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Alzheimer's disease (AD) represents the most common type of dementia. A crucial mechanism attributed to its development is amyloid beta (Aß) dynamics dysregulation. The extent to which exercise can modulate this phenomenon is uncertain. The aim of this study was to summarize the existing literature evaluating this issue. A comprehensive systematic search was performed in Pubmed, Scopus, Embase, Web of Science, and SciELO databases and completed in August 2023, aiming to identify randomized controlled trials investigating the effect of exercise upon Aß-related pathology. The keywords "exercise" and "amyloid beta", as well as all their equivalents and similar terms, were used. For the analysis, the negative or positive dementia status of the subjects was initially considered and then the soluble amyloid precursor protein (sAPP) components and Aß fragments separately. A meta-analysis was performed and involved eight studies (moderate-to-high quality) and 644 assessments, which were 297 for control and 347 for exercise. No overall effect favoring exercise interventions was observed for both negative (SMD95%=0,286 [-0,131; 0,704]; p = 0,179) or positive AD dementia status (SMD95%=0,110 [-0,155; 0,375]; p = 0,416). The absence of an overall effect favoring exercise interventions was also found for Aß peptides (SMD95%=0,226 [-0,028; 0,480]; p = 0,081) and for sAPP components (SMD95%=-0,038 50 [-0,472; 0,396]; p = 0,863) levels. Our findings suggest that exercise interventions do not improve Aß-related pathology in both healthy individuals and individuals with dementia (SMD95%=0,157 [-0,059; 0,373]; p = 0,155), indicating that the beneficial effects of exercise for AD reported in previous studies are related to other mechanistic effects rather than direct amyloid effects (PROSPERO registration number: CRD42023426912).
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Enfermedad de Alzheimer , Péptidos beta-Amiloides , Humanos , Péptidos beta-Amiloides/metabolismo , Ejercicio Físico/fisiología , Terapia por Ejercicio/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto/métodosRESUMEN
PURPOSE: Delayed-onset muscle soreness (DOMS) describes an entity characterized by ultrastructural muscle damage. Hesperidin methyl chalcone (HMC) is a synthetic flavonoid presenting analgesic, anti-inflammatory, and antioxidant properties. We evaluated the effects of HMC upon DOMS. METHOD: In a preventive paradigm, 31 sedentary young men were submitted to a randomized, double-blinded parallel trial and received HMC 500 mg or one placebo capsule × 3 days before an intense dynamic exercise protocol (concentric/eccentric actions) applied for lower limbs for inducing muscle damage. Assessments were conducted at baseline, and 24 and 48 h after, comprising physical performance, and post-muscle soreness and damage, inflammation, recovery of muscle strength, and postural balance associated with DOMS. HMC safety was also evaluated. Thirty participants completed the study. RESULTS: HMC improved the performance of participants during exercise (40.3 vs 51.3 repetitions to failure, p = 0.0187) and inhibited CPK levels (90.5 vs 57.9 U/L, p = 0.0391) and muscle soreness during passive quadriceps palpation (2.6 vs 1.4 VAS cm, p = 0.0439), but not during active actions, nor did it inhibit IL-1ß or IL-10 levels. HMC improved muscle strength recovery, and satisfactorily refined postural balance, without inducing injury to kidneys or liver. CONCLUSIONS: Preemptive HMC supplementation may be beneficial for boosting physical performance and for the amelioration of clinical parameters related to DOMS, including pain on muscle palpation, increased blood CPK levels, and muscle strength and proprioceptive deficits, without causing adverse effects. These data advance the understanding of the benefits provided by HMC for DOMS treatment, which supports its usefulness for such purpose.
