Quality of lean body mass and jump capacity in high performance young basketball players lean body mass and jump capacity.

The lean body mass (LBM) components have been suggested as important predictors of anaerobic performance, which is highly involved in basketball. We explored with descriptive cross-sectional design the relationship between anaerobic performance and full molecular and cellular body composition profile in young male basketball players. Twenty-one players (age = 16.8 ± 1.6 years; body mass = 76.3 ± 15.7 kg, height = 189.3 ± 12.6 cm) were recruited, 11 elite and 10 local level. Participants were evaluated on multicomponent body composition [LBM, appendicular lean soft tissue (ALST), bone mineral content (BMC), total body water (TBW), intracellular water (ICW) and extracellular water (ECW)] and field-based anaerobic performance (vertical jump, linear sprint, and handgrip strength). The stepwise regression analyses adjusted for confounders showed significant relationships of whole-body and regional body composition components with handgrip and jump performance (P ≤ 0.03). Prediction models combining body composition variables assessed by bioimpedance analysis (BIA) and double-energy X-ray absorptiometry (DXA) revealed that lean mass and hydration ratios (ICW/ECW and ECW/TBW) were strongly associated with jump performance (CMJ and CMJ25kg), independently of the competition level (P < 0.01). The novel finding in this study was that water quality (ICW/ECW) and water distribution (ECW/TBW, ICW) of total and regional LBM were the main predictors of vertical jump capacity in young basketball players.

Twenty-four hour assessments of substrate oxidation reveal differences in metabolic flexibility in type 2 diabetes that are improved with aerobic training.

AIMS/HYPOTHESIS: The aim of this study was to assess metabolic flexibility (MetFlex) in participants with type 2 diabetes within the physiologically relevant conditions of sleeping, the post-absorptive (fasting) state and during meals using 24 h whole-room indirect calorimetry (WRIC) and to determine the impact of aerobic training on these novel features of MetFlex. METHODS: Normal-weight, active healthy individuals (active; n = 9), obese individuals without type 2 diabetes (ND; n = 9) and obese individuals with type 2 diabetes (n = 23) completed baseline metabolic assessments. The type 2 diabetes group underwent a 10 week supervised aerobic training intervention and repeated the metabolic assessments. MetFlex was assessed by indirect calorimetry in response to insulin infusion and during a 24 h period in a whole-room indirect calorimeter. Indices of MetFlex evaluated by WRIC included mean RQ and RQ kinetic responses after ingesting a standard high-carbohydrate breakfast (RQBF) and sleep RQ (RQsleep). Muscle mitochondrial energetics were assessed in the vastus lateralis muscle in vivo and ex vivo using 31P-magnetic resonance spectroscopy and high-resolution respirometry, respectively. RESULTS: The three groups had significantly different RQsleep values (active 0.823 ± 0.04, ND 0.860 ± 0.01, type 2 diabetes 0.842 ± 0.03; p < 0.05). The active group had significantly faster RQBF and more stable RQsleep responses than the ND and type 2 diabetes groups, as demonstrated by steeper and flatter slopes, respectively. Following the training intervention, the type 2 diabetes group displayed significantly increased RQBF slope. Several indices of RQ kinetics had significant associations with in vivo and ex vivo muscle mitochondrial capacities. CONCLUSIONS/INTERPRETATION: Twenty-four hour WRIC revealed that physiological RQ responses exemplify differences in MetFlex across a spectrum of metabolic health and correlated with skeletal muscle mitochondrial energetics. Defects in certain features of MetFlex were improved with aerobic training, emphasising the need to assess multiple aspects of MetFlex and disentangle insulin resistance from MetFlex in type 2 diabetes. TRIAL REGISTRATION: ClinicalTrials.gov NCT01911104. FUNDING: This study was funded by the ADA (grant no. 7-13-JF-53).

Chemical Oxygen Demand Can Be Converted to Gross Energy for Food Items Using a Linear Regression Model.

