Cardiopulmonary fitness is strongly associated with body cell mass and fat-free mass: The Study of Health in Pomerania (SHIP)

Associations between 47 anthropometric markers derived from a body scanner and relative fat-free mass in a population-based study

BACKGROUND

Low relative fat free mass (FFM) is associated with a greater risk of chronic diseases and mortality. Unfortunately, FFM is currently not being measured regularly to allow for individuals therapy.

OBJECTIVE

One reason why FFM is not being used may be related to additional equipment and resources, thus we aimed to identify easily accessible anthropometric markers related with FFM.

MATERIALS AND METHODS

We analyzed data of 1,593 individuals (784 women; 49.2%, age range 28-88 years) enrolled in the population-based Study of Health in Pomerania (SHIP-TREND 1). Forty-seven anthropometric markers were derived from a 3D optical body-scanner. FFM was assessed by bioelectrical impedance analysis (FFMBIA) or air displacement plethysmography (FFMADP). In sex-stratified linear regression models, FFM was regressed on anthropometric measurements adjusted for body height and age. Anthropometric markers were ranked according to the coefficient of determination (R2) derived from these regression models.

RESULTS

Circumferences of high hip, belly, middle hip, waist and high waist showed the strongest inverse associations with FFM. These relations were stronger in females than in males. Associations of anthropometric markers with FFMAPD were greater compared to FFMBIA.

CONCLUSION

Anthropometric measures were more strongly associated with FFMADP compared to FFMBIA. Anthropometric markers like circumferences of the high or middle hip, belly or waist may be appropriate surrogates for FFM to aid in individualized therapy. Given that the identified markers are representative of visceral adipose tissue, the connection between whole body strength as surrogate for FFM and fat mass should be explored in more detail.

Body Cell Mass to Fat-Free Mass Ratio and Extra- to Intracellular Water Ratio Are Related to Maximal Oxygen Uptake

Fat-free mass (FFM) is a heterogeneous compartment comprising body cell mass (BCM), intracellular water (ICW), extracellular solids, and extracellular water (ECW). The BCM/FFM and ECW/ICW ratios vary among individuals and decrease with age. This study aimed to determine whether BCM/FFM and ECW/ICW ratios are predictors of maximal oxygen uptake (V̇̇O2peak) independently of age, sex, and objectively measured physical activity (PA). A total of 115 Japanese males and females, aged 55.3 ± 8.0 years (mean ± standard deviation), were included in the study. Anthropometry, explosive leg muscle power, and V̇̇O2peak were measured, and BCM, FFM, ICW, and ECW were estimated. Step count and PA were objectively measured using a triaxial accelerometer. Blood flow volume was assessed using ultrasonography. BCM and ICW were negatively correlated with age, whereas FFM and ECW were not significantly correlated with age. FFM, ICW/ECW, BCM/FFM, step counts, moderate and vigorous PA, and leg muscle power were positively correlated with V̇̇O2peak, even after adjusting for age and sex (p < .05). Multiple regression analysis indicated that either BCM/FFM or ECW/ICW, leg power, and objectively measured PA were associated with V̇̇O2peak independent of age, sex, and FFM. Blood flow volume was significantly correlated with ECW (p < .05), but not with BCM. The BCM/FFM and ECW/ICW ratios were significant predictors of V̇̇O2peak, independent of age, sex, FFM, leg power, and objectively measured PA.

Cardiac output and arteriovenous oxygen difference contribute to lower peak oxygen uptake in patients with fibromyalgia

BACKGROUND

Patients with fibromyalgia (FM) exhibit low peak oxygen uptake ([Formula: see text]O_2peak). We aimed to detect the contribution of cardiac output to ([Formula: see text]) and arteriovenous oxygen difference [Formula: see text] to [Formula: see text] from rest to peak exercise in patients with FM.

