibition (Stroop test), working memory (Visual Memory Span test, Digit Span test), cognitive flexibility (Trailmaking test), and planning (Tower of London). Children in the intervention group showed significantly greater improvement than children in the control group on the Stroop test and Digit Span test, reflecting enhanced inhibition and verbal working memory skills, respectively. No differences were found on any of the physical fitness variables. A physical activity program including aerobic exercise and cognitively engaging physical activities can enhance aspects of executive functioning in primary school children.
Calum Mattocks, Andy Ness, Sam Leary, Kate Tilling, Steven N. Blair, Julian Shield, Kevin Deere, Joanne Saunders, Joanne Kirkby, George Davey Smith, Jonathan Wells, Nicholas Wareham, John Reilly and Chris Riddoch
Objective methods can improve accuracy of physical activity measurement in field studies but uncertainties remain about their use.
Children age 11 years from the Avon Longitudinal Study of Parents and Children (ALSPAC), were asked to wear a uni-axial accelerometer (MTI Actigraph) for 7 days.
Of 7159 children who attended for assessment, 5595 (78%) provided valid measures. The reliability coefficient for 3 days of recording was .7 and the power to detect a difference of 0.07 SDs (P ≤ .05) was > 90%. Measures tended to be higher on the first day of recording (17 counts/min; 95% CI, 10–24) and if children wore the monitor for fewer days, but these differences were small. The children who provided valid measures of activity were different from those who did not, but the differences were modest.
Objective measures of physical activity can be incorporated into large longitudinal studies of children.