Cardiorespiratory fitness and muscular fitness correlates in youth: A hierarchy of behavioral, contextual, and health-related outcomes.

OBJECTIVES: Despite the health importance of identifying correlates of physical fitness in youth, no investigation to date has explored the influence of behavioral, health-related, and contextual correlates simultaneously. We investigated the hierarchical relationship of multiple modifiable correlates favoring or diminishing cardiorespiratory and muscular fitness in youth. DESIGN: Cross-sectional investigation. METHODS: In a sample of 5174 children and adolescents, 31 correlates were hierarchized according to their impact on cardiorespiratory and muscular fitness assessed using the FITESCOLA® fitness battery. A Chi-squared Automatic Interaction Detection approach was employed and measures of correlation and association were used to investigate the relationship between physical fitness and correlates. RESULTS: In children, body mass index was the most relevant factor to discriminate between high and low cardiorespiratory and muscular fitness of the upper, middle, and lower body. While body mass index was more important than any other correlate to differentiate levels of upper and lower body muscular fitness during adolescence, specific characteristics of sports participation emerged as key factors to discriminate between high and low cardiorespiratory fitness and middle body muscular fitness. Other correlates, including the self-report of active recess time, active commuting to school, favorable neighborhood conditions, and limited time on screens and cellphones, were demonstrative of favorable physical fitness levels. CONCLUSIONS: Both body composition and sports-related characteristics emerged as the two most relevant factors of physical fitness in youth. Additional health benefits may be obtained from building supportive environments for sports and healthy exercise habits within the household and at different school education levels.

Associations Between D3Cr Muscle Mass and Magnetic Resonance Thigh Muscle Volume With Strength, Power, Physical Performance, Fitness, and Limitations in Older Adults in the SOMMA Study.

BACKGROUND: How magnetic resonance (MR) derived thigh muscle volume and deuterated creatine dilution derived muscle mass (D3Cr muscle mass) differentially relate to strength, fitness, and other functions in older adults-and whether associations vary by sex-is not known. METHODS: Men (N = 345) and women (N = 482) aged ≥70 years from the Study of Muscle, Mobility, and Aging completed leg extension strength (1-repetition max) and cardiopulmonary exercise testing to assess fitness (VO2peak). Correlations and adjusted regression models stratified by sex were used to assess the association between muscle size measures, study outcomes, and sex interactions. RESULTS: D3Cr muscle mass and MR thigh muscle volume were correlated (men: r = 0.62, women: r = 0.51, p < .001). Each standard deviation (SD) decrement in D3Cr muscle mass was associated with lower 1-repetition max strength (-14 kg men, -4 kg women, p < .001 for both; p-interaction = .003) and lower VO2peak (-79 mL/min men, -30 mL/min women, p < .001 for both, p-interaction: .016). Each SD decrement in MR thigh muscle volume was also associated with lower strength (-32 kg men, -20 kg women, p < .001 for both; p-interaction = .139) and lower VO2peak (-217 mL/min men, -111 mL/min women, p < .001 for both, p-interaction = .010). There were associations, though less consistent, between muscle size or mass with physical performance and function; associations varied by sex. CONCLUSIONS: Less muscle-measured by either D3Cr muscle mass or MR thigh muscle volume-was associated with lower strength and fitness. Varied associations by sex and assessment method suggest consideration be given to which measurement to use in future studies.

Limb-specific isometric and isokinetic strength in adults: The potential role of regional bioelectrical impedance analysis-derived phase angle.