METHODS

Thirty-five women with FM, aged 23 to 65 years, and 23 healthy controls performed a step incremental cycle ergometer test until volitional fatigue. Alveolar gas exchange and pulmonary ventilation were measured breath-by-breath and adjusted for fat-free body mass (FFM) where appropriate. [Formula: see text] (impedance cardiography) was monitored. [Formula: see text] was calculated using Fick's equation. Linear regression slopes for oxygen cost (∆[Formula: see text]O₂/∆work rate) and [Formula: see text] to [Formula: see text]O₂ (∆[Formula: see text]/∆[Formula: see text]O₂) were calculated. Normally distributed data were reported as mean ± SD and non-normal data as median [interquartile range].

RESULTS

[Formula: see text]O_2peak was lower in FM patients than in controls (22.2 ± 5.1 vs. 31.1 ± 7.9 mL∙min^-1∙kg^-1, P < 0.001; 35.7 ± 7.1 vs. 44.0 ± 8.6 mL∙min^-1∙kg FFM^-1, P < 0.001). [Formula: see text] and C(a-v)O₂ were similar between groups at submaximal work rates, but peak [Formula: see text] (14.17 [13.34-16.03] vs. 16.06 [15.24-16.99] L∙min^-1, P = 0.005) and C(a-v)O₂ (11.6 ± 2.7 vs. 13.3 ± 3.1 mL O₂∙100 mL blood^-1, P = 0.031) were lower in the FM group. No significant group differences emerged in ∆[Formula: see text]O₂/∆work rate (11.1 vs. 10.8 mL∙min^-1∙W^-1, P = 0.248) or ∆[Formula: see text]/∆[Formula: see text]O₂ (6.58 vs. 5.75, P = 0.122) slopes.

CONCLUSIONS

Both [Formula: see text] and C(a-v)O₂ contribute to lower [Formula: see text]O_2peak in FM. The exercise responses were normal and not suggestive of a muscle metabolism pathology.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03300635. Registered 3 October 2017-Retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT03300635 .

Adaptations to 4 weeks of high-intensity interval training in healthy adults with different training backgrounds

PURPOSE

This study investigated the physical fitness and oxygen uptake kinetics ([Formula: see text]) along with the exercise-onset O₂ delivery (heart rate kinetics, τHR; changes in normalized deoxyhemoglobin/[Formula: see text] ratio, Δ[HHb]/[Formula: see text]) adaptations of individuals with different physical activity (PA) backgrounds responding to 4 weeks of high-intensity interval training (HIIT), and the possible effects of skeletal muscle mass (SMM) on training-induced adaptations.

METHODS

Twenty subjects (10 high-PA level, HIIT-H; 10 moderate-PA level, HIIT-M) engaged in 4 weeks of treadmill HIIT. Ramp-incremental (RI) test and step-transitions to moderate-intensity exercise were performed. Cardiorespiratory fitness, body composition, muscle oxygenation status, VO₂ and HR kinetics were assessed at baseline and post-training.

RESULTS

HIIT improved fitness status for HIIT-H ([Formula: see text], + 0.26 ± 0.07 L/min; SMM, + 0.66 ± 0.70 kg; body fat, - 1.52 ± 1.93 kg; [Formula: see text], - 7.11 ± 1.05 s, p < 0.05) and HIIT-M ([Formula: see text], 0.24 ± 0.07 L/min, SMM, + 0.58 ± 0.61 kg; body fat, - 1.64 ± 1.37 kg; [Formula: see text], - 5.48 ± 1.05 s, p < 0.05) except for visceral fat area (p = 0.293) without between-group differences (p > 0.05). Oxygenated and deoxygenated hemoglobin amplitude during the RI test increased for both groups (p < 0.05) except for total hemoglobin (p = 0.179). The Δ[HHb]/[Formula: see text] overshoot was attenuated for both groups (p < 0.05) but only eliminated in HIIT-H (1.05 ± 0.14 to 0.92 ± 0.11), and no change was observed in τHR (p = 0.144). Linear mixed-effect models presented positive effects of SMM on absolute [Formula: see text] (p < 0.001) and ΔHHb (p = 0.034).

