Walking with a rollator and the level of physical intensity in adults 75 years of age or older.

Eggermont LH, van Heuvelen MJ, van Keeken BL, Hollander AP, Scherder EJ. Walking with a rollator and the level of physical intensity in adults 75 years of age or older. Objective: To determine whether walking with a rollator by persons 75 years of age or older is of sufficient intensity to improve aerobic fitness. Design: A cross-sectional cohort study. Setting: University movement laboratory. Participants: Fifteen subjects 75 years of age or older (mean age, 83.7y) who could only walk by using a rollator. Interventions: Not applicable. Main Outcome Measures: During 6 minutes of self-paced treadmill walking using a rollator at a mean walking speed of 0.6m/s, oxygen uptake (V̇

A systematic review and quantitative analysis of resting energy expenditure prediction equations in healthy overweight and obese children and adolescents

© The British Dietetic Association Ltd. This is the peer reviewed version of 'Chima, L., Mulrooney, H. M., Warren, J., & Madden, A. (2020). A systematic review and quantitative analysis of resting energy expenditure prediction equations in healthy overweight and obese children and adolescents. Journal of Human Nutrition and Dietetics. https://doi.org/10.1111/jhn.12735'. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Background:  Resting energy expenditure (REE) estimate sare often needed in young people and can be predicted using prediction equations based on body weight.  However,these equations may perform poorly in obesity and overweight. The aim of this systematic review was to identify equations based on simple anthropometric and demographic variables which provide the most accurate and precise estimates of REE in healthy obese and overweight young people. Methodology:Systematic searches for relevant studies in healthy obese and overweight young people aged ≤18 years were undertaken using PubMed, Scopus, Cinahl, OpenGrey and Cochrane Library (completed January 2018). Search terms included metabolism, calorimetry, obesity and prediction equation. Data extraction,study appraisal and synthesis followed PRISMA guidelines. Results:From 390 screened titles, 13 studies met inclusion criteria. The most accurate REE predictions (least biased) were provided by Schofield equations (+0.8%[3-18 years]; 0% [11-18 years]; +1.1% [3-10 years]). The most precise REE estimations (percentage of predictions ±10% of measured) for 11-18 years were provided by Mifflin equations (62%), and for 7-18 years by the equations of Schmelzle (57%), Henry (56%) and Harris Benedict (54%). Precision of Schofield predictions was 43% in both age groups. No accuracy data were available for those <3 years or for precision for those <7 years. Principal conclusions: No single equation provided accurate and precise REE estimations in this population.  Schofield equations provided the most accurate REE predictions so are useful for groups.  Mifflin equations provided the most precise estimates for individuals aged 11-18 but tended to underestimate REE.  Peer reviewedFinal Accepted Versio

The effect of ambient temperature on gross-efficiency in cycling

Time-trial performance deteriorates in the heat. This might potentially be the result of a temperature-induced decrease in gross-efficiency (GE). The effect of high ambient temperature on GE during cycling will be studied, with the intent of determining if a heat-induced change in GE could account for the performance decrements in time trial exercise found in literature. Ten well-trained male cyclists performed 20-min cycle ergometer exercise at 60% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P_{V{\text{O}}_{{\text{2max}}} }$$\end{document} (power output at which VO2max was attained) in a thermo-neutral climate (N) of 15.6 ± 0.3°C, 20.0 ± 10.3% RH and a hot climate (H) of 35.5 ± 0.5°C, 15.5 ± 3.2% RH. GE was calculated based on VO2 and RER. Skin temperature (Tsk), rectal temperature (Tre) and muscle temperature (Tm) (only in H) were measured. GE was 0.9% lower in H compared to N (19.6 ± 1.1% vs. 20.5 ± 1.4%) (P < 0.05). Tsk (33.4 ± 0.6°C vs. 27.7 ± 0.7°C) and Tre (37.4 ± 0.6°C vs. 37.0 ± 0.6°C) were significantly higher in H. Tm was 38.7 ± 1.1°C in H. GE was lower in heat. Tm was not high enough to make mitochondrial leakage a likely explanation for the observed reduced GE. Neither was the increased Tre. Increased skin blood flow might have had a stealing effect on muscular blood flow, and thus impacted GE. Cycling model simulations showed, that the decrease in GE could account for half of the performance decrement. GE decreased in heat to a degree that could explain at least part of the well-established performance decrements in the heat