BACKGROUND & AIMS: It is not yet known whether regional bioelectrical impedance (BIA) phase angle (PhA) may be informative of different types of strength performed by the lower and upper limbs, independently of lean soft tissue mass (LSTM). Using a sample of healthy adults, we aimed to examine the association and relevance of regional PhA relative to isometric and isokinetic strength of each limb. METHODS: A total of 57 participants (32.7 ± 12.9 years; 24.7 ± 3.5 kg/m2) were included in the present investigation. Regional raw BIA variables were determined using a phase-sensitive BIA device. Dual-energy X-ray absorptiometry was used to evaluate LSTM. Absolute isometric and isokinetic (i.e., 60°/s and 180°/s) strength of each limb (extension and flexion) was assessed using an isokinetic dynamometer and used to calculate relative strength. RESULTS: In absolute strength, only dominant leg PhA was associated with isometric extension strength (ß = 0.283) and isokinetic 180°/s flexion strength (ß = 0.354), regardless of LSTM (p < 0.05). In relative strength, a significant association of regional PhA was found for dominant arm flexion isometric strength (ß = 0.336), and non-dominant arm and dominant leg extension isometric strength (ß = 0.377, ß = 0.565, respectively; p < 0.05), independently of LSTM. Similarly, for isokinetic 180°/s strength, regional PhA significantly explained the variance in the relative strength of both arms and dominant leg (ß = 0.350 to 0.506), regardless of LSTM (p < 0.05). Relative isokinetic 60°/s strength was not consistently associated with regional PhA (p ≥ 0.05). CONCLUSIONS: Regional PhA significantly explained relative (isometric and 180°/s isokinetic strength of both arms and dominant leg), but not absolute muscle strength, independently of regional LSTM. Thus, after accounting for body size, regional PhA seems to have its own characteristics that explain relative strength independently of LSTM.

Nutrient Metabolites Associated With Low D3Cr Muscle Mass, Strength, and Physical Performance in Older Men.

BACKGROUND: The relationship between amino acids, B vitamins, and their metabolites with D3-creatine (D3Cr) dilution muscle mass, a more direct measure of skeletal muscle mass, has not been investigated. We aimed to assess associations of plasma metabolites with D3Cr muscle mass, as well as muscle strength and physical performance in older men from the Osteoporotic Fractures in Men cohort study. METHODS: Out of 1 425 men (84.2 ±â€…4.1 years), men with the lowest D3Cr muscle mass (n = 100), slowest walking speed (n = 100), lowest grip strength (n = 100), and a random sample (n = 200) serving as a comparison group to the low groups were included. Metabolites were analyzed using liquid chromatography-tandem mass spectrometry. Metabolite differences between the low groups and random sample and their relationships with the muscle outcomes adjusted for confounders and multiple comparisons were assessed using t-test/Mann-Whitney-Wilcoxon and partial correlations, respectively. RESULTS: For D3Cr muscle mass, significant biomarkers (p < .001) with ≥10% fold difference and largest partial correlations were tryptophan (Trp; r = 0.31), kynurenine (Kyn)/Trp; r = -0.27), nicotinamide (Nam)/quinolinic acid (Quin; r = 0.21), and alpha-hydroxy-5-methyl-tetrahydrofolate (hm-THF; r = -0.25). For walking speed, hm-THF, Nam/Quin, and Quin had the largest significance and fold difference, whereas valine (r = 0.17), Trp (r = 0.17), HKyn/Xant (r = -0.20), neopterin (r = -0.17), 5-methyl-THF (r = -0.20), methylated folate (r = -0.21), and thiamine (r = -0.18) had the strongest correlations. Only hm-THF was correlated with grip strength (r = -0.21) and differed between the low group and the random sample. CONCLUSIONS: Future interventions focusing on how the Trp metabolic pathway or hm-THF influences D3Cr muscle mass and physical performance declines in older adults are warranted.

Associations between D3Cr muscle mass and MR thigh muscle volume with strength, power, physical performance, fitness, and limitations in older adults in the SOMMA study.

