Validation of a 7-day physical activity diary against doubly-labelled water

Background: The assessment of physical activity intensity and duration is essential for understanding group activity patterns.

Methods: The present study evaluated the validity of measurement of total energy expenditure (TEE) and physical activity level (PAL) using a categorized physical activity diary. In 29 young healthy men, aged 18–27 years, with body mass index range 21–43 kg m^?2, TEE using doubly-labelled water (DLW), resting metabolic rate (RMR) by indirect calorimetry, physical activity level (PAL defined as TEE/RMR) and activity pattern, timing and level from 7-day physical activity diaries were determined.

Results: TEE by DLW and estimated by activity diary were correlated (r?=?0.61, p?=?0.005). The mean underestimation of TEE by the activity diary compared with the DLW method was 2.50?±?0.72 MJ day^?1. Sedentary (lying, sitting and standing) time averaged 18 h day^?1 and was negatively correlated with PAL (r?=??0.44, p?=?0.018) whilst time spent in light intensity activity (5 h day^?1) was positively correlated (r?=?0.51, p?=?0.005).

Conclusions: It is concluded that the categorized physical activity diary measured TEE with limited accuracy but presents an inexpensive, convenient method of discriminating individual and group physical activity patterns.     

The H2020 “NoHoW Project”: A Position Statement on Behavioural Approaches to Longer-Term Weight Management

There is substantial evidence documenting the effects of behavioural interventions on weight loss (WL). However, behavioural approaches to initial WL are followed by some degree of longer-term weight regain, and large trials focusing on evidence-based approaches to weight loss maintenance (WLM) have generally only demonstrated small beneficial effects. The current state-of-the-art in behavioural interventions for WL and WLM raises questions of (i) how we define the relationship between WL and WLM, (ii) how energy balance (EB) systems respond to WL and influence behaviours that primarily drive weight regain, (iii) how intervention content, mode of delivery and intensity should be targeted to keep weight off, (iv) which mechanisms of action in complex interventions may prevent weight regain and (v) how to design studies and interventions to maximise effective longer-term weight management. In considering these issues a writing team within the NoHoW Consortium was convened to elaborate a position statement, and behaviour change and obesity experts were invited to discuss these positions and to refine them. At present the evidence suggests that developing the skills to self-manage EB behaviours leads to more effective WLM. However, the effects of behaviour change interventions for WL and WLM are still relatively modest and our understanding of the factors that disrupt and undermine self-management of eating and physical activity is limited. These factors include physiological resistance to weight loss, gradual compensatory changes in eating and physical activity and reactive processes related to stress, emotions, rewards and desires that meet psychological needs. Better matching of evidence-based intervention content to quantitatively tracked EB behaviours and the specific needs of individuals may improve outcomes. Improving objective longitudinal tracking of energy intake and energy expenditure over time would provide a quantitative framework in which to understand the dynamics of behaviour change, mechanisms of action of behaviour change interventions and user engagement with intervention components to potentially improve weight management intervention design and evaluation.     

New method to differentiate surface damping behavior and stress absorption capacities of common CAD/CAM restorative materials

ObjectivesTo assess energy dissipation capacities and surface damping abilities of different CAD/CAM restorative materials (CRMs) to characterize stress resistance during load peaks.MethodsUsing instrumented indentation testing (IIT), Martens hardness (HM) together with its elastic (η_IT) and plastic index (η_ITdis) and Leeb hardness (HLD) together with its deduced energy dissipation (HLD_dis) were determined for eight ceramic, eight composite, and four polymer-based materials as well as three metals. The results were compared to those of bovine enamel. Ten indentations per material were performed at room temperature (23 ± 1 °C) on two separate specimens (12.0 × 12.0 × 3.5 mm³) after water storage (24 h; 37.0 ± 1.0 °C). Hardness parameters were recorded, and data were analyzed with one-way MANOVA (Games-Howell post hoc tests, α = 0.05). Correlations between different parameters were tested (Pearson, α = 0.05).ResultsIndependently determined HLD_dis, and η_ITdis values substantiated different energy dissipation characteristics of CRM, whereby a strong correlation was observed for the two datasets (r = 0.956, p = 0.011). Ceramics had the significantly lowest values (p < 0.001) while both parameters revealed the highest surface damping effects for metals (p < 0.001), followed in both cases by bovine enamel. Energy dissipation of polymer and composite CRM was in between ceramics and bovine enamel (p < 0.001), whereas only for HLD_dis did both show no significant difference (p > 0.05).SignificancePromising new HLD_dis and η_ITdis data allow a reliable differentiation of energy dissipation and surface damping capacities of CRMs. Previously published rankings of edge chipping and loss tangent results were perfectly reproduced, especially by HLD_dis.     