BACKGROUND: Human and microbial metabolism are distinct disciplines. Terminology, metrics, and methodologies have been developed separately. Therefore, combining the 2 fields to study energetic processes simultaneously is difficult. OBJECTIVES: When developing a mechanistic framework describing gut microbiome and human metabolism interactions, energy values of food and digestive materials that use consistent and compatible metrics are required. As an initial step toward this goal, we developed and validated a model to convert between chemical oxygen demand (COD) and gross energy (${E_g}$) for >100 food items and ingredients. METHODS: We developed linear regression models to relate (and be able to convert between) theoretical gross energy (${E_g}^{\prime}$) and chemical oxygen demand (COD'); the latter is a measure of electron equivalents in the food's carbon. We developed an overall regression model for the food items as a whole and separate regression models for the carbohydrate, protein, and fat components. The models were validated using a sample set of computed ${E_g}^{\prime}$ and COD' values, an experimental sample set using measured ${E_g}$ and COD values, and robust statistical methods. RESULTS: The overall linear regression model and the carbohydrate, protein, and fat regression models accurately converted between COD and ${E_g}$, and the component models had smaller error. Because the ratios of COD per gram dry weight were greatest for fats and smallest for carbohydrates, foods with a high fat content also had higher ${E_g}$ values in terms of kcal · g dry weight-1. CONCLUSION: Our models make it possible to analyze human and microbial energetic processes in concert using a single unit of measure, which fills an important need in the food-nutrition-metabolism-microbiome field. In addition, measuring COD and using the regressions to calculate ${E_g}$ can be used instead of measuring ${E_g}$ directly using bomb calorimetry, which saves time and money.

Thigh and abdominal adipose tissue depot associations with testosterone levels in postmenopausal females.

OBJECTIVE: Research findings on the relationship between serum androgens and adipose tissue in older females are inconsistent. We aimed to clarify the relationship using state-of-the-art techniques to evaluate associations between body fat distribution and plasma testosterone (T) levels in older postmenopausal women. DESIGN: Observational, cross-sectional study of healthy, community dwelling postmenopausal women. PATIENTS AND MEASUREMENTS: Postmenopausal women (60-80 years old) were included in this study. Overall body composition was evaluated by dual-energy X-ray absorptiometry. Abdominal and thigh fat depots were measured by magnetic resonance imaging. Circulating T concentrations were analysed by liquid chromatography-tandem mass spectrometry. RESULTS: Thirty-five women (66.6 ± 0.8 years) participated in this study. T levels were positively associated with clinical proxy measures of adiposity including weight (ρ = 0.39), BMI (ρ = 0.43) and waist circumference (ρ = 0.39) (all P < 0.05). Fat mass and % body fat were correlated with T levels (ρ = 0.42 and 0.38 respectively, both P < 0.05). T correlated with overall and superficial abdominal fat (ρ = 0.34 and 0.37 respectively, both P < 0.05) but not with visceral adipose tissue. T increased with greater thigh fat (ρ = 0.49, P < 0.05) in both superficial and deep depots (ρ = 0.50 and 0.35 respectively, both P < 0.05). CONCLUSION: Our results suggest that postmenopausal women with higher circulating T levels have both higher regional and overall body adiposity. These findings underscore the sexual dimorphism in the relationship between serum androgen levels and adiposity.

Exercise and Bariatric Surgery: An Effective Therapeutic Strategy.

The long-term efficacy of bariatric surgery is not entirely clear, and weight regain and diabetes relapse are problems for some patients. Exercise is a feasible and clinically effective adjunct therapy for bariatric surgery patients. We hypothesize that exercise is also a critical factor for long-term weight loss maintenance and lasting remission of type 2 diabetes.

Changes in the Force-Velocity Mechanical Profile After Short Resistance Training Programs Differing in Set Configurations.