Background: Different measures to assess muscle size - magnetic resonance (MR) derived thigh muscle volume and d3-creatine dilution derived muscle mass (D3Cr muscle mass) - may have similar associations with strength, power, physical performance, fitness, and functional limitations in older adults. Methods: Men (N=345) and women (N=482) aged ≥70 years from the Study of Muscle, Mobility and Aging completed exams including leg extension strength (1-repetition max) and cardiopulmonary exercise testing to assess fitness (VO2peak). Correlations and adjusted regression models stratified by sex were used to assess the association between muscle size measures and study outcomes; we tested for sex interactions. Results: D3Cr muscle mass and MR thigh muscle volume were correlated (men: r=0.62, women: r=0.51, p<.001). Lower D3Cr muscle mass and lower MR thigh muscle volume were associated with lower strength and lower VO2peak in both men and women; D3Cr muscle mass was more strongly associated with strength in men than in women (p-int<0.05). There were correlations, though less consistent, between muscle size or mass with physical performance and function. Associations between the muscle size measures and the study outcomes occasionally varied by sex, and associations of MR thigh muscle volume were, at times, slightly more strongly associated with the study outcomes than was D3Cr muscle mass. Conclusions: Less muscle -measured by either D3Cr muscle mass or MR thigh muscle volume - was associated with lower strength and worse performance. Varied associations by sex and assessment method suggest consideration be given to which measurement to use in future studies.

Associations between regional adipose tissue distribution and skeletal muscle bioenergetics in older men and women.

Objective: Examine the association of ectopic adipose tissue (AT) with skeletal muscle (SM) mitochondrial bioenergetics in older adults. Methods: Cross-sectional data from 829 older adults ≥70 years was used. Total abdominal, subcutaneous, and visceral AT; and thigh muscle fat infiltration (MFI) was quantified by MRI. SM mitochondrial energetics were characterized using in vivo 31 P-MRS (ATP max ) and ex vivo high-resolution respirometry (maximal oxidative phosphorylation (OXPHOS)). ActivPal was used to measure PA (step count). Linear regression models adjusted for covariates were applied, with sequential adjustment for BMI and PA. Results: Independent of BMI, total abdominal (standardized (Std.) ß=-0.21; R 2 =0.09) and visceral AT (Std. ß=-0.16; R 2 =0.09) were associated with ATP max ( p <0.01), but not after further adjustment for PA (p≥0.05). Visceral AT (Std. ß=-0.16; R 2 =0.25) and thigh MFI (Std. ß=-0.11; R 2 =0.24) were negatively associated with carbohydrate-supported maximal OXPHOS independent of BMI and PA ( p <0.05). Total abdominal AT (Std. ß=-0.19; R 2 =0.24) and visceral AT (Std. ß=-0.17; R 2 =0.24) were associated with fatty acid-supported maximal OXPHOS independent of BMI and PA (p<0.05). Conclusions: Skeletal MFI and abdominal visceral, but not subcutaneous AT, are inversely associated with SM mitochondrial bioenergetics in older adults independent of BMI. Associations between ectopic AT and in vivo mitochondrial bioenergetics are attenuated by PA.

Functional fitness trends among older adults in Portugal between 2008 and 2018: Keeping up with a healthy aging process.

OBJECTIVES: Maintaining a healthy aging process is vital to combating and delaying the adverse health outcomes faced by the growing older adult population, where a key aspect to achieving healthy aging is the preservation of functional fitness. This study aims to present trends on the functional fitness of Portuguese older adults between 2008 and 2018 and build new normative reference standards for the Senior Fitness Battery Tests. DESIGN: Cross-sectional study. METHODS: Functional fitness was measured with the Senior Fitness Battery Tests in two national representative cohorts of the Portuguese older adult population (≥65 years) using the 2008 (n = 4712) and 2018 (n = 2717) surveys. Changes were assessed according to sex and age group. Sex and age-group normative fitness scores were developed. RESULTS: Overall findings suggested that older adults' point prevalence for arm-curl, 8-ft up-and-go, and 30-s chair sit-to-stand remained stable between 2008 and 2018, with declining trends being observed for the 6-min walk and back-scratch tests. However, results for trends varied when stratified by sex and age categories. CONCLUSIONS: Our results suggest a trend toward a stabilization of most of the functional fitness tests over the past decade, but with a critical decline in the 6-min walk test. Thus, this test should be targeted by future health-care policies. Moreover, this investigation provides new and updated normative reference standards for the Senior Fitness Battery Tests that should be used as a tool to promote a healthy aging process among Portuguese older adults.

Physical fitness trends in a nationally representative sample of Portuguese youth: What has changed from 2008 to 2018?

