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.

Effects of pre- or post-exercise whey protein supplementation on body fat and metabolic and inflammatory profile in pre-conditioned older women: A randomized, double-blind, placebo-controlled trial.

BACKGROUND AND AIM: Protein supplementation and resistance training (RT) are interventions that may counteract decline in muscle mass and increase in fat mass, thus reducing the risk of developing chronic diseases during the aging process. The objective of this study was to investigate the effect of whey protein (WP) pre- or post-RT on metabolic and inflammatory profile in pre-conditioned older women. METHODS AND RESULTS: Seventy older women participated in this investigation and were randomly assigned to one of three groups: WP pre-RT and placebo post-RT (WP-PLA, n = 24), placebo pre-RT and WP post-RT (PLA-WP, n = 23) and placebo pre and post-RT (PLA-PLA, n = 23). Each group ingested 35 g of PLA or WP pre- and post-RT. RT was carried out over 12 weeks (three times/week; 3 x 8-12 repetition maximum). Body composition, blood pressure, blood samples and dietary intake were assessed pre- and post-intervention. After the intervention, WP groups showed greater improvements in appendicular lean soft tissue (ALST: WP-PLA, 3.1%; PLA-WP, 3.9%; PLA-PLA, 1.8%) and total cholesterol/high density lipoprotein cholesterol ratio (TC/HDL-C: WP-PLA, -12.11%; PLA-WP, -13.2%; PLA-PLA, -0.7) when compared with PLA-PLA. WP post-RT also showed improvements (P < 0.05) in ALST/appendicular fat mass ratio (PLA-WP, 5.8%; PLA-PLA, 1.3%), total body fat (PLA-WP, -3.8%; PLA-PLA: -0.1) and trunk fat mass (PLA-WP, -3.1%; PLA-PLA, -0.3%) when compared with PLA-PLA. CONCLUSION: WP pre- or post- RT promotes improvements in ALST and TC/HDL-C ratio in pre-conditioned older women. WP administered after RT was more effective in improving metabolic health Z-score and in reducing body fat compared to placebo group.

Correlations between resistance training-induced changes on phase angle and biochemical markers in older women.

The main purpose of this study was to investigate the effects of 12 weeks of resistance training (RT) on phase angle (PhA), inflammatory and oxidative stress biomarkers, and to evaluate whether these RT-induced adaptations are related to PhA changes. Fifty-one older women (70.6 ± 5.1 years; 26.9 ± 4.2 kg/m2 ) were randomly allocated into a training group (TG) that performed 12-week RT or a nonexercising control group (CG). The PhA (Xitron), body composition (DXA), and blood sample measurements (after a 12 hours fast) were performed before and after the intervention. The TG showed a significant (P < .05) increase in PhA (TG: +7.4±5.9% vs CG: -3.6 ± 8.8%), and interleukin-10 (IL-10; TG: +51.8 ± 71.1% vs CG: -46.6 ± 38.0%), and a decrease in tumor necrosis factor alpha (TNF-α; TG: -15.2 ± 11.1% vs CG: +6.9±17.7%), interleukin-6 (IL-6; TG: -17.9 ± 17.8% vs CG: +6.1 ± 24.8%), and C-reactive protein (CRP; TG: -24.1 ± 19.9% vs CG: +43.8 ± 31.1%). Moreover, TG upregulated catalase (TG: +11.4 ± 15.0% vs CG: -6.7 ± 10.2%). Changes in TNF-α (r = -.71), CRP (r = -.65), lower advanced oxidation protein products (r = -.55), and catalase (r = +.73) after RT were correlated with changes in PhA (P < .05). These results suggest that RT improves PhA, inflammatory and oxidative stress biomarkers, and the changes in inflammatory and oxidative damage markers are correlated with changes in PhA.

Birth weight, biological maturation and obesity in adolescents: a mediation analysis.

This study was aimed to investigate associations between birth weight and multiple adiposity indicators in youth, and to examine potential mediating effects by biological maturation. This was a school-based study involving 981 Brazilian adolescents aged between 10 and 17 years. Birth weight was reported retrospectively by mothers. Maturation was estimated by age of peak height velocity. Adiposity indicators included body mass index (BMI), waist circumference and percent body fat estimated from triceps and subscapular skinfolds. Multilevel mediation analyses were performed using the Sobel test, adjusted for chronological age, gestational age, cardiorespiratory fitness and socio-economic status. Except for body fat in girls, biological maturation partly or fully mediated (P<0.05) positive relationships between birth weight with all other obesity indicators in both sexes with their respective values of indirect effects with 95% confidence intervals: BMI [boys: 0.44 (0.06-0.82); girls: 0.38 (0.13-0.64)], waist circumference [boys: 1.14 (0.22-2.05); girls: 0.87 (0.26-1.48)] and body fat [boys: 0.60 (0.13-1.07)]. To conclude, birth weight is associated with elevated obesity risk in adolescence and biological maturation seems to at least partly mediate this relationship.

Effect of resistance training on phase angle in older women: A randomized controlled trial.