The main aim of this study was to analyze the effect of resistance training programs differing in set configuration on mechanical force-velocity profiles. Thirteen participants performed 10 unilateral knee extension training sessions over 5 weeks. Each limb was randomized to one of the following set configurations: traditional (4 sets of 8 repetitions at maximum intended velocity, 10RM load, 3-min pause between sets) or interrepetition rest (32 maximum intended velocity repetitions, 10RM load, 17.4 s of rest between each repetition). Velocity of each repetition was recorded throughout the program. Before and after training, individual linear force velocities were calculated, and the following parameters were obtained: force and velocity axis intercept, slope, and estimated maximum power. Mean velocity was higher throughout the program for interrepetition rest configuration (0.54 ± 0.01 vs. 0.48 ± 0.01 m∙s-1 for interrepetition rest, and traditional configuration respectively; main effect of set configuration: P < .001). There was a significant increase in force and velocity intercepts, but a steeper negative slope after both training protocols (main effect of time: P < .001 for every variable). Differences in resistance training velocity did not affect the adaptations. Our results suggest that, in a short-term program, maximum intended rather than actual velocity is a key factor to modulate strength adaptations.

24-h energy expenditure in people with type 1 diabetes: impact on equations for clinical estimation of energy expenditure.

BACKGROUND/OBJECTIVES: Type 1 diabetes (T1D) is associated with an increase in resting metabolic rate (RMR), but the impact of T1D on other components of 24-h energy expenditure (24-h EE) is not known. Also, there is a lack of equations to estimate 24-h EE in patients with T1D. The aims of this analysis were to compare 24-h EE and its components in young adults with T1D and healthy controls across the spectrum of body mass index (BMI) and derive T1D-specific equations from clinical variables. SUBJECTS/METHODS: Thirty-three young adults with T1D diagnosed ≥1 year prior and 33 healthy controls matched for sex, age and BMI were included in this analysis. We measured 24-h EE inside a whole room indirect calorimeter (WRIC) and body composition with dual x-ray absorptiometry. RESULTS: Participants with T1D had significantly higher 24-h EE than healthy controls (T1D = 2047 ± 23 kcal/day vs control= 1908 ± 23 kcal/day; P < 0.01). We derived equations to estimate 24-h EE with both body composition (fat free mass + fat mass) and anthropometric (weight + height) models, which provided high coefficients of determination (R2 = 0.912 for both). A clinical model that did not incorporate spontaneous physical activity yielded high coefficients of determination as well (R2 = 0.897 and R2 = 0.880 for body composition and anthropometric models, respectively). CONCLUSION: These results confirm that young adults with established T1D have increased 24-h EE relative to controls without T1D. The derived equations from clinically available variables can assist clinicians with energy prescriptions for weight management in patients with T1D.

Cardiopulmonary Exercise Testing in a Prospective Multicenter Cohort of Older Adults.

PURPOSE: Cardiorespiratory fitness (CRF) measured by peak oxygen consumption (VO 2 peak) declines with aging and correlates with mortality and morbidity. Cardiopulmonary Exercise Testing (CPET) is the criterion method to assess CRF, but its feasibility, validity and reliability in older adults is unclear. Our objective was to design and implement a dependable, safe and reliable CPET protocol in older adults. METHODS: VO 2 peak was measured by CPET, performed using treadmill exercise in 875 adults ≥70 years in the Study of Muscle, Mobility and Aging (SOMMA). The protocol included a symptom-limited peak (maximal) exercise and two submaximal walking speeds. An adjudication process was in place to review tests for validity if they met any prespecified criteria [VO 2 peak < 12.0 ml/kg/min; maximum heart rate (HR) <100 bpm; respiratory exchange ratio (RER) <1.05 and a rating of perceived exertion <15]. A subset (N = 30) performed a repeat test to assess reproducibility. RESULTS: CPET was safe and well tolerated, with 95.8% of participants able to complete the VO 2 peak phase of the protocol. Only 56 (6.4%) participants had a risk alert and only two adverse events occurred: a fall and atrial fibrillation. Mean ± SD VO 2 peak was 20.2 ± 4.8 mL/kg/min, peak HR 142 ± 18 bpm, and peak RER 1.14 ± 0.09. Adjudication was indicated in 47 tests; 20 were evaluated as valid, 27 as invalid (18 data collection errors, 9 did not reach VO 2 peak). Reproducibility of VO 2 peak was high (intraclass correlation coefficient = 0.97). CONCLUSIONS: CPET was feasible, effective and safe for older adults, including many with multimorbidity or frailty. These data support a broader implementation of CPET to provide insight into the role of CRF and its underlying determinants of aging and age-related conditions.