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Chalconas , Hesperidina , Masculino , Humanos , Adulto Joven , Mialgia/tratamiento farmacológico , Mialgia/prevención & control , Mialgia/etiología , Hesperidina/farmacología , Hesperidina/uso terapéutico , Chalconas/farmacología , Chalconas/uso terapéutico , Ejercicio Físico/fisiología , Músculo EsqueléticoRESUMEN
This study's purpose was to compare the effects of different carbohydrate (CHO) intakes on body composition and muscular strength following eight weeks of resistance training (RT) in pre-conditioned men. In addition, we explored the individual responses to different CHO intakes. Twenty-nine young men volunteered to participate in this study. The participants were divided into two groups according to their relative CHO intake: lower (L-CHO; n = 14) and higher (H-CHO; n = 15). Participants performed a RT program four days a week for eight weeks. The lean soft tissue (LST) and fat mass were determined by dual-energy X-ray absorptiometry. Muscular strength was determined by a one-repetition maximum (1RM) test in the bench press, squat, and arm curl exercises. Both groups increased LST (P < 0.05) with no statistical differences between conditions (L-CHO = +0.8% vs. H-CHO = +3.5%). Neither group demonstrated changes in fat mass. Both groups increased 1RM (P < 0.05) in the bench press (L-CHO = +3.6% vs. H-CHO = +5.8%) and squat (L-CHO = +7.5% vs. H-CHO = +9.4%); however, only H-CHO significantly increased arm curl 1RM (P < 0.05) at post-training (L-CHO = +3.0% vs. H-CHO = +6.6%). Responsiveness was greater in H-CHO vs. L-CHO for LST and arm curl 1RM. In conclusion, lower and higher CHO intakes promote similar increase in LST and muscular strength; however, a greater intake may improve the responsiveness to gains in lean mass and arm curl strength in pre-conditioned men.
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ABSTRACT: Nunes, JP, Marcori, AJ, Ribeiro, AS, Cunha, PM, Kassiano, W, Costa, BDV, Aguiar, AF, Nakamura, M, Mayhew, JL, and Cyrino, ES. Differential responsiveness for strength gain between limbs after resistance training in older women: Impact on interlimb asymmetry reduction. J Strength Cond Res 36(11): 3209-3216, 2022-The present study compared strength responses between preferred (PREF) and nonpreferred (N-PREF) legs in older women. Muscular strength was measured unilaterally using an isokinetic dynamometer and was analyzed for reproducibility scores, acute performance, and responsiveness to a resistance training (RT) program. One hundred eleven women (aged ≥60 years) performed 12 weeks of whole-body RT (3 times a week; 4 lower-body exercises). Reproducibility scores (intraclass correlation coefficient ≥0.920; following test-retests in part of the sample at pretraining; n = 19), average acute performances, and average strength gains (PREF = â¼6.9%; N-PREF = â¼7.2%) were similar between legs (p > 0.05). However, the individual analyses showed that some subjects were considered responders to strength gains in 1 leg, whereas nonresponders in the other. Nonetheless, when considering the responses in all strength tests, most subjects (91%) were considered responder to at least 1 measure. In addition, it was observed that the strength ratio between PREF/N-PREF legs was altered for those who presented some asymmetry at baseline, as the limbs became more symmetrical in all strength measures after the RT. In conclusion, we observed that some older women may have different levels of strength between legs; however, a traditional 12-week RT program with bilateral exercises can reduce such asymmetry by inducing greater strength gains in the weaker leg.
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Entrenamiento de Fuerza , Femenino , Humanos , Anciano , Reproducibilidad de los Resultados , Músculo Esquelético/fisiología , Fuerza Muscular/fisiología , PiernaRESUMEN
AIMS: The main purpose of the present study was to investigate the acute effects of different resistance training loads on the session rating of perceived exertion (sRPE) and feelings of pleasure displeasure (sFPD) of the session in older women. METHODS: In a randomized, counterbalanced, and cross-over design, 16 older women (66.1 ± 3.9 years, 67.0 ± 8.4 kg, 154.1 ± 6.8 cm, 28.3 ± 4.4 kg/m2) performed 3 sets of 8 exercises in three experimental conditions, 1 session with a heavy load (HEV), one with a moderate load (MOD), and one session with a light load (LIT), all performed until momentary muscle failure. The sRPE and sFPD were assessed 15 min after the end of each session using specific scales. RESULTS: A significant difference (P < 0.05) was observed among conditions for sFPD in which HEV produced feelings of displeasure, and MOD produced greater feelings of pleasure (HEV = -1.38 ± 1.7, MOD = 3.38 ± 1.2, LIT = 0.69 ± 1.04). For sRPE, a significant (P < 0.05) difference was observed between MOD and LIT; whereby the LIT load induced a greater score compared to the MOD load (HEV = 4.56 ± 1.4, MOD = 4.31 ± 1.7, LIT = 5.75 ± 1.2). CONCLUSION: Our results suggest that the training load affects perceived effort and feelings of pleasure/displeasure when exercise is performed until concentric failure. The use of moderate loads induces greater pleasure feelings and a reduced degree of effort in older women.
