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Leucine Supplementation Increases Muscle Strength and Volume, Reduces Inflammation, and Affects Wellbeing in Adults and Adolescents with Cerebral Palsy.
Theis, N, Brown, MA, Wood, P, Waldron, M
The Journal of nutrition. 2021;(1):59-64
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Abstract
BACKGROUND Spastic cerebral palsy (CP) is characterized by muscle weakness owing, in part, to a blunted muscle protein synthetic response. This might be normalized by long-term leucine supplementation. OBJECTIVES The study assessed the effects of 10 wk leucine supplementation in adolescents and adults with CP. METHODS The study was a single-center randomized controlled trial. Twenty-four participants were randomly assigned to a control group (n = 12) or a leucine group (n = 12). l-Leucine (192 mg/kg body mass) was dissolved in water and administered daily for 10 wk. The primary outcome measures of elbow flexor muscle strength and muscle volume (measured by 3D ultrasound technique) and inflammation [C-reactive protein (CRP) concentration] were assessed before and after the 10 wk, alongside the secondary outcomes of body composition (measured by CP-specific skinfold assessment), metabolic rate (measured by indirect calorimetry), and wellbeing (measured by a self-reported daily questionnaire). Data were compared via a series of 2-factor mixed ANOVAs. RESULTS Twenty-one participants completed the intervention (control group: n = 11, mean ± SD age: 18.3 ± 2.8 y, body mass: 48.8 ± 11.9 kg, 45% male; leucine group: n = 10, age: 18.6 ± 1.7 y, body mass: 58.3 ± 20.2 kg, 70% male). After 10 wk, there was a 25.4% increase in strength (P = 0.019) and a 3.6% increase in muscle volume (P = 0.001) in the leucine group, with no changes in the control group. This was accompanied by a 59.1% reduction in CRP (P = 0.045) and improved perceptions of wellbeing (P = 0.006) in the leucine group. No changes in metabolism or body composition were observed in either group (P > 0.05). CONCLUSIONS Improvements in muscle strength and volume with leucine supplementation might provide important functional changes for adults and adolescents with CP and could be partly explained by reduced inflammation. The improved wellbeing highlights its capacity to improve the quality of daily living. This trial was registered at clinicaltrials.gov as NCT03668548.
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Modulation of Countermovement Jump-Derived Markers of Neuromuscular Function With Concurrent vs. Single-Mode Resistance Training.
Pattison, KJ, Drinkwater, EJ, Bishop, DJ, Stepto, NK, Fyfe, JJ
Journal of strength and conditioning research. 2020;(6):1497-1502
Abstract
Pattison, KJ, Drinkwater, EJ, Bishop, DJ, Stepto, NK, and Fyfe, JJ. Modulation of countermovement jump-derived markers of neuromuscular function with concurrent vs. single-mode resistance training. J Strength Cond Res 34(6): 1497-1502, 2020-This study assessed changes in countermovement jump (CMJ)-derived markers of neuromuscular function with concurrent training vs. resistance training (RT) alone and determined associations between changes in CMJ parameters and other neuromuscular adaptations (e.g., maximal strength gain). Twenty-three recreationally active men performed 8 weeks of RT alone (RT group, n = 8) or combined with either high-intensity interval training cycling (HIIT + RT group, n = 8) or moderate-intensity continuous cycling (MICT + RT group, n = 7). Maximal strength and CMJ performance were assessed before (PRE), after 4 weeks of training (MID), and >72 hours (maximal strength) or >5-7 days (CMJ performance) after (POST) the training intervention. Improvements in CMJ relative peak force from both PRE to MID and PRE to POST were attenuated for both HIIT + RT (effect size [ES]: -0.44; ±90% confidence limit, ±0.51 and ES: -0.72; ±0.61, respectively) and MICT + RT (ES: -0.74; ±0.49 and ES: -1.25; ±0.63, respectively). Compared with RT alone, the change in the flight time to contraction time ratio (FT:CT) was attenuated from PRE to MID for MICT + RT (ES: -0.38; ±0.42) and from PRE to POST for both MICT + RT (ES: -0.60; ±0.55) and HIIT + RT (ES: -0.75; ±0.30). PRE to POST changes in both CMJ relative peak force and flight time:contraction time (F:C) ratio were also associated with relative 1 repetition maximum leg press strength gain (r = 0.26 and 0.19, respectively). These findings highlight the utility of CMJ testing for monitoring interference to improvements in neuromuscular function with concurrent training.