Reprogramming the Human Gut Microbiome Reduces Dietary Energy Harvest.

The gut microbiome is emerging as a key modulator of host energy balance1. We conducted a quantitative bioenergetics study aimed at understanding microbial and host factors contributing to energy balance. We used a Microbiome Enhancer Diet (MBD) to reprogram the gut microbiome by delivering more dietary substrates to the colon and randomized healthy participants into a within-subject crossover study with a Western Diet (WD) as a comparator. In a metabolic ward where the environment was strictly controlled, we measured energy intake, energy expenditure, and energy output (fecal, urinary, and methane)2. The primary endpoint was the within-participant difference in host metabolizable energy between experimental conditions. The MBD led to an additional 116 ± 56 kcals lost in feces daily and thus, lower metabolizable energy for the host by channeling more energy to the colon and microbes. The MBD drove significant shifts in microbial biomass, community structure, and fermentation, with parallel alterations to the host enteroendocrine system and without altering appetite or energy expenditure. Host metabolizable energy on the MBD had quantitatively significant interindividual variability, which was associated with differences in the composition of the gut microbiota experimentally and colonic transit time and short-chain fatty acid absorption in silico. Our results provide key insights into how a diet designed to optimize the gut microbiome lowers host metabolizable energy in healthy humans.

Host-diet-gut microbiome interactions influence human energy balance: a randomized clinical trial.

The gut microbiome is emerging as a key modulator of human energy balance. Prior studies in humans lacked the environmental and dietary controls and precision required to quantitatively evaluate the contributions of the gut microbiome. Using a Microbiome Enhancer Diet (MBD) designed to deliver more dietary substrates to the colon and therefore modulate the gut microbiome, we quantified microbial and host contributions to human energy balance in a controlled feeding study with a randomized crossover design in young, healthy, weight stable males and females (NCT02939703). In a metabolic ward where the environment was strictly controlled, we measured energy intake, energy expenditure, and energy output (fecal and urinary). The primary endpoint was the within-participant difference in host metabolizable energy between experimental conditions [Control, Western Diet (WD) vs. MBD]. The secondary endpoints were enteroendocrine hormones, hunger/satiety, and food intake. Here we show that, compared to the WD, the MBD leads to an additional 116 ± 56 kcals (P < 0.0001) lost in feces daily and thus, lower metabolizable energy for the host (89.5 ± 0.73%; range 84.2-96.1% on the MBD vs. 95.4 ± 0.21%; range 94.1-97.0% on the WD; P < 0.0001) without changes in energy expenditure, hunger/satiety or food intake (P > 0.05). Microbial 16S rRNA gene copy number (a surrogate of biomass) increases (P < 0.0001), beta-diversity changes (whole genome shotgun sequencing; P = 0.02), and fermentation products increase (P < 0.01) on an MBD as compared to a WD along with significant changes in the host enteroendocrine system (P < 0.0001). The substantial interindividual variability in metabolizable energy on the MBD is explained in part by fecal SCFAs and biomass. Our results reveal the complex host-diet-microbiome interplay that modulates energy balance.

Glucagon-like peptide-1/glucagon receptor agonism associates with reduced metabolic adaptation and higher fat oxidation: A randomized trial.

OBJECTIVE: This study tested the hypothesis that treatment with the glucagon-like peptide-1/glucagon receptor agonist SAR425899 would lead to a smaller decrease in sleeping metabolic rate (SMR; kilocalories/day) than expected from the loss of lean and fat mass (metabolic adaptation). METHODS: This Phase 1b, double-blind, randomized, placebo-controlled study was conducted at two centers in inpatient metabolic wards. Thirty-five healthy males and females with overweight and obesity (age = 36.5 ± 7.1 years) were randomized to a calorie-reduced diet (-1000 kcal/d) and escalating doses (0.06-0.2 mg/d) of SAR425899 (n = 17) or placebo (n = 18) for 19 days. SMR was measured by whole-room calorimetry. RESULTS: Both groups lost weight (-3.68 ± 1.37 kg placebo; -4.83 ± 1.44 kg SAR425899). Those treated with SAR425899 lost more weight, fat mass, and fat free mass (p < 0.05) owing to a greater achieved energy deficit than planned. The SAR425899 group had a smaller reduction in body composition-adjusted SMR (p = 0.002) as compared with placebo, but not 24-hour energy expenditure. Fat oxidation and ketogenesis increased in both groups, with significantly greater increases with SAR425899 (p < 0.05). CONCLUSIONS: SAR425899 led to reduced selective metabolic adaptation and increased lipid oxidation, which are believed to be beneficial for weight loss and weight-loss maintenance.