This investigation aimed to describe the current physical fitness (PF) status of Portuguese youth, compare secular trends from 2008 and 2018, and establish updated age- and sex-specific percentile values for distinct PF tests. In 2008 and 2018, 22 048 and 8960 children and adolescents (10-18 years) were included in two national cross-sectional investigations. PF was evaluated using the FITESCOLA® battery tests and the handgrip strength test. Independent sample t-tests and chi-squared tests were used to model the results. Weight smoothed percentile values were calculated using Cole's Lambda-Mu-Sigma (LMS) method. All analyses were weighted according to age, sex, and geographic region. In 2018, boys surpassed girls in the 20-m shuttle run, curl-ups, push-ups, standing long, and vertical jump tests, while girls performed better in the sit-and-reach (p < 0.05). The percentage of boys and girls meeting the healthy zone in the 20-min shuttle run test did not differ between 2008 and 2018 (p ≥ 0.05). In boys, a higher percentage fell in the healthy zone for the curl-up and push-up tests in 2018 compared to 2008 (85.8% vs. 83.4%, and 57.8% vs. 53.8%; p < 0.05). Girls improved their flexibility component (sit-and-reach test), with a higher percentage meeting the healthy zone in 2018 (32.6% vs. 36.9%; p < 0.05); an opposite trend was seen for boys (65.5% vs. 50.1%; p < 0.05). The present investigation provides new and updated PF percentile curves for Portuguese youth, which can be used as a general overview of the current PF state among the Portuguese young population.

Effects of home-based exercise programs on physical fitness in cancer patients undergoing active treatment: A systematic review and meta-analysis of randomized controlled trials.

OBJECTIVES: This systematic review and meta-analysis aimed to investigate the effects of home-based exercise on physical fitness (cardiorespiratory fitness, muscle strength, and body composition) in cancer patients undergoing active treatment. DESIGN: Systematic review with meta-analysis and Grading Recommendations Assessment, Development, and Evaluation of the evidence. METHODS: A comprehensive search of existing literature was carried out in four electronic databases: PubMed, Web of Science, Scopus, and PEDro. All databases were searched for randomized controlled trials assessing the effects of home-based exercise on physical fitness outcomes in cancer patients during active treatment. Multicomponent interventions (i.e., exercise plus diet/behavioral therapy) were excluded. The methodological quality of each study was assessed using the Revised Cochrane risk-of-bias tool for randomized trials. Meta-analytical procedures were performed when appropriate and standardized mean differences (SMD) were calculated. RESULTS: Twenty-eight randomized controlled trials (n = 2424 cancer patients) were included. Most of the interventions were conducted in breast cancer patients (n = 13) during the adjuvant treatment period (n = 17); 18 studies included a walking component in their home-based protocol. Home-based exercise was effective at improving the distance of the 6-minute walk test (k = 6; SMD = 0.321, p = 0.010). However, the results were no longer significant when performing sensitivity analysis based on exclusively walking (k = 1) and non-exclusively walking interventions (k = 5; SMD = 0.258; p = 0.072). No effects were found for muscle strength and body composition outcomes (p > 0.05). CONCLUSIONS: Regular home-based exercise programs are an effective strategy to improve 6-minutes walk test in cancer patients undergoing active treatment. Conversely, no alterations were found in muscle strength and body composition.

Physical Activity and Sedentary Behavior in the Portuguese Population: What Has Changed from 2008 to 2018?

PURPOSE: Assessment of trends in physical activity (PA) and sedentary time (ST) is important for evaluating the effectiveness of national policies and setting goals to improve population PA. This study describes changes in measured PA and ST through motion sensors of the Portuguese population from 2008 to 2018. METHODS: PA and ST were measured with accelerometry from individuals (≥10 yr) participating in the 2008 ( n = 4 532) and 2018 ( n = 6 369) Portuguese PA Surveillance Systems. Changes were analyzed using generalized linear and logistic models adjusted for accelerometer wear time. A weight factor was applied to all analyses in order to achieve national representativeness of the present results. RESULTS: In 2018, 15.4%, 71.2%, and 30.6% of Portuguese youth, adults, and older adults met the PA recommendations. Compared with 2008, the percentage meeting the PA guidelines increased in youth females (4.7% vs 7.7%, P < 0.05) and adult males (72.2% vs 79.4%, P < 0.05). A decrease in ST was observed for adult males, whereas ST increased in all youth. Male youth decreased the number of breaks in ST (BST per hour), whereas a favorable increase was found for both adult and older adult males and females. CONCLUSIONS: PA has remained fairly stable between 2008 and 2018 for all groups, except for youth females and adult males. For ST, a favorable decrease was observed for adult males; however, an inverse trend was found in youth. These results are relevant for policy makers to develop health care policies aimed at promoting PA and reducing ST across all age-groups.