Phase angle (PhA) is an angular-derived bioelectrical impedance parameter based on resistance and reactance that has been widely used in different populations as an objective indicator of cellular health. The purpose of this study was to analyze the effect of resistance training (RT) on PhA in older women. Forty-one older women (67.2 ± 4.5 years, 64.0 ± 12.3 kg, 154.7 ± 5.2 cm, and 26.6 ± 4.8 kg/m2 ) were randomly assigned to one of two groups: a training group (TG, n = 19) that underwent progressive RT for 12 weeks (eight exercises, three sets of 10-15 repetitions maximum, three times per week) or a control group (CG, n = 22) that did not perform any type of exercise during the intervention period. Resistance, reactance, PhA, total body water (TBW), intracellular (ICW) and extracellular (ECW) water were assessed by spectral bioelectrical impedance. There was a significant group by time interaction (P < 0.05) for PhA, TBW, and ICW in which only the TG increased their scores after the intervention period (PhA = +6.5%, TBW = +2.8%, and ICW = +5.1%). The results suggest that progressive RT promotes an increase in PhA in older women. Therefore, the PhA seems to be a good parameter to assess changes in cellular health during RT intervention.

Hypertrophy-type Resistance Training Improves Phase Angle in Young Adult Men and Women.

The main purpose of the present study was to investigate the effect of a hypertrophy-type resistance training protocol on phase angle, an indicator of cellular integrity, in young adult men and women. 28 men (22.2±4.3 years, 67.8±9.0 kg and 174.2±6.8 cm) and 31 women (23.2±4.1 years, 58.7±12.1 kg and 162.7±6.4 cm) underwent a progressive RT for 16 weeks (2 phases, 8 weeks each), 3 times per week, consisting of 10 to 12 whole body exercises with 3 sets of 8-12 repetitions maximum. Phase angle, resistance, reactance and total body water (intra and extracellular water compartments) were assessed by bioimpedance spectroscopy (Xitron 4200 Bioimpedance Spectrum Analyzer). Total body water, intracellular water and phase angle increased significantly (P<0.05) in men (7.8, 8.3, and 4.3%, respectively) and women (7.6, 11.7, and 5.8% respectively), with no significant difference between sexes (P>0.05). Bioimpedance resistance decreased (P<0.05) similarly in both sex (men=-4.8%, women=-3.8%). The results suggest that regardless of sex, progressive RT induces an increase in phase angle and a rise in cellular hydration.

Changes in phase angle and body composition induced by resistance training in older women.

BACKGROUND: Resistance training (RT) has selective effects on body composition that may counteract the deleterious effects of aging. Changes in phase angle (PhA) may serve to monitor the influence of RT in older people. OBJECTIVES: To describe the effect of RT in training, detraining and retraining on body composition, including PhA in older women. SUBJECTS/METHODS: Thirty-three older women (⩾60 years old) participated. The RT program was carried out over 12 weeks for each stage (training, detraining and retraining). Whole-body fat-free mass and fat mass (FM) and appendicular lean soft tissue (ALST) measurements were carried out using a dual energy X-ray absorptiometry. Bioimpedance spectroscopy was used to estimate total body water (TBW), intra (ICF) and extracellular (ECF) fluids, whole-body resistance (R) and reactance (Xc) and PhA. Upper and lower body muscle strength were also assessed. RESULTS: From baseline to after training muscle strength, ALST and PhA significantly (P<0.05) increased. In detraining, significant (P<0.05) reductions in muscle strength, TBW, ECF, ICF and PhA along with significant (P<0.05) increases in R were observed, with the greatest magnitude observed for PhA (Δ=-7.6%). From detraining to retraining a significant reduction in FM along with increases in Xc, PhA and muscle strength were observed. Although an increase was observed from detraining to retraining in PhA, the values were still lower than baseline PhA. CONCLUSIONS: In untrained older women, a RT is associated with increases in PhA, whereas detraining results in a marked decrease in PhA, and more time may be required in retraining to counteract the negative influence of absence of exercise stimulus.

Influence of Skeletal Maturity on Size, Function and Sport-specific Technical Skills in Youth Soccer Players.

This study compared variation in size, function and sport-specific technical skills of youth soccer players associated with differences in biological maturity status. 60 male soccer players of under-14 (U14) and under-17 (U17) categories were submitted to anthropometric and body composition measurements as well as motor and soccer-specific technical skill tests. Skeletal maturity was determined by skeletal age. Athletes of both categories were classified as early, on-time or late-maturing, according to the difference between chronological age and skeletal age. Body mass and height were lower in the late athletes, independent of category (P<0.01). Differences in adiposity were found only between athletes of the U14 (late

Cardiovascular adaptations to resistance training in elderly postmenopausal women.