Cardiopulmonary Exercise Testing in a Prospective Multicenter Cohort of Older Adults: The Study of Muscle, Mobility and Aging (SOMMA).

BACKGROUND: Cardiorespiratory fitness (CRF) measured by peak oxygen consumption (VO2peak) declines with aging and correlates with mortality and morbidity. Cardiopulmonary Exercise Testing (CPET) has long been the criterion method to assess CRF, but its feasibility, efficacy and reliability in older adults is unclear. The large, multicenter Study of Muscle, Mobility and Aging (SOMMA) employed CPET to evaluate the mechanisms underlying declines in mobility with aging among community-dwelling older adults. Our primary objective was to design and implement a CPET protocol in older adults that was dependable, safe, scientifically valuable, and methodologically reliable. METHODS: CPET was performed using treadmill exercise in 875 adults ≥70 years. A composite protocol included a symptom-limited peak exercise phase and two submaximal phases to assess cardiopulmonary ventilatory indices during 1) participants' preferred walking speed and 2) at slow walking speed of 1.5 mph (0.67 m/s). An adjudication process was in place to review tests for validity if they met any prespecified criteria (VO2peak <12.0 ml/kg/min; maximum heart rate (HR) <100 bpm; respiratory exchange ratio (RER) <1.05 and a rating of perceived exertion <15). A repeat test was performed in a subset (N=30) to assess reproducibility. RESULTS: CPET was safe and well tolerated, with 95.8% of participants able to complete the VO2peak phase of the protocol. Only 56 (6.4%) participants had a risk alert during any phase of testing and only two adverse events occurred during the peak phase: a fall and atrial fibrillation. The average ± standard deviation for VO2peak was 20.2 ± 4.8 mL/kg/min, peak HR 142 ± 18 bpm, and peak RER 1.14 ± 0.09. VO2peak and RER were slightly higher in men than women. Adjudication was indicated in 47 participants; 20 were evaluated as valid, 27 as invalid (18 had a data collection error, 9 did not reach VO2peak). Reproducibility of VO2peak was high (intraclass correlation coefficient=0.97). CONCLUSIONS: CPET was feasible, effective and safe for community-dwelling older adults, many of whom had multimorbidity and frailty. These data support a broader implementation of CPET to provide important insight into the role of CRF and its underlying determinants in aging and age-related conditions and diseases. Clinical Perspective: What Is New?: Performing cardiopulmonary exercise testing in a community dwelling older adult with multimorbidities or frailty is feasible and exceptionally safe under highly trained exercise physiologists and physician supervision.Reproducibility of VO2peak among community-dwelling older adults with significant clinical complexity was high (intraclass correlation coefficient=0.97).The VO2peak observed was comparable to established normative data for older adults, and adds merit to the limited data collected on VO2peak norms in older adults.What Are the Clinical Implications?: Ventilatory gas collection during clinical cardiac stress testing may be valuable to plan of care in routine management of older adults due to the important role of aerobic fitness on morbidity and mortality.Cardiopulmonary exercise testing can provide insight into the role of cardiorespiratory fitness and its underlying determinants in aging and age-related conditions and diseases.

Weight Loss and Exercise Differentially Affect Insulin Sensitivity, Body Composition, Cardiorespiratory Fitness, and Muscle Strength in Older Adults With Obesity: A Randomized Controlled Trial.

