A Preliminary Investigation into the Effect of Continuous Vigorous Exercise and Lifestyle-embedded Physical Activity upon Acute Glycaemic Regulation

Background and Purpose Continuous glucose monitoring (CGM) has recently emerged as a new tool for patients with diabetes mellitus to monitor glucose levels and aid maintainenance of euglycaemia. CGM provides information on ambulatory, postprandial and nocturnal glucose excursions. Extant research has thus far focused upon charting glucose excursions in diabetic patients, with limited normoglycaemic comparative data available. Additionally little is known upon how physical activity affects acute blood glucose regulation. The purpose of this study was to investigate the effect of continuous exercise and lifestyle-embedded physical activity upon glucose regulation, and assess the feasibility of prolonged CGM data collection in a normoglycaemic individual. Method One physically active non-diabetic male [age: 22 y; mass: 71.5 kg; height: 181 cm] underwent 7 days CGM, performing 3 trial conditions: a sedentary control (< 2500 steps, pedometer controlled), a continuous exercise condition (2 x 30 min treadmill running at 70% HRmax), and a lifestyle-embedded physical activity condition (100 min fractionalized moderate activity). Diet was standardised and physical activity levels were monitored via accelerometry throughout. Results Descriptive results displayed lower whole day mean blood glucose levels in both the continuous (Mean ± SD: 5.2 ± 0.3 mmol.L-1) and lifestyle conditions (5.3 ± 1.1 mmol.L-1), compared to sedentary control (5.6 ± 0.5 mmol.L-1). A post exercise decrease in glucose levels (2 h pre-6 h post (5.3 – 5.1 mmol.L-1)) with a carryover effect for the following day (reduced mean glucose 24 h pre-post (5.5 ± 0.5 - 5.2 ± 0.3 mmol.L-1)) was identified in the continuous exercise condition. In addition a significant correlation (R= 0.75, P = 0.02) was found between physical activity counts and CGM glucose values (mmol.L-1) during the continuous bout of vigorous exercise. Discussion and Conclusions It was concluded that day to day glucose homeostasis may be optimised through bouts of continuous vigorous exercise. The utilisation of CGM in exercise protocols and prolonged data collection is deemed a feasible proposition; however larger scale studies may pose logistical problems. This study was limited by its single subject design and specificity to normoglycaemic populations, future studies should look to include a greater sample size and characterise glycaemic regulation in pre-diabetic and diabetic populations

Average acceleration and intensity gradient of primary school children and associations with indicators of health and wellbeing

Average acceleration (AvAcc) and intensity gradient (IG) have been proposed as standardised metrics describing physical activity (PA) volume and intensity, respectively. We examined hypothesised between-group PA differences in AvAcc and IG, and their associations with health and wellbeing indicators in children. ActiGraph GT9X wrist accelerometers were worn for 24-h·d−1 over seven days by 145 children aged 9-10. Raw accelerations were averaged per 5-s epoch to represent AvAcc over 24-h. IG represented the relationship between log values for intensity and time. Moderate-to-vigorous PA (MVPA) was estimated using youth cutpoints. BMI z-scores, waist-to-height ratio (WHtR), peak oxygen uptake (VO2peak), Metabolic Syndrome risk (MetS score), and wellbeing were assessed cross-sectionally, and 8-weeks later. Hypothesised between-group differences were consistently observed for IG only (p<.001). AvAcc was strongly correlated with MVPA (r=0.96), while moderate correlations were observed between IG and MVPA (r=0.50) and AvAcc (r=0.54). IG was significantly associated with health indicators, independent of AvAcc (p<.001). AvAcc was associated with wellbeing, independent of IG (p<.05). IG was significantly associated with WHtR (p<.01) and MetS score (p<.05) at 8-weeks follow-up. IG is sensitive as a gauge of PA intensity that is independent of total PA volume, and which relates to important health indicators in children

The backwards comparability of wrist worn GENEActiv and waist worn ActiGraph accelerometer estimates of sedentary time in children