CONCLUSION

Four weeks of HIIT promoted positive adaptations in physical fitness and [Formula: see text] kinetics, with the peripheral adaptations attributing to the observed improvements. The training effects are similar between groups suggesting that HIIT is effective for reaching higher physical fitness levels.

Body surface scan anthropometrics are related to cardiorespiratory fitness in the general population

The assessment of cardiorespiratory fitness (CRF) is an important tool for prognosis evaluation of cardiovascular events. The gold standard to measure CRF is cardiopulmonary exercise testing (CPET) to determine peak oxygen uptake (VO2peak). However, CPET is not only time consuming but also expensive and is therefore not widely applicable in daily practice. The aim of our study was to analyze, whether and which anthropometric markers derived from a 3D body scanner were related to VO2peak in a general population-based study. We analyzed data (SHIP-START-3) from 3D body scanner and CPET of 1035 subjects (529 women; 51.1%, age range 36-93). A total of 164 anthropometric markers were detected with the 3D body scanner VITUS Smart XXL using the software AnthroScan Professional. Anthropometric measurements were standardized and associated with CRF by sex-stratified linear regression models adjusted for age and height. Anthropometric markers were ranked according to the  - log- p values derived from these regression models. In men a greater left and right thigh-knee-ratio, a longer forearm-fingertip length, a greater left thigh circumference and greater left upper arm circumference were most strongly associated with a higher VO2peak. In women a greater left and right thigh circumference, left calf circumference, thigh thickness and right calf circumference were most strongly associated with a higher VO2peak. The detected VO2peak-related anthropometric markers could be helpful in assessing CRF in clinical routine. Commonly used anthropometric markers, e.g. waist and hip circumference, were not among the markers associated with VO2peak.

Bioelectrical Impedance Vector Analysis Discriminates Aerobic Power in Futsal Players: The Role of Body Composition

Aims: The present study aimed to assess the ability of bioelectrical impedance vector analysis (BIVA) in discriminating fitness levels in futsal players, exploring the association of body composition and bioelectrical parameters with aerobic power. Methods: Forty-eight professional futsal players (age 23.8 ± 5.3 years) were involved in a cross-sectional study during their pre-season phase. Fat mass (FM) and muscle mass were determined by dual-energy X-ray absorptiometry. VO2max was obtained by indirect calorimetry through a graded exercise test performed on a treadmill. Bioelectrical resistance (R), reactance (Xc), and phase angle (PhA) were directly measured using a foot-to-hand bioimpedance technology at a 50 kHz frequency. Bioelectric R and Xc were standardized for the participants’ height and used to plot the bioimpedance vector in the R-Xc graph according to the BIVA approach. Results: The participants divided into groups of VO2max limited by tertiles showed significant differences in mean vector position in the R-Xc graph (p < 0.001), where a higher VO2max resulted in a longer vector and upper positioning. FM, muscle mass, and PhA differed (p < 0.01) among the athletes grouped by tertiles of VO2max, where athletes with a greater aerobic power showed a lower percentage of FM and a higher percentage of muscle mass and PhA. FM and PhA were associated with VO2max (FM: r = −0.658, p < 0.001; PhA: r = 0.493, p < 0.001). These relationships remained significant after adjusting for age and body mass (FM: ß = −0.335, p = 0.046; PhA: ß = 0.351, p = 0.003). Conclusions: Bioelectrical impedance vectors positioned on the lower pole of the R-Xc graph identified futsal players with a lower VO2max, while longer vectors corresponded to a greater aerobic power. Additionally, PhA, that describes the vector direction, was positively associated with VO2max, while a higher FM negatively affected VO2max in the futsal players. BIVA and PhA evaluation may represent a valid support for screening the aerobic fitness level in professional futsal players, when more sophisticated assessment methods are not available.

Low cardiopulmonary fitness is associated with higher liver fat content and higher gamma-glutamyltransferase concentrations in the general population - "The Sedentary's Liver"

BACKGROUND

We investigated the association between low cardiorespiratory fitness and liver fat content (LFC) in the general population.

