Total body fat does not influence maximal aerobic capacity

Grip strength performance from 9431 participants of the GenoFit study: normative data and associated factors

Weak grip strength is a strong predictor of multiple adverse health outcomes and an integral diagnostic component of sarcopenia. However, the limited availability of normative data for certain populations impedes the interpretation of grip performance across adulthood. This study aimed to establish normative data and low grip strength thresholds in a large adult population, and to examine associations between grip strength and clinically relevant health variables. A total of 9431 adults aged between 18 and 92 years participated in this study (mean age: 44.8 ± 13.4 years; 57% females). Grip strength, body composition, and cardiorespiratory (CR) fitness were assessed using hand dynamometry, dual-energy x-ray absorptiometry and physical work capacity tests, respectively. Low grip strength was established according to criteria of the European Working Group on Sarcopenia in Older People. Normative data and t-scores, stratified by sex and age groups, are presented. Grip performance was associated with lean mass, skeletal muscle index (SMI), fat mass, CR fitness, bone mineral density (BMD), android/gynoid ratio, disease prevalence and physical activity levels (all p < 0.001) after controlling for multiple potential confounders. Individuals with weak grip strength had lower lean mass, SMI, CR fitness (all p < 0.001) and BMD (p = 0.001), and higher disease prevalence (p < 0.001), compared to healthy controls, although sex-specific differences were observed. Grip strength has practical screening utility across a range of health domains. The normative data and grip strength thresholds established in this study can guide the clinical interpretation of grip performance and facilitate timely therapeutic strategies targeting sarcopenia.

Differential weight loss with intermittent fasting or daily calorie restriction in low- and high-fitness phenotypes

NEW FINDINGS

What is the central question of this study? How does intrinsic aerobic capacity impact weight loss with 50% daily caloric restriction and alternate-day fasting? What is the main finding and its importance? Intermittent fasting is effective for weight loss in rats with low fitness, which highlights the importance of how intermittent fasting interacts with aerobic fitness.

ABSTRACT

Recent interest has focused on the benefits of time-restricted feeding strategies, including intermittent fasting, for weight loss. It is not yet known whether intermittent fasting is more effective than daily caloric restriction at stimulating weight loss and how each is subject to individual differences. Here, rat models of leanness and obesity, artificially selected for intrinsically high (HCR) and low (LCR) aerobic capacity, were subjected to intermittent fasting and 50% calorie restrictive diets in two separate experiments using male rats. The lean, high-fitness HCR and obesity-prone, low-fitness LCR rats underwent 50% caloric restriction while body weight and composition were monitored. The low-fitness LCR rats were better able to retain lean mass than the high-fitness HCR rats, without significantly different proportional loss of weight or fat. In a separate experiment using intermittent fasting in male HCR and LCR rats, alternate-day fasting induced significantly greater loss of weight and fat mass in LCR compared with HCR rats, although the HCR rats had a more marked reduction in ad libitum daily food intake. Altogether, this suggests that intermittent fasting is an effective weight-loss strategy for those with low intrinsic aerobic fitness; however, direct comparison of caloric restriction and intermittent fasting is warranted to determine any differential effects on energy expenditure in lean and obesity-prone phenotypes.

Cardiopulmonary Capacity in Overweight and Obese Children and Adolescents: A Cross-Sectional Study

Background: One of the objective methods of assessing the level of cardiopulmonary capacity in overweight and obese children and adolescents is cardiopulmonary exercise testing (CPET).

Aims: The purpose of present study is an evaluation of aerobic capacity in high body mass index (BMI) children and adolescents by comparing them with a normal weight control group by CPET.

Methods and Procedures: The subjects were recruited from participants of the Program of Treatment for Overweight and Obese Children organized by a local pediatric rehabilitation center in Poland. Based on BMI for age and gender, two validation groups were selected: (1) a group of overweight children (n = 49) and (2) a group of obese children (n = 48). The study included also 53 normal weight participants as a reference group (REF). The study consisted of two parts: anthropometric measurements and CPET. The Godfrey protocol for CPET was applied.

Outcomes and Results: In this study, obese children and adolescents showed similar absolute VO_2peak values in liters per minute (1.64 L/min) compared to overweight children (1.48 L/min), but significantly higher than children with normal body weight (1.39 L/min). The obese children and adolescents presented lower VO_2peak in relation to body weight (25.44 ml/kg/min) compared to their peers with normal body weight (36.5 ml/kg/min), and overweight children (29.18 ml/kg/min).

Conclusion and Implications: The main finding of our study was recognition of significant differences between cardiopulmonary capacity parameters in obese children in comparison not only to normal weight peers, but to overweight, too.

Somatotype, Accumulated Workload, and Fitness Parameters in Elite Youth Players: Associations with Playing Position

The purpose of this study was three-fold: (1) to describe anthropometric, maturation, and somatotype differences of players based on playing positions; (2) to analyze variations of accumulated load training (AcL) and fitness parameters between playing positions; and finally (3) to explain the variation of maximal oxygen uptake (VO_2max) and peak power (PP) through the AcL, body fat (BF), maturity, somatotype and fitness levels. Twenty-seven male youth soccer players under-16 were divided by the following positions participated in this study: six central midfielders, four wingers (WG), five forwards, eight defenders, and four goalkeepers (GK). They were evaluated on two occasions: pre-season and after-season. Height, sitting height, body mass, BF, girths, percentage of BF (BF%), lean body mass, maturity, somatotype, sprint test, change of direction test, Yo-Yo intermittent recovery test level 1, Wingate, PP, VO_2max and fatigue index were assessed. Then, AcL was monitored during training sessions. The main results revealed significant differences between player positions for maturity offset (p = 0.001), for BF (p = 0.006), BF% (p = 0.015), and lean body mass kg (p = 0.003). Also, there were significant differences for AcL and fatigue index in pre-season between player positions (p < 0.05). In addition, there were some significant differences in pre- and after-season for VO_2max and PP between player positions (p < 0.05). In conclusion, GK showed higher values in anthropometric, body composition variables and maturity offset compared to the other positions, while WG presented lower levels of BF. In pre-season, there were more differences by player positions for the different variables analyzed than after-season that reinforces the tactical role of the positions, and the emphasis in increased load in the beginning of the season. This study could be used by coaches, staff, and researchers as a reference for athletes of the same sex, age, and competitive level.

Traditional and New Perspectives on Youth Cardiorespiratory Fitness

PURPOSE

This study aimed to review traditional and new perspectives in the interpretation of the development of youth cardiorespiratory fitness (CRF).

METHODS

We analyzed data from (i) the literature which for 80 yr has been traditionally based on interpretations of peak oxygen uptake (V˙O2) in ratio with body mass (BM) and (ii) recent multilevel allometric models founded on 994 (475 from girls) determinations of 10- to 16-yr-olds' peak V˙O2 with measures of age, maturity status, and morphological covariates (BM and fat-free mass), and from 10 to 13 yr, 110 peak V˙O2 determinations of maximum cardiovascular covariates (stroke volume, cardiac output, and arteriovenous oxygen difference).

RESULTS

The application of ratio scaling of physiological variables requires satisfying specific statistical assumptions that are seldom met. In direct conflict with the ratio-scaled data interpretation of CRF, multilevel allometric modeling shows that with BM controlled, peak V˙O2 increases with age but the effect is smaller in girls than boys. Maturity status exerts a positive effect on peak V˙O2, in addition to those of age and BM. Changes in maximum cardiovascular covariates contribute to explaining the development of CRF, but fat-free mass (as a surrogate for active muscle mass) is the most powerful single influence. With age, maturity status, morphological covariates, and maximum cardiovascular covariates controlled, there remains an unexplained ~4% to ~9% sex difference in peak V˙O2.

CONCLUSIONS

The traditional interpretation of peak V˙O2 in ratio with BM is fallacious and leads to spurious correlations with other health-related variables. Studies of the development of CRF require analyses of sex-specific, concurrent changes in age- and maturation-driven morphological and maximum cardiovascular covariates. Multilevel allometric modeling provides a rigorous, flexible, and sensitive method of data analysis.

