Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 12 de 12
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Strength Cond Res ; 34(3): 678-688, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29927888

RESUMO

Schoenfeld, BJ, Nickerson, BS, Wilborn, CD, Urbina, SL, Hayward, SB, Krieger, J, Aragon, AA, and Tinsley, G. Comparison of multifrequency bioelectrical impedance vs. dual-energy x-ray absorptiometry for assessing body composition changes after participation in a 10-week resistance training program. J Strength Cond Res 34(3): 678-688, 2020-The purpose of this study was to assess the ability of multifrequency bioelectrical impedance analysis (MF-BIA) to determine alterations in total and segmental body composition across a 10-week resistance training (RT) program in comparison with the criterion reference dual-energy X-ray absorptiometry (DXA). Twenty-one young male volunteers (mean ± SD; age = 22.9 ± 3.0 years; height = 175.5 ± 5.9 cm; body mass = 82.9 ± 13.6 kg; body mass index = 26.9 ± 3.6) performed an RT program that included exercises for all major muscle groups. Body composition was assessed using both methods before and after the intervention; change scores were determined by subtracting pre-test values from post-test values for percent body fat ([INCREMENT]%BF), fat mass ([INCREMENT]FM), and fat-free mass ([INCREMENT]FFM). Mean changes were not significantly different when comparing MF-BIA with DXA for [INCREMENT]%BF (-1.05 vs. -1.28%), [INCREMENT]FM (-1.13 vs. -1.19 kg), and FFM (0.10 vs. 0.37 kg, respectively). Both methods showed strong agreement for [INCREMENT]%BF (r = 0.75; standard error of the estimate [SEE] = 1.15%), [INCREMENT]FM (r = 0.84; SEE 1.0 kg), and [INCREMENT]FFM (r = 0.71; SEE of 1.5 kg). The 2 methods were poor predictors of each other in regards to changes in segmental measurements. Our data indicate that MF-BIA is an acceptable alternative for tracking changes in FM and FFM during a combined diet and exercise program in young, athletic men, but segmental lean mass measurements must be interpreted with circumspection.


Assuntos
Absorciometria de Fóton , Composição Corporal , Impedância Elétrica , Treinamento Resistido , Adiposidade , Adulto , Índice de Massa Corporal , Terapia por Exercício , Humanos , Masculino , Esportes , Adulto Jovem
2.
J Sports Sci Med ; 16(4): 459-467, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29238244

RESUMO

Dietary supplementation is commonly employed by individuals seeking to improve body composition and exercise performance. The purpose of the present study was to examine the safety and effectiveness of a commercially available dietary supplement designed to promote thermogenesis and fat loss. In a randomized double-blind trial, participants were assigned to consume placebo or a multi-ingredient supplement containing caffeine, green tea extract, l-carnitine, evodiamine and other ingredients that purportedly enhance thermogenesis. The study included acute baseline testing, a 6-week progressive resistance training and supplementation intervention, and post-intervention testing. Laboratory assessments included resting energy expenditure responses to acute supplement ingestion, evaluation of body composition and muscular performance, and analysis of blood variables (metabolic panel, testosterone, estrogen and cortisol). Dependent variables were analyzed using ANOVA with repeated measures. No unfavorable effects of supplementation were reported, and the supplement did not adversely affect safety markers. However, the supplement did not reduce fat mass or increase lean mass relative to placebo. In the supplement group, lower body maximal strength was increased relative to placebo (+18%, d=1.1 vs. +10%, d=0.5), and cortisol concentrations were decreased relative to placebo (-16%; d=-0.4 vs. +15%, d=.75). However, no differences were observed for upper body maximal strength or muscular endurance. REE increased in response to both supplement and placebo ingestion (placebo: +5%; supplement: +11.5%), but the difference between conditions was not statistically significant. Overall, some select parameters may have been beneficially modified by supplementation, but this did not result in superior weight or fat loss over 6 weeks of supplementation and resistance training.

