Accuracy of Wrist-worn Physical Activity Monitors to Measure Energy Expenditure

IIn recent years, the popularity and demand of physical activity monitors has drastically risen with the need and want to improve physical fitness. Newer devices worn on the wrist measure both heart rate and energy expenditure but the accuracy of these measurements is unclear. PURPOSE: To measure the accuracy of three separate wrist-worn activity monitors to estimate energy expenditure during structured periods of aerobic exercise. METHODS: Twelve men and three women (22 ± 3 years, 25 ± 3 kg/m2) consented to participate in this study. Three different physical activity monitors, TomTom Cardio (TT), Microsoft Band (MB), and Fitbit Surge (FB), were randomly assigned to either the left or right wrist of each participant. The instructions for the testing procedure were thoroughly explained to every participant at the start of each trial. The treadmill started at a speed of 2 mph and increased by 1 mph every three minutes up to a max speed of 6 mph. Energy expenditure was estimated through direct measurement of oxygen consumed and carbon dioxide produced through a metabolic cart (MC, Parvo Medics True One ®2400). The mean bias in energy expenditure between MC and each device was calculated. Pearson product-moment correlations and 95% equivalence testing were also calculated. Statistical significance was set at an alpha level of 0.05. RESULTS: The mean bias between the MC and devices at 2 mph varied from -1.9 ± 1.1 kcal/min (FB) to 0.7 ± 1.0 kcal/min (MB) while the mean bias at 6 mph varied from -1.7 ± 2.1 kcal/min (MB) to 5.2 ± 1.7 kcal/min (TT). For total energy expenditure, all devices were significantly correlated with the MC (FB: r=0.66, p=0.007; TomTom: r=0.77, p\u3c0.001; MB: r=0.59, p=0.02). The mean bias for total energy expenditure was -25 ± 16 kcal for the FB, 26 ± 13 kcal for the TT, and -11 ± 17 kcal for the MB. The equivalence zone for MC was 88 kcal to 108 kcal but 90% confidence intervals of devices did not fall within this zone. CONCLUSION: The wrist-worn physical activity monitors used in this study that measure heart rate and energy expenditure tend to either underestimate or overestimate total energy expenditure from treadmill walking and running

Associations between pQCT-based fat and muscle area and density and DXA-based total and leg soft tissue mass in healthy women and men

Peripheral Quantitative Computed Tomography (pQCT) can be used for muscle and fat area and density assessments. These may independently influence muscle and fat mass measurements from Dual Energy X-ray Absorptiometry (DXA). Objective: To determine associations between pQCT-derived soft tissue density and area measures and DXA-derived soft tissue mass. Methods: Linear regression models were developed based on BMI and calf fat and muscle cross-sectional area (FCSA and MCSA) and density measured by pQCT in healthy women (n=76) and men (n=82) aged 20-59 years. Independent variables for these models were leg and total bone-free lean mass (BFLM) and fat mass (FM) measured by DXA. Results:Sex differences (p Conclusion: Calf muscle and fat area and density independently predict lean and fat tissue mass

Effect of fibre configurations on mechanical properties of flax/tannin composites.

Flax reinforced tannin-based composites have a potential to be used in vehicle applications due to the environmental advantages and good mechanical properties. In this paper, the effects of fibre configuration on mechanical properties of flax/tannin composites were investigated for nonwoven and woven fabric lay-up angles (UD, [0°, 90°]2 and [0°, +45°, 90°, -45°]2). The tannin/flax composites were prepared by compression moulding. The manufactured specimens were then characterized for quasi-static tensile properties, dynamic mechanical properties and low-energy impact performance. Failure mechanism was further investigated using microscopy and demonstrated the need for further adhesion improvements. The study shows that the UD fabric reinforced composite performs better in tensile strength and modulus whereas [0°, +45°, 90°, -45°]2 composite provides the best impact energy absorption performance

The acute muscular effects of cycling with and without different degrees of blood flow restriction

The aim was to compare the acute effects of work matched high intensity (75% peak aerobic capacity) aerobic exercise to low intensity (40% peak aerobic capacity) aerobic exercise with different degrees of blood flow restriction (BFR) [40% estimated arterial occlusion (40 BFR) and 60% estimated arterial occlusion (60 BFR)] on variables previously hypothesized to be important for muscle adaptation. There were no meaningful changes in torque. Anterior thigh muscle thickness was increased from baseline with high intensity cycling and 40 BFR (~2 mm increase, p ≤ 0.008). A significant increase in lactate occurred in all exercise conditions but was greatest with high intensity cycling (~5.4 mmol/L increase). Muscle activation was significantly higher with high intensity cycling compared to low intensity cycling with BFR, regardless of pressure (~25% vs. ~12% MVC). Mean power frequency was not different between conditions but did increase from the first 5 minutes of exercise to the last 5 minutes (93% vs. 101%, p < 0.001). Ratings of perceived exertion (RPE) were higher with high intensity cycling but discomfort was similar between conditions. We wish to suggest that high intensity cycling produces greater muscular stress than that observed with work matched low intensity cycling in combination with BFR