Objectives: To examine the backward comparability of a range of wrist-worn accelerometer estimates of sedentary time (ST) with ActiGraph 100 count∙min-1 waist ST estimates. Design: Cross-sectional, secondary data analysis Method: One hundred and eight 10-11-year-old children (65 girls) wore an ActiGraph GT3X+ accelerometer (AG) on their waist and a GENEActiv accelerometer (GA) on their non-dominant wrist for seven days. GA ST data were classified using a range of thresholds from 23-56 mg. ST estimates were compared to AG ST 100 count∙min-1 data. Agreement between the AG and GA thresholds was examined using Cronbach’s alpha, intraclass correlation coefficients (ICC), limits of agreement (LOA), Kappa values, percent agreement, mean absolute percent error (MAPE) and equivalency analysis. Results: Mean AG total ST was 492.4 minutes over the measurement period. Kappa values ranged from 0.31-0.39. Percent agreement ranged from 68-69.9%. Cronbach’s alpha values ranged from 0.88-0.93. ICCs ranged from 0.59-0.86. LOA were wide for all comparisons. Only the 34 mg threshold produced estimates that were equivalent at the group level to the AG ST 100 count∙min-1 data though sensitivity and specificity values of ~64% and ~74% respectively were observed. Conclusions: Wrist-based estimates of ST generated using the 34 mg threshold are comparable with those derived from the AG waist mounted 100 count∙min-1 threshold at the group level. The 34 mg threshold could be applied to allow group-level comparisons of ST with evidence generated using the ActiGraph 100 count∙min-1 method though it is important to consider the observed sensitivity and specificity results when interpreting findings

Choice of activity-intensity classification thresholds impacts upon accelerometer-assessed physical activity-health relationships in children

It is unknown whether using different published thresholds (PTs) for classifying physical activity (PA) impacts upon activity-health relationships. This study explored whether relationships between PA (sedentary [SED], light PA [LPA], moderate PA [MPA], moderate-to-vigorous PA, vigorous PA [VPA]) and health markers differed in children when classified using three different PTs

Comparability of measured acceleration from accelerometry-based activity monitors

Accelerometers that provide triaxial measured acceleration data are now available. However, equivalence of output between brands cannot be assumed and testing is necessary to determine whether features of the acceleration signal are interchangeable.National Osteoporosis Societ

Cut-point-free accelerometer metrics to assess children's physical activity: an example using the school day

The aims were to (i) investigate associations between a novel accelerometer metric: the minimum acceleration value above which the most active 30-minutes were accumulated during the school day (M30ACC), and health indicators, and (ii) demonstrate that applying an equivalent cut-point to the M30ACC metric gives comparable prevalence results as a moderate-to-vigorous physical activity (MVPA) cut-point approach. Two-hundred-and-ninety-six children (age 9-10-years) wore wrist-mounted accelerometers for 7-days. School day MVPA and M30ACC were calculated. Body mass index (BMI), waist-to-height ratio (WHtR), and cardiorespiratory fitness (CRF) were also measured. Mixed linear models investigated associations between M30ACC and health indicators. Agreement between ranked MVPA and M30ACC values was assessed using percent agreement, kappa, sensitivity, and specificity statistics. M30ACC thresholds associated with health indicators were 213 mg (BMI), 206 mg (WHtR), and 269 mg (CRF) for girls. The equivalent values for boys were 234mg (BMI), 230 mg (WHtR), and 327 mg (CRF). Less than half of girls and 75% of boys accumulated 30 minutes of school day MVPA. Just less than 50% of girls and >80% of boys had M30ACC values ≥200 mg, which is equivalent to brisk walking. Agreement between MVPA and M30ACC tertiles was high, reflected by the sensitivity and specificity values of > 90%. Results demonstrate the utility of M30ACC as a PA metric that is not heavily influenced by researcher decisions. M30ACC has potential as an accelerometer-specific metric for generating PA guidelines related to health indicators, and easily understood forms of activity such as brisk walking

Validating the Sedentary Sphere method in children: does wrist or accelerometer brand matter?

This study aimed to validate the Sedentary Sphere posture classification method from wrist-worn accelerometers in children. Twenty-seven 9-10-year-old children wore ActiGraph GT9X (AG) and GENEActiv (GA) accelerometers on both wrists, and activPAL on the thigh while completing prescribed activities: five sedentary activities, standing with phone, walking (criterion for all 7: observation) and ten minutes free-living play (criterion: activPAL). In an independent sample, 21 children wore AG and GA accelerometers on the non-dominant wrist and activPAL for two days of free-living. Percent accuracy, pairwise 95% equivalence tests (±10% equivalence zone) and intra-class correlation coefficients (ICC) analyses were completed. Accuracy was similar, for prescribed activities irrespective of brand (non-dominant wrist: 77%-78%; dominant wrist: 79%). Posture estimates were equivalent between wrists within brand (±6%, ICC>0.81, lower 95% CI>0.75), between brands worn on the same wrist (±5%, ICC>0.84, lower 95% CI>0.80) and between brands worn on opposing wrists (±6%, ICC>0.78, lower 95% CI>0.72). Agreement with activPAL during free-living was 77%, but sedentary time was underestimated by 7% (GA) and 10% (AG). The Sedentary Sphere can be used to classify posture from wrist-worn AG and GA accelerometers for group-level estimates in children, but future work is needed to improve the algorithm for better individual-level results