4.
PeerJ ; 5: e2825, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28070459

RESUMO

The purpose of this study was to test the anabolic window theory by investigating muscle strength, hypertrophy, and body composition changes in response to an equal dose of protein consumed either immediately pre- versus post-resistance training (RT) in trained men. Subjects were 21 resistance-trained men (>1 year RT experience) recruited from a university population. After baseline testing, participants were randomly assigned to 1 of 2 experimental groups: a group that consumed a supplement containing 25 g protein and 1 g carbohydrate immediately prior to exercise (PRE-SUPP) (n = 9) or a group that consumed the same supplement immediately post-exercise (POST-SUPP) (n = 12). The RT protocol consisted of three weekly sessions performed on non-consecutive days for 10 weeks. A total-body routine was employed with three sets of 8-12 repetitions for each exercise. Results showed that pre- and post-workout protein consumption had similar effects on all measures studied (p > 0.05). These findings refute the contention of a narrow post-exercise anabolic window to maximize the muscular response and instead lends support to the theory that the interval for protein intake may be as wide as several hours or perhaps more after a training bout depending on when the pre-workout meal was consumed.

5.
J Sports Sci Med ; 15(4): 704-714, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27928217

RESUMO

We examined if two different dietary interventions affected markers of soreness and inflammation over a 5-day high-volume resistance training protocol in females that resistance-trained 8 weeks prior. Twenty-eight females (age: 20 ± 1 yr; body mass: 63.5 ± 1.6 kg, height: 1.67 ± 0.01 m) completed 4 weeks of pre-training (weeks 1-4) followed by a subsequent 4-week training period along with a dietary intervention (weeks 5-8). Dietary interventions from weeks 5-8 included: a) no intervention (CTL, n = 10) b) a higher-protein diet supplemented with hydrolyzed whey protein (50 g/d) and omega-3 fatty acids (900 mg/d) (DI, n = 8), and c) the DI condition as well as creatine monohydrate (5 g/d) (DI+C, n = 10). During week 9, participants resistance-trained for five consecutive days whereby 8 sets of 10 target repetitions at 70% one repetition maximum (1RM) were performed each day for bench press, back squat, deadlift, and hip-thrusters with the intent of eliciting muscle soreness and inflammation. Prior to and 24 h following each of the 5 bouts muscle soreness (DOMS) was assessed via questionnaire, and fasting blood was obtained and analyzed for serum cortisol, interleukin-6 (IL-6) and C-reactive protein (CRP). No group*time (G*T) or time effects were observed for training volume over the 5-d overreaching protocol. Furthermore, no group*time (G*T) or time effects were observed for serum cortisol, IL-6 or CRP, and DOMS actually decreased in all groups 24 h following the fifth day training bout. This study demonstrates that, regardless of protein, omega-3 fatty acid and/or creatine supplementation, 5 days of consecutive resistance training does not alter perceived muscle soreness, training volume, and/or markers of inflammation in novice resistance-trained females.

6.
Ann Nutr Metab ; 69(3-4): 190-199, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27866187

RESUMO

AIMS: We performed a pilot study examining the effects of whey protein and creatine supplementation (PRO + CRE group) versus whey protein supplementation (PRO group) alone on body composition and performance variables in a limited number of resistance-trained women. METHODS: Seventeen resistance-trained women (21 ± 3 years, 64.7 ± 8.2 kg, 23.5 kg/m2, 26.6 ± 4.8% body fat, >6 months of training) performed a 4-day per week split-body resistance training program for 8 weeks. Subjects ingested either 24 g PRO (n = 9) or 24 g whey plus 5 g creatine monohydrate (PRO + CRE, n = 8) following each exercise bout. At baseline (T1), 4 weeks (T2) and 8 weeks (T3), body composition was measured by dual X-ray absorptiometry (DXA), strength measures (leg press and bench press one repetition maximum) and lower-body power measures were determined. RESULTS: DXA lean mass increased from T1 to T3 in both groups (PRO: +2.5 kg, p < 0.001; PRO + CRE: +2.5 kg, p < 0.001), although no differences between groups were observed. Compared to T1 values, performance measures similarly increased in both groups from T1 to T3 although, no between-group differences were observed. CONCLUSIONS: PRO + CRE did not enhance training adaptations compared to PRO, albeit studies employing longer-term interventions with larger sample sizes are needed in order to confirm or disprove our findings.