Validity of wrist-worn consumer products to measure heart rate and energy expenditure

Introduction: The ability to monitor physical activity throughout the day and during various activities continues to improve with the development of wrist-worn monitors. However, the accuracy of wrist-worn monitors to measure both heart rate and energy expenditure during physical activity is still unclear. The purpose of this study was to determine the accuracy of several popular wrist-worn monitors at measuring heart rate and energy expenditure. Methods: Participants wore the TomTom Cardio, Microsoft Band and Fitbit Surge on randomly assigned locations on each wrist. The maximum number of monitors per wrist was two. The criteria used for heart rate and energy expenditure were a three-lead electrocardiogram and indirect calorimetry using a metabolic cart. Participants exercised on a treadmill at 3.2, 4.8, 6.4, 8 and 9.7 km/h for 3 minutes at each speed, with no rest between speeds. Heart rate and energy expenditure were manually recorded every minute throughout the protocol. Results: Mean absolute percentage error for heart rate varied from 2.17 to 8.06% for the Fitbit Surge, from 1.01 to 7.49% for the TomTom Cardio and from 1.31 to 7.37% for the Microsoft Band. The mean absolute percentage error for energy expenditure varied from 25.4 to 61.8% for the Fitbit Surge, from 0.4 to 26.6% for the TomTom Cardio and from 1.8 to 9.4% for the Microsoft Band. Conclusion: Data from these devices may be useful in obtaining an estimate of heart rate for everyday activities and general exercise, but energy expenditure from these devices may be significantly over- or underestimated

Validity of Wrist-worn Physical Activity Monitors to Measure Heart Rate

Numerous physical activity monitors exist and are used to track and improve fitness levels. Due to the increasing popularity of these devices, newer products have been developed that measure heart rate (HR) at the wrist. Little is known about how accurate these devices are at measuring HR at the wrist and how they compare to each other. PURPOSE: To determine how accurately HR was measured by three different wrist-worn physical activity monitors. METHODS: Recreationally active men (n=9) and women (n=3) participated in this study. The average age and weight of participants was 22 ± 3 years and 73.9 ± 12 kg. TomTom Cardio (TT), Fitbit Surge (FB) and Microsoft Band (MB) physical activity monitors were used. The TT, FB, and MB were randomly assigned to the right or left wrist for each participant. The testing procedure included speeds of 2, 3, 4, 5, and 6 mph with each speed lasting three minutes. HR was measured by electrocardiography (ECG) using standard limb lead II and by the three different physical activity monitors. HR was recorded from each device every minute throughout the duration of the procedure. Pearson product moment correlations and bias between electrocardiography (ECG) and physical activity monitors with 95% limits of agreement (Bland-Altman analysis) were calculated. Repeated measures ANOVA [Speed x Device] were also calculated. Statistical significance was set at pRESULTS: At 2 mph and 3 mph, only TT HR was significantly correlated with ECG heart rate (r=0.693, p=0.012 and r=0.592, p=0.043). At 4 mph and 6 mph TT was significantly correlated with ECG (r=0.911, pCONCLUSION: With increasing speeds, physical activity monitors more accurately measure HR but individuals should be aware that these devices may overestimate HR during slower walking speeds

Influence of anthropometric parameters and biochemical markers of bone metabolism on quantitative ultrasound of bone in the institutionalized elderly