MATERIALS AND METHODS

We evaluated data from 2151 adults (51.1% women) from two population-based cohorts of the Study of Health in Pomerania (SHIP-2 and SHIP-TREND-0). We analysed the cross-sectional associations of peak oxygen uptake (VO_2peak ) with LFC, assessed by magnetic resonance imaging proton density fat fraction, as well as serum gamma-glutamyltransferase (GGT) and aminotransferase concentrations by multivariable regression models.

RESULTS

We observed significant inverse associations of VO_2peak with LFC and serum GGT, but not with serum aminotransferase levels. Specifically, a 1 L/min lower VO_2peak was associated with a 1.09% (95% confidence interval [CI]: 0.45-1.73; P = .002) higher LFC and a 0.18 μkatal/L (95% CI: 0.09-0.26; P < .001) higher GGT levels. The adjusted odds ratio (OR) for the risk of prevalent hepatic steatosis (HS) by a 1 L/min decrease in VO_2peak was 1.61 (95% CI: 1.22-2.13; P = .001). Compared to subjects with high VO_2peak , obese and overweight individuals with low VO_2peak had 1.78% (95% CI: 0.32-3.25; P = .017) and 0.94% (95% CI: 0.15-1.74; P = .021) higher mean LFC, respectively. Compared to those with high VO_2peak , low VO_2peak was independently associated with a higher risk of prevalent HS in the obese (adjusted-OR 2.29, 95% CI=1.48-3.56; P < .001) and overweight (adjusted OR 1.57, 95% CI=1.16-2.14; P = .04) groups.

CONCLUSIONS

Lower VO_2peak was significantly associated with greater LFC and higher serum GGT levels in a population-based cohort of adult individuals. Our results suggest that low VO_2peak might be a risk factor for HS.

Cardiac MRI shows an association of lower cardiorespiratory fitness with decreased myocardial mass and higher cardiac stiffness in the general population - The Sedentary's Heart

BACKGROUND

The heart has the capacity to adapt to different demands. The pathophysiological mechanisms involved with sedentarism are not fundamentally the opposite of those related with physical activity and regular exercise. We investigated the impact of lower cardiorespiratory fitness (CRF) on heart's plasticity and function in a population-based setting.

METHODS

We used data from 1165 participants (539 women; 46.3%) aged 21-81 years from two independent cohorts of the Study of Health in Pomerania (SHIP-2 and SHIP-TREND-0). We analyzed the cross-sectional associations of peak oxygen uptake (VO_2peak), determined by symptom-limited cardiopulmonary exercise testing, with structural and functional left ventricular (LV) and left atrial (LA) parameters determined by magnetic resonance imaging (MRI) using multivariable- adjusted linear regression models.

RESULTS

A 1 L/min lower VO_2peak was associated with a 10.5 g (95% confidence interval: 8.00 to 12.9; p < 0.001) lower LV mass, a 14.8 mL (10.9 to 18.6; p < 0.001) lower LV end-diastolic volume, a 0.29 mm (0.19 to 0.40; p < 0.001) lower LV wall-thickness, a 8.85 mL/beat (6.53 to 11.2; p < 0.001) lower LV stroke volume, a 0.42 L/min (0.25 to 0.60; p < 0.001) lower LV cardiac output and a 7.51 mL (3.88 to 11.1; p < 0.001) lower LA end-diastolic volume. Moreover, there were no associations with a concentric or eccentric remodeling and LV and LA ejection fraction.

CONCLUSIONS

Lower CRF was associated with a smaller heart, LV wall-thickness and mass, LV and LA stroke volume and cardiac output. Conversely, there was no association with LA and LV ejection fraction. Our cross-sectional observations are consistent with cardiac adaptations reflecting reduced volume loading demands of a sedentary lifestyle - "the sedentary's heart".