Compensatory mechanisms from different exercise intensities in type 2 diabetes: a secondary analysis of a 1-year randomized controlled trial.

AIMS: This investigation aimed to determine the effect of different intensities of training on non-exercise physical activity (NEPA) and estimated thermogenesis (NEAT) from a 1-year exercise randomized controlled trial (RCT) in individuals with type 2 diabetes mellitus (T2DM) on non-training days. Additionally, changes in NEPA and estimated NEAT in those who failed (low-responders) or succeeded (high-responders) in attaining exercise-derived clinically meaningful reductions in body weight (BW) and fat mass (FM) (i.e., 6% for FM and 3% for BW) was assessed. METHODS: Individuals with T2DM (n = 80) were enrolled in a RCT with three groups: resistance training combined with moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT) and a control group. Of the 80 participants, 56 (completed data) were considered for this secondary analysis. NEPA and estimated NEAT were obtained by accelerometry and body composition through dual-energy X-ray absorptiometry. RESULTS: After adjustments, no time*group interactions were found for estimated NEAT in the MICT (ß = - 5.33, p = 0.366) and HIIT (ß = - 5.70, p = 0.283), as well as for NEPA in the MICT (ß = - 452.83, p = 0.833) and HIIT (ß = - 2770.76, p = 0.201), when compared to controls. No compensatory changes in NEPA and estimated NEAT were observed when considering both low-responders and high-responders to FM and BW when compared to controls. CONCLUSIONS: Both MICT and HIIT did not result in any compensatory changes in estimated NEAT and NEPA with the intervention on non-training days. Moreover, no changes in estimated NEAT and NEPA were found when categorizing our participants as low-responders and high-responders to FM and BW when compared to controls. Trial registration clinicaltrials.gov ID. NCT03144505.

A hierarchy of correlates for objectively measured physical activity, sedentary time, and physical fitness in older adults: A CHAID analysis.

The aging process reflects, in many cases, not only a decline in physical activity (PA) and physical fitness (PF), but also an increase in overall levels of sedentary time (ST). In order to hierarchically identify the most powerful correlates related to low and high levels of objectively assessed PA, ST, and PF during the late adulthood, a total of 2666 older adults were cross-sectionally evaluated. Multidimensional correlates were obtained through interview. Using chi-squared automatic detection analysis to identify the cluster of correlates with most impact on PA (<21.4 min/day), ST (≥8 h/day), and PF (<33.3th percentile), was found that the most likely subgroup to be physically inactive consisted of widowers not owning a computer and sport facilities in the neighbourhood (94.7%), while not being widowed, reporting to have a family that exercises and a computer at home (54.3%) represented the subgroup less likely to be inactive. Widowers without sidewalks in the neighbourhood were the most sedentary group (91.0%), while being a married woman and reporting to have space to exercise at home (40%) formed the most favourable group of correlates regarding ST. Men reporting a financial income <500€ and physical problems frequently formed the group with the lowest PF level (70.3%). In contrast, the less likely subgroup to have low levels of PF level consisted of having a financial income ≥1000€ and a computer at home (3.4%). Future interventions should target widowers with limited accessibility to computer and urban/sport-related infrastructures, as well as impaired older adults with low financial income.HighlightsChi-squared automatic interaction detection was used to identify and hierarchise correlates of objectively measured physical activity, sedentary time, and fitness.Widowers not having a computer at home and sport facilities in the neighbourhood were the most likely to be physically inactive, while not being widowed, having a family that exercises and a computer at home represented the subgroup less likely to be physically inactive.The most likely to be classified as sedentary were widowers without sidewalks in the neighbourhood, while the most favourable group of correlates regarding ST was formed by married women and reporting to have space to exercise at home.Individuals with a low financial income and physical problems comprised the population subgroup with the lowest PF levels, while having a medium-high financial income and a computer at home represented the less likely subgroup to have low levels of PF.