Anthropometry does not fully explain low fitness among adults with Down syndrome

BACKGROUND

Cardiorespiratory fitness, expressed as peak oxygen uptake during exercise (VO₂ peak), is an important predictor of cardiovascular health and is related to anthropometry in the general population. Individuals with Down syndrome (DS) have reduced cardiorespiratory fitness and often exhibit different anthropometrics compared with the general population. Interestingly, the relation between anthropometry and cardiorespiratory fitness found in the general population is not apparent in individuals with DS. However, accurate measures with dual energy X-ray absorptiometry (DEXA) scan have not been used to investigate this relationship in this population. The purpose of this paper was to investigate the relationship between accurate measures of anthropometry and cardiorespiratory fitness in adults with DS compared with an age-matched and sex-matched control group.

METHODS

Anthropometrics (height, weight, waist and hip circumference, body composition via DEXA) and cardiorespiratory fitness (VO₂ peak, measured during a graded maximal exercise test) were assessed in adults with (n = 9; 25 ± 3 years; 6 male patients) and without DS (n = 10, 24 ± 4 years; 5 male patients).

RESULTS

Participants with DS were shorter (P < 0.01) than without DS and had a higher body mass index (P < 0.01), waist circumference (WC) (P = 0.026) and waist/height ratio (WHtR) (P < 0.01), but similar weight, body surface area (BSA), waist/hip ratio and body composition (P > 0.05). Participants with DS had significantly lower relative VO₂ peak and VO₂ peak corrected for total lean mass (TLM), but similar absolute VO₂ peak, compared with without DS. In participants with DS, only WC and WHtR were associated with VO₂ peak, whereas in participants without DS, height, weight, BSA, TLM, leg lean mass and body fat percentage were associated with VO₂ peak.

CONCLUSIONS

These results suggest that the relation between anthropometry and cardiorespiratory fitness found in the general population is not the same in adults with DS and that anthropometrics do not fully explain cardiorespiratory fitness in adults with DS. Further research into potential alternative explanations is required.

Heart rate rather than heart rate variability is better associated with cardiorespiratory fitness in adults

This study aimed to examine the association of heart rate (HR) and heart rate variability (HRV) with cardiorespiratory fitness (CRF) in adults. This cross-sectional study included 204 participants: 132 young adults (67% women; 22.3 ± 2.3 years) and 72 middle-aged adults (53% women; 53.2 ± 5 years). HR and HRV were measured using a Polar RS800CX heart rate monitor. CRF was assessed using a metabolic cart during an incremental test. HR was negatively associated with CRF relative to body weight (BW) in young adults adjusting for sex, age, and physical activity (β ranged from -0.200 to -0.195; all P ≤ 0.022). These associations disappeared after including fat mass as a covariate (all P ≥ 0.106) while remained significant after adjusting for fat-free mass (FFM; all P ≤ 0.008). Neither HR nor HRV variables were associated with CRF expressed as absolute values or relative to FFM in young and middle-aged adults after adjusting for the abovementioned covariates (all P ≥ 0.074). Our results suggest that HR rather than HRV is better associated with CRF relative to BW in young adults. However, this association seems to be explained by the inclusion of fat mass in the calculation of CRF relative to BW.Highlights Heart rate and heart rate variability variables have been associated with cardiorespiratory fitness.Our present results, and previous literature, suggest that the "simple" measurement of the heart rate could be easier to obtain and interpret than the heart rate variability variables.The heart rate variable rather than the heart rate variability variables is better associated with cardiorespiratory fitness relative to body weight in healthy young adults.

Sex-related differences in accumulated O2 deficit incurred by high-intensity rowing exercise during childhood and adolescence

PURPOSE

The aims of the present study were to determine during childhood and adolescence (i) the effect of sex on non-oxidative energy production, quantified by the accumulated oxygen deficit (AOD), and (ii) the influence of AOD on high-intensity performance.

METHODS

Thirty-nine boys and 35 girls aged 10-17 years performed a 60 s all-out test on a rowing ergometer to determine AOD and mean power output (MPO). Multiplicative allometric modelling was used to assess the concurrent effects of lean body mass (LBM) and age on AOD.

RESULTS

AOD significantly increased with age in both sexes (p < 0.001) with boys exhibiting significantly higher AOD than girls from the age of 14 years (10-11.9 yr: 1.9 vs 1.9 L, 12-13.9 yr: 2.4 vs 2.7 L, 14-15.9 yr: 2.8 vs 4.6 L and 16-17.9 yr: 2.9 vs 5.2 L, in girls and boys respectively, p < 0.001). However, a sex difference was no longer significant when AOD was analysed using an allometric model including age and LBM (p = 0.885). Finally, significant correlations were found between AOD and MPO in boys and girls but with lower evidence in girls (r² = 0.41 vs. 0.89).

CONCLUSION

Non-oxidative energy production increased more extensively in boys than girls from the age of 14 years. Age and LBM accounted for the sexual differentiation of AOD during childhood and adolescence. In addition, AOD was found to be a determinant factor of high-intensity performance, more particularly in boys.

Anthropometric Profiles and Physical Characteristics in Competitive Female English Premiership Rugby Union Players

Rugby union (RU) is a field-based team sport with a large number of high-intensity actions such as sprinting, change of direction, tackling, scrummaging, rucking, and mauling. Competitive success in female RU has previously been related to anthropometric and physical characteristics, and with the recent introduction of professionalism in female rugby, characterizing such physical attributes may provide insight into selection and training processes.

PURPOSE

To identify anthropometric and physical characteristics of competitive female RU players and differences between playing positions.

METHODS

Twenty-two players were recruited from the top tier of female RU in the United Kingdom during the 2018-2019 Premiership season. Players were split into forwards and backs and underwent body composition testing via dual-X-ray absorptiometry and physical characteristic tests (10- and 20-m speed, 1-repetition-maximum bench press and squat, countermovement jump, drop jump, isometric midthigh pull, and 1200-m shuttle).

RESULTS

Moderate to large significant differences between playing positions in both anthropometric and physical characteristics were found (P < .01). Forwards displayed greater body mass (P = .03), fat mass (P = .01), and absolute upper-body strength (P = .03), whereas backs demonstrated superior countermovement jump height (P = .01), drop jump height (P = .01), greater reactive strength (P = .03), and speed (P = .03).

CONCLUSION

These findings provide practitioners with a greater understanding of anthropometric and physical characteristics of professional female RU players.

Sympathetic Nervous System and Exercise Affects Cognition in Youth (SNEACY): study protocol for a randomized crossover trial

BACKGROUND

There is an increasing prevalence of physical inactivity during childhood, which is associated with a variety of health problems. However, the mechanisms by which acute exercise benefits cognition in childhood remains unknown. Here we describe the protocol for a randomized crossover trial called SNEACY (Sympathetic Nervous System & Exercise Affects Cognition in Youth), a study designed to better understand mechanisms linking acute exercise and cognition in 9-10-year-old healthy, cognitively normal children.

METHODS

Children from the Greater Boston, MA region will be recruited to participate in this single center study. A randomized crossover design will be utilized, such that participants will act as their own controls, through initial randomization to condition assignment and condition counterbalancing across participants. One hundred three children will participate in three randomized acute interventions: moderate intensity treadmill exercise (20 min, 70-75% of their maximal heart rate), seated rest (20 min), and a Trier Social Stress Test for Children (14 min). These visits will occur on 3 three separate days, approximately 5-8 days apart. Before and after each intervention, children complete a variety of cognitive tasks measuring attentional inhibition while their neuroelectric activity is recorded. Variables of interest include EEG data, accuracy and reaction time, academic achievement, and salivary alpha amylase. Academic achievement is also assessed following interventions. In addition, children provide passive drool samples throughout the interventions to measure various biomarkers that may explain the acute exercise benefit on cognition.

DISCUSSION

The results from this study could influence educational and public health recommendations to enhance cognition and learning in pre-adolescent children.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03592238 . Registered on 19 July 2018.