Differences in the biomechanical behaviors of natural teeth and dental implants

ObjectiveThe lack of a PDL, which acts as an energy absorber, is a contributor to implants’ early failure; however, these discrepancies are not well understood because of limited in vivo research. This study investigated the discrepancy in biomechanical behaviors between natural teeth and dental implants by detecting micro-movements in vivo.MethodsWe designed a device that could measure precisely mechanical behaviors such as creep, stress relaxation, and hysteresis by using load–control displacement on teeth and implants. We also compared energy dissipation between natural teeth and dental implants by subtracting the area of the hysteresis loop of natural teeth from that of dental implants.ResultsBiphasic curves with an initial phase of rapid response and a subsequent phase of slow response were confirmed in creep and stress relaxation curves for the load–time relationship in natural teeth. By contrast, the behavior of creep or stress relaxation was less prominent when the dental implants were tested. We observed that the periodontal ligament under an axial intrusive load of 300 g in a loading rate 3 g/s could dissipate the energy of 7.35 ± 1.18 × 10^?2 mJ, approximately 50 times that of the dental implants (1.47 ± 1.22 × 10^?3) with statistically significant (p < 0.05).SignificanceWe confirmed natural teeth could achieve greater energy dissipation compared to dental implants, which owe to that natural teeth exhibited fluid and viscoelastic properties.     

扩张型心肌病患者左心室能量损耗及室壁剪应力的血流向量成像评价

目的应用血流向量成像（VFM）技术定量评估扩张型心肌病（DCM）患者的左心功能异常。 方法选取2019年1月至2019年4月于武汉亚洲心脏病医院确诊DCM的患者29例为DCM组,同期匹配健康志愿者32例为对照组。VFM模式下获取两组心尖四腔心、三腔心切面二维彩色多普勒血流动态图,脱机分析对比不同切面等容收缩期（P0）、快速射血期（P1）、等容舒张期（P2）、快速充盈期（P3）、心房收缩期（P4）能量损耗（EL）及各节段室壁剪应力（WSS）平均值的差异,评估DCM患者左心室血流动力学的改变。 结果与对照组相比,DCM组在P0、P1及P3期EL均减低［分别为（2.24±1.33）J/（s·m³）vs（1.39±0.49）J/（s·m³）、（6.14±3.58）J/（s·m³）vs（4.17±2.12）J/（s·m³）、（10.38±6.67）J/（s·m³）vs（4.92±2.73）J/（s·m³）,均P＜0.05］。DCM组左心室壁在P0期基底段［（0.45±0.30）N/m² vs（0.23±0.13）N/m²］,P1、P2期基底段和中间段［分别为（1.24±0.39）N/m² vs（0.93±0.40）N/m²、（0.55±0.30）N/m² vs（0.36±0.23）N/m²,（0.29±0.08）N/m² vs（0.12±0.05）N/m²、（0.14±0.08）N/m² vs（0.10±0.06）N/m²］,P3期各节段［分别为（0.60±0.24）N/m² vs（0.26±0.08）N/m²、（0.47±0.29）N/m² vs（0.14±0.04）N/m²、（0.13±0.06）N/m² vs（0.06±0.02）N/m²］以及P4期基底段［（0.40±0.15）N/m² vs（0.25±0.12）N/m²］的WSS较对照组均减低（均P＜0.05）。对照组WSS同一时相呈现基底段＞中间段＞心尖段,而DCM组P0、P2和P4期基底段与中间段WSS差异无统计学意义（均P＞0.05）。对照组WSS同一节段P0→P1→P2→P3→P4期表现为升高－减低－升高－减低改变（均P＜0.05）,而DCM组WSS仅基底段P0→P1→P2→P3期表现为升高－减低－升高趋势（均P＜0.05）,余节段WSS在各时相间变化差异均无统计学意义（均P＞0.05）。 结论VFM技术中的EL及WSS作为新的血流动力学量化参数,可评估DCM患者左心室功能异常。     

Comparison of a Mediterranean to a low-fat diet intervention in adults with type 1 diabetes and metabolic syndrome: A 6–month randomized trial

Background and aims

The metabolic syndrome (MS) is an emerging complication in patients with type 1 diabetes (T1D), with no preventive or therapeutic treatment reported yet. We wanted to compare the impact of two 6-month nutritional interventions, based on a Mediterranean (MED) or a low-fat diet, on waist circumference, anthropometric and metabolic outcomes in patients with both T1D and the MS.

Energy utilization associated with regular activity breaks and continuous physical activity: A randomized crossover trial

Aims

To quantify and compare energy utilization associated with prolonged sitting alone, or interrupted with regular activity breaks and/or an additional bout of continuous physical activity.