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Higher Muscle Mass Implies Increased Free-Thyroxine to Free-Triiodothyronine Ratio in Subjects With Overweight and Obesity.
Zupo, R, Castellana, F, Sardone, R, Lampignano, L, Paradiso, S, Giagulli, VA, Triggiani, V, Di Lorenzo, L, Giannelli, G, De Pergola, G
Frontiers in endocrinology. 2020;:565065
Abstract
UNLABELLED Thyroid hormones control both metabolic pathways and body composition, whereas little knowledge is available about the possible influence of skeletal muscle mass (MM) on thyroid hormone metabolism and circulating levels. This was a cross-sectional study conducted at the Population Health Unit of the National Institute of Gastroenterology IRCCS "S. de Bellis" (Italy) and investigating the extent to which skeletal MM affects thyroid function in obesity. Two hundred twenty-seven consecutive healthy volunteers (155 women and 72 men) with overweight and obesity (BMI ≥ 25 kg/m2) and taking no medication or supplement were assessed for hormone, metabolic and routine laboratory parameters. Body composition parameters were collected by using bioelectrical impedance analysis (BIA). MM was directly related to the body mass index (BMI), waist circumference (WC), insulin, triglycerides, uric acid and free-triiodothyronine (FT3) serum levels, FT3 to the free-thyroxine (FT4) ratio, and insulin-resistance (HOMA-IR), and inversely related to age, total, and HDL-cholesterol serum levels. Multiple regression models confirmed the relationship between MM and the FT3 to FT4 ratio, independently of age, BMI, TSH, triglycerides, and insulin serum levels. The same analyses run by gender showed that this relationship maintained significance only in men. Increased skeletal MM in obesity results in improved thyroid activity mediated by increased T4 conversion to T3, and higher FT3 circulating levels, particularly in men. In conclusion, preserving a greater skeletal MM in obesity helps to enhance thyroid activity. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov, identifier NCT04327375.
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Effect of Acute Beetroot Juice Supplementation on Bench Press Power, Velocity, and Repetition Volume.
Williams, TD, Martin, MP, Mintz, JA, Rogers, RR, Ballmann, CG
Journal of strength and conditioning research. 2020;(4):924-928
Abstract
Williams, TD, Martin, MP, Mintz, JA, Rogers, RR, and Ballmann, CG. Effect of acute beetroot juice supplementation on bench press power, velocity, and repetition volume. J Strength Cond Res 34(4): 924-928, 2020-The purpose of this study was to examine the effects of acute beetroot juice (BRJ) supplementation on power, velocity, and repetitions to failure (RTF) during bench press exercise. Resistance-trained male subjects (n = 11) were recruited for this study. Using a double-blinded, counterbalanced, crossover study design, subjects were supplemented with either 70 ml of BRJ or placebo (PL; black currant juice) 2 hours before exercise. During each exercise trial, subjects began by completing 2 sets × 2 repetitions of bench press at 70% 1 repetition maximum (1RM) with maximum explosive intent. Barbell velocity and power were measured using a linear position transducer. Subjects then completed 3 sets × RTF at 70% 1RM separated by 2 minutes of rest between each set. Maximum mean power, velocity, and repetitions were analyzed. Mean velocity (p = 0.011; effect size [ES] = 0.54) and mean power (p = 0.015; ES = 0.51) were significantly higher with BRJ when compared with PL. Total RTF (p = 0.002; ES = 0.46) was higher during the BRJ condition vs. PL. Results indicate that acute BRJ supplementation positively impacts velocity, power, and total repetitions during free-weight bench press exercise.
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Effects of Different Weekly Sets-Equated Resistance Training Frequencies on Muscular Strength, Muscle Mass, and Body Fat in Older Women.