The purpose of this study was to investigate the effect of resistance training on resting blood pressure and heart rate variability in elderly postmenopausal women. 29 untrained, non-hypertensive elderly women were randomly assigned to 2 groups: an intervention group (n=15, 65.5±5.0 years, 57.3±6.5 kg, 156.7±5.1 cm) that underwent a supervised resistance training program (8 exercises, 2 sets, 10-15 repetitions, 3 times/week) or a control group (n=14, 66.2±4.1 years, 61.1±11.7 kg, 157.5±7.1 cm) that participated in a supervised stretching program (25-30 min/session, 2 times/week). Resting auscultatory blood pressure, heart rate variability, evaluated from short recordings in a seated position, and maximal dynamic strength (1-RM test) were measured at baseline and after 12 weeks. A group x time ANOVA revealed that muscular strength increased significantly in the resistance training group (+ 10.2% for bench press and +12.7% for leg extension, P<0.05). Systolic blood pressure was reduced significantly in the resistance training group from pre- to post-intervention period (- 5 mmHg; P<0.05), while no significant effect was noted for diastolic blood pressure and heart rate variability indexes (P>0.05). None of these variables changed in the control group throughout the study. In conclusion, a supervised resistance training program improved muscular strength and reduced systolic blood pressure without affecting diastolic blood pressure and heart rate variability in elderly postmenopausal women.

Changes in skeletal muscle mass assessed by anthropometric equations after resistance training.

The aim of this study was to analyze the validity of anthropometric equations to identify changes in skeletal muscle mass (SMM) after resistance training (RT). Anthropometric and dual energy x-ray absorptiometry (DXA) measurements were obtained at baseline and after RT in 15 trained Caucasian college men. Participants performed RT over 8 weeks, consisting of 8-9 exercises of 4 sets with 12/10/8/6 maximal repetitions and 1-2 min interval between sets. The training loads were gradually increased according to gains in muscular strength. 4 anthropometric equations were used for estimation of SMM: EQ1 (SMM, g=height×[0.0553×corrected thigh girth2 + 0.0987×forearm girth2 + 0.0331×corrected calf girth2] - 2445), EQ2 (SMM, g=height×[0.031×medial thigh girth2 + 0.064×corrected calf girth2 + 0.089×corrected arm girth2] - 3006), EQ3 (SMM, kg=height×[0.00744×corrected arm girth2 + 0.00088×corrected thigh girth2 + 0.00441×corrected calf girth2] + 2.4×gender - 0.048×age + race + 7.8) and EQ4 (SMM, kg=0.244×weight + 7.8×height + 6.6×gender - 0.098×age + race - 3.3). EQ1 and EQ2 overestimated the SMM (41.3% and 19.9%, respectively; P<0.05) while EQ3 and EQ4 were similar (P>0.05) to DXA at baseline. Although all equations and DXA revealed a significant increase in SMM after RT, changes were overestimated by EQ1 and EQ2 (P<0.05), but not by EQ3 and EQ4 (P>0.05). In addition, changes in SMM over time between EQ4 and DXA were significantly correlated (r=0.62; P<0.01). Thus, changes in SMM that occur after RT can be detected by EQ4 in trained young men.

Modelling developmental changes in repeated-sprint ability by chronological and skeletal ages in young soccer players.

This study investigated the influence of chronological (CA) and skeletal ages (SA), anthropometry, aerobic endurance and lower limb explosive strength on developmental changes in repeated-sprint ability (RSA) in soccer players aged 11-17 years. Participants were annually followed over 5 years, resulting in 366 measurements. Multilevel regression modelling analysed longitudinal data aligned by CA and SA (Model 1 and 2, respectively). After diagnosing for multicollinearity, it was possible to predict RSA with 2-level hierarchical models [Model 1 (CA as Level 2 predictor): Log-Likelihood=1,515.29, p<0.01; Model 2 (SA as Level 2 predictor): Log-Likelihood=1,513.89, p<0.01]. Estimating sum of sprints for young soccer players are given by equations: sum of sprints=84.47 - 1.82 × CA + 0.03 × CA2 - 0.05 × aerobic endurance - 0.10 × lower limb explosive strength -0.09 × fat-free mass + 0.13 × fat mass (Model 1); 73.58 - 0.43 × SA - 0.05 × aerobic endurance - 0.10 × lower limb explosive strength - 0.08 × fat-free mass - 0.45 × training experience + 0.13 × fat mass (Model 2). The models produced performance curves that may be used to estimate individual performance across adolescent years. Finally, the validity of each model was confirmed based on corresponding measurements taken on an independent cross-sectional sample.

Time-of-day effect on hip flexibility associated with the modified sit-and- reach test in males.

Flexibility is a key component of physical fitness. It has been suggested that measures of physical fitness components may vary throughout the day. The aim of this study was to analyse the effects of the time of day on flexibility performance. 26 men (mean age=25.4 years, SD=2.5) were evaluated by hip flexion on kinematic analysis and also by an absolute score in the modified Sit-and-Reach test during a repeated measure design. This was done during 3 experimental sessions, which took place at 8:00 a.m., 1:00 p.m. and 6:00 p.m., in random order. All subjects were previously familiarized with the test parameters. There was a diurnal variation only in the modified Sit-and-Reach test score between 8:00 a.m and 6:00 p.m. (P=0.01). There was no significant difference in the hip kinematic analysis between hours. These findings suggest that flexibility performance in the modified Sit-and-Reach test, in absolute scores, is affected by the time of day, with higher performance in the evening.