Changes in physical activity behavior and development of cardiovascular risk in children

The study aimed to investigate the association of changes in physical activity, screen time, and cardiorespiratory fitness (CRF) with development of body mass index (BMI), blood pressure (BP), and retinal microvascular health in children over four years. In 2014, 391 children aged 6-8 years were screened, and thereof 262 children were reexamined after four years following standardized protocols. Retinal arteriolar (CRAE) and venular diameters were measured by a retinal vessel analyzer. CRF was objectively assessed by a 20 m shuttle run, physical activity, and screen time by use of a questionnaire. Children who achieved higher CRF levels reduced their BMI (β [95% CI] -0.35 [-0.46 to -0.25] kg/m² per stage, P ≤ .001) and thereby developed wider CRAE (β [95% CI] 0.25 [0.24 to 0.48] µm per stage, P = .03) at follow-up. Moreover, children with elevated or high systolic BP at baseline, but lower levels of screen time during the observation period, had wider CRAE at follow-up (β [95% CI] -0.37 [-0.66 to -0.08] µm per 10 min/d, P = .013). Change in CRF was not directly associated with better microvascular health at follow-up. However, an increase of CRF over four years was associated with a reduced BMI and consequently wider retinal arterioles at follow-up. In children with elevated or high systolic BP, a reduction of screen time significantly improved retinal microvascular health as a primary prevention strategy to promote childhood health and combat development of manifest CV disease later in life.

The differential relationship of an afterschool physical activity intervention on brain function and cognition in children with obesity and their normal weight peers

BACKGROUND

Physical activity (PA) is beneficial for cognitive and brain health during preadolescence. Given that childhood obesity (OB) is a public health concern, investigating this effect in children with OB is an important societal consideration.

OBJECTIVES

To identify the effects of weight status and PA on neuroelectric indices of executive function in preadolescence.

METHODS

Children were randomly assigned to a PA intervention or a wait-list control group and completed a task that manipulated inhibitory control, while task performance and neuroelectric (P3 component) outcomes were assessed. About 103 children with OB were matched to a sample of 103 normal weight (NW) children based on treatment allocation and demographic variables.

RESULTS

Children with OB in the control group demonstrated reduced P3 amplitude from pre- to post-test, meanwhile those with OB in the PA intervention maintained P3 amplitude at post-test compared to pre-test. Additionally, NW children in the PA intervention group showed that decreased visceral adipose tissue corresponded with faster task performance, a relationship not observed in children with OB.

CONCLUSIONS

These results suggest that a 9-month PA intervention may be particularly beneficial to the cognitive and brain health of children with OB. These results are important to consider given the public health concerns associated with childhood OB.

A Generalized Equation for Prediction of VO2peak from a Step Test

This study aimed to develop an equation to reduce variability of VO₂peak prediction from a step test and compare VO₂peak prediction from the new equation to the Queen's College Step Test (QCST). The development group (n=86; 21.7±2 years) was utilized to develop the SDState step test equation to predict relative VO₂peak. The cross-validation group (n=99; 21.6±2 years) was used to determine the validity of the SDState step test VO₂peak prediction equation. A regression analysis was used to identify the best model to predict VO₂peak. Analysis of variance (ANOVA) was further used to determine differences among predicted and measured VO₂peak values. Forward stepwise multiple regression identified age, sex, abdominal circumference, and active heart rate at the 3-min mark of the step test to be significant predictors of VO₂peak (mL·kg^-1·min^-1). No differences among measured VO₂peak (47.3±7.1 mL·kg^-1·min^-1) and predicted VO₂peak (QCST, 46.9±9.3 mL·kg^-1·min^-1; SDState 48.3±5.7 mL·kg^-1·min^-1) were found. Pearson correlations, ICC, SEE, TEE, Bland-Altman plots, and Mountain plots indicate the SDState step test equation provides less variation in the prediction of VO₂peak compared to the QCST. The SDState step test equation is effective for predicting VO₂peak from the YMCA step test in young, healthy adults.

Reference values and secular trends for cardiorespiratory fitness in children and adolescents with obesity

AIM

To present specific reference values for cardiorespiratory fitness (CRF) in children with obesity and to analyse secular trends of CRF in the studied population.

METHODS

Cardiorespiratory fitness, the maximal oxygen uptake (VO₂ max), was estimated with the Åstrand-Rhyming submaximal bicycle test, in 705 Swedish children (356 girls, 8-20 years) with obesity according to the International Obesity Task Force (IOTF). Data were collected from 1999 to 2013. Secular trends, analysed with multiple linear regression, were adjusted for age, height and body mass index standard deviation score (BMI SDS).

RESULTS

All children had low CRF compared with normal weight standards but there was a marked variability of CRF in children with obesity, which was possible to quantify with the developed obesity specific CRF reference values. The mean value of absolute VO₂ max (L/min) increased with age and relative VO₂ max (mL/kg/min) decreased with age in both boys and girls. There was a negative secular trend in both sexes (P < .001).

CONCLUSION

These are the first obesity specific reference values of CRF in children enabling clinical evaluation in childhood obesity treatment. Cardiorespiratory fitness in children with obesity has declined the last decades, indicating that also within this vulnerable group physical activity has gone down.

Changes in Oxidative Stress, Inflammation, and Muscle Damage Markers Following Diet and Beetroot Juice Supplementation in Elite Fencers

The aim of this study was to assess the impact of diet and active substances in beetroot juice on the parameters of oxidative stress, inflammation, and muscle damage as well as on the maximum rate of oxygen uptake (VO_2max) in elite fencers (10 women, 10 men). Athletes during four weeks realized dietary recommendations (ID) and, after that, diet with freeze-dried beetroot juice supplementation (ID&BEET). At baseline and after each stage, fasting antioxidants, biomarkers of oxidative stress, inflammation, and skeletal muscle damage were measured, and a VO_2max test was performed. Only after ID&BEET was a significant increase of VO_2max observed, and changes of this parameter were negatively related with changes of serum lactate dehydrogenase (∆LDH) activity, as well as with serum ∆β-carotene and malondialdehyde concentration (∆MDA). Additionally, positive relationships were observed between ∆β-carotene versus changes of the serum concentration of advanced oxidation protein products (∆AOPP), changes of serum glutathione peroxidase activity (∆GPx3) versus both changes of physical activity level and ∆LDH, as well as erythrocyte glutathione peroxidase activity (∆GPx1) versus ∆LDH. To summarize, we showed that long-term beetroot juice supplementation increases lipid peroxidation, and improvement of VO_2max after ID&BEET seems to be dependent on LDH activity, as well as on the serum concentration of MDA and β-carotene.

Weight Loss Intervention Impact on the Physical Fitness Test Scores of Air Force Service Members

INTRODUCTION

Overweight and obesity are a major public health concern in the United States, including among active duty military personnel. Approximately 51% of active duty personnel are classified as overweight and 15% are classified as obese. This may impact military readiness. The current study aimed to determine if a weight loss intervention impacted fitness test scores among Air Force personnel.

MATERIALS AND METHODS

From 2014 to 2016, 204 Air Force members with overweight/obesity were randomized into either a Self-paced or counselor-initiated arm in a weight loss program. Study procedures were approved by the Institutional Review Board of the 59th Medical Wing in San Antonio and were acknowledged by the Institutional Review Board at the University of Tennessee Health Science Center. Fitness test scores from before, during, and after the intervention were used to determine if the intervention resulted in improvements in overall fitness test ratings and scores on individual components of the test.

RESULTS

Participants who lost at least 5% of their weight had better fitness ratings during the intervention compared to individuals who did not lose 5%. However, in the overall sample, fitness ratings worsened from preintervention to during the intervention, and from during to postintervention. Participants with overweight had better aerobic scores pre- and postintervention as well as better abdominal circumference scores and better fitness test ratings preintervention, during the intervention and postintervention compared to participants with obesity.

CONCLUSIONS

Behavioral weight management interventions that achieve 5% weight loss may help improve military fitness test ratings.

A Pilot Study of Cardiorespiratory Fitness, Adiposity, and Cardiometabolic Health in Youth With Overweight and Obesity

OBJECTIVE

To conduct a preliminary assessment of the relationships between cardiorespiratory fitness, adiposity, and cardiometabolic health using gold standard measures in diverse youth ranging from overweight to severe obesity.

METHODS

Twenty of 30 participants (mean [SD]; age 13.2 [1.8] y, 55% female, 45% African American) met the criteria for VO2peak during a graded cycle ergometer test to volitional fatigue. The body composition was measured by dual-energy X-ray absorptiometry (percentage of body fat, fat mass index, and fat-free mass) and magnetic resonance imaging (abdominal visceral and subcutaneous [SAT] adipose tissue). The VO2peak was expressed relative to fat-free mass. Fasting lipid levels, glycemic biomarkers, and vital signs were examined individually and used in a composite cardiometabolic risk score. Accelerometer-measured physical activity and sedentary time were included as covariates.