Pina, FLC, Nunes, JP, Schoenfeld, BJ, Nascimento, MA, Gerage, AM, Januário, RSB, Carneiro, NH, Cyrino, ES, Oliveira, AR
Journal of strength and conditioning research. 2020;(10):2990-2995
Abstract
Pina, FLC, Nunes, JP, Schoenfeld, BJ, Nascimento, MA, Gerage, AM, Januário, RSB, Carneiro, NH, Cyrino, ES, and Oliveira, AR. Effects of different weekly sets-equated resistance training frequencies on muscular strength, muscle mass and body fat in older women. J Strength Cond Res 34(10): 2990-2995, 2020-The aim of this study was to analyze the effects of different resistance training (RT) frequencies (2 vs. 3 times per week) with an equivalent number of weekly sets performed between conditions on muscular strength and body composition in older women. Forty-seven older women (65 ± 4 years) were divided into 2 groups that performed a 12-week RT program either 2 (G2x and 3 sets) or 3 (G3x and 2 sets) times per week. The groups were evaluated before and after study on measures of body composition through dual-energy x-ray absorptiometry, and muscular strength through one repetition maximum (1RM) testing. Lean soft tissue was significantly increased in both groups (G2x = +1.7%, G3x = +1.7%), while only G3x reduced body fat after the intervention period (G2x = -0.7%, G3x = -2.9%). Similarly, significant increases were noted between conditions for 1RM scores in bench press (G2x = +11.8%, G3x = +11.9%) and knee extension (G2x = +17.4%, G3x = +10.8%). The results indicate that performing 2 or 3 RT sessions per week promotes similar improvements in muscular outcomes, while training more frequently may reduce body fat after 12 weeks of weekly sets-equated RT in untrained older women.
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Order of same-day concurrent training influences some indices of power development, but not strength, lean mass, or aerobic fitness in healthy, moderately-active men after 9 weeks of training.
Lee, MJ, Ballantyne, JK, Chagolla, J, Hopkins, WG, Fyfe, JJ, Phillips, SM, Bishop, DJ, Bartlett, JD
PloS one. 2020;(5):e0233134
Abstract
BACKGROUND The importance of concurrent exercise order for improving endurance and resistance adaptations remains unclear, particularly when sessions are performed a few hours apart. We investigated the effects of concurrent training (in alternate orders, separated by ~3 hours) on endurance and resistance training adaptations, compared to resistance-only training. MATERIALS AND METHODS Twenty-nine healthy, moderately-active men (mean ± SD; age 24.5 ± 4.7 y; body mass 74.9 ± 10.8 kg; height 179.7 ± 6.5 cm) performed either resistance-only training (RT, n = 9), or same-day concurrent training whereby high-intensity interval training was performed either 3 hours before (HIIT+RT, n = 10) or after resistance training (RT+HIIT, n = 10), for 3 d.wk-1 over 9 weeks. Training-induced changes in leg press 1-repetition maximal (1-RM) strength, countermovement jump (CMJ) performance, body composition, peak oxygen uptake ([Formula: see text]), aerobic power ([Formula: see text]), and lactate threshold ([Formula: see text]) were assessed before, and after both 5 and 9 weeks of training. RESULTS After 9 weeks, all training groups increased leg press 1-RM (~24-28%) and total lean mass (~3-4%), with no clear differences between groups. Both concurrent groups elicited similar small-to-moderate improvements in all markers of aerobic fitness ([Formula: see text] ~8-9%; [Formula: see text] ~16-20%; [Formula: see text] ~14-15%). RT improved CMJ displacement (mean ± SD, 5.3 ± 6.3%), velocity (2.2 ± 2.7%), force (absolute: 10.1 ± 10.1%), and power (absolute: 9.8 ± 7.6%; relative: 6.0 ± 6.6%). HIIT+RT elicited comparable improvements in CMJ velocity only (2.2 ± 2.7%). Compared to RT, RT+HIIT attenuated CMJ displacement (mean difference ± 90%CI, -5.1 ± 4.3%), force (absolute: -8.2 ± 7.1%) and power (absolute: -6.0 ± 4.7%). Only RT+HIIT reduced absolute fat mass (mean ± SD, -11.0 ± 11.7%). CONCLUSIONS In moderately-active males, concurrent training, regardless of the exercise order, presents a viable strategy to improve lower-body maximal strength and total lean mass comparably to resistance-only training, whilst also improving indices of aerobic fitness. However, improvements in CMJ displacement, force, and power were attenuated when RT was performed before HIIT, and as such, exercise order may be an important consideration when designing training programs in which the goal is to improve lower-body power.