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Entrenamiento de Fuerza , Anciano , Estudios Cruzados , Femenino , Humanos , Percepción/fisiología , Esfuerzo Físico/fisiología , Entrenamiento de Fuerza/métodosRESUMEN
The purpose of this study was to investigate the effects of supplementation of whey protein (WP) versus leucine-matched collagen peptides (CP) on muscle thickness MT and performance after a resistance training (RT) program in young adults. Twenty-two healthy untrained participants were randomly assigned to either a WP (n = 11) or leucine-matched CP (n = 11) group and then submitted to a supervised 10-week RT program (3 days/week). The groups were supplemented with an equivalent amount of WP (35 g, containing 3.0 g of leucine) and CP (35 g, containing 1.0 g of leucine and 2.0 g of free leucine) during the intervention period (after each workout and in the evening on nontraining days). MT of the vastus lateralis and biceps brachii, isokinetic peak torque and mean power output of the elbow flexors, and peak power output of the lower body were assessed before and after the RT program. The WP group experienced a greater (interaction, p < .05) increase in the vastus lateralis (effect size, WP = 0.68 vs. CP = 0.38; % Δ, WP = 8.4 ± 2.5 vs. CP = 5.6 ± 2.6%) and biceps brachii muscle thickness (effect size, WP = 0.61 vs. CP = 0.35; % , WP = 10.1 ± 3.8 vs. CP = 6.0 ± 3.2%), with a similar increase in muscle performance (peak torque, mean power output, and peak power output) between groups (time p < .05). Supplementation with WP was superior to leucine content-matched CP supplementation in increasing muscle size, but not strength and power, after a 10-week RT program in young adults.
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Entrenamiento de Fuerza , Composición Corporal , Colágeno/metabolismo , Suplementos Dietéticos , Método Doble Ciego , Humanos , Leucina/metabolismo , Fuerza Muscular , Músculo Esquelético/fisiología , Péptidos/metabolismo , Proteína de Suero de Leche , Adulto JovenRESUMEN
PURPOSE: Resistance training (RT) combined with appropriate dietary intake can promote a concomitant increase in skeletal muscle mass (SMM) and reduction in fat mass, a condition termed body recomposition. This study's primary purpose was to explore the effects of protein ingestion on body recomposition after 24 wk of RT in older women. METHODS: Data from 130 untrained older women (68.7 ± 5.6 yr, 66.5 ± 11.5 kg, 155.5 ± 6.0 cm, and 27.4 ± 4.0 kg·m-2) across six studies were retrospectively analyzed. The participants were divided into tertiles according to their customary protein intake (g·kg-1·d-1): lower (LP; n = 45), moderate (MP; n = 42), and higher (HP; n = 43) protein intake. Participants performed a whole-body RT program carried out over 24 wk (eight exercises, three sets, 8-15 repetitions, three sessions a week). SMM and fat mass were determined by dual-energy x-ray absorptiometry. RESULTS: All groups increased SMM from baseline (P < 0.05), with the HP and MP groups showing greater increases than the LP group (LP, 2.3%; MP, 5.4%; and HP, 5.1%; P < 0.05). Reductions in fat mass were similar for all three groups (LP, 1.7%; MP, 3.7%; and HP, 3.1%; P > 0.05). The composite z-score of the percentage changes from pretraining to posttraining indicated greater positive body recomposition values for HP and MP compared with LP (P < 0.05). CONCLUSIONS: Results suggest that protein intake is a moderating variable for body recomposition in older women undergoing RT, with a low protein intake having a less favorable effect on body recomposition.