BACKGROUND: Aging-related disease risk is exacerbated by obesity and physical inactivity. It is unclear how weight loss and increased activity improve risk in older adults. We aimed to determine the effects of diet-induced weight loss with and without exercise on insulin sensitivity, VO2peak, body composition, and physical function in older obese adults. METHODS: Physically inactive older (68.6 ± 4.5 years) obese (body mass index 37.4 ± 4.9 kg/m2) adults were randomized to health education control (HEC; n = 25); diet-induced weight loss (WL; n = 31); or weight loss and exercise (WLEX; n = 28) for 6 months. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp, body composition by dual-energy X-ray absorptiometry and MRI, strength by isokinetic dynamometry, and VO2peak by graded exercise test. RESULTS: WLEX improved (p < .05) peripheral insulin sensitivity (+75 ± 103%) versus HEC (+12 ± 67%); WL (+36 ± 47%) versus HEC did not reach statistical significance. WLEX increased VO2peak (+7 ± 12%) versus WL (-2 ± 24%) and prevented reductions in strength and lean mass induced by WL (p < .05). WLEX decreased abdominal adipose tissue (-16 ± 9%) versus HEC (-3 ± 8%) and intermuscular adipose tissue (-15 ± 13%) versus both HEC (+9 ± 15%) and WL (+2 ± 11%; p < .01). CONCLUSIONS: Exercise with weight loss improved insulin sensitivity and VO2peak, decreased ectopic fat, and preserved lean mass and strength. Weight loss alone decreased lean mass and strength. Older adults intending to lose weight should perform regular exercise to promote cardiometabolic and functional benefits, which may not occur with calorie restriction-induced weight loss alone.

External validation of a prediction model for estimating fat mass in children and adolescents in 19 countries: individual participant data meta-analysis.

OBJECTIVE: To evaluate the performance of a UK based prediction model for estimating fat-free mass (and indirectly fat mass) in children and adolescents in non-UK settings. DESIGN: Individual participant data meta-analysis. SETTING: 19 countries. PARTICIPANTS: 5693 children and adolescents (49.7% boys) aged 4 to 15 years with complete data on the predictors included in the UK based model (weight, height, age, sex, and ethnicity) and on the independently assessed outcome measure (fat-free mass determined by deuterium dilution assessment). MAIN OUTCOME MEASURES: The outcome of the UK based prediction model was natural log transformed fat-free mass (lnFFM). Predictive performance statistics of R2, calibration slope, calibration-in-the-large, and root mean square error were assessed in each of the 19 countries and then pooled through random effects meta-analysis. Calibration plots were also derived for each country, including flexible calibration curves. RESULTS: The model showed good predictive ability in non-UK populations of children and adolescents, providing R2 values of >75% in all countries and >90% in 11 of the 19 countries, and with good calibration (ie, agreement) of observed and predicted values. Root mean square error values (on fat-free mass scale) were <4 kg in 17 of the 19 settings. Pooled values (95% confidence intervals) of R2, calibration slope, and calibration-in-the-large were 88.7% (85.9% to 91.4%), 0.98 (0.97 to 1.00), and 0.01 (-0.02 to 0.04), respectively. Heterogeneity was evident in the R2 and calibration-in-the-large values across settings, but not in the calibration slope. Model performance did not vary markedly between boys and girls, age, ethnicity, and national income groups. To further improve the accuracy of the predictions, the model equation was recalibrated for the intercept in each setting so that country specific equations are available for future use. CONCLUSION: The UK based prediction model, which is based on readily available measures, provides predictions of childhood fat-free mass, and hence fat mass, in a range of non-UK settings that explain a large proportion of the variability in observed fat-free mass, and exhibit good calibration performance, especially after recalibration of the intercept for each population. The model demonstrates good generalisability in both low-middle income and high income populations of healthy children and adolescents aged 4-15 years.

Body composition, muscle strength, functional capacity, and physical disability risk in liver transplanted familial amyloidotic polyneuropathy patients.