Dose-response effects of aerobic exercise on adiposity markers in postmenopausal women: pooled analyses from two randomized controlled trials

BACKGROUND/OBJECTIVE

Exercise may reduce the risk of breast cancer through adiposity changes, but the dose-response effects of exercise volume on adiposity markers are unknown in postmenopausal women. We aimed to compare the dose-response effects of prescribed aerobic exercise volume on adiposity outcomes.

PARTICIPANTS/METHODS

Data from the Alberta Physical Activity and Breast Cancer Prevention (ALPHA) and Breast Cancer and Exercise Trial in Alberta (BETA) were pooled for this analysis (N = 720). These were 12-month randomized controlled trials, where participants were randomized to 225 min/week (mid-volume) of aerobic exercise versus usual inactive lifestyle (ALPHA), or 150 min/week (low-volume) versus 300 min/week (high-volume) (BETA). Fat mass and fat-free mass were measured using DXA and intra-abdominal and subcutaneous fat area were assessed with computed tomography.

RESULTS

After 12 months of aerobic exercise, increasing exercise volumes from no exercise/control to 300 min/week resulted in statistically significant reductions in BMI, weight, fat mass, fat percentage, intra-abdominal and subcutaneous fat area (P < 0.001). Compared with controls, fat mass loss was -1.13, -1.98 and -2.09 kg in the low-, mid- and high-volume groups, respectively. Similarly, weight loss was -1.47, -1.83, -2.21 kg in the low-, mid- and high-volume groups, respectively, compared to controls, and intra-abdominal fat area loss was -7.44, -15.56 and -8.76 cm² in the low-, mid- and high-volume groups, respectively, compared to controls. No evidence for a dose-response effect on fat-free mass was noted.

CONCLUSION

A dose-response effect of exercise volume on adiposity markers was noted, however, the differences in adiposity markers were smaller when comparing 225 min/week to 300 min/week of exercise. Given the strong positive associations between obesity and postmenopausal breast cancer risk, this study provides evidence on the importance of exercise volume as part of the exercise prescription to reduce adiposity and, ultimately, postmenopausal breast cancer risk.

Association between cardiorespiratory fitness and handgrip strength with age-related macular degeneration: a population-based study

AIM

To assess whether cardiorespiratory fitness (CRF) and handgrip strength, two objective markers of physical fitness, are associated with age-related macular degeneration (AMD).

METHODS

We analysed cross-sectional data from the population-based Study of Health in Pomerania (2008-2012) including 1173 adult men and women aged 20-79 years. Fundus photography of the central retina was recorded with a non-mydriatic camera, and images were graded according to an established clinical AMD classification scale by an experienced reader. CRF was measured using peak oxygen uptake (peakVO₂), oxygen uptake at the anaerobic threshold (VO₂@AT), and maximum power output (W_max) from standardised cardiopulmonary exercise testing on a bicycle ergometer according to a modified Jones protocol. Handgrip strength was assessed using a handheld dynamometer. Adjusted prevalence ratios (PR) for the associations of peakVO₂, VO₂@AT, W_max and handgrip strength with AMD were derived from multivariable Poisson regression models.

RESULTS

PeakVO₂, VO₂@AT, W_max and handgrip strength were not associated with AMD. Adjusted PR for AMD associated with a 1-SD increment in peakVO₂, VO₂@AT, W_max and handgrip strength were 1.05 (95% CI 0.82 to 1.34), 0.96 (95% CI 0.78 to 1.18), 1.10 (95% CI 0.86 to 1.41) and 1.01 (95% CI 0.79 to 1.30), respectively. These associations were not modified by age, sex, smoking, body mass index and diabetes. Estimates in sensitivity analysis for confounding, selection bias and missing data were similar.

CONCLUSION

In our study, CRF and handgrip strength were not associated with AMD. Nevertheless, longitudinal studies with bigger sample sizes are needed to furtherly examine these associations.