RESULTS

VO2peak was negatively associated with abdominal SAT (r = -.49, P < .05), but not visceral adipose tissue or markers of cardiometabolic health. The association between SAT and VO2peak was partly explained by habitual sedentary time.

CONCLUSIONS

We demonstrated a significant negative association between cardiorespiratory fitness and SAT in a diverse group of high-risk youth. The inclusion of rigorous, laboratory-based measures and youth with severe obesity extends the previous work in pediatric populations.

What do Firefighting Ability Tests Tell Us About Firefighter Physical Fitness? A Systematic Review of the Current Evidence

Fyock-Martin, MB, Erickson, EK, Hautz, AH, Sell, KM, Turnbaugh, BL, Caswell, SV, and Martin, JR. What do firefighting ability tests tell us about firefighter physical fitness? A systematic review of the current evidence. J Strength Cond Res 34(7): 2093-2103, 2020-The firefighting profession is a physiologically demanding occupation. Currently, sudden cardiac deaths account for 40-50% of firefighter job-related deaths, for which, inadequate aerobic fitness (AF) and obesity are established as risk factors. Departments have instituted firefighting physical ability tests (FPATs) as a method of quantifying readiness for occupational-related demands. A systematic review of the current literature examining the correlation between field fitness test performance and FPAT completion times was performed. The search identified 5 studies that met the eligibility criteria. The total number of subjects in the 5 studies was 265 (259 men and 6 women), including 200 professional firefighters (75.5%), 40 volunteer (15.1%), 20 officers (7.5%), and 5 recruits (1.9%). Upper-body strength (UBs) and upper-body endurance (UBe) had the strongest correlation to FPATs (r = -0.31 to -0.66; R = 0.10 to 0.44 and r = -0.27 to -0.61; R = 0.07 to 0.37; p < 0.05, respectively). Two studies suggested that AF has a weak-to-moderate relationship with FPATs (r = 0.38 and r = -0.62). Two studies showed that anaerobic capacity had weak-to-strong correlations with FPATs (r = -0.40 and r = 0.79; R = 0.16 to 0.62; p < 0.05). No studies found a statistically significant correlation between lower-body strength and FPAT performance. Further research is needed to better understand the role of field-based fitness test results on FPAT performance. An annual department-driven multicomponent fitness assessment measuring UBs, UBe, anaerobic capacity, and AF is recommended based on the evidence reviewed.

OBEDIS Core Variables Project: European Expert Guidelines on a Minimal Core Set of Variables to Include in Randomized, Controlled Clinical Trials of Obesity Interventions

Heterogeneity of interindividual and intraindividual responses to interventions is often observed in randomized, controlled trials for obesity. To address the global epidemic of obesity and move toward more personalized treatment regimens, the global research community must come together to identify factors that may drive these heterogeneous responses to interventions. This project, called OBEDIS (OBEsity Diverse Interventions Sharing - focusing on dietary and other interventions), provides a set of European guidelines for a minimal set of variables to include in future clinical trials on obesity, regardless of the specific endpoints. Broad adoption of these guidelines will enable researchers to harmonize and merge data from multiple intervention studies, allowing stratification of patients according to precise phenotyping criteria which are measured using standardized methods. In this way, studies across Europe may be pooled for better prediction of individuals' responses to an intervention for obesity - ultimately leading to better patient care and improved obesity outcomes.

Análisis de la condición física según sexo, edad, índice de masa corporal y nivel de actividad física en estudiantes de primaria en España

Introducción. La evidencia científica sugiere que la calidad de vida de los escolares se relaciona de forma directa con el estado de su condición física (CF).Objetivo. Analizar la CF según edad, sexo, índice de masa corporal (IMC) y nivel de actividad física en estudiantes de primaria.Materiales y métodos. Se realizó un estudio descriptivo transversal con 103 escolares entre 8 y 12 años de España. La CF se midió mediante la batería ALPHA-Fitness y la actividad física, con el cuestionario Physician-based Assessment and Counseling for Exercise. Los participantes se categorizaron según su nivel de actividad física (no activos versus activos) y su IMC (normo-peso versus sobrepeso-obesidad). Para el análisis se aplicó estadística paramétrica.Resultados. Los varones tuvieron un mejor nivel de CF, pero en ambos sexos se observó un leve incremento de esta a medida que aumentaba la edad. Los escolares con normopeso o activos físicamente tuvieron una mejor capacidad aeróbica y una composición corporal más saludable.Conclusión. Mantener niveles óptimos de CF a lo largo de la vida requiere de la adopción de un estilo de vida saludable desde la infancia, por tanto, es necesario promover la práctica autónoma de actividad física en los escolares.

The Understanding of Peak Oxygen Uptake in Children Aged 8-16

Objective: To examine the understanding of the concept peak oxygen uptake (peak VO₂) among children and adolescents at different ages from a developmental perspective. Methods: A total of 549 children and adolescents aged 8 to 16 were recruited and instructed to fill in a 20-item Peak VO ₂ Understanding Inventory developed with reference to the research literature on peak VO₂. We presented the participants with twenty scenarios and asked them to indicate whether peak VO₂ would "remain unchanged," "increase," or "decrease," or that there was "insufficient information for a definite answer." The cross-sectional data was analyzed by employing a series of ANOVA analyses and chi-square association tests. Additional statistical analyses were performed to examine the error patterns and if there were gender differences. Results: Except for the 8-year-old group, the overall accuracy rate did not improve with age. Age-related differences in the choice of answers ("increase," "decrease," "unchanged," and "uncertain") for determining the resulting peak VO₂ after a change of antecedent were observed. Error analysis by item showed that prefactual thinking that is important to understand the concept was emerging rather than fully developed in our child and adolescent samples. Conclusion: The mastery of peak VO₂ is not subject to age-related maturation but might demand the acquisition of specific logical reasoning skill such as perfactual thinking. Early introduction of peak VO₂ and related concepts is advocated and should be emphasized on the reasoning rather than providing model answers in physical literacy education.

The 20 m shuttle run is not a valid test of cardiorespiratory fitness in boys aged 11-14 years

Objectives

The 20 m shuttle run test (20mSRT) is used to estimate cardiorespiratory fitness (CRF) through the prediction of peak oxygen uptake ( V ˙ O 2 ), but its validity as a measure of CRF during childhood and adolescence is questionable. This study examined the validity of the 20mSRT to predict peak V ˙ O 2 .

Methods

Peak V ˙ O 2 was measured during treadmill running. Log-linear regression was used to correct peak V ˙ O 2 for body mass and sum of skinfolds plus age. Boys completed the 20mSRT under standardised conditions. Maximum speed (km/h) was used with age to predict peak V ˙ O 2 using the equation developed by Léger et al. Validity was examined from linear regression methods and limits of agreement (LoA). Relationships between 20mSRT performance and allometrically adjusted peak V ˙ O 2 , and predicted per cent fat were examined.

Results

The sample comprised 76 boys aged 11-14 years. Predicted and measured mass-related peak V ˙ O 2 (mL/kg/min) shared common variance of 32%. LoA revealed that measured peak V ˙ O 2 ranged from 15% below to 25% above predicted peak V ˙ O 2 . There were no significant relationships (p>0.05) between predicted peak V ˙ O 2 and measured peak V ˙ O 2 adjusted for mass, age and skinfold thicknesses. Adjusted for body mass and age, peak V ˙ O 2 was not significantly related (p>0.05) to 20mSRT final speed but a weak, statistically significant (r=0.24, p<0.05) relationship was found with peak V ˙ O 2 adjusted for mass and fatness. Predicted per cent fat was negatively correlated with 20mSRT speed (r=-0.61, p<0.001).

Conclusions

The 20mSRT reflects fatness rather than CRF and has poor validity grounded in its flawed estimation and interpretation of peak V ˙ O 2 in mL/kg/min.

Exploring Energy Expenditure and Body Movement of Exergaming in Children of Different Weight Status

PURPOSE

This study examined differences in energy expenditure and bodily movement among children of different weight status during exergames that varied in mode and intensity.