The assessment of bone quality by quantitative ultrasound (QUS), a transportable and relatively cheap method, shows some correlations with bone mineral density (BMD) as measured by dual-energy X-ray absorptiometry (DXA) and with fracture risk. To examine its correlation with bone metabolism in a population of institutionalized elderly people known to be at high risk for vitamin D deficiency and secondary hyperparathyroidism, QUS of the calcaneus and biochemical parameters were measured in 264 women aged 85 +/- 7 (SD) years and in 103 men aged 81 +/- 8 years living in 19 nursing homes. Vitamin D deficiency was frequent in this population: 41.9% of the women and 31.4% of the men had a serum 25-hydroxyvitamin (25OHD) level below the 2.5th percentile level of 3276 normal Swiss adults (6.2 micrograms/l or 15.5 mmol/l). Hyperparathyroidism was less frequent: serum parathyroid hormone (PTH) levels were above the 97.5th percentile level of normal adults (70 pg/l) in 18.9% of women and 9.8% of men. In women, QUS data correlated significantly with age (r = -0.297), body mass index (BMI) (r = 0.403), calcium (r = 0.220), PTH (r = -0.296), 25OHD (r = 0.298) and alkaline phosphatase (AP) (r = -0.170) for broadband ultrasound attenuation (BUA), and with age (r = -0.195), BMI (r = 0.208), PTH (r = -0.174), 25OHD (r = 0.140) and AP (r = -0.130) for speed of sound (SOS). In men, ultrasound data correlated with BMI (r = 0.326), calcium (r = 0.199), 25OHD (r = 0.258) and AP (r = -0.311) for BUA, and with AP (r = -0.196) for SOS. In women, but not in men because of their smaller number, a multivariate analysis was performed to examine relationships between age, BMI, biochemical markers and QUS. Age, BMI, PTH and phosphate explained 30% of the variance of BUA and 10% for SOS. In conclusion, QUS of bone evaluates characteristics of bone that are influenced, at least partially, by age, BMI and the secondary hyperparathyroidism due to vitamin D deficiency

Trends in publications regarding evidence-practice gaps: A literature review

<p>Abstract</p> <p>Background</p> <p>Well-designed trials of strategies to improve adherence to clinical practice guidelines are needed to close persistent evidence-practice gaps. We studied how the number of these trials is changing with time, and to what extent physicians are participating in such trials.</p> <p>Methods</p> <p>This is a literature-based study of trends in evidence-practice gap publications over 10 years and participation of clinicians in intervention trials to narrow evidence-practice gaps. We chose nine evidence-based guidelines and identified relevant publications in the PubMed database from January 1998 to December 2007. We coded these publications by study type (intervention versus non-intervention studies). We further subdivided intervention studies into those for clinicians and those for patients. Data were analyzed to determine if observed trends were statistically significant.</p> <p>Results</p> <p>We identified 1,151 publications that discussed evidence-practice gaps in nine topic areas. There were 169 intervention studies that were designed to improve adherence to well-established clinical guidelines, averaging 1.9 studies per year per topic area. Twenty-eight publications (34%; 95% CI: 24% - 45%) reported interventions intended for clinicians or health systems that met Effective Practice and Organization of Care (EPOC) criteria for adequate design. The median consent rate of physicians asked to participate in these well-designed studies was 60% (95% CI, 25% to 69%).</p> <p>Conclusions</p> <p>We evaluated research publications for nine evidence-practice gaps, and identified small numbers of well-designed intervention trials and low rates of physician participation in these trials.</p

Impact of flavonoid-rich black tea and beetroot juice on postprandial peripheral vascular resistance and glucose homeostasis in obese, insulin-resistant men: a randomized controlled trial.

BACKGROUND: Insulin-stimulated muscle blood flow facilitates plasma glucose disposal after a meal, a mechanism that is impaired in obese, insulin-resistant volunteers. Nitrate- or flavonoid-rich products, through their proposed effects on nitric oxide, may improve postprandial blood flow and, subsequently, glucose disposal. To investigate whether a single dose of nitrate-rich beetroot juice or flavonoid-rich black tea lowers postprandial muscle vascular resistance in obese volunteers and alters postprandial glucose or insulin concentrations. METHOD: In a randomised, controlled, cross-over study, 16 obese, insulin-resistant males consumed 75 g glucose, which was combined with 100 ml black tea, beetroot juice or control (water). Peripheral vascular resistance (VR), calculated as mean arterial pressure divided by blood flow, was assessed in the arm and leg conduit arteries, resistance arteries and muscle microcirculation across 3 h (every 30-min) after the oral glucose load. RESULTS: During control, we found no postprandial response in VR in conduit, resistance and microvessels (all P > 0.05). Black tea decreased VR compared to control in conduit, resistance and microvessels (all P < 0.05). Beetroot juice decreased postprandial VR in resistance vessels, but not in conduit artery and microvessels. Although postprandial glucose response was similar after all interventions, postprandial insulin response was attenuated by ~29 % after tea (P < 0.0005), but not beetroot juice. CONCLUSIONS: A single dose of black tea decreased peripheral VR across upper and lower limbs after a glucose load which was accompanied by a lower insulin response. Future studies in insulin-resistant subjects are warranted to confirm the observed effects and to explore whether long-term regular tea consumption affects glucose homeostasis. TRIAL REGISTRATION: The study was registered at clinicaltrials.gov on 30(th) November 2012 (NCT01746329)