Correlates of sedentary behaviour in youths with Down syndrome: the UP&DOWN study

The aim of this study was to identify potential correlates of sedentary time and television (TV) viewing time in youth with Down syndrome (DS). A total of 98 adolescents with DS (63 males) aged 11–20 years old participated in this study. Total sedentary time was measured using accelerometers, while total TV viewing time and potential correlates were measured using proxy-report questionnaire. Analyses of covariance and a stepwise multiple linear regression were performed to examine correlates of total sedentary time and total TV viewing time. Different potential correlates were associated with total sedentary time (mother age, mother TV viewing time, perceived benefits of physical activity, birth order and having nearby shops in the neighbourhood) and total TV viewing time (father TV viewing time, TV viewing time with parents, family dietary habits during watching TV and weekend days time indoor). The identification of correlates associated with sedentary behaviour, principally those considered modifiable such as social and environmental factors, may contribute to development strategies to decrease sedentary behaviour in adolescents with DS and consequently promote a healthier lifestyle.     

Aerobic exercise did not have compensatory effects on physical activity levels in type 2 diabetes patients

Although exercise promotes beneficial effects in diabetic patients, some studies have questioned the degree of their importance in terms of the increase in total energy expenditure. In these studies, the decrease of physical activity levels (PAL) was referred as “compensatory effect of exercise”. However, our aim was to investigate whether aerobic exercise has compensatory effects on PAL in type 2 diabetes patients. Eight volunteers (51.1 ± 8.2 years) were enrolled in a supervised exercise programme for 8 weeks (3 d · wk^?1, 50–60% of VO₂ peak for 30–60 min). PAL was measured using tri-axial accelerometers in the 1st, 8th and 12th weeks. Biochemical tests, cardiorespiratory fitness, anthropometric assessment and body composition were measured in the 2nd and 11th weeks. Statistical analysis was performed using non-parametric tests (Friedman and Wilcoxon, P < 0.05). We found no significant differences in PAL between intervention periods, and participants spent the majority of their awake time in sedentary activities. However, the exercise programme generated a significant 14.8% increase in VO₂ peak and a 15% reduction in fructosamine. The exercise programme had no compensatory effects on PAL in type 2 diabetes patients, but improved their cardiorespiratory fitness and glycaemic control.     

La integración de la representación audiovisual en la Reforma Educativa

La palabra y la imagen son los grandes medios para la comunicación pedagógica. En este artículo se analizan la perspectiva y posibilidades que la LOGSE (cuyos presupuestos, se afirma, apuestan casi al cien por cien por el medio verbal) ofrece para contar con la comunicación audiovisual en la educación.     

A model‐based approach to science exhibition evaluation: A case study in a Brazilian astronomy museum

A models and modelling approach was adopted to investigate the educational potential of a science museum exhibition. It focused on patterns of relationship between the teaching models proposed by designers and students models in regard to four exhibits concerning astronomical cycles. Student’s models were elicited by interviewing 21 pupils selected from among those who showed a change of their models between pre‐visit and post‐visit questionnaires. Four patterns of relationship were identified, ranging from low to high degrees of convergence between designers and students. Exhibits designed by fragmenting the phenomena (analytical approach) tend to promote less convergent patterns than exhibits that maintain the complexity of the phenomena (synthetic approach). We argue that the two approaches are complementary: without synthetic models visitors find it difficult to identify the phenomenon addressed by analytical models, while the latter may bring to visitors’ attention aspects that otherwise might be hidden by the complexity of synthetic models.     