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Specificity and Transfer of Lower-Body Strength: Influence of Bilateral or Unilateral Lower-Body Resistance Training.
Appleby, BB, Cormack, SJ, Newton, RU
Journal of strength and conditioning research. 2019;(2):318-326
Abstract
Appleby, BB, Cormack, SJ, and Newton, RU. Specificity and transfer of lower-body strength: Influence of bilateral or unilateral lower-body resistance training. J Strength Cond Res 33(2): 318-326, 2019-To examine the development of lower-body strength using either bilateral or unilateral resistance training. Developmental rugby players (n = 33; mean training age = 5.4 ± 2.9 years; 1 repetition maximum [1RM] 90° squat = 178 ± 27 kg) completed an 18-week randomized controlled training design (bilateral group [BIL], n = 13; unilateral group [UNI], n = 10; comparison, n = 10). The 8-week training phase involved 2 lower-body, volume-load matched resistance sessions per week (6-8 sets × 4-8 reps at 45-88% 1RM), differing only in the prescription of a bilateral (back squat) or unilateral (step-up) resistance exercise. Maximum strength was assessed by a randomized order of 1RM back squat and step-up testing and analyzed for within- and between-group differences using effect sizes (ES ± 90% confidence limits [CL]). Both training groups showed practically important improvements in their trained exercise (ES ± 90% CL: BIL = 0.67 ± 0.48; UNI = 0.74 ± 0.38) with transfer to their nontrained resistance exercise (BIL step-up = 0.27 ± 0.39: UNI squat = 0.42 ± 0.39). The difference between groups in adaptation of squat strength was unclear (BIL ES = -0.34 ± 0.55), while the UNI group showed an advantage in step-up training (ES = 0.41 ± 0.36). The results demonstrate that practically important increases in lower-body strength can be achieved using bilateral or unilateral resistance training and development of that strength may be expressed in the movement not trained, supporting the transfer of strength training between exercises of similar joint movements and muscles. Coaches may choose to incorporate unilateral strength training where the prescription of bilateral training may be inhibited.
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Influence of the "Slingshot" Bench Press Training Aid on Bench Press Kinematics and Neuromuscular Activity in Competitive Powerlifters.
Dugdale, JH, Hunter, AM, Di Virgilio, TG, Macgregor, LJ, Hamilton, DL
Journal of strength and conditioning research. 2019;(2):327-336
Abstract
Dugdale, JH, Hunter, AM, Di Virgilio, TG, Macgregor, LJ, and Hamilton, DL. Influence of the "Slingshot" bench press training aid on bench press kinematics and neuromuscular activity in competitive powerlifters. J Strength Cond Res 33(2): 327-336, 2019-This study examined the acute effects of the "Slingshot" (SS) on bench press performance, prime mover surface electromyographic (sEMG) amplitude, and barbell velocity during maximal and submaximal bench pressing in competitive male powerlifters. Fifteen male powerlifters (mean ± SD; age: 27.05 ± 5.94 years; mass: 94.15 ± 13.43 kg; 1 repetition maximum [1RM] bench press: 139.7 ± 16.79 kg) participated in the study. Bench press strength, average barbell velocity, and sEMG amplitude of the prime mover muscles (triceps brachii, pectoralis major, and anterior deltoid) were measured during 2 conditions; "Raw" (without use of any assistance) and "SS" (using the "Slingshot" to perform both the weight achieved during "Raw" 1RM testing [Raw max/SS], and absolute 1RM using the "SS"). The results showed that the "SS" significantly increased bench press 1RM performance by a mean ± SD of 20.67 ± 3.4 kg. Barbell velocity and stick point analysis indicate that this improvement is likely driven by an increase in peak and prestick barbell velocity as triceps root mean square (RMS) was lower throughout all rep max phases with the "SS." The "SS" also caused reductions in RMS, specifically of the triceps at all rep ranges but barbell velocity was better maintained in the last reps of all sets. These data indicate that the "SS" specifically deloaded the triceps muscle throughout all rep ranges and provide assistance to maintaining barbell velocity under fatigue during later repetitions of multiple repetition sets. The "SS" training aid could therefore be used in deload phases of bench press training or as an overreaching and velocity training aid.