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Entrenamiento de Fuerza , Absorciometría de Fotón , Anciano , Composición Corporal/fisiología , Proteínas en la Dieta , Femenino , Humanos , Persona de Mediana Edad , Músculo Esquelético/fisiología , Estudios RetrospectivosRESUMEN
Although the ergogenic mechanisms of supplementation with citrulline malate are well known, unclear findings regarding variables of muscle strength have been recorded. Such misleading findings in the literature illustrate the need for well-conducted meta-analysis research to elucidate the possible ergogenic impact, which could have major practical consequences for athletes and recreational practitioners seeking to optimize gains in muscle strength. The objective of this systematic review was to summarize the existing literature that evaluated the effects of citrulline malate supplementation on muscle strength outcomes from resistance exercise in resistance-trained individuals. A systematic electronic search in Medline and Scientific Electronic Library Online (SciELO) was completed in August 2020 identifying randomized controlled trials investigating the effect of citrulline malate supplementation on muscle strength in resistance-trained adults. A subsequent meta-analysis was performed. The meta-analysis involved four studies and 138 assessments (69 in citrulline-malate and 69 in placebo groups). We did not observe an overall effect favoring citrulline-malate supplementation (SMD95% = 0.13 [-0.21; 0.46]). Considering the lower (SMD95% = 0.06 [-0.47; 0.60]) and upper (SMD95% = 0.17 [-0.26; 0.60]) limbs, a non-significant overall effect was identified. The mean effects were similar for "limbs" (upper vs lower) [p = 0.763]. Accordingly, our findings suggest that citrulline malate supplementation does not improve muscle strength in healthy and resistance-trained individuals (PROSPERO registration number: CRD42020159338).
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Sustancias para Mejorar el Rendimiento , Entrenamiento de Fuerza , Adulto , Humanos , Citrulina/farmacología , Malatos , Suplementos Dietéticos , Ensayos Clínicos Controlados Aleatorios como Asunto , Fuerza Muscular , Músculo EsqueléticoRESUMEN
This study aimed to investigate the effects of free leucine supplementation on muscle recovery from resistance exercise (RE) in young adults. Fourteen untrained subjects (23.9 ± 3.6 years old) underwent RE sessions (leg press and hack squat: three sets of 8-12 reps at 70% 1RM) supplemented with leucine (LEU: two daily doses of 3g) or a placebo (PLA), separated by a seven-day washout period. Following each occasion, participants were evaluated in three subsequent days (24h, 48h, and 72h) for muscle recovery via a repetition-to-failure test. The following markers were assessed: repetition performance, perceived exertion, lactate, creatine kinase, muscle soreness (DOMS), testosterone, and cortisol. No significant difference was observed between LEU and PLA conditions (p > 0.05). Number of repetitions performed in the repetition-to-failure tests, perceived exertion, cortisol, and testosterone:cortisol ratio did not change over time (p > 0.05). Creatine kinase increased immediately after exercise, at 24h, and 48h, and was attenuated at 72h post-exercise, while testosterone, lactate, and DOMS increased at 24h post-exercise (p < 0.05) and remained elevated up to 72h. All outcomes were similar between LEU and PLA. Results indicate that a 6g daily dose of free leucine supplementation does not improve muscle recovery following lower-limb RE in untrained young adults.
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This study aimed to compare the effects of resistance training performed with low versus moderate loads on systemic resting blood pressure (BP) in older women. A total of 29 women (72.6 ± 5.1 years) were randomized into two groups: low load (LOW, n = 15) and moderate load (MOD, n = 14). An 8-week whole-body resistance training program was carried out 3 days/week (eight exercises, three sets, 10 or 15 repetition maximum). The LOW and MOD groups trained with a relative load of 15 and 10 repetition maximum, respectively. Outcome measures included resting systolic and diastolic BP. After 8 weeks, both groups presented significant changes (p < .05) in systolic BP (LOW = -3.0%; MOD = -4.6%) and mean BP (LOW = -1.9%; MOD = -3.1%). There was no change for diastolic BP in the posttest in both groups. The results suggest that low and moderate loads are equally effective for promoting decreases in resting BP in older women.