Muscle coordination,activation and kinematics of world-class and elite breaststroke swimmers during submaximal and maximal efforts

The aims of this study were to describe muscular activation patterns and kinematic variables during the complete stroke cycle (SC) and the different phases of breaststroke swimming at submaximal and maximal efforts. Surface electromyography (sEMG) was collected from eight muscles in nine elite swimmers; five females (age 20.3 ± 5.4 years; Fédération Internationale de Natation [FINA] points 815 ± 160) and four males (27.7 ± 7.1 years; FINA points 879 ± 151). Underwater cameras were used for 3D kinematic analysis with automatic motion tracking. The participants swam 25 m of breaststroke at 60%, 80% and 100% effort and each SC was divided into three phases: knee extension, knee extended and knee flexion. With increasing effort, the swimmers decreased their SC distance and increased their velocity and stroke rate. A decrease during the different phases was found for duration during knee extended and knee flexion, distance during knee extended and knee angle at the beginning of knee extension with increasing effort. Velocity increased for all phases. The mean activation pattern remained similar across the different effort levels, but the muscles showed longer activation periods relative to the SC and increased integrated sEMG (except trapezius) with increasing effort. The muscle activation patterns, muscular participation and kinematics assessed in this study with elite breaststroke swimmers contribute to a better understanding of the stroke and what occurs at different effort levels. This could be used as a reference for optimising breaststroke training to improve performance.     

Acute and chronic effect of sodium bicarbonate ingestion on Wingate test performance: a systematic review and meta-analysis

The aim of this study was to perform a systematic review and meta-analysis on the acute and chronic effects of sodium bicarbonate (NaHCO₃) ingestion on Wingate performance. Following a search through PubMed, Scopus and Web of Science, 9 studies were found meeting inclusion criteria (6 acute and 3 chronic). Random-effects meta-analysis of standardized mean difference (SMD) for peak and mean power was performed. Study quality was assessed using the QualSyst. Results of the meta-analysis showed that acute ingestion of NaHCO₃ did not improve Wingate test peak (weighted average effect size Hedges’s g = 0.02, 95%CI: – 0.19 to 0.23, P = 0.87) or mean power (weighted average effect size Hedges’s g = 0.15, 95%CI: ?0.06 to 0.36, P = 0.92). However, chronic ingestion of NaHCO₃ improved Wingate test peak (weighted average effect size Hedges’s g = 1.21, 95%CI: 0.83 to 1.42, P = 0.001) and mean power (weighted average effect size Hedges’s g = 1.26, 95%CI: 0.96 to 1.56, P = 0.001). Quality assessment of selected articles was classified as strong. This meta-analysis provides evidence that chronic, but not acute, ingestion of NaHCO₃ increases both Wingate test peak and mean power.     

Predicting centre of mass horizontal speed in low to severe swimming intensities with linear and non-linear models

We aimed to compare multilayer perceptron (MLP) neural networks, radial basis function neural networks (RBF) and linear models (LM) accuracy to predict the centre of mass (CM) horizontal speed at low-moderate, heavy and severe swimming intensities using physiological and biomechanical dataset. Ten trained male swimmers completed a 7 × 200 m front crawl protocol (0.05 m.s^?1 increments and 30 s intervals) to assess expiratory gases and blood lactate concentrations. Two surface and four underwater cameras recorded independent images subsequently processed focusing a three-dimensional reconstruction of two upper limb cycles at 25 and 175 m laps. Eight physiological and 13 biomechanical variables were inputted to predict CM horizontal speed. MLP, RBF and LM were implemented with the Levenberg-Marquardt algorithm (feed forward with a six-neuron hidden layer), orthogonal least squares algorithm and decomposition of matrices. MLP revealed higher prediction error than LM at low-moderate intensity (2.43 ± 1.44 and 1.67 ± 0.60%), MLP and RBF depicted lower mean absolute percentage errors than LM at heavy intensity (2.45 ± 1.61, 1.82 ± 0.92 and 3.72 ± 1.67%) and RBF neural networks registered lower errors than MLP and LM at severe intensity (2.78 ± 0.96, 3.89 ± 1.78 and 4.47 ± 2.36%). Artificial neural networks are suitable for speed model-fit at heavy and severe swimming intensities when considering physiological and biomechanical background.