Assuntos
Creatina/administração & dosagem , Suplementos Nutricionais , Força Muscular , Treinamento Resistido , Proteínas do Soro do Leite/administração & dosagem , Absorciometria de Fóton , Composição Corporal , Feminino , Humanos , Projetos Piloto , Resultado do Tratamento , Adulto Jovem
7.
Artigo em Inglês | MEDLINE | ID: mdl-26766930

RESUMO

BACKGROUND: Theacrine (1,3,7,9-tetramethyluric acid) is a purine alkaloid found in certain coffee (Coffea) species, fruits (Cupuacu [Theobroma grandiflorum]), and tea (Camellia assamica, var. kucha) that has anti-inflammatory, analgesic, and neuro-locomotor properties. Recent preliminary research has also reported increased feelings of energy, reduced fatigue, and strong effects on improving focus, concentration, and motivation to exercise. The purpose of this study was to examine the safety and non-habituating effects of TeaCrine®, a nature-identical, chemically equivalent bioactive version of theacrine. METHODS: Sixty healthy men (mean ± SD age, height, weight: 22.9 ± 4.7 years, 183.5 ± 9.2 cm, 86.5 ± 13.7 kg) and women (22.3 ± 4.5 years, 165.2 ± 12.3 cm, 69.0 ± 17.4 kg) were placed into one of three groups: placebo (PLA, n = 20), 200 mg TeaCrine® (LD, n = 19) or 300 mg Teacrine® (HD, n = 21) and ingested their respective supplement once daily for 8 weeks. Primary outcomes were fasting clinical safety markers (heart rate, blood pressure, lipid profiles, hematologic blood counts, biomarkers of liver/kidney/immune function) and energy, focus, concentration, anxiety, motivation to exercise, and POMS measured prior to daily dosing to ascertain potential tachyphylactic responses and habituation effects. Data were analyzed via two-way (group × time) ANOVAs and statistical significance was accepted at p < 0.05. RESULTS: All values for clinical safety markers fell within normal limits and no group × time interactions were noted. No evidence of habituation was noted as baseline values for energy, focus, concentration, anxiety, motivation to exercise, and POMS remained stable in all groups across the 8-week study protocol. CONCLUSIONS: These findings support the clinical safety and non-habituating neuro-energetic effects of TeaCrine® supplementation over 8 weeks of daily use (up to 300 mg/day). Moreover, there was no evidence of a tachyphylactic response that is typical of neuroactive agents such as caffeine and other stimulants.


Assuntos
Anti-Inflamatórios/administração & dosagem , Suplementos Nutricionais , Voluntários Saudáveis , Extratos Vegetais/administração & dosagem , Folhas de Planta/química , Ácido Úrico/análogos & derivados , Adulto , Anti-Inflamatórios/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Camellia/química , Café/química , Cognição/efeitos dos fármacos , Método Duplo-Cego , Feminino , Humanos , Masculino , Atividade Motora/efeitos dos fármacos , Extratos Vegetais/farmacologia , Resultado do Tratamento , Ácido Úrico/administração & dosagem , Ácido Úrico/química , Ácido Úrico/farmacologia
8.
J Strength Cond Res ; 30(9): 2627-37, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25486294