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Entrenamiento de Fuerza , Anciano , Presión Sanguínea , Ejercicio Físico , Terapia por Ejercicio , Femenino , Humanos , DescansoRESUMEN
CONTEXT: Chronic low-back pain (CLBP) may be associated with changes in postural balance in athletes as poor postural control during sports practice. OBJECTIVE: To compare the postural control of athletes with and without CLBP during 2 one-legged stance tasks and identify the center of pressure (COP) cutoff values to determine the main differences. Designed: A cross-sectional study. SETTING: Laboratory of functional evaluation and human motor performance. PARTICIPANTS: A total of 56 male athletes, 28 with and 28 without CLBP (mean age = 26 y). INTERVENTION: The one-legged stance with knee extension and with the knee at 30° flexion tasks were measured and analyzed on a force platform. The participants completed three 30-second trials (30 s of rest between each trial). MAIN OUTCOME MEASURES: The COP parameters: the area of COP, mean COP sway velocity in both the anteroposterior and mediolateral directions, and total COP displacement were computed, and a receiver operating characteristics curve analysis was applied to determine the group differences. RESULTS: Athletes with CLBP had poorer postural control (P < .01) in both tasks. The 30° knee flexion reported more postural instability than the knee extension for all COP parameters (a large effect size d = 0.80).The knee extension cutoffs identified were >7.1 cm2 for the COP area, >2.6 cm/s for the COP sway velocity in the anterior-posterior direction, and >3.2 cm/s for the mediolateral direction. Whereas, the 30° knee flexion cutoffs were >10.9 cm2 for the COP area, >2.9 cm/s for the COP sway velocity in the anterior-posterior direction, and >4.1 cm/s for the mediolateral direction. Both measures showed enough sensitivity and specificity (ie, area under the curve = 0.88 in and 0.80, respectively) to discriminate both groups. CONCLUSIONS: The athletes with CLBP had poorer postural control than the healthy athletes and obtained specific cutoff scores from the COP values.
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Atletas , Dolor Crónico/fisiopatología , Articulación de la Rodilla , Dolor de la Región Lumbar/fisiopatología , Equilibrio Postural/fisiología , Postura/fisiología , Adulto , Estudios de Casos y Controles , Estudios Transversales , Humanos , Masculino , Dimensión del Dolor , Presión , Curva ROC , Ensayos Clínicos Controlados Aleatorios como Asunto , Sensibilidad y Especificidad , Factores de Tiempo , Adulto JovenRESUMEN
The authors aimed to compare the effects of creatine (Cr) supplementation combined with resistance training on skeletal muscle mass (SMM), total body water, intracellular water (ICW), and extracellular water (ECW) in resistance-trained men as well as to determine whether the SMM/ICW ratio changes in response to the use of this ergogenic aid. Twenty-seven resistance-trained men received either Cr (n = 14) or placebo (n = 13) over 8 weeks. During the same period, subjects performed two split resistance training routines four times per week. SMM was estimated from appendicular lean soft tissue assessed by dual-energy X-ray absorptiometry. Total body water, ICW, and ECW were determined by spectral bioelectrical impedance. Both groups showed improvements (p < .05) in SMM, total body water, and ICW, with greater values observed for the Cr group compared with placebo. ECW increased similarly in both groups (p < .05). The SMM/ICW ratio did not change in either group (p > .05), whereas the SMM/ECW ratio decreased only in the Cr group (p < .05). A positive correlation was observed (p < .05) between SMM and ICW changes (r = .71). The authors' results suggest that the increase in muscle mass induced by Cr combined with resistance training occurs without alteration of the ratio of ICW to SMM in resistance-trained men.