Physical fitness and nutritional status in female adolescents with anorexia nervosa

ABSTRACT Objective This study aimed to determine whether physical fitness is related to nutritional status in a sample of female adolescents with anorexia nervosa, to contrast the nourished and undernourished patients, and to compare the physical fitness in these patients with normative data of healthy subjects stratified by age and gender. Methods Nutritional status was determined using the body mass index Z-score, fat mass, fat-free mass (bioelectrical impedance analysis), and the Controlling Nutritional Status score in 15 anorexic adolescents with 14.3±1.6 years. Physical fitness was assessed using the ALPHA-Fitness Battery (handgrip strength, standing broad jump, 4x10m shuttle run, and 20m shuttle run tests). Results Handgrip strength was significantly associated with all variables of nutritional status, except with the three blood components of the Controlling Nutritional Status score. The undernourished anorexic patients showed significantly worse physical fitness than the nourished anorexic patients in all tests, except in the standing broad jump and the 4x10m shuttle run tests. The physical fitness tests of the female anorexic adolescents showed scores significantly worse than those of the normative European female adolescent population. Conclusion The observation of female adolescents with anorexia nervosa showed associations between higher physical fitness levels and better nutritional statuses. Handgrip strength and 20m shuttle run tests may be options of additional indicators of undernutrition in anorexic female adolescents. The undernourished anorexic patients showed worse physical fitness than the nourished ones. According to normative data for healthy sex- and agematched adolescents, physical fitness is severely impaired in anorexic female adolescents.

Glucose and insulin levels are associated with arterial stiffness and concentric remodeling of the heart

BACKGROUND

Mortality attributable to heart failure remains high. The prevalence of heart failure in patients with diabetes mellitus ranges from 19 to 26%. It is estimated that up to 21.1 million adults in the United States have diagnosed diabetes mellitus and around 80.8 million have impaired fasting glucose. We investigated the associations of fasting glucose (FG) and fasting insulin (FI), the homeostasis model assessment-insulin resistance index (HOMA-IR) and 2-h postload glucose (2HG) and insulin (2HI) with parameters of left ventricular geometry and function and arterial stiffness determined by magnetic resonance imaging in individuals without diagnosed type 2 diabetes.

METHODS

Cross-sectional analyses of 1001 individuals (453 women, 45.3%), aged 21 to 80 years, from two independent population-based studies, the Study of Health in Pomerania (SHIP-TREND-0) and KORA FF4 Study. FG, FI, HOMA-IR, 2HG and 2HI, as well as glucose tolerance categories, were analyzed for associations with heart and arterial parameters using multivariable-adjusted linear regression models.

RESULTS

In total, 390 individuals (39%) had prediabetes (isolated impaired fasting glucose, isolated glucose tolerance or both), and 49 (4.9%) were found to have unknown type 2 diabetes. In the multivariable-adjusted analysis, positive linear associations of FG, FI, HOMA-IR, 2HG and 2HI with arterial stiffness index and left ventricular wall-thickness and concentricity and inverse linear associations with left ventricular end-diastolic volume were observed. A 1 mmol/l higher FG was associated with a 1.18 ml/m^2.7 (1.80 to 0.57; p < 0.001) lower left ventricular end-diastolic volume index, a 0.042 mm/m^2.7 (0.014 to 0.070) higher left ventricular wall-thickness index, a 0.12 mmHg m^2.7/ml (0.06 to 0.17; p < 0.001) greater arterial stiffness index and a 0.037 g/ml (0.018 to 0.056; p < 0.001) higher left ventricular concentricity.

CONCLUSIONS

Our findings suggest that higher glucose levels in the prediabetic range and insulin resistance might lead to higher arterial stiffness and concentric remodeling of the heart.

Sex-Related Differences in Blood Glucose Responses to Resistance Exercise in Adults With Type 1 Diabetes: A Secondary Data Analysis

OBJECTIVES

In adults with type 1 diabetes, resistance exercise (RE) is associated with more stable blood glucose (BG) levels than aerobic exercise, both during and after exercise. In individuals without diabetes, growth hormone and epinephrine responses to RE differ between the sexes. These hormones are known to affect BG levels in individuals with type 1 diabetes. In this study, we explored whether sex-related differences may exist in BG responses to RE in individuals with type 1 diabetes.

