Systematic review of the use of "magnitude-based inference" in sports science and medicine.

Magnitude-based inference (MBI) is a controversial statistical method that has been used in hundreds of papers in sports science despite criticism from statisticians. To better understand how this method has been applied in practice, we systematically reviewed 232 papers that used MBI. We extracted data on study design, sample size, and choice of MBI settings and parameters. Median sample size was 10 per group (interquartile range, IQR: 8-15) for multi-group studies and 14 (IQR: 10-24) for single-group studies; few studies reported a priori sample size calculations (15%). Authors predominantly applied MBI's default settings and chose "mechanistic/non-clinical" rather than "clinical" MBI even when testing clinical interventions (only 16 studies out of 232 used clinical MBI). Using these data, we can estimate the Type I error rates for the typical MBI study. Authors frequently made dichotomous claims about effects based on the MBI criterion of a "likely" effect and sometimes based on the MBI criterion of a "possible" effect. When the sample size is n = 8 to 15 per group, these inferences have Type I error rates of 12%-22% and 22%-45%, respectively. High Type I error rates were compounded by multiple testing: Authors reported results from a median of 30 tests related to outcomes; and few studies specified a primary outcome (14%). We conclude that MBI has promoted small studies, promulgated a "black box" approach to statistics, and led to numerous papers where the conclusions are not supported by the data. Amidst debates over the role of p-values and significance testing in science, MBI also provides an important natural experiment: we find no evidence that moving researchers away from p-values or null hypothesis significance testing makes them less prone to dichotomization or over-interpretation of findings.

Light physical activity is positively associated with cognitive performance in older community dwelling adults.

OBJECTIVES: To evaluate the associations between an objective measure of different intensities of physical activity, upper- and lower-limb muscle strength and psychomotor performance and set-shifting domains of cognitive executive function in older adults. DESIGN: A cross-sectional study. METHODS: From the Tasmanian Older Adult Cohort Study, 188 community-dwelling older adults (53.7% female; mean age±SD 63.98±7.3 years) undertook 7-day physical activity behaviour monitoring using an accelerometer. Dynamometers were used to assess leg extension strength. The Trail Maker Tests were used to measure psychomotor processing speed and set-shifting performance. RESULTS: When controlling for age, smoking history, alcohol intake, educational achievement and neuropsychological functioning, higher levels of light physical activity, but not sedentary behaviour or moderate or vigorous physical activity, was found to be associated with better set-shifting performance. Neither physical activity behaviour or muscle strength were found to be associated with psychomotor performance. In addition, older age, greater alcohol intake, and lower levels of educational attainment, verbal learning and memory performance were significantly associated with lower scores on the set-shifting task; whereas older age and reduced neuropsychological functioning were associated with lower psychomotor processing speed scores. CONCLUSIONS: Light physical activity is associated with higher executive functioning in community-dwelling older adults and this strengthens the evidence supporting exercise as a neuroprotective agent. Further studies are needed to understand why light physical activity behaviour positively influences executive functioning, and how such physical activity can be implemented into the daily routine of older adults.

Fundamental Movement Skills Are More than Run, Throw and Catch: The Role of Stability Skills.

INTRODUCTION: In motor development literature fundamental movement skills are divided into three constructs: locomotive, object control and stability skills. Most fundamental movement skills research has focused on children's competency in locomotor and object control skills. The first aim of this study was to validate a test battery to assess the construct of stability skills, in children aged 6 to 10 (M age = 8.2, SD = 1.2). Secondly we assessed how the stability skills construct fitted into a model of fundamental movement skill. METHOD: The Delphi method was used to select the stability skill battery. Confirmatory factor analysis (CFA) was used to assess if the skills loaded onto the same construct and a new model of FMS was developed using structural equation modelling. RESULTS: Three postural control tasks were selected (the log roll, rock and back support) because they had good face and content validity. These skills also demonstrated good predictive validity with gymnasts scoring significantly better than children without gymnastic training and children from a high SES school performing better than those from a mid and low SES schools and the mid SES children scored better than the low SES children (all p < .05). Inter rater reliability tests were excellent for all three skills (ICC = 0.81, 0.87, 0.87) as was test re-test reliability (ICC 0.87-0.95). CFA provided good construct validity, and structural equation modelling revealed stability skills to be an independent factor in an overall FMS model which included locomotor (r = .88), object control (r = .76) and stability skills (r = .81). DISCUSSION: This study provides a rationale for the inclusion of stability skills in FMS assessment. The stability skills could be used alongside other FMS assessment tools to provide a holistic assessment of children's fundamental movement skills.

Assessing motor imagery using the hand rotation task: does performance change across childhood?

This study examined at what age children can engage in the hand rotation task (as a measure of motor imagery); whether engagement changes across development and; the influence of age and motor skill on performance. Children were aged 5-12 years (N=101; 52 girls), with no IQ or motor skill impairment. Less than 40% of 5-6 year olds completed the hand rotation with sufficient accuracy for further analysis, compared with 80% of 7-8 year olds, and 90% aged 9 and above. From age 7, either or both response time (RT) and accuracy conformed to the biomechanical constraints of corresponding physical movements. Although RT did not improve with age, accuracy did, with 11 year olds significantly more accurate than 7 and 8 year olds. Importantly, efficiency (RT/accuracy) improved with age and both age, in months, and motor skill level were significant predictors of efficiency, accounting for 35% and 8% of variability, respectively. Improvements in motor imagery ability during childhood are likely the result of increased neural efficiency, developing as the result of complex interactions between endogenous and exogenous factors. This highlights the need for a multidisciplinary approach to further our understanding of the emergence of motor imagery ability.

Examining the role of parental self-regulation in family physical activity: a mixed-methods approach.

Physical activity (PA) is essential for good health. However, parents risk becoming less active because of the demands of parenting. This has consequences for children as parents are role models. The present study used a mixed-methods approach to explore parental self-regulation associated with PA. Data were collected from 36 parents with preschool-aged children. They were interviewed about their PA and their family's PA. Parents also completed PA and self-regulation questionnaires and wore an accelerometer for five days. Qualitative data were examined using an inductive approach to thematic analysis. It showed that parents felt that they had limited time for personal PA. Mothers' self-regulation was driven by an ethic of care and subjective norms, whereas fathers' self-regulation was driven by beliefs about the importance of autonomy. Nevertheless, both parents saw caring for their children as the main priority. Quantitative data were examined using multiple regression analyses. Results showed that different self-regulatory behaviours predicted the PA of mothers and fathers. Which predictors were significant depended on the type of activity and how it was measured. The findings warrant longitudinal research that would enable the effect of family dynamics on self-regulation associated with PA to be assessed.