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Muscular strength and hypertrophy following resistance training may be obtained in different degrees depending on the approach performed. This study was designed to compare the responses of the biceps brachii to two preacher curl exercises, one performed on a cable-pulley system (CAB; in which a greater torque was applied during the exercise when elbows were flexed and biceps shortened) and one performed with a barbell (BAR; in which greater torque was applied when the elbows were extended and biceps stretched). Thirty-five young adults (CAB: 13 men, 5 women; BAR: 12 men, 5 women; age = 24 ± 5 years) performed a resistance training program three times per week for 10 weeks, with preacher curl exercises performed in three sets of 8-12 repetitions. Outcomes measured included elbow flexion peak isokinetic torque at angles of 20°, 60°, and 100° (considering 0° as elbow extended), and biceps brachii thickness (B-mode ultrasound). Following the training period, there were significant increases for both groups in elbow flexion peak torque at the 20° (CAB: 30%; BAR = 39%; p = 0.046), 60° (CAB: 27%; BAR = 32%; p = 0.874), and 100° (CAB: 17%; BAR = 19%; p = 0.728), and biceps brachii thickness (CAB: 7%; BAR = 8%; p = 0.346). In conclusion, gains in muscular strength were greater for BAR only at longer muscle length, whereas hypertrophy was similar regardless of whether torque emphasis was carried out in the final (CAB) or initial (BAR) degrees of the range of motion of the preacher curl in young adults.
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Fuerza Muscular , Músculo Esquelético , Entrenamiento de Fuerza , Adulto , Femenino , Humanos , Hipertrofia , Masculino , Músculo Esquelético/patología , Músculo Esquelético/fisiología , Rango del Movimiento Articular , Torque , Adulto JovenRESUMEN
The aim of this study was to evaluate the impact of 2 types of beer barrels on postural control, trunk activation, and kinematic measures in adult workers. Twelve (12) males randomly performed 4 tasks on a force platform for 20 s: (1) hold an empty recyclable barrel, (2) hold a full recyclable barrel (30 L), (3) hold an empty steel barrel, and (4) hold a full steel barrel (30 L). Trunk muscular activation, force platform and kinematic measures at the trunk, hip, and knee joints were computed. The full steel barrel produced greater postural oscillation than other conditions. Higher trunk activity was also reported during the full steel barrel task. Significant kinematic changes only in the trunk were observed between the empty steel barrel and the full recyclable barrel tasks. In conclusion, the full steel barrel produced a negative impact on postural control, increasing trunk activity and changing trunk flexion angle in adult workers.
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Elevación , Músculo Esquelético/fisiología , Postura , Adulto , Fenómenos Biomecánicos , Electromiografía , Humanos , Masculino , Equilibrio Postural/fisiología , Distribución Aleatoria , Rango del Movimiento ArticularRESUMEN
The purpose of this study was to determine the effects of different amounts of energy intake in combination with progressive resistance training on muscle mass and body fat in bodybuilders. Eleven male bodybuilders (26.8 ± 2.3 years, 90.1 ± 9.7 kg, and 176.9 ± 7.1 cm) were randomly assigned into one of two groups: a group that ingested higher amounts of energy (G1, 67.5 ± 1.7 kcal/kg/d, n = 6), and a group that ingested moderate amounts of energy (G2, 50.1 ± 0.51 kcal/kg/d, n = 5). Both groups performed resistance training 6 days per week over a 4-week study period. Measures of body composition were assessed before and after the intervention period. For body fat, only the G1 presented significant changes from pre- to post-training (G1 = +7.4% vs. G2 = +0.8%). For muscle mass, both groups showed significant increases after the intervention period, with G1 presenting a greater increase compared to G2 (G1 = +2.7% vs. G2 = +1.1%). Results suggest that greater energy intake in combination with resistance training induces greater increases in both muscle mass and body fat in competitive male bodybuilders.