METHODS

A secondary data analysis was conducted on pooled data from 2 studies with identical RE protocols for individuals with type 1 diabetes (13 males, age range 16 to 63 years; 10 females, age range 19 to 45 years). The RE session consisted of 7 resistance-based exercises performed at 5 pm. Plasma glucose samples were collected before, immediately after and 1 h after exercise. Interstitial glucose levels were recorded through blinded continuous glucose monitoring 24 h before, during and 24 h after exercise.

RESULTS

There was a significant sex-by-time interaction (p<0.001) in plasma glucose responses to RE. Plasma glucose decreased significantly in males from 8.6±2.5 to 6.3±2.1 mmol/L (p<0.001) during exercise, whereas females experienced no significant change (7.2±1.3 to 7.3±1.3 mmol/L, p=0.999). In the 6 h after RE, males developed significantly more hypoglycemia, as measured by continuous glucose monitoring (p=0.048).

CONCLUSIONS

Males may have a greater risk of hypoglycemia with an acute bout of RE than females. Further research is needed to examine this phenomenon more closely, as sex-specific recommendations for preventing hypoglycemia around RE may be necessary in type 1 diabetes.

Peak oxygen uptake reference values for cycle ergometry for the healthy Dutch population: data from the LowLands Fitness Registry

Peak oxygen uptake (V′_O2peak) is recognised as the best expression of aerobic fitness. Therefore, it is essential that V′_O2peak reference values are accurate for interpreting a cardiopulmonary exercise test (CPET). These values are country specific and influenced by underlying biological ageing processes. They are normally stratified per paediatric and adult population, resulting in a discontinuity at the transition point between prediction equations. There are currently no age-related reference values available for the lifespan of individuals in the Dutch population. The aim of this study is to determine the best-fitting regression model for V′_O2peak in the healthy Dutch paediatric and adult populations in relation to age.

In this retrospective study, CPET cycle ergometry results of 4477 subjects without reported somatic diseases were included (907 females, age 7.9–65.0 years). Generalised additive models were employed to determine the best-fitting regression model. Cross-validation was performed against an independent dataset consisting of 3518 subjects (170 females, age 6.8–59.0 years).

An additive model was the best fitting with the largest predictive accuracy in both the primary (adjusted R²=0.57, standard error of the estimate (see)=556.50 mL·min⁻¹) and cross-validation (adjusted R²=0.57, see=473.15 mL·min⁻¹) dataset.

This study provides a robust additive regression model for V′_O2peak in the Dutch population.

Peak oxygen uptake has a nonlinear dependence on years of age in the paediatric and adult Dutch populationshttp://ow.ly/H3fH30nIjRy

Genetic, Physiologic, and Behavioral Predictors of Cardiorespiratory Fitness in Specialized Military Men

Introduction

Cardiorespiratory fitness (CRF) is a crucial performance requirement of specialized military occupations. Age and physical activity are established predictors of CRF, but it is not clear how these predictors combine with each other and/or with genetic predisposition. The goal of this study was to derive inclusive explanatory models of CRF in US Navy Explosive Ordnance Disposal (EOD) operators, synthesizing conventional (e.g., age, body composition, and physical activity) and novel influences (e.g., genetic variance).

Materials and Methods

In this cross-sectional study, 40 male, active duty EOD operators completed a graded exercise test to assess maximal oxygen consumption and ventilatory threshold (VT) using the Bruce protocol. Aerobic performance was further quantified via time of test termination and time at which VT was achieved. Body composition was determined via dual x-ray absorptiometry, and physical activity was assessed by self-report. Genetic variants underlying human stress systems (5HTTLPR, BclI, −2 C/G, and COMT) were assayed. Descriptive analyses were conducted to summarize subject characteristics. Hypotheses were tested with linear regression models. Specifically, separate univariate regression models first determined associations between each of the independent and dependent variables. This protocol was approved by the Naval Health Research Center Institutional Review Board (NHRC.2015.0013).