METHODS

Fifty-seven 8- to 12-year-old children including overweight/obesity (n = 28) and normal weight (n = 29) played three 10-minute interval Xbox One exergames (Fruit Ninja, Kung-Fu, and Shape Up) categorized based on predominantly upper-, whole-, or lower-limb movement, respectively. The authors measured bodily movement through accelerometry and obtained energy expenditure and metabolic equivalent (MET) via indirect calorimetry.

RESULTS

Energy expended during gameplay was the highest in Shape Up (P < .01) and higher in Kung-Fu than Fruit Ninja (P < .01). Absolute energy expenditure was significantly higher in overweight/obese children (P < .01), but not when controlling for body mass across 3 exergames (P > .05). Based on the MET cut-points, overweight/obese children spent more time at light intensity (<3 METs) for Fruit Ninja (P < .05) and Shape Up (P < .01), but less time at vigorous intensity (≥6 METs) for Kung-Fu (P < .01) and Shape Up (P < .01). Lower-limb movements during Shape Up were less in overweight/obese children (P = .03).

CONCLUSION

Although children in both groups expended similar energy relative to their body mass during gameplay, overweight/obese children spent more time at light intensity but less time at vigorous intensity with fewer movements especially while playing a lower limb-controlled exergame.

Increase in Physical Activity After Bariatric Surgery Demonstrates Improvement in Weight Loss and Cardiorespiratory Fitness

Background

Low cardiorespiratory fitness is strongly associated with cardiovascular diseases and mortality. Although increased physical activity can improve cardiorespiratory fitness, this relationship has not been examined in a large bariatric population undergoing perioperative care focusing on long-term lifestyle change.

Objectives

To evaluate changes in physical activity, weight loss, and cardiorespiratory fitness up to 24 months after bariatric surgery, and to evaluate the relationships of change in physical activity with weight loss and change in cardiorespiratory fitness.

Materials and Methods

Four thousand seven hundred eighty-five patients who underwent primary Roux-en-Y gastric bypass or sleeve gastrectomy between January 2012 and December 2014 were included. Physical activity was assessed by the Baecke questionnaire (work, leisure, and sport activity) and cardiorespiratory fitness, defined as VO₂max relative to fat-free mass (VO₂max/FFM), was assessed by the Åstrand test.

Results

Twenty-four months postoperative, significant improvements were seen in sport and leisure activity assessments (n = 3548, P < 0.001), weight loss (n = 3695, P < 0.001), and VO₂max/FFM (n = 1852, P < 0.001). Furthermore, regression analysis showed that change in leisure activity was positively associated with weight loss (n = 3535, ß = 1.352, P < 0.001) and change in sport activity was positively associated with change in VO₂max/FFM (n = 1743, ß = 1.730, P < 0.001).

Conclusion

Bariatric surgery complemented by a comprehensive bariatric care program can lead to improvement in physical activity, as well as weight loss and improvement in cardiorespiratory fitness. The positive associations of change in leisure activity with weight loss and change in sport activity with cardiorespiratory fitness suggest that bariatric care programs can enhance postoperative outcomes by improving the patient’s physical activity.

Youth cardiorespiratory fitness: evidence, myths and misconceptions

Rigorously determined peak oxygen uptake is internationally recognized as the criterion measure of youth cardiorespiratory fitness. The assessment and interpretation of children’s and adolescents’ peak oxygen uptake and the relationship of the measure with other health-related variables are well documented. There has been a recent resurgence of interest in the prediction of peak oxygen uptake from field performance tests in young people. However, coupled with ratio-scaling of data and the raising of clinical red flags, these practices risk clouding our understanding of youth cardiorespiratory fitness and its relationship with current and future health. We believe these methods have the potential to mislead clinical practice and misguide recommendations for the promotion of youth cardiovascular health. We discuss relevant scientific evidence and interpretations that have emerged from predicting youth cardiorespiratory fitness from performance test scores. We argue that children deserve to have health care founded on evidence-based science and not on myths and misconceptions.

Does High-Intensity Endurance Training Increase the Risk of Atrial Fibrillation? A Longitudinal Study of Left Atrial Structure and Function

BACKGROUND

Exercise mitigates many cardiovascular risk factors associated with atrial fibrillation. Endurance training has been associated with atrial structural changes which can increase the risk for atrial fibrillation. The dose of exercise training required for these changes is uncertain. We sought to evaluate the impact of exercise on left atrial (LA) mechanical and electrical function in healthy, sedentary, middle-aged adults.

METHODS

Sixty-one adults (52±5 years) were randomized to either 10 months of high-intensity exercise training or yoga. At baseline and post-training, all participants underwent maximal exercise stress testing to assess cardiorespiratory fitness, P-wave signal-averaged electrocardiography for filtered P-wave duration and atrial late potentials (root mean square voltage of the last 20 ms), and echocardiography for LA volume, left ventricular end-diastolic volume, and mitral inflow for assessment of LA active emptying. Post-training data were compared with 14 healthy age-matched Masters athletes.

RESULTS

LA volume, Vo₂ max, and left ventricular end-diastolic volume increased in the exercise group (15%, 17%, and 16%, respectively) with no change in control (P<0.0001). LA active emptying decreased post-exercise versus controls (5%; P=0.03). No significant changes in filtered P-wave duration or root mean square voltage of the last 20 ms occurred after exercise training. LA and left ventricular volumes remained below Masters athletes. The athletes had longer filtered P-wave duration but no difference in the frequency of atrial arrhythmia.

CONCLUSIONS

Changes in LA structure, LA mechanical function, and left ventricular remodeling occurred after 10 months of exercise but without significant change in atrial electrical activity. A longer duration of training may be required to induce electrical changes thought to cause atrial fibrillation in middle-aged endurance athletes.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique Identifier: NCT02039154.

Clarity and Confusion in the Development of Youth Aerobic Fitness

Peak oxygen uptake (V˙O2) is internationally recognized as the criterion measure of youth aerobic fitness, but flawed laboratory assessments and fallacious interpretations of peak V˙O2 in ratio with body mass have confused our understanding of the development of aerobic fitness. Moreover, the recent emergence of specious predictions of peak V˙O2 from performance tests and the promotion of spurious “clinical red flags” and cardiometabolic cut-points have confused our understanding of the relationship between youth aerobic fitness and health. Recent longitudinal studies of 10–18-year-olds using multilevel allometric modeling have empirically demonstrated that peak V˙O2 increases in accord with sex-specific, concurrent changes in age- and maturity status-driven morphological covariates with the timing and tempo of changes specific to individuals. During both cycle ergometry and treadmill running age- and maturity status- driven changes in fat free mass have been revealed as the most powerful morphological influences on the development of youth aerobic fitness. To bring some clarity to current confusion, this paper argues that future studies must be founded on rigorous assessment and interpretation of peak V˙O2 and ensure that they address the development of youth aerobic fitness and its relationship with present and future health in relation to appropriate sex-specific morphological covariates governed by individual biological clocks.

Physiological, anthropometric parameters, and balance skill response of healthy bankers to fitness training

Sedentary lifestyle as a predisposing factor of chronic diseases like hypertension, diabetes, stroke and obesity is a common phenomenon in the banking job. Studies suggest that fitness training improves health of bankers but has not been established among Ghanaian bankers. This study examined the physiological, anthropometric parameters, and balance skill responses of relatively healthy bankers to fitness training. Twelve bankers aged 28 to 55 years (36.41±7.16 years) in Kumasi completed a 6-month fitness training program (FTP) of 30-min gym workouts and 1-hr swimming per session. Physiological, anthropometric parameters, and balance skill variables assessments were conducted in three trials: pretraining, midtraining and post-FTP. FTP caused significant decrease in pre-post systolic blood pressure (P=0.001), diastolic blood pressure (P=0.000), heart rate (P=0.006), waist circumference (P= 0.007), waist-to-hip ratio (P=0.007), and bone density (P=0.038). There was significance decrease in body mass index (P=0.047) between pre- and midtraining status. Weight significantly decreased among the three trials (P=0.017). Pre-post opened (P=0.043) and closed (P=0.015) eye balance skills increased significantly. Effects of FTP were significantly higher in female (P<0.05). Participants who were at the stage 1 and 2 hypertensions pretraining became normotensive posttraining. Six months FTP has beneficial effects on the physiological, anthropometric parameters, and balance skill of relatively healthy bankers.