The between and within day variation in gross efficiency

Before the influence of divergent factors on gross efficiency (GE) [the ratio of mechanical power output (PO) to metabolic power input (PI)] can be assessed, the variation in GE between days, i.e. the test–retest reliability, and the within day variation needs to be known. Physically active males (n = 18) performed a maximal incremental exercise test to obtain VO2max and PO at VO2max (PVO2max), and three experimental testing days, consisting of seven submaximal exercise bouts evenly distributed over the 24 h of the day. Each submaximal exercise bout consisted of six min cycling at 45, 55 and 65% PVO2max, during which VO2 and RER were measured. GE was determined from the final 3 min of each exercise intensity with: GE = (PO/PI) × 100%. PI was calculated by multiplying VO2 with the oxygen equivalent. GE measured during the individually highest exercise intensity with RER <1.0 did not differ significantly between days (F = 2.70, p = 0.08), which resulted in lower and upper boundaries of the 95% limits of agreement of 19.6 and 20.8%, respectively, around a mean GE of 20.2%. Although there were minor within day variations in GE, differences in GE over the day were not significant (F = 0.16, p = 0.99). The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of ~0.6% can be reliably detected. Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO2 and RER <1.0 are applied

Efficacy of a meal replacement diet plan compared to a food-based diet plan after a period of weight loss and weight maintenance: a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Obesity has reached epidemic proportions in the United States. It is implicated in the development of a variety of chronic disease states and is associated with increased levels of inflammation and oxidative stress. The objective of this study is to examine the effect of Medifast's meal replacement program (MD) on body weight, body composition, and biomarkers of inflammation and oxidative stress among obese individuals following a period of weight loss and weight maintenance compared to a an isocaloric, food-based diet (FB).</p> <p>Methods</p> <p>This 40-week randomized, controlled clinical trial included 90 obese adults with a body mass index (BMI) between 30 and 50 kg/m², randomly assigned to one of two weight loss programs for 16 weeks and then followed for a 24-week period of weight maintenance. The dietary interventions consisted of Medifast's meal replacement program for weight loss and weight maintenance, or a self-selected, isocaloric, food-based meal plan.</p> <p>Results</p> <p>Weight loss at 16 weeks was significantly better in the Medifast group (MD) versus the food-based group (FB) (12.3% vs. 6.9%), and while significantly more weight was regained during weight maintenance on MD versus FB, overall greater weight loss was achieved on MD versus FB. Significantly more of the MD participants lost ≥ 5% of their initial weight at week 16 (93% vs. 55%) and week 40 (62% vs. 30%). There was no difference in satiety observed between the two groups during the weight loss phase. Significant improvements in body composition were also observed in MD participants compared to FB at week 16 and week 40. At week 40, both groups experienced improvements in biochemical outcomes and other clinical indicators.</p> <p>Conclusions</p> <p>Our data suggest that the meal replacement diet plan evaluated was an effective strategy for producing robust initial weight loss and for achieving improvements in a number of health-related parameters during weight maintenance, including inflammation and oxidative stress, two key factors more recently shown to underlie our most common chronic diseases.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov NCT01011491</p

Is bioelectrical impedance accurate for use in large epidemiological studies?

Percentage of body fat is strongly associated with the risk of several chronic diseases but its accurate measurement is difficult. Bioelectrical impedance analysis (BIA) is a relatively simple, quick and non-invasive technique, to measure body composition. It measures body fat accurately in controlled clinical conditions but its performance in the field is inconsistent. In large epidemiologic studies simpler surrogate techniques such as body mass index (BMI), waist circumference, and waist-hip ratio are frequently used instead of BIA to measure body fatness. We reviewed the rationale, theory, and technique of recently developed systems such as foot (or hand)-to-foot BIA measurement, and the elements that could influence its results in large epidemiologic studies. BIA results are influenced by factors such as the environment, ethnicity, phase of menstrual cycle, and underlying medical conditions. We concluded that BIA measurements validated for specific ethnic groups, populations and conditions can accurately measure body fat in those populations, but not others and suggest that for large epdiemiological studies with diverse populations BIA may not be the appropriate choice for body composition measurement unless specific calibration equations are developed for different groups participating in the study