BACKGROUND: Familial amyloidotic polyneuropathy (FAP) is a neurodegenerative disease leading to sensory and motor polyneuropathies, and functional limitations. Liver transplantation is the only treatment for FAP, requiring medication that negatively affects bone and muscle metabolism. The aim of this study was to compare body composition, levels of specific strength, level of physical disability risk, and functional capacity of transplanted FAP patients (FAPTx) with a group of healthy individuals (CON). METHODS: A group of patients with 48 FAPTx (28 men, 20 women) was compared with 24 CON individuals (14 men, 10 women). Body composition was assessed by dual-energy X-ray absorptiometry, and total skeletal muscle mass (TBSMM) and skeletal muscle index (SMI) were calculated. Handgrip strength was measured for both hands as was isometric strength of quadriceps. Muscle quality (MQ) was ascertained by the ratio of strength to muscle mass. Functional capacity was assessed by the six-minute walk test. RESULTS: Patients with FAPTx had significantly lower functional capacity, weight, body mass index, total fat mass, TBSMM, SMI, lean mass, muscle strength, MQ, and bone mineral density. CONCLUSION: Patients with FAPTx appear to be at particularly high risk of functional disability, suggesting an important role for an early and appropriately designed rehabilitation program.

Skeletal mass in adolescent male athletes and nonathletes: relationships with high-impact sports.

Dias Quiterio, AL, Canero, EA, Baptista, FM, and Sardinha, LB. Skeletal mass in adolescent male athletes and nonathletes: relationships with high-impact sports. J Strength Cond Res 25(12): 3439-3447, 2011-This study examined the relationships between the practice of different categories of sports (high-impact vs. nonimpact) and bone status in adolescent male athletes and investigated differences from an age-matched control group. A total of 54 adolescent male athletes and 26 adolescent nonathletes were evaluated. Bone mineral density, bone mineral content (BMC), and bone area at the whole-body, limbs, and lumbar spine were determined by dual-energy x-ray absorptiometry, along with total and regional fat-free mass and body fat. The high-impact group included 34 athletes: 9 gymnasts, 18 basketball players, and 7 handball players (age: 15.7 ± 1.6 years; weight: 72.0 ± 15.0 kg; height: 178.5 ± 12.5 cm). The nonimpact group consisted of 20 swimmers (age: 16.4 ± 2.5 years; weight: 66.9 ± 10.4 kg; height: 173.7 ± 10.9 cm). The nonathletic control group included 26 male adolescents (age: 15.9 ± 2.8 years; weight: 64.7 ± 16.3 kg; height: 168.6 ± 15.1 cm). No differences were observed between the nonimpact and the control group in all bone variables, before and after adjustments for maturation level, body weight, and height (p > 0.05). After adjustments for these variables, the high-impact group displayed greater bone mass in most of the measured sites when compared to the other 2 groups (p < 0.001). Subjects in the nonimpact group showed lower values of BMC, particularly in the lower limbs, than both the high-impact and the nonathletic control groups (p < 0.05) after adjustments for maturation, high, and fat-free mass. This study reinforces the positive associations between high-impact physical activities and skeletal health in adolescent boys.

Developing a model for estimating the activity of colonic microbes after intestinal surgeries.

BACKGROUND: The large intestine provides a compensatory role in energy recovery when surgical interventions such as extensive small intestinal resections or bypass operations lower the efficiency of nutrient absorption in the upper gastrointestinal (GI) tract. While microorganisms in the colon are known to play vital roles in recovering energy, their contributions remain to be qualified and quantified in the small intestine resection. OBJECTIVE: We develop a mathematical model that links nutrient absorption in the upper and lower GI tract in two steps. METHODS: First, we describe the effects of small intestine resection on the ileocecal output (ICO), which enters the colon and provides food for microbes. Second, we describe energy recovered by the colon's microorganisms via short-chain fatty acid (SCFA) production. We obtain model parameters by performing a least-squares regression analysis on clinical data for subjects with normal physiology and those who had undergone small intestine resection. RESULTS: For subjects with their intestines intact, our model provided a metabolizable energy value that aligns well with the traditional Atwater coefficients. With removal of the small intestine, physiological absorption became less efficient, and the metabolizable energy decreased. In parallel, the inefficiencies in physiological absorption by the small intestine are partly compensated by production of short-chain fatty acids (SCFA) from proteins and carbohydrates by microorganisms in the colon. The colon recovered more than half of the gross energy intake when the entire small intestine was removed. Meanwhile, the quality of energy absorbed changed, because microbe-derived SCFAs, not the original components of food, become the dominant form of absorbed energy. CONCLUSION: The mathematical model developed here provides an important framework for describing the effect of clinical interventions on the colon's microorganisms.