TRACKING OF CARDIORESPIRATORY FITNESS FROM CHILDHOOD TO EARLY ADOLESCENCE: MODERATION EFFECT OF SOMATIC MATURATION

Objective:

To evaluate cardiorespiratory fitness’ tracking from childhood to adolescence, as well as to test the moderation role of somatic maturation.

Methods:

Our sample was composed by 375 children (197 boys), with a baseline age between 7 and 10 years old. The children were followed-up over three years. Body mass and stature were measured as anthropometric indicators and were used to estimate maturity status through Moore’s method. Cardiorespiratory fitness was evaluated through 9-minute running test. Body adiposity was estimated through the subcutaneous skinfold method, with measures of triceps and subscapular skinfolds and used as a covariate. Sample was categorized into tertiles. Thereafter, the Kappa (k) coefficient and Lin’s concordance correlation coefficient (LCCC) tests were adopted to verify stability. Dummy variable in regression was used to test moderation effects. All analyses were conducted in Stata 14.0, adopting p<0.05.

Results:

Cardiorespiratory fitness presented a moderate to low tracking from childhood to adolescence (k=0.294; LCCC=0.458). Moreover, maturity status significantly moderated the association between cardiorespiratory fitness at childhood and adolescence (regardless of cohort and body adiposity) among boys (β=0.644; p=0.003) and role sample (β=0.184; p=0.020), but not girls (-0.217; p=0.413).

Conclusions:

Tracking of cardiorespiratory fitness from childhood to adolescence is moderate to low in both sexes. Moreover, maturity status moderated the relationship between cardiorespiratory fitness at baseline and in adolescence. A lower age at peak height velocity was associated to a greater cardiorespiratory fitness.

The 20-m Shuttle Run: Assessment and Interpretation of Data in Relation to Youth Aerobic Fitness and Health

Cardiorespiratory fitness (CRF) is a good summative measure of the body's ability to perform continuous, rhythmic, dynamic, large-muscle group physical activity, and exercise. In children, CRF is meaningfully associated with health, independent of physical activity levels, and it is an important determinant of sports and athletic performance. Although gas-analyzed peak oxygen uptake is the criterion physiological measure of children's CRF, it is not practical for population-based testing. Field testing offers a simple, cheap, practical alternative to gas analysis. The 20-m shuttle run test (20mSRT)-a progressive aerobic exercise test involving continuous running between 2 lines 20 m apart in time to audio signals-is probably the most widely used field test of CRF. This review aims to clarify the international utility of the 20mSRT by synthesizing the evidence describing measurement variability, validity, reliability, feasibility, and the interpretation of results, as well as to provide future directions for international surveillance. The authors show that the 20mSRT is an acceptable, feasible, and scalable measure of CRF and functional/exercise capacity, and that it has moderate criterion validity and high to very high reliability. The assessment is pragmatic, easily interpreted, and results are transferable to meaningful and understandable situations. The authors recommend that CRF, assessed by the 20mSRT, be considered as an international population health surveillance measure to provide additional insight into pediatric population health.

Sex-Specific Longitudinal Modeling of Youth Peak Oxygen Uptake

Purpose: To investigate peak oxygen uptake ( V˙O2 ) in relation to sex, age, body mass, fat-free mass (FFM), maturity, and overweight status. Methods: Multiplicative, allometric models of 10- to 18-year-olds were founded on 1057 determinations of peak V˙O2 supported by anthropometry and estimates of maturity status. Results: Baseline models with body mass controlled for showed age to exert a positive effect on peak V˙O2 , with negative estimates for age², sex, and a sex-by-age interaction. Sex-specific models showed maturity status to have a positive effect on peak V˙O2 in addition to the effects of age and body mass. Introducing skinfold thicknesses to provide, with body mass, a surrogate for FFM explained maturity effects and yielded a significantly (P < .05) better statistical fit in all models compared with those based on FFM estimated from youth-specific skinfold equations. With girls only, the introduction of overweight, defined by body mass index, resulted in a small but significant (P < .05) negative effect, with an age-by-overweight status interaction. Conclusions: FFM has a powerful influence on peak V˙O2 in both sexes. Interpretation of the development of youth aerobic fitness and its application to health should reflect the sex- and maturity-associated variation in FFM.

New Reference Values for Cardiopulmonary Exercise Testing in Children

INTRODUCTION

Cardiopulmonary exercise testing is an essential tool to assess cardiorespiratory fitness (CRF) in children. There is a paucity of adequate pediatric reference values that are independent of body size and pubertal stage. The purpose of this study is to provide Z score equations for several maximal and submaximal CRF parameters derived from a prospectively recruited sample of healthy children.

METHODS

In this cross-sectional multicenter study, we prospectively recruited 228 healthy children 12 to 17 yr old in local schools. We performed a symptom-limited cardiopulmonary exercise testing progressive ramp protocol on an electronically braked cycle ergometer. Eighteen CRF parameters were analyzed. We tested several regression models to obtain prediction curves that minimized residual association with age, body size, and pubertal stage. Both the predicted mean and the predicted SD were modeled to account for heteroscedasticity.

RESULTS

We identified nonlinear association of CRF parameters with body size and significant heteroscedasticity. To normalize CRF parameters, the use of a single body size variable was not sufficient. We therefore used multivariable models with various combination of height, corrected body mass, and age. Final prediction models yielded adjusted CRF parameters that were independent of age, sex, body mass, height, body mass index, and Tanner stages.

CONCLUSIONS

We present Z score equations for several CRF parameters derived from a healthy pediatric population. These reference values provide updated predicted means and range of normality that are independent of sex and body size. Further testing is needed to assess if these reference values increase sensitivity and specificity to identify abnormal cardiorespiratory response in children with chronic diseases.

Development of peak oxygen uptake from 11-16 years determined using both treadmill and cycle ergometry

PURPOSES

To investigate the development of peak oxygen uptake ([Formula: see text]) assessed on both a treadmill and a cycle ergometer in relation with sex and concurrent changes in age, body mass, fat-free mass (FFM), and maturity status and to evaluate currently proposed 'clinical red flags' or health-related cut-points for peak [Formula: see text].

METHODS

Multiplicative multilevel modelling, which enables the effects of variables to be partitioned concurrently within an allometric framework, was used to analyze the peak [Formula: see text]s of 138 (72 boys) students initially aged 11-14 years and tested on three annual occasions. Models were founded on 640 (340 from boys) determinations of peak [Formula: see text], supported by anthropometric measures and maturity status.

RESULTS

Mean peak [Formula: see text]s were 11-14% higher on a treadmill. The data did not meet the statistical assumptions underpinning ratio scaling of peak [Formula: see text] with body mass. With body mass appropriately controlled for boys' peak [Formula: see text]s were higher than girls' values and the difference increased with age. The development of peak [Formula: see text] was sex-specific, but within sex models were similar on both ergometers with FFM the dominant anthropometric factor.

CONCLUSIONS

Data should not be pooled for analysis but data from either ergometer can be used independently to interpret the development of peak [Formula: see text] in youth. On both ergometers and in both sexes, FFM is the most powerful morphological influence on the development of peak [Formula: see text]. 'Clinical red flags' or health-related cut-points proposed without consideration of exercise mode and founded on peak [Formula: see text] in ratio with body mass are fallacious.

Isolated Obesity Is Not Enough to Impair Cardiac Autonomic Modulation in Metabolically Healthy Men

PURPOSE

To evaluate whether excess body mass influences the heart rate variability (HRV) indexes at rest, and to correlate adiposity indicators and the aerobic fitness with cardiac autonomic variables in metabolically healthy young adults.

METHOD

In all, 41 untrained males (M_age = 21.80, SD = 2.14 years), 14 normal weight (M_BMI = 22.28, SD = 1.86 kg∙m^-2), 11 overweight (M_BMI = 26.95, SD = 1.43 kg∙m^-2), and 16 obese (M_BMI = 33.58, SD = 3.06 kg∙m^-2) metabolically healthy (normal values of blood pressure, fasting blood glucose, triglycerides, and total cholesterol), underwent evaluations of the HRV at rest and of the peak oxygen consumption (VO₂ peak) during maximal exercise on a cycle ergometer.