Associations between cardiorespiratory fitness, physical activity and clustered cardiometabolic risk in children and adolescents: the HAPPY study

Clustering of cardiometabolic risk factors can occur during childhood and predisposes individuals to cardiometabolic disease. This study calculated clustered cardiometabolic risk in 100 children and adolescents aged 10-14 years (59 girls) and explored differences according to cardiorespiratory fitness (CRF) levels and time spent at different physical activity (PA) intensities. CRF was determined using a maximal cycle ergometer test, and PA was assessed using accelerometry. A cardiometabolic risk score was computed as the sum of the standardised scores for waist circumference, blood pressure, total cholesterol/high-density lipoprotein ratio, triglycerides and glucose. Differences in clustered cardiometabolic risk between fit and unfit participants, according to previously proposed health-related threshold values, and between tertiles for PA subcomponents were assessed using ANCOVA. Clustered risk was significantly lower (p < 0.001) in the fit group (mean 1.21 ± 3.42) compared to the unfit group (mean -0.74 ± 2.22), while no differences existed between tertiles for any subcomponent of PA. Conclusion These findings suggest that CRF may have an important cardioprotective role in children and adolescents and highlights the importance of promoting CRF in youth

GRANADA consensus on analytical approaches to assess associations with accelerometer-determined physical behaviours (physical activity, sedentary behaviour and sleep) in epidemiological studies.

The inter-relationship between physical activity, sedentary behaviour and sleep (collectively defined as physical behaviours) is of interest to researchers from different fields. Each of these physical behaviours has been investigated in epidemiological studies, yet their codependency and interactions need to be further explored and accounted for in data analysis. Modern accelerometers capture continuous movement through the day, which presents the challenge of how to best use the richness of these data. In recent years, analytical approaches first applied in other scientific fields have been applied to physical behaviour epidemiology (eg, isotemporal substitution models, compositional data analysis, multivariate pattern analysis, functional data analysis and machine learning). A comprehensive description, discussion, and consensus on the strengths and limitations of these analytical approaches will help researchers decide which approach to use in different situations. In this context, a scientific workshop and meeting were held in Granada to discuss: (1) analytical approaches currently used in the scientific literature on physical behaviour, highlighting strengths and limitations, providing practical recommendations on their use and including a decision tree for assisting researchers' decision-making; and (2) current gaps and future research directions around the analysis and use of accelerometer data. Advances in analytical approaches to accelerometer-determined physical behaviours in epidemiological studies are expected to influence the interpretation of current and future evidence, and ultimately impact on future physical behaviour guidelines

Application of the Nanofiltration Process for Concentration of Polyphenolic Compounds from Geranium robertianum and Salvia officinalis Extracts

The aim of this study was to prove the efficiency of the nanofiltration process for the concentration of polyphenolic compounds from Geranium robertianum and Salvia officinalis extracts and to evaluate the extract’s antioxidant activity. A lab-scale cross-flow set-up using flat-sheet configuration membrane was employed for all experiments. Two nanofiltration membranes have been used: SelRO MPF-36 (Koch membrane) and an organic-inorganic membrane (polysulfone with SBA-15-NH2). When the organic-inorganic membranes were used in the nanofiltration process, the obtained concentrated extracts proved to have higher polyphenol and flavonoid rejections, in both cases (Geranium robertianum and Salvia officinalis). The obtained values were over 88 % DPPH inhibition, for concentrated extracts, using the DPPH method. The concentrated extracts obtained after nanofiltration NF2 (organic-inorganic membrane) had the strongest scavenging activity for all extracts and almost completely inhibited DPPH absorption (92.9 % for Geranium robertianum concentrated extract and 90.1 % for Salvia officinalis concentrated extract). These features turn the studied, concentrated extracts into a good source for further medicinal applications