Increases in intracellular water explain strength and power improvements over a season.

Changes in body components occur over a season, but their impact on performance is still unclear. We aimed to analyze the relationship between changes in leg strength and jump performance with body composition over a season in highly trained athletes. Measures from the beginning to the main competitive periods of a season were obtained in 40 male and 23 female basketball, handball and volleyball players (20±5 years) for fat (FM) and fat-free mass (FFM) estimated by DXA. Total body water (TBW) and extracellular water (ECW) were assessed by deuterium and bromide dilution, respectively, and intracellular water (ICW) was calculated as TBW minus ECW. Maximal strength was determined by the leg press, while jumping height was assessed with squat (SJ) and countermovement (CMJ) jumps. Significant improvements in strength (12.5±20.8%) and jumping height (SJ:8.3±13.9%; CMJ:6.3±8.5%) were found. FFM, TBW and ECW significantly increased (3.0±2.7%; 1.7±5.5%; 3.0±8.6%, respectively), while %FM decreased (-4.5±9.1%) and no changes were observed in ICW (1.2±9.7%). Among body composition changes only ICW was associated with performance even adjusted for gender, age, season length and sport (strength: ß=71.209, p=0.012; SJ: ß=0.311, p=0.049; CMJ: ß=0.366, p=0.018). Body composition, strength and jumping height improved over a season and ICW was the main predictor of performance in national level players.

Association of basketball season with body composition in elite junior players.

AIM: Body composition changes among elite athletes may influence competitive performance. This study aimed to characterize the body composition changes at the molecular, cellular, tissue, and whole-body level of analysis in elite junior basketball players during the course of a season. METHODS: Twelve males and 11 females (16 to 17 years) were evaluated. Dual-energy X-ray absorptiometry (DXA) was used to assess bone mineral (Mo) and lean-soft tissue (LST). Total-body water (TBW) and extracellular water (ECW) were assessed using isotope dilution techniques, and extracellular (ECF) and intracellular fluids (ICF) were calculated. Fat mass (FM) and fat-free mass (FFM) were assessed with a four-compartment model. Body cell mass was calculated (LST - (ECF + ECS)). Skeletal muscle (SM) was estimated using appendicular LST (ALST) as: (1.19 x ALST) - 1.65. At the whole-body level, weight, sum of 7 skinfolds, and muscle circumferences (Mc) were measured. The handgrip and the countermovement jump tests were used for performance assessment. RESULTS: Males increased FFM (4.4±2.3%), TBW (3.5±4.6%), SM (4.5±2.3%), and arm (3.4±2.7%) and thigh (3.8±3%) Mc. Females increased SM (5.9±4.6%) and arm (3.6±3.8%) and thigh (4±5.2%) Mc and decreased ICF (-9.7±13.6%). FFM components differed from the established values based on cadaver analysis. Both genders increased their performance and associations were found between changes in molecular and whole-body components with performance. CONCLUSION: In conclusion the season was associated with an improved body composition profile in males and few changes in females.

Leucine metabolites do not induce changes in phase angle, bioimpedance vector analysis patterns, and strength in resistance trained men.

We aimed to assess the effects of off-the-shelf leucine metabolite supplements on phase angle (PhA), bioimpedance vector analysis (BIVA) patterns and strength during an 8-week resistance training protocol. Fifty-three male participants were allocated into 4 groups: α-hydroxyisocaproic acid (n = 12, age = 30.9 ± 9.3 years), ß-hydroxy-ß-methylbutyrate free acid (n = 12, age = 31.0 ± 9.3 years), calcium ß-hydroxy-ß-methylbutyrate (n = 15, age = 32.1 ± 5.2 years) or placebo (n = 14, age = 28.9 ± 6.6 years). Bioimpedance parameters and 1-repetition maximum (1RM) for back squat and bench press were assessed at baseline and at the end of weeks 4 and 8. Additionally, fat-free mass and fat mass were evaluated by dual-energy X-ray absorptiometry. No statistically group by time interactions were found, even adjusting for age. PhA and vector did not change over the training period, while time-dependent increases were observed for 1RM back squat and 1RM bench press. A direct association was observed between PhA and 1RM bench press changes (whole sample), while PhA and strength were correlated throughout the study, even when adjusting for fat-free mass and percentage of fat mass. Leucine metabolites have no effect on PhA, BIVA patterns or strength during an 8-week resistance training program, in resistance trained subjects. The trial was registered at ClincicalTrials.gov: NCT03511092. Novelty: Supplementation with leucine metabolites is not a supplementation strategy that improves bioelectrical phase angle, cellular health, and strength after an 8-week resistance training program. When consuming a high protein diet, none of the α-hydroxyisocaproic acid, ß-hydroxy-ß-methylbutyrate free acid, and calcium ß-hydroxy-ß-methylbutyrate metabolites resulted in an ergogenic effect in resistance trained men.