RESUMO

Outlaw, JJ, Smith-Ryan, AE, Buckley, AL, Urbina, SL, Hayward, S, Wingfield, HL, Campbell, B, Foster, C, Taylor, LW, and Wilborn, CD. Effects of ß-alanine on body composition and performance measures in collegiate women. J Strength Cond Res 30(9): 2627-2637, 2016-The purpose of this study was to evaluate the effects of ß-alanine (BA) supplementation and resistance training on body composition and performance. In a double-blind placebo-controlled design, 16 untrained collegiate females (mean ± SD: 21.0 ± 2.2 years; 64.8 ± 8.5 kg; 164.5 ± 7.0 cm; 30.1 ± 5.1 percent body fat [%BF]) completed 8 weeks of resistance training while consuming either 3.4 g BA or placebo (PL; 5 g maltodextrin) before training sessions. Training consisted of 4 days per week upper- and lower-body exercises. Lean body mass (LBM), fat mass (FM), and %BF were assessed using dual-energy x-ray absorptiometry. Maximal oxygen consumption (V[Combining Dot Above]O2max), aerobic time to exhaustion, Wingate peak power, bench press and leg press 1RM (BPmax; LPmax), and repetitions at 65% (BPreps; LPreps), vertical jump (VJ), and standing broad jump were assessed using standard National Strength and Conditioning Association guidelines. All measurements were taken at baseline (T1), 4 weeks (T2), and 8 weeks (T3). Repeated-measures analysis of variance and 95% confidence intervals were used to determine significance. Body composition (LBM, FM, and %BF) improved over time (p < 0.01) for both groups. Maximal strength and VJ increased significantly from baseline to T3 (p ≤ 0.05). There was a significant interaction for LPreps (p = 0.040), with only BA group resulting in significantly greater LPreps (p = 0.041) at T2 and T3. Results from this study suggest that 8 weeks, 4 days per week progressive resistance training and BA supplementation may be effective for improving lower-body muscular endurance. ß-alanine had no additive effects on body composition or maximal strength in collegiate women.


Assuntos
Composição Corporal/efeitos dos fármacos , Fadiga Muscular/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Resistência Física/efeitos dos fármacos , Treinamento Resistido , beta-Alanina/farmacologia , Absorciometria de Fóton , Adolescente , Suplementos Nutricionais , Método Duplo-Cego , Feminino , Humanos , Força Muscular/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/fisiologia , Adulto Jovem
9.
J Int Soc Sports Nutr ; 11: 40, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25302053

RESUMO

BACKGROUND: Pre-workout supplements containing numerous ingredients claim to increase performance and strength. Product-specific research is important for identifying efficacy of combined ingredients. The purpose of this study was to evaluate the effects of a proprietary pre-workout dietary supplement containing creatine monohydrate, beta-alanine, L-Tarurine, L-Leucine, and caffeine, on anaerobic power, muscular strength, body composition, and mood states. METHODS: In a double-blind, randomized, matched-pair design, twenty male subjects (mean ± SD; 22.4 ± 9.5 yrs, 76.9 ± 11.2 kg, 22.7 ± 9.5% body fat), consumed either 30 g of a pre-workout supplement (SUP) or maltodextrin placebo (PLC) 30 minutes before a resistance training workout, after completing baseline testing. Body composition was determined via dual-energy x-ray absorptiometry (DEXA). Subjects completed 12 vertical jumps for height (VJ) and one repetition maximum (1RM) and repetitions to failure lifts on bench (BPM) and leg press (LPM). Finally, subjects completed a Wingate power test on a cycle ergometer [mean power (WMP) and peak power (WPP)]. After baseline testing, participants completed eight days of supplementation and four split-body resistance-training bouts. Side effect questionnaires were completed daily 30 minutes after consuming the supplement. Subjects completed post-supplement testing on Day 8. Data were analyzed utilizing a 2 × 2 repeated measures ANOVA [treatment (PLC vs SUP) × time (T1 vs T2)] and ninety-five percent confidence intervals. RESULTS: There were no significant treatment × time interactions (p > 0.05). There were no significant changes in %body fat (%BF; ∆-0.43 ± 0.58; p = 0.920), fat mass (∆-2.45 ± 5.72; p = 0.988), or lean body mass (LBM; 10.9 ± 12.2; p = 0.848). 95% CI demonstrated significant LBM increases for both groups. There was a main effect for time for WPP (∆100.5 ± 42.7W; p = 0.001), BPM (∆8.0 ± 12.9 lbs; p = 0.001), and LPM (∆80.0 ± 28.8 lbs; p = 0.001), with no significant differences between treatments. There was no significant difference in mood states between groups or over time. CONCLUSION: The proprietary pre-workout blend combined with eight days of training did not significantly (ANOVA) improve body composition or performance. While not significant, greater gains in LPM were demonstrated in the SUP group for lean body mass and lower body strength. Future studies should evaluate more chronic effects of proprietary pre-workout blends on total training volume and performance outcomes.