Combined high-intensity interval training as an obesity-management strategy for adolescents.

Effective and safe exercise protocols for obesity management in adolescents are imperative. This study aimed to analyse compliance, efficacy, and safety of combined high-intensity interval training circuit (HIIT) in the management of obesity (including overweight) in adolescents, compared to traditional training (TT). Data from 55 adolescents (47.3% girls) (TT n = 31; HIIT n = 24), aged 12-18 (mean age of 14.3 ± 1.7), with overweight and obesity (median BMI z-score of 2.95), were assessed at baseline and month 6 (Clinicaltrials.gov/NCT02941770). During the 6-month intervention, participants in both exercise groups attended two exercise sessions/week (60 min/session) along with a set of appointments with a paediatrician, nutritionist, and exercise physiologist. Forty-six participants completed the intervention (TT n = 23; HIIT n = 23). Exercise session attendance (≥80%) was significantly higher among HIIT participants (73.9 vs. 13.0%, p < .001). HIIT, but not TT, showed a significant decrease in BMI z-score (d = 0.40, p < .001), body fat mass (BFM, %) (d = 0.41, p = .001), and trunk fat mass (d = 0.56, p < .001), as well as a significant increase in muscle mass (MM, %) (d = 0.28, p = .001) between baseline and 6 months. According to generalized estimating equations, time-by-attendance interactions (instead of time-by group) were found in BMI z-score (ß = 0.25, 95%CI: 0.17, 0.33), BFM (ß = 2.29, 95%CI: 1.02, 3.56), trunk fat mass (ß = 2.94, 95%CI: 1.70, 4.18), and MM (ß = -1.16, 95%CI: -1.87, -0.45). No adverse events were reported during HIIT sessions. Although compliance may mediate the impact of an exercise protocol on health-related outcomes, HIIT showed to be safe, with higher compliance compared to TT, which may result in improved outcomes overtime.

Development and validation of bioelectrical impedance prediction equations estimating regional lean soft tissue mass in middle-aged adults.

BACKGROUND/OBJECTIVES: Bioelectrical impedance (BIA) whole-body and regional raw parameters have been used to develop prediction models to estimate whole-body lean soft tissue (LSTM), with less attention being given to the development of models for regional LSTM. Therefore, we aimed to develop and validate BIA-derived equations predicting regional LSTM against dual x-ray absorptiometry (DXA) in healthy adults. SUBJECTS/METHODS: 149 adults were included in this cross-sectional investigation. Whole-body and regional LSTM were assessed by DXA, and raw bioelectrical parameters of distinct body regions were measured using a 50 kHz phase sensitive BIA analyzer. BIA-derived equations were developed using a stepwise multiple linear regression approach in 2/3 of the sample and cross-validated in the remaining sample. RESULTS: Slopes and intercepts of predicted LSTM and DXA measured LSTM did not differ from 1 and 0, respectively, for each region (p ≥ 0.05), with the exception for the trunk (p < 0.05). The BIA-derived equations exhibited a strong relationship (p < 0.001) between the predicted and measured LSTM for each of the following body regions: right and left arms (R = 0.94; R = 0.96), right and left legs (R = 0.88; R = 0.88), upper body (R = 0.96), lower body (R = 0.89), right and left sides of the body (R = 0.94; R = 0.94), and trunk (R = 0.90). Agreement analyses revealed no associations between the differences and the means of the predicted and DXA-derived LSTM. CONCLUSION: The developed BIA-derived equations provide a valid estimate of regional LSTM in middle-aged healthy adults, representing a cost-effective and time-efficient alternative to DXA for the assessment and identification of LSTM imbalances in both clinical and sport-specific contexts.

Breaking-Up Sedentary Behavior and Detraining Effects on Glycemic Control: A Randomized Crossover Trial in Trained Older Adults.