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Oral Contraceptive Use does not Negatively Affect Body Composition and Strength Adaptations in Trained Women.
Romance, R, Vargas, S, Espinar, S, Petro, JL, Bonilla, DA, Schöenfeld, BJ, Kreider, RB, Benítez-Porres, J
International journal of sports medicine. 2019;(13):842-849
Abstract
The purpose was to analyze the influence of oral contraceptive use on body composition and strength levels in trained women. Twenty-three resistance-trained women participated in this study (age=27.4±3.4 years; fat mass=28.0±5.0%; BMI=22.9±2.7 kg∙m-2). Subjects performed an 8-week non-linear resistance-training program. Participants were assigned to either a group that consumed oral contraceptives (n=12, OC) or to a group that did not consume (n=11, NOC). Changes in body composition were measured by dual energy X-ray absorptiometry. Strength performance was assessed via the one maximum repetition (1RM) test in the squat and bench press, and muscular power was evaluated using the countermovement jump (CMJ) test. Fat free mass increased significantly in OC but no changes were seen in NOC. There were no changes in fat mass for either OC or NOC. Significant changes were found in bench press 1RM for both OC and NOC; similarly, increases in squat 1RM were reported in OC and NOC. Alternatively, no significant changes were found in CMJ in both OC and NOC. No significant between-group differences were detected in any of the studied variables. The use of oral contraceptives during resistance training did not negatively affect body composition or strength levels in trained women.
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10.
Resistance training does not induce uniform adaptations to quadriceps.
Mangine, GT, Redd, MJ, Gonzalez, AM, Townsend, JR, Wells, AJ, Jajtner, AR, Beyer, KS, Boone, CH, La Monica, MB, Stout, JR, et al
PloS one. 2018;(8):e0198304
Abstract
Resistance training may differentially affect morphological adaptations along the length of uni-articular and bi-articular muscles. The purpose of this study was to compare changes in muscle morphology along the length of the rectus femoris (RF) and vastus lateralis (VL) in response to resistance training. Following a 2-wk preparatory phase, 15 resistance-trained men (24.0 ± 3.0 y, 90.0 ± 13.8 kg, 174.9 ± 20.7 cm) completed pre-training (PRE) assessments of muscle thickness (MT), pennation angle (PA), cross-sectional area (CSA), and echo-intensity in the RF and VL at 30, 50, and 70% of each muscle's length; fascicle length (FL) was estimated from respective measurements of MT and PA within each muscle and region. Participants then began a high intensity, low volume (4 x 3-5 repetitions, 3min rest) lower-body resistance training program, and repeated all PRE-assessments after 8 weeks (2 d ∙ wk-1) of training (POST). Although three-way (muscle [RF, VL] x region [30, 50, 70%] x time [PRE, POST]) repeated measures analysis of variance did not reveal significant interactions for any assessment of morphology, significant simple (muscle x time) effects were observed for CSA (p = 0.002) and FL (p = 0.016). Specifically, average CSA changes favored the VL (2.96 ± 0.69 cm2, p < 0.001) over the RF (0.59 ± 0.20 cm2, p = 0.011), while significant decreases in average FL were noted for the RF (-1.03 ± 0.30 cm, p = 0.004) but not the VL (-0.05 ± 0.36 cm, p = 0.901). No other significant differences were observed. The findings of this study demonstrate the occurrence of non-homogenous adaptations in RF and VL muscle size and architecture following 8 weeks of high-intensity resistance training in resistance-trained men. However, training does not appear to influence region-specific adaptations in either muscle.