10.
Springerplus ; 3: 369, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25110627

RESUMO

PURPOSE: The purpose was to assess effects of a pre- and a post-workout protein-carbohydrate supplement on CrossFit-specific performance and body composition. METHODS: In an open label randomized study, 13 male and 16 female trained Crossfit participants (mean ± SD; age: 31.87 ± 7.61 yrs, weight: 78.68 ± 16.45 kg, percent body fat: 21.97 ± 9.02) were assessed at 0 and 6 weeks for body composition, VO2max, Wingate peak (WPP) and mean power (WMP), in addition to sport-specific workouts (WOD1: 500 m row, 40 wall balls, 30 push-ups, 20 box jumps, 10 thrusters for time; WOD2: 15 minutes to complete an 800 m run "buy in", followed by as many rounds as possible (AMRAP) of 5 burpees, 10 Kettlebell swings, 15 air squats). The supplement (SUP) group consisted of 19 g of a pre-workout drink (extracts of pomegranate, tart cherry, green and black tea) taken 30 minutes before and a post-workout protein (females: 20 g; males: 40 g) and carbohydrate (females: 40 g; males: 80 g) supplement consumed immediately after each workout. The control (CTL) group consumed only water one hour before or after workouts. Participants completed three (minimum) varied workouts per week at a CrossFit gym as typical to habitual training throughout the six week study. Data were analyzed by repeated measures ANOVA (p <0 .05), 95% Confidence Intervals, and Magnitude Inferences. RESULTS: There were no time × group interactions for body composition, WMP, or WOD1 based on ANOVA statistics. VO2MAX, WPP, and WOD2 results revealed that the pre/post supplements were likely beneficial after 95% Confidence Intervals and Magnitude Inferences analysis. CONCLUSION: The combination of proprietary supplements taken for 6 weeks may provide benefits during certain sport-specific performance in trained CrossFit athletes but not others.