In a randomized crossover trial, we examined the effects of interrupting sedentary behavior on glycemic control in trained older adults, before and after 2 weeks of detraining. Fourteen participants (65-90 years old) completed two 7-hr conditions before and after 2 weeks of detraining: (a) uninterrupted sitting (SIT) and (b) sitting plus 2 min of moderate-intensity activity every 30 min (INT). Both before and after detraining, no differences were observed for 7-hr glucose area under the curve (7 hr AUC) and mean glucose between sitting plus 2 min of moderate-intensity activity and uninterrupted sitting conditions. After detraining and for the SIT condition, higher values of 7-hr AUC (p = .014) and mean glucose (p = .015) were observed, indicating worsened glycemic control. No changes were observed in INT condition between both time points. Frequent interruptions in sedentary behavior had no effect on glycemic control, prior to or after detraining. Even so, older adults experiencing a short-term detraining period should avoid prolonged bouts of sedentary behavior that may jeopardize their glycemic control.

Intensity matters: impact of physical activity energy expenditure at moderate and vigorous intensity on total and abdominal obesity in children.

BACKGROUND/OBJECTIVES: Physical activity (PA) guidelines advocate that children should accumulate at least 60 min of moderate-to-vigorous PA daily. Still, it is not clear how body fat may differ if the same dose of PA is accumulated at different intensities. We aimed to determine the independent associations of energy expenditure (EE) at moderate (MPA) and vigorous (VPA) PA intensity on total and abdominal fat in children and if these associations were moderated by cardiorespiratory fitness (CRF). SUBJECTS/METHODS: A total of 326 children (girls = 171, boys = 151) aged 10-12 years had PA assessed with accelerometers. Total fat mass index (FMI) and abdominal FMI were assessed with DXA. CRF was assessed by a cycle ergometer test. Linear regression models were used to model the outcomes with the inclusion of an interaction term to test for moderation effects. RESULTS: An inverse association was found between VPA EE and FMI (ß = -0.013, p < 0.001) and abdominal FMI (ß = -0.0014, p < 0.001) independent of MPA EE. In contrast, MPA EE was not related to adiposity independent of VPA EE (p > 0.05). The relationships between the PA intensities and FMI and abdominal FMI were moderated by CRF. MPA EE was positively associated with adiposity in children with high levels of CRF, whereas VPA EE remained inversely associated with adiposity regardless of CRF level, although the strength of the association was lower in those with higher CRF levels. CONCLUSION: PA programs should provide opportunities for children to perform VPA in order to achieve healthier body fat profiles and avoid excess adiposity.

Recommendations for Determining the Validity of Consumer Wearables and Smartphones for the Estimation of Energy Expenditure: Expert Statement and Checklist of the INTERLIVE Network.

BACKGROUND: Consumer wearables and smartphone devices commonly offer an estimate of energy expenditure (EE) to assist in the objective monitoring of physical activity to the general population. Alongside consumers, healthcare professionals and researchers are seeking to utilise these devices for the monitoring of training and improving human health. However, the methods of validation and reporting of EE estimation in these devices lacks rigour, negatively impacting on the ability to make comparisons between devices and provide transparent accuracy. OBJECTIVES: The Towards Intelligent Health and Well-Being Network of Physical Activity Assessment (INTERLIVE) is a joint European initiative of six universities and one industrial partner. The network was founded in 2019 and strives towards developing best-practice recommendations for evaluating the validity of consumer wearables and smartphones. This expert statement presents a best-practice validation protocol for consumer wearables and smartphones in the estimation of EE. METHODS: The recommendations were developed through (1) a systematic literature review; (2) an unstructured review of the wider literature discussing the potential factors that may introduce bias during validation studies; and (3) evidence-informed expert opinions from members of the INTERLIVE network. RESULTS: The systematic literature review process identified 1645 potential articles, of which 62 were deemed eligible for the final dataset. Based on these studies and the wider literature search, a validation framework is proposed encompassing six key domains for validation: the target population, criterion measure, index measure, testing conditions, data processing and the statistical analysis. CONCLUSIONS: The INTERLIVE network recommends that the proposed protocol, and checklists provided, are used to standardise the testing and reporting of the validation of any consumer wearable or smartphone device to estimate EE. This in turn will maximise the potential utility of these technologies for clinicians, researchers, consumers, and manufacturers/developers, while ensuring transparency, comparability, and replicability in validation. TRIAL REGISTRATION: PROSPERO ID: CRD42021223508.