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The main purpose of this study was to compare the effects of resistance training (RT) performed two versus three times per week on phase angle (a cellular health indicator) in older women. A total of 39 women (69.1 ± 5.5 years) were randomly assigned to perform a RT program two (G2X) or three (G3X) days per week for 12 weeks. The RT was a whole-body program (eight exercises, one set, 10-15 repetitions). Phase angle, resistance, reactance, and total body water were assessed by bioimpedance spectroscopy. Intracellular water, reactance, and phase angle increased significantly in G2X (2.1%, 3.0%, and 5.6%, respectively) and G3X (5.0%, 6.9%, and 10.3%, respectively) from pretraining to posttraining, with no significant difference between groups. Bioimpedance resistance decreased similarly in both groups (G2X = -1.7% vs. G3X = -3.2%). We conclude that a single set RT program with a frequency of 2 days per week may be sufficient to promote an improvement in cellular health in older women.
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Entrenamiento de Fuerza/métodos , Anciano , Composición Corporal , Agua Corporal , Impedancia Eléctrica , Femenino , Humanos , Persona de Mediana EdadRESUMEN
Ribeiro, AS, Aguiar, AF, Schoenfeld, BJ, Nunes, JP, Cavalcanti, EF, Cadore, EL, and Cyrino, ES. Effects of different resistance training systems on muscular strength and hypertrophy in resistance-trained older women. J Strength Cond Res 32(2): 545-553, 2018-The purpose of this study was to investigate the effect of resistance training (RT) performed in a pyramid (PR) vs. constant (CT) load system on muscular strength and hypertrophy in resistance-trained older women. Thirty-three older women (69.7 ± 5.9 years, 69.1 ± 15.0 kg, 156.6 ± 6.2 cm, and 28.1 ± 5.4 kg·m) were randomized into 2 groups: one that performed RT with a CT load (n = 16) and another group that performed RT in an ascending PR fashion (n = 17). Outcomes included 1 repetition maximum (RM) tests and assessment of skeletal muscle mass estimated by dual-energy X-ray absorptiometry. The study lasted 32 weeks, with 24 weeks dedicated to preconditioning and 8 weeks for the actual experiment. The RT program was conducted 3 d·wk; the CT consisted of 3 sets of 8-12RM with same load across sets, whereas the PR consisted of 3 sets of 12/10/8RM with incremental loads for each set. A significant (p ≤ 0.05) change from pretraining to posttraining was observed for chest press total strength (CT: pre = 122.8 ± 21.0 kg, post = 128.9 ± 21.4 kg, effect size [ES] = 0.28; PR: pre = 120.5 ± 22.8 kg, post = 125.8 ± 22.9 kg, ES = 0.24) and muscle mass (CT: pre = 21.4 ± 3.6 kg, post = 21.7 ± 3.5 kg, ES = 0.09; PR: pre = 20.9 ± 3.4 kg, post = 21.1 ± 3.4 kg, ES = 0.06) without differences between groups. Results suggest that both systems are effective to improve strength and muscle growth, but PR is not superior to CT for inducing improvements in previously trained older women.