11.
J Sports Sci Med ; 12(1): 74-9, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24149728

RESUMO

Two of the most popular forms of protein on the market are whey and casein. Both proteins are derived from milk but each protein differs in absorption rate and bioavailability, thus it is possible that each type of protein may contribute differently to the adaptations elicited through resistance training. Therefore, the purpose of this study was to investigate the potential effects of ingestion of two types of protein in conjunction with a controlled resistance training program in collegiate female basketball players. Sixteen NCAA Division III female basketball players were matched according to body mass and randomly assigned in a double-blind manner to consume 24 g whey protein (WP) (N = 8, 20.0 ± 1.9 years, 1.58 ± 0.27 m, 66. 0 ± 4.9 kg, 27.0 ± 4.9 %BF) or 24 g casein protein (CP) (N = 8, 21.0 ± 2.8 years, 1.53 ± 0.29 m, 68.0 ± 2.9 kg, 25.0 ± 5.7 %BF) immediately pre- and post-exercise for eight weeks. Subjects participated in a supervised 4-day per week undulating periodized training program. At 0 and 8 weeks, subjects underwent DXA body composition analysis, and at 0 and 8 weeks underwent one repetition maximum (1RM) strength, muscle endurance, vertical jump, 5-10-5 agility run, and broad jump testing sessions. Data were analyzed using repeated measures ANOVA, and presented as mean ± SD changes from baseline after 60 days. No significant group x time interaction effects were observed among groups in changes in any variable (p > 0.05). A significant time effect was observed for body fat (WP: -2.0 ± 1.1 %BF; CP: -1.0 ± 1.6 %BF, p < 0.001), lean mass (WP: 1.5 ± 1.0 kg; CP: 1. 4 ± 1.0 kg, p < 0.001), fat mass (WP: -1.3 ± 1.2 kg; CP: -0.6 ± 1.4 kg, p < 0.001), leg press 1RM (WP: 88.7 ± 43.9 kg; CP: 90.0 ± 48.5 kg, p < 0.001), bench press 1RM (WP: 7.5 ± 4.6 kg; CP: 4.3 ± 4.5 kg, p = 0.01), vertical jump (WP: 4.1 ± 1.8 cm; CP: 3.5 ± 7.6 cm, p < 0.001), 5-10-5 (WP: -0.3 ± 0.2 sec; CP: -0.09 ± 0.42 sec, p < 0.001), and broad jump (WP: 10.4 ± 6.6 cm; CP: 12. 9 ± 7.1 cm, p < 0.001). The combination of a controlled undulating resistance training program with pre- and post-exercise protein supplementation is capable of inducing significant changes in performance and body composition. There does not appear to be a difference in the performance- enhancing effects between whey and casein proteins. Key pointsFemales can experience and increase in performance makers from consuming protein after resistance training.Females can have a decreased body fat composition when ingesting protein with daily resistance training and conditioning.There was no significant difference in performance markers between whey and casein.

12.
J Int Soc Sports Nutr ; 10(1): 25, 2013 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-23627832

RESUMO

BACKGROUND: Increasing metabolism is a primary focus of many commercially available dietary supplements marketed to support weight management. Caffeine (e.g. anhydrous and herbal) and green tea are key ingredients in such products, augmenting resting energy expenditure (REE) and improving reported mood states (alertness, fatigue, focus, etc.). The purpose of this study was to evaluate the effects of a thermogenic dietary supplement (DBX) on REE, respiratory exchange ratio (RER), reported measures of alertness, focus, energy, concentration, fatigue, and hunger, as well as the general safety of the product based on electrocardiogram (ECG) and hemodynamic responses in habitual caffeine consumers. METHODS: Six male and six female subjects (mean ± SD; 22.50 ± 3.22 years; 76.94 ± 14.78 kg; 22.7 ± 9.5% body fat), physically active (≥12 months), and moderate habitual caffeine consumers (<200 mg/day) received either two capsules of DBX containing 340 mg of total caffeine plus green tea extract, yerba mate extract, carnitine tartrate and other active ingredients or a placebo (PLC) in a double-blinded, crossover design. Heart rate (HR), blood pressure (BP), REE, RER and perceived mood states were measured at baseline and then hourly for four hours after ingesting either treatment. RESULTS: Resting energy expenditure was significantly increased at all four time points and significant increases were determined for perceived alertness (p = 0.026) and focus (p = 0.05) at hour 1 and for energy at 1 and 2 hours after treatment for the DBX group (p = 0.008 and p = 0.017, respectively). Additionally, perceived fatigue was decreased at the hour 1 assessment (p = 0.010). No significant differences were seen between DBX and placebo for hunger, anxiety, HR, BP, ECG patterns or RER. CONCLUSIONS: The results of this investigation support that the proprietary blend of this thermogenic aid is capable of increasing REE for four hours post-ingestion while supporting increased focus, alertness, and energy as well as decreasing fatigue without promoting anxiety or causing significant changes in HR, BP, or ECG measurements in habitual caffeine consumers.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...