Results

In univariate regression models, age, body composition, physical activity, and 5HTTLPR consistently predicted CRF and/or aerobic performance (R2 range 0.07–0.55). Multivariate regression models routinely outperformed the univariate models, explaining 36–62% of variance.

Conclusion

This study signifies a shift toward inclusive explanatory models of CRF and aerobic performance, accounting for combined roles of genetic, physiologic, and behavioral influences. Although we were able to quantify combined effects, we were unable to evaluate interaction effects (e.g., gene–gene, gene–behavior) due to limited statistical power. Other limitations are that this specialized military population may not readily generalize to broader populations, and the current sample was all male. Considering these limitations, we aim to replicate this study in various populations, both male and female. Despite its limitations, this study reflects a shift toward more comprehensive predictive models of CRF, explaining the unique and shared contributions of genetic predisposition, physiology, and behavior. These findings have implications for assessment, selection, and training of specialized military members, and may also impact mission success and survivability. Future studies are needed to better characterize additive, interactive, and mediated effects.

Effect of 12-Week Swimming Training on Body Composition in Young Women

Background: Systematic physical activity can permanently prevent disadvantageous developments in the human body. This is very important especially for women, for whom the maintenance of a lean body in good shape is sometimes a primary consideration. However, in most cases, this activity is taken randomly and does not produce the desired effects such as reducing body fat. The purpose of the study was to evaluate changes in female body composition induced by 12 weeks of swimming training compared to sedentary controls. Methods: Training sessions occurred three times per week (60 min/session). Height, body mass, and waist/hip circumference and waist/hips ratio (WHR) were measured. Body cell mass (BCM), total body water (TBW), extracellular (ECW) and intracellular water (ICW), fat mass (FM), lean mass (FFM), and muscle mass (MM) were measured using bioelectrical impedance (pre/post). Results: Training elicited decreases in hip circumference and increase in WHR. No changes were recorded in BCM, TBW, ECW, ICW, FM, FFM, and MM. Controls experienced decreases in values of BCM, ICW, and MM and increases in ECW. Conclusion: The applied swimming training did not significantly affect the body composition parameters. Inactivity also triggered a tendency toward unhealthy movement of water from the intracellular to extracellular space.

Representative body composition percentiles from bioelectrical impedance analyses among children and adolescents. The MoMo study

BACKGROUND & AIMS

With high prevalence of overweight and obesity in developed countries, the assessment of body composition in children and adolescents is of growing interest. The aim of this study was (i) to provide up-to-date population wide percentiles for meaningful diagnostic bioelectrical impedance outcome parameters and (ii) to specify reference values for these measures in a normal weight subpopulation.

METHODS

A representative nationwide sample of 4 to 24-year-old children and adolescents (n = 3593) was drawn out of 167 primary sample points across Germany from 2009 to 2012 (Motorik-Modul study wave 1). Fat free mass index (FFMI), fat mass index (FMI), body cell mass index (BCMI) and phase angle (PA) were derived from four electrodes 50 kHz bioelectrical impedance analyses. Sex-specific percentiles were calculated using the LMS-method for the total study population and a normal weight subsample (defined according to the international BMI-standard by Cole).

RESULTS

Percentile curves for body composition parameters are similar between boys and girls until puberty. Subsequently, girls show a higher FMI than boys, and boys increase their FFM, BCM, and PA time-shifted, in that order. Differences in FMI between the overall and the normal weight sample increase with age, showing an age-dependent prevalence for overweight and obesity among the representative German sample.

CONCLUSIONS

Results from the normal weight sample can be used as reference values to define a healthy body composition. Differences in body composition between the representative German sample and the normal weight subsample reveal a high prevalence of elevated fat mass in the population of children and adolescents living in Germany.