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Fuerza Muscular/fisiología , Músculo Esquelético/fisiología , Entrenamiento de Fuerza/métodos , Absorciometría de Fotón , Anciano , Femenino , Humanos , Hipertrofia , Masculino , Persona de Mediana EdadRESUMEN
The purpose of this study was to examine the effects of training volume (1 vs. 3 sets) on lower-body muscle strength in untrained young men. Methodsː Eighteen untrained young men were recruited and their legs were trained with 1 or 3 sets (in a contralateral design) for 6 weeks, using a knee extension machine. Isokinetic peak torque and one repetition maximum (1RM) were assessed at pre- and post-training. Resultsː There was a similar improvement in the 1RM strength (1SET: +14.8% vs. 3SET: 16.3%, P > 0.05) and peak torque (1SET: +8.1% vs. 3SET: 9.3%, P > 0.05) for both conditions from pre- to post-training. The effect size (ES) for the change in 1RM was moderate for both conditions (1SET: 1.39 vs. 3SET: 1.41), and peak torque was trivial and small for 1SET (0.47) and 3SET (0.55), respectively. Additionally, there were no significant (P > 0.05) differences in the dietary intakes from pre- to post-training. Conclusionsː Our results indicate that 1 set is as effective as 3 sets for increasing lower-body muscle strength after a short-term RT period (6 weeks) in untrained young men.(AU)
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Humanos , Masculino , Adulto , Adulto Joven , Músculo Cuádriceps/fisiología , Fuerza Muscular , Entrenamiento de Fuerza , Alimentos/análisisRESUMEN
The effects of citrulline malate (CM) on muscle recovery from resistance exercise remains unknown. We aimed to determine if citrulline malate supplementation improves muscle recovery after a single session of high-intensity resistance exercise (RE) in untrained young adult men. Nine young adult men (24.0 ± 3.3 years) participated in a double-blind crossover study in which they received 6 g of CM and placebo (PL) on two occasions, separated by a seven-day washout period. Each occasion consisted of a single session of high-intensity RE (0 h) and three subsequent fatigue tests sessions (at 24, 48, and 72 h) to assess the time course of muscle recovery. During the tests sessions, we assessed the following variables: number of maximum repetitions, electromyographic signal (i.e., root mean square (RMS) and median frequency (MF)), muscle soreness and perceived exertion, as well as blood levels of creatine kinase (CK), lactate, insulin, and testosterone:cortisol ratio. CK levels increased at 24 h post-exercise and remained elevate at 48 and 72 h, with no difference between CM and PL conditions. Muscle soreness increased at 24 h post-exercise, which progressively returned to baseline at 72 h in both conditions. Lactate levels increased immediately post-exercise and remained elevated at 24, 48, and 72 h in both conditions. No significant treatment × time interaction was found for all dependents variables (maximum repetitions, perceived exertion, CK, lactate, RMS, MF, and testosterone:cortisol ratio) during the recovery period. In conclusion, our data indicate that CM supplementation (single 6 g dose pre-workout) does not improve the muscle recovery process following a high-intensity RE session in untrained young adult men.
Asunto(s)
Citrulina/análogos & derivados , Suplementos Dietéticos , Malatos/uso terapéutico , Contracción Muscular , Fatiga Muscular/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Entrenamiento de Fuerza , Adulto , Biomarcadores/sangre , Citrulina/efectos adversos , Citrulina/uso terapéutico , Creatina Quinasa/sangre , Estudios Cruzados , Suplementos Dietéticos/efectos adversos , Método Doble Ciego , Humanos , Hidrocortisona/sangre , Ácido Láctico/sangre , Malatos/efectos adversos , Masculino , Músculo Esquelético/metabolismo , Recuperación de la Función , Testosterona/sangre , Factores de Tiempo , Resultado del Tratamiento , Adulto JovenRESUMEN
Physical training has been shown to be important to the control of muscle mass during aging, through the activation of several pathways including, IGF1-AKT and PGC-1α. Also, it was demonstrated that LRP130, a component of the PGC-1α complex, is important for the PGC-1α-dependent transcription of several mitochondrial genes in vivo. To explore the role of physical training during aging, we investigated the effects on muscle recovery after short-term immobilization followed by 3 or 7 days with aerobic or resistance training. Using morphological (myofibrillar adenosine triphosphatase activity, to assess the total muscle fiber cross-sectional area (CSA) and the frequency of specific fiber types), biochemical (myosin heavy chain), and molecular analyses (quantitative real-time PCR, functional pathways analyses, and Western blot), our results indicated that after an atrophic stimulus, only animals subjected to aerobic training showed entire recovery of cross-sectional area; aerobic training reduced the ubiquitin-proteasome system components involved in muscle atrophy after 3 days of recovery, and the upregulation in PGC-1α expression enhanced the process of muscle recovery by inhibiting the FoxO pathway, with the possible involvement of LRP130. These results suggest that aerobic training enhanced the muscle regeneration process after disuse-induced atrophy in aged rats possibly through of the LRP130/PGC-1α complex by inhibiting the ubiquitin-proteasome system.