RESULTS

Blood pressure, heart rate, HRV indexes, casual blood glucose, oxidative stress, and antioxidant activity did not differ among the groups. The VO₂ peak (mL∙kg^-1∙min^-1) was lower in the obese group compared with the normal weight and overweight groups. The body mass (r = -.40 to -.45) and abdominal circumference (r = -.39 to -.52) were slightly to moderately correlated with SD1, SD2, RMSSD, SDNN, pNN50, LF, and HF indexes and total power. The VO₂ peak (mL∙kg^-1∙min^-1) was slightly to moderately correlated (r = .48 to .51) with SD2, SDNN, and LF indexes in the individuals with excess body mass.

CONCLUSION

Cardiac autonomic modulation at rest was preserved in metabolically healthy obese young men. However, the indicators of adiposity, as well as the aerobic fitness were correlated with cardiac autonomic modulation in the individuals with excess body mass.

Effects of different protocols of high intensity interval training for VO2max improvements in adults: A meta-analysis of randomised controlled trials

OBJECTIVES

To examine the effects of different protocols of high-intensity interval training (HIIT) on VO₂max improvements in healthy, overweight/obese and athletic adults, based on the classifications of work intervals, session volumes and training periods.

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, Scopus, Medline, and Web of Science databases were searched up to April 2018. Inclusion criteria were randomised controlled trials; healthy, overweight/obese or athletic adults; examined pre- and post-training VO₂max/peak; HIIT in comparison to control or moderate intensity continuous training (MICT) groups.

RESULTS

Fifty-three studies met the eligibility criteria. Overall, the degree of change in VO₂max induced by HIIT varied by populations (SMD=0.41-1.81, p<0.05). When compared to control groups, even short-intervals (≤30s), low-volume (≤5min) and short-term HIIT (≤4weeks) elicited clear beneficial effects (SMD=0.79-1.65, p<0.05) on VO₂max/peak. However, long-interval (≥2min), high-volume (≥15min) and moderate to long-term (≥4-12weeks) HIIT displayed significantly larger effects on VO₂max (SMD=0.50-2.48, p<0.05). When compared to MICT, only long-interval (≥2min), high-volume (≥15min) and moderate to long-term (≥4-12weeks) HIIT showed beneficial effects (SMD=0.65-1.07, p<0.05).

CONCLUSIONS

Short-intervals (≤30s), low-volume (≤5min) and short-term (≤4weeks) HIIT represent effective and time-efficient strategies for developing VO₂max, especially for the general population. To maximize the training effects on VO₂max, long-interval (≥2min), high-volume (≥15min) and moderate to long-term (≥4-12weeks) HIIT are recommended.

Plant-Based Diets for Cardiovascular Safety and Performance in Endurance Sports

Studies suggest that endurance athletes are at higher-than-average risk for atherosclerosis and myocardial damage. The ability of plant-based regimens to reduce risk and affect performance was reviewed. The effect of plant-based diets on cardiovascular risk factors, particularly plasma lipid concentrations, body weight, and blood pressure, and, as part of a healthful lifestyle, reversing existing atherosclerotic lesions, may provide a substantial measure of cardiovascular protection. In addition, plant-based diets may offer performance advantages. They have consistently been shown to reduce body fat, leading to a leaner body composition. Because plants are typically high in carbohydrate, they foster effective glycogen storage. By reducing blood viscosity and improving arterial flexibility and endothelial function, they may be expected to improve vascular flow and tissue oxygenation. Because many vegetables, fruits, and other plant-based foods are rich in antioxidants, they help reduce oxidative stress. Diets emphasizing plant foods have also been shown to reduce indicators of inflammation. These features of plant-based diets may present safety and performance advantages for endurance athletes. The purpose of this review was to explore the role of nutrition in providing cardioprotection, with a focus on plant-based diets previously shown to provide cardiac benefits.

VO2max is associated with measures of energy expenditure in sedentary condition but does not predict weight change

BACKGROUND/OBJECTIVES

Energy expenditure measured under sedentary conditions predicts weight change but evidence that directly measured VO₂max is associated with weight change is lacking. The aim of this study was to determine the associations of VO₂max with measures of predominantly sedentary 24-h thermogenesis, and subsequent weight change.

SUBJECTS/METHODS

Three hundred fifty-seven individuals (162 females; 27 Blacks, 72 Caucasians, and 258 American Indians) had measures of body composition, resting metabolic rate (RMR), and intermittent treadmill run test for assessment of VO₂max. On a separate day, 24-h energy expenditure (EE), diet-induced thermogenesis (DIT) expressed as "awake and fed" thermogenesis (AFT), sleeping metabolic rate (SMR), and spontaneous physical activity (SPA) were measured in a whole-room indirect calorimeter. Follow-up weight for 217 individuals was available (median follow-up time, 9.5 y; mean weight change, 12.4 ± 14.9 kg).

RESULTS

After adjustment for fat free mass, fat mass, age, sex, and race, a higher VO₂max was associated with a higher RMR (β = 68.2 kcal/day per L/min, P < 0.01) and 24-h EE (β = 62.2 kcal/day per L/min, P < 0.05) and including additional adjustment for energy intake higher AFT (β = 66.1 kcal/day per L/min, P = 0.01). Neither SMR (P > 0.2) nor SPA (P > 0.8) were associated with VO₂max. VO₂max at baseline did not predict follow-up weight after adjustment for baseline weight, follow-up time, sex, and race (P > 0.4).

CONCLUSION

VO₂max is associated with measures of EE including 24-h EE, RMR and DIT implying a common mechanism regulating the energetics of skeletal muscle during exercise and thermogenesis. However, this did not translate to VO₂max as a predictor of weight change.

Body mass index and cardiorespiratory fitness in persons with multiple sclerosis

OBJECTIVE

This study examined body fatness and its association with cardiorespiratory fitness (CRF) in persons with multiple sclerosis (pwMS) accounting for disability status.

MATERIALS AND METHODS

This study involved a secondary data analysis from a previous study of 62 pwMS. Body fatness was indirect measured as body mass index (BMI), and CRF was measured as peak oxygen consumption from an incremental exercise test with spirometry. Participants were allocated into 3 different groups based on established BMI categories (ie, normal, overweight, and obese), and data were analyzed using SPSS.

RESULTS

The average BMI was 27.0 (6.7) kg/m² , and CRF was 19.5 (7.2) mL/kg/min. There was an inverse correlation (pr = -.38 [-.57; -.14]; P = .003) between BMI and CRF controlling for age, sex, disease duration, and disability level. ANCOVA with linear contrast analysis revealed a statistical significant reduction in CRF between groups of different BMI categories; normal weight 20.8 (0.85); overweight 19.8 (1.13); and obese 16.9 (1.73) mL/kg/min; F (2, 55) = 3.33, P = .043; η²  = .11.

CONCLUSIONS

The findings suggest that BMI has a negative impact on CRF in pwMS, with a marked reduction in CRF for those classified as obese compared to those in the normal and overweight category.

The Effect of Body Mass Index on Acute Cardiometabolic Responses to Graded Exercise Testing in Children: A Narrative Review

Although the beneficial role of exercise for health is widely recognized, it is not clear to what extent the acute physiological responses (e.g., heart rate (HR) and oxygen uptake (VO₂)) to a graded exercise test are influenced by nutritional status (i.e., overweight vs. normal-weight). Therefore, the main objectives of the present narrative review were to examine the effect of nutritional status on acute HR, and VO₂ responses of children to exercise testing. For this purpose, we examined existing literature using PubMed, ISI, Scopus, and Google Scholar search engines. Compared with their normal-body mass index (BMI) peers, a trend of higher HRrest, higher HR during submaximal exercise testing, and lower HRmax was observed among overweight and obese children (according to BMI). Independent from exercise mode (walking, running, cycling, or stepping), exercise testing was metabolically more demanding (i.e., higher VO₂) for obese and overweight children than for their normal-weight peers. Considering these cardiometabolic differences according to BMI in children might help exercise specialists to evaluate the outcome of a graded exercise test (GXT) (e.g., VO2max, HRmax) and to prescribe optimal exercise intensity in the context of development of exercise programs for the management of body mass.