Reliability of measurements of energy expenditure and substrate oxidation using whole-room indirect calorimetry.

OBJECTIVE: This analysis aimed to measure the intraparticipant reliability-the intraclass correlation coefficient-of all the components of daily energy expenditure (EE) (24-hour EE, sleep EE, resting EE, basal EE, and thermic effect of food) over a period of 3 consecutive days in 35 study participants. METHODS: The components of daily EE and substrate use (respiratory exchange ratio) were measured over 3 consecutive days before and after a 3-week 1,000-kcal/d caloric restriction/weight-loss intervention. RESULTS: There was a high degree of reliability for sleep EE (96.8%), 24-hour EE (97.8%), basal EE (90.6%), and resting EE (93.2%) during the run-in period. The intraclass correlation coefficient for the follow-up period after weight loss (3.67 ± 1.10 kg) remained high for sleep EE (95.6%), 24-hour EE (100%), basal EE (96.1%), and resting EE (92.5%). The minimal detectable differences in EE were reduced by 30% for both 24-hour EE and sleep EE when comparing 2 days versus 1 day spent in the whole-room indirect calorimeter. CONCLUSIONS: The reliability of the daily components of EE is very high both prior to and after a weight-loss intervention. We here provide instrumental data for investigators to adequately power studies investigating energy metabolism using whole-room indirect calorimetry.

Prolonged Glucagon Infusion Does Not Affect Energy Expenditure in Individuals with Overweight/Obesity: A Randomized Trial.

OBJECTIVE: The aim of this study was to determine the effects of prolonged (72 hours) glucagon administration at a low dose (LD) (12.5 ng/kg/min) and high dose (HD) (25 ng/kg/min) on energy expenditure (EE) in healthy individuals with overweight or obesity. METHODS: Thirty-one healthy participants with overweight or obesity (BMI of 27-45 kg/m2 , 26-55 years old, 23 females) were randomized into LD, HD, or placebo groups and underwent 72-hour intravenous infusion of glucagon. Whole-room calorimetry was used to assess EE and substrate use during five overnight stays (2 days at baseline, 3 days of infusion) and during two 24-hour stays (baseline vs. day 3). Blood was sampled at regular intervals throughout the inpatient stay and analyzed for glucagon and biomarkers of metabolism. RESULTS: HD infusion elevated plasma glucagon levels compared with the placebo and LD infusion (P < 0.001). Sleeping, basal, and 24-hour EE was not significantly different among groups at any time point. Those receiving HD had significantly higher basal fat oxidation (Fat Ox) at days 2 and 3 than those receiving the placebo (P < 0.05); however, no differences in 24-hour Fat Ox were observed among groups (baseline vs. day 3). CONCLUSIONS: An HD plasma glucagon infusion over 72 hours does not increase any aspects of EE in healthy individuals with overweight or obesity.

Sedentariness and Physical Activity during School Recess Are Associated with VO2Peak.

Recess time (RT) is a main component of school-based activities, and could contribute up to 40% of the physical activity (PA) recommended in the health guidelines. The main goal was to analyze the association between accelerometer-measured PA and sedentary time during RT with cardiorespiratory fitness (CRF). A total of 146 children and adolescents, aged 8-19 years, were recruited from six schools. PA levels were measured with GT3X accelerometers over 7 days. CRF was measured using a portable breath-by-breath gas analyzer. A general linear model (GML) was conducted to analyze the association between PA intensities and CRF during RT. Additionally, a logistic binary regression was used to evaluate the risk of unhealthy CRF among different categories of PA and sedentary time. Participants classified as healthy showed higher PA levels during RT than those classed as unhealthy. GML analysis showed that sedentary time during RT was significantly associated with VO2Peak. Finally, individuals who were sedentary for more than 15 min during RT presented 97.7% lower odds of having unhealthy CRF (adjusted Odds Ratio = 0.023, 95% CI -0.002 to 0.263). Our data suggest an association between recess sedentary time and unhealthy CRF. Thus, school-aged children and adolescents must be empowered to perform PA during RT to prevent the deleterious effects of sedentary time on CRF.