Predictive equation for assessing appendicular lean soft tissue mass using bioelectric impedance analysis in older adults: Effect of body fat distribution.

BACKGROUND: Low muscle mass is associated with sarcopenia and increased mortality. Muscle mass, especially that of the limbs, is commonly estimated by dual-energy X-ray absorptiometry (DXA) or bioimpedance analysis (BIA). However, BIA-based predictive equations for estimating lean appendicular soft tissue mass (ALST) do not take into account body fat distribution, an important factor influencing DXA and BIA measurements. OBJECTIVES: To develop and cross-validate a BIA-based equation for estimating ALST with DXA as criterion, and to compare our new formula to three previously published models. METHODS: One-hundred eighty-four older adults (140 women and 44 men) (age 71.5 ±â€¯7.3 years, body mass index 27.9 ±â€¯5.3 kg/m2) were recruited. Participants were randomly split into validation (n = 118) and cross-validation groups (n = 66). Bioelectrical resistance was obtained with a phase-sensitive 50 kHz BIA device. RESULTS: A BIA-based model was developed for appendicular lean soft tissue mass [ALST (kg) = 5.982 + (0.188 × S2 / resistance) + (0.014 × waist circumference) + (0.046 × Wt) + (3.881 × sex) - (0.053 × age), where sex is 0 if female or 1 if male, Wt is weight (kg), and S is stature (cm) (R2 = 0.86, SEE = 1.35 kg)]. Cross validation revealed r2 of 0.91 and no mean bias. Two of three previously published models showed a trend to significantly overestimate ALST in our sample (p < 0.01). CONCLUSIONS: The new equation can be considered valid, with no observed bias and trend, thus affording practical means to quantify ALST mass in older adults.

Phase angle predicts physical function in older adults.

BACKGROUND: Phase angle (PhA) is recognized as an indicator of cellular health and may be a useful marker of physical functions in geriatric populations. AIMS: We aim to analyse the ability of the Phase angle (PhA) to predict the physical function in older adults. METHOD: 113 healthy older adults (67 female and 46 male) performed physical tests using the Fullerton Battery - Senior Fitness Test, to assess their physical fitness. Bioelectrical impedance spectroscopy was used to determine PhA at 50KHz and dual-energy x-ray absorptiometry to assess body composition. RESULTS: PhA was positively associated with functional fitness composite, chair stand, arm curl and 6 min walk test and negatively related with chair sit-and-reach and 8-foot and go (p < 0.05). Even after adjusting for potential confounding variables such as age, sex and appendicular lean soft tissue, PhA showed an association with arm curl (ß = 0.23,p = 0.038), and 8-foot and go (ß=-0.214,p = 0.042). CONCLUSIONS: Higher values of PhA are related with a better physical function. Regardless of sex, age, and skeletal muscle, PhA predicts body strength, agility and dynamic balance in healthy older adults.

Accuracy of a combined heart rate and motion sensor for assessing energy expenditure in free-living adults during a double-blind crossover caffeine trial using doubly labeled water as the reference method.

BACKGROUND/OBJECTIVES: A combined heart rate (HR) and motion sensor (Actiheart) has been proposed as an accurate method for assessing total energy expenditure (TEE) and physical activity energy expenditure (PAEE). However, the extent to which factors such as caffeine may affect the accuracy by which the estimated HR-related PAEE contribution will affect TEE and PAEE estimates is unknown. Therefore, we examined the validity of Actiheart in estimating TEE and PAEE in free-living adults under a caffeine trial compared with doubly labeled water (DLW) as reference criterion. SUBJECTS/METHODS: Using a double-blind crossover trial (Clinicaltrials.gov ID: #NCT01477294) with two conditions (4-day each with a 3-day-washout period), randomly ordered as caffeine (5 mg/kg per day) and placebo (malt-dextrine) intake, TEE was measured by DLW in 17 physically active men (20-38 years) who were non-caffeine users. In each condition, resting energy expenditure (REE) was assessed by indirect calorimetry and PAEE was calculated as (TEE-(REE+0.1 TEE)). Simultaneously, PAEE and TEE were estimated by Actiheart using an individual calibration (ACC+HRstep). RESULTS: Under caffeine, ACC+HRstep explained 76 and 64% of TEE and PAEE from DLW, respectively; corresponding results for the placebo condition were 82 and 66%. No mean bias was found between ACC+HRstep and DLW for TEE (caffeine:-468 kJ per day; placebo:-407 kJ per day), although PAEE was slightly underestimated (caffeine:-856 kJ per day; placebo:-1147 kJ per day). Similar limits of agreement were observed in both conditions ranging from -2066 to 3002 and from -3488 to 1776 kJ per day for TEE and PAEE, respectively. CONCLUSIONS: Regardless of caffeine intake, the combined HR and motion sensor is valid for estimating free-living energy expenditure in a group of healthy men but is less accurate for an individual assessment.