The Associations between Adiposity, Cognitive Function, and Achievement in Children

Although obesity has been related to measures of academic achievement and cognition in children, the influence of fat distribution, specifically visceral adiposity, on select aspects of achievement and cognitive function remains poorly characterized among preadolescent children.

PURPOSE

The aim of this study was to evaluate the relation of adiposity, particularly visceral adipose tissue (VAT), on achievement and cognitive function among children.

METHODS

Children with obesity (ages 8-9 yr old, N = 55, 35 females) completed cognitive and academic tests. Normal weight children (N = 55, 35 females) were matched to this group on demographic characteristics and aerobic fitness. Covariate analyses included age, Brief Intellectual Ability, socioeconomic status, and fat-free V˙O2 (V˙O2 peak adjusted for lean mass; mL·kg lean·min). Adiposity (i.e., whole body percent fat, subcutaneous abdominal adipose tissue, and VAT) was assessed using dual-energy x-ray absorptiometry.

RESULTS

The results of this study revealed that, relative to their normal weight counterparts, children with obesity had significantly lower performance on tests of reading and math. Analyses revealed that among children with obesity, %Fat and subcutaneous abdominal adipose tissue were not related to cognitive abilities. However, higher VAT was associated with poorer intellectual abilities (Ps ≤ 0.04) and cognitive performance (i.e., thinking ability and cognitive efficiency, Ps ≤ 0.04). However, among normal weight children, VAT was positively associated with intellectual abilities and cognitive efficiency.

CONCLUSION

In conclusion, the results suggest that VAT was selectively and negatively related with cognition among children with obesity. Along with the dangerous metabolic nature of VAT, its detrimental relationship with obese children's intellectual and cognitive functioning is concerning.

Physical deconditioning is the common denominator in both obese and overweight subjects with nonalcoholic steatohepatitis

BACKGROUND

Obesity and decreased physical activity mirror increasing prevalence of nonalcoholic fatty liver disease (NAFLD).

AIM

We aimed to investigate associations between aerobic fitness, anthropometrics and disease parameters in patients with nonalcoholic steatohepatitis (NASH). We hypothesised that NASH subjects have lower aerobic power and capacity than untrained, sedentary, normal subjects.

METHODS

Forty subjects (60% obese, 40% overweight) with biopsy-confirmed NASH and NAFLD activity score (NAS) ≥4 were enrolled in a clinical trial where anthropometrics, laboratories, liver fat content by MRI, activity, and aerobic fitness by cycle ergometry data were obtained.

RESULTS

NASH subjects were significantly deconditioned compared to 148 untrained, sedentary, healthy subjects from our laboratory in aerobic power (VO2peak) (NASH 16.8 ± 6.6 vs control 28.4 ± 10.6 mL/kg/min, P < 0.0001) and capacity (VO2 at lactate threshold [LT]) (NASH 8.3 ± 2.5 vs control 14.1 ± 5.9 mL/kg/min, P < 0.0001). NASH subjects' fitness was comparable to the "least fit" tertile of controls: VO2peak [NASH 16.8 ± 6.6 vs "least fit" 17.3 ± 3.3, P = 0.64]) and VO2 at LT (NASH 8.3 ± 2.5 vs "least fit" 9.3 ± 2.1, P = 0.31). Fitness was similar in obese compared to overweight subjects (adjusted for gender) and was not correlated with visceral adiposity or NAS. Engaging in dedicated cardiovascular activity correlated with higher VO2peak and VO2peak at LT.

CONCLUSIONS

Aerobic deconditioning was universally present in NASH subjects. NASH subjects' fitness was similar to our laboratory's "least fit" untrained, sedentary control subjects. Further research investigating NASH patients' ability to improve low baseline aerobic fitness is warranted.

Size Exponents for Scaling Maximal Oxygen Uptake in Over 6500 Humans: A Systematic Review and Meta-Analysis

BACKGROUND

Maximal oxygen uptake ([Formula: see text] _2max) is conventionally normalized to body size as a simple ratio or using an allometric exponent < 1. Nevertheless, the most appropriate body size variable to use for scaling and the value of the exponent are still enigmatic. Studies tend to be based on small samples and can, therefore, lack precision.

OBJECTIVE

The objective of this systematic review was to provide a quantitative synthesis of reported static allometric exponents used for scaling [Formula: see text] _2max to whole body mass and fat-free mass.

METHODS

Eight electronic databases (CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, PubMed, Scopus, SPORTDiscus and Web of Science) were searched for relevant studies published up to January 2016. Search terms included 'oxygen uptake', 'cardiorespiratory fitness', '[Formula: see text] _2max', '[Formula: see text] _2peak', 'scaling' and all interchangeable terms. Inclusion criteria included human cardiorespiratory fitness data; cross-sectional study designs; an empirical derivation of the exponent; reported precision statistics; and reported information regarding participant sex, age and sports background, [Formula: see text] _2max protocol, whole body composition protocol and line-fitting methods. A random-effects model was used to quantify weighted pooled exponents and 95% confidence limits (Cls). Heterogeneity was quantified with the tau-statistic (τ). Meta-regression was used to quantify the impact of selected moderator variables on the exponent effect size. A 95% prediction interval was calculated to quantify the likely range of true fat-free mass exponents in similar future studies, with this distribution used to estimate the probability that an exponent would be above theorised universal values of [Formula: see text].

RESULTS

Thirty-six studies, involving 6514 participants, met the eligibility criteria. Whole body mass and fat-free mass were used as the scaling denominator in 27 and 15 studies, respectively. The pooled allometric exponent (95% Cls) was found to be 0.70 (0.64 to 0.76) for whole body mass and 0.90 (0.83 to 0.96) for fat-free mass. The between-study heterogeneity was greater for whole body mass (τ = ±0.15) than for fat-free mass (τ = ±0.11). Participant sex explained 30% of the between-study variability in the whole body mass exponent, but the influence on the fat-free mass exponent was trivial. The whole body mass exponent of 0.52 (0.40 to 0.64) for females was substantially lower than the 0.76 (0.70 to 0.83) for males, whereas the fat-free mass exponent was similar for both sexes. The effects of all other moderators were trivial. The 95% PI for fat-free mass ranged from 0.68 to 1.12. The estimated probability of a true fat-free mass exponent in a future study being greater than [Formula: see text] power scaling is 0.98 (very likely) and 0.92 (likely), respectively.

CONCLUSIONS

In this quantitative synthesis of published studies involving over 6500 humans, the whole body mass exponent was found to be spuriously low and prone to substantial heterogeneity. We conclude that the scaling of [Formula: see text] _2max in humans is consistent with the allometric cascade model with an estimated prediction interval for the fat-free mass exponent not likely to be consistent with the [Formula: see text] power laws.

No-cost gym visits are associated with lower weight and blood pressure among non-Latino black and Latino participants with a diagnosis of hypertension in a multi-site demonstration project

Well documented, persistent racial/ethnic health disparities in obesity and hypertension in the US demonstrate the continued need for interventions that focus on people of color who may be at higher risk. We evaluated a demonstration project funded by the CDC's Racial/Ethnic Approaches to Community Health (REACH) program at four federally qualified health centers (FQHC) and YMCA fitness and wellness centers in Boston. No-cost YMCA memberships were offered from June 2014 to June 2015 to non-Latino black and Latino adults with a diagnosis of hypertension. YMCA visit data were merged with health data for 224 participants (n = 1265 health center visits). We assessed associations between gym visit frequency and weight, body mass index (BMI), systolic blood pressure (SBP), and diastolic blood pressure (DBP) using longitudinal time-varying linear fixed-effects models. The total number of gym visits over the entire program duration was 5.5, while the conditional total number of visits (after the first gym visit has been made) was 17.3. Having visited the gym at least 10 times before an FQHC exam was, on average, associated with lower weight (1.19 kg, p = 0.01), lower BMI (0.43 kg/m2, p = 0.01) and reductions in SBP (-3.20 mm Hg, p = 0.01) and DBP (-2.06 mm Hg p = 0.01). Having visited the gym an average of 1.4 times per month (study average) was associated with reductions in weight, BMI, and DBP. No-cost gym visits were associated with improved weight and blood pressure in hypertensive non-Latino black and Latino adults in this program. Additional evaluation is necessary to assess the sustainability of these effects.