Validity of Estimating the Maximal Oxygen Consumption by Consumer Wearables: A Systematic Review with Meta-analysis and Expert Statement of the INTERLIVE Network.

BACKGROUND: Technological advances have recently made possible the estimation of maximal oxygen consumption (VO2max) by consumer wearables. However, the validity of such estimations has not been systematically summarized using meta-analytic methods and there are no standards guiding the validation protocols. OBJECTIVE: The aim was to (1) quantitatively summarize previous studies investigating the validity of the VO2max estimated by consumer wearables and (2) provide best-practice recommendations for future validation studies. METHODS: First, we conducted a systematic review and meta-analysis of studies validating the estimation of VO2max by wearables. Second, based on the state of knowledge (derived from the systematic review) combined with the expert discussion between the members of the Towards Intelligent Health and Well-Being Network of Physical Activity Assessment (INTERLIVE) consortium, we provided a set of best-practice recommendations for validation protocols. RESULTS: Fourteen validation studies were included in the systematic review and meta-analysis. Meta-analysis results revealed that wearables using resting condition information in their algorithms significantly overestimated VO2max (bias 2.17 ml·kg-1·min-1; limits of agreement - 13.07 to 17.41 ml·kg-1·min-1), while devices using exercise-based information in their algorithms showed a lower systematic and random error (bias - 0.09 ml·kg-1·min-1; limits of agreement - 9.92 to 9.74 ml·kg-1·min-1). The INTERLIVE consortium proposed six key domains to be considered for validating wearable devices estimating VO2max, concerning the following: the target population, reference standard, index measure, testing conditions, data processing, and statistical analysis. CONCLUSIONS: Our meta-analysis suggests that the estimations of VO2max by wearables that use exercise-based algorithms provide higher accuracy than those based on resting conditions. The exercise-based estimation seems to be optimal for measuring VO2max at the population level, yet the estimation error at the individual level is large, and, therefore, for sport/clinical purposes these methods still need improvement. The INTERLIVE network hereby provides best-practice recommendations to be used in future protocols to move towards a more accurate, transparent and comparable validation of VO2max derived from wearables. PROSPERO ID: CRD42021246192.

Relative Sit-to-Stand Muscle Power Predicts an Older Adult's Physical Independence at Age of 90 Yrs Beyond That of Relative Handgrip Strength, Physical Activity, and Sedentary Time: A Cross-sectional Analysis.

OBJECTIVES: Muscle power is important for an older adult's physical independence and can be easily estimated using the sit-to-stand test. This investigation aimed to assess whether muscle power estimated using the sit-to-stand test could identify older adults at risk of losing physical independence beyond handgrip strength, physical activity, and sedentary time and to develop minimal sit-to-stand power thresholds. DESIGN: Physical independence was assessed cross-sectionally in older adults using a composite physical function questionnaire. Muscle power was calculated using the 30-sec sit-to-stand test. Muscle strength was determined using a handgrip dynamometer. Physical activity and sedentary time were assessed by accelerometry. Multiple logistic regression was used to assess the independent association between sit-to-stand power and projected physical independence ( n = 737). Receiver operator characteristic curves were used to develop sit-to-stand power cut points ( N = 1748). RESULTS: Sit-to-stand power proved to be the best predictor of physical independence in later life regardless of handgrip strength, physical activity, and sedentary time (standardized B = 0.45, -0.02, 0.12, -0.28, respectively). Sex- and age-specific cutoffs for sit-to-stand power had good discriminatory ability (area under the curve = 0.75-0.78 [women], 0.76-0.82 [men]). CONCLUSIONS: Sit-to-stand power can be used as a simple and practical screening tool to assess an older adult's future physical independence.