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Daily L-Leucine Supplementation in Novice Trainees During a 12-Week Weight Training Program

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Abstract

To investigate the effects of daily oral L-leucine ingestion on strength, bone mineral-free lean tissue mass (LTM) and fat mass (FM) of free living humans during a 12-wk resistance-training program. Twenty-six initially untrained men (n = 13 per group) ingested either 4 g/d of L-leucine (leucine group: age 28.5 ± 8.2 y, body mass index 24.9 ± 4.2 kg/m2) or a corresponding amount of lactose (placebo group: age 28.2 ± 7.3 y, body mass index 24.9 ± 4.2 kg/m2). All participants trained under supervision twice per week following a prescribed resistance training program using eight standard exercise machines. Testing took place at baseline and at the end of the supplementation period. Strength on each exercise was assessed by five repetition maximum (5-RM), and body composition was assessed by dual energy X-ray absorptiometry (DXA). The leucine group demonstrated significantly higher gains in total 5-RM strength (sum of 5-RM in eight exercises) and 5-RM strength in five out of the eight exercises (P < .05). The percentage total 5-RM strength gains were 40.8% (± 7.8) and 31.0% (± 4.6) for the leucine and placebo groups respectively. Significant differences did not exist between groups in either total percentage LTM gains or total percentage FM losses (LTM: 2.9% ± 2.5 vs 2.0% ± 2.1, FM: 1.6% ± 15.6 vs 1.1% ± 7.6). These results suggest that 4 g/d of L-leucine supplementation may be used as a nutritional supplement to enhance strength performance during a 12-week resistance training program of initially untrained male participants.
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... It has been suggested that daily supplementation with as little as 5 g of BCAAs can aid in the reduction of exercise-induced muscle damage (42). Although not including all BCAAs, it has further been reported that 12 weeks of resistance training in combination with as little as 4 g of leucine alone promotes significant strength increases in untrained men compared with consuming nothing (19). Lastly, caffeine and creatine are known to increase power output and volume of training in athletes and strength-trained populations (7,17,45,49). ...
... Individually, the aforementioned ingredients have been reported to mediate one or more of the following: (a) increases in serum testosterone levels (9,11), (b) enhancements of muscle size (43), and/or (c) enhancements of muscular strength (19). However, the combined effects of these ingredients have not been investigated despite the increasing popularity of MIPS. ...
... Because strength was significantly increased, this may confirm that the doses of BA in SUP suffice for young resistance-trained men, at least in combination with other ingredients in the current formulation. Leucine, one of the BCAAs, taken in 4 g$d 21 doses provided over 12 weeks in combination with a resistance training program was shown to increase strength compared with a lactose PL in untrained men (19). The range of daily BCAA consumption in the SUP was 2.5-5.0 g$d 21 (average, 3.75 g) of BCAAs, falling just short of the recommendations. ...
... Co-ingestion of LEU with a meal has been shown to improve MPS in older individuals (18,19). When provided as a daily supplement to healthy male participants in a resistance training intervention, there was a significant increase in strength and a nonsignificant increase in muscle mass versus placebo (20). Bukhari et al. (21) found that a daily-administered LEUenriched amino acid supplement at 3 grams/day stimulated MPS among older women, while another study utilizing LEU-enriched amino acid mixtures of approximately 3 and 6 grams/day in older men and women only found a significant increase in lean mass accretion at the higher dose (22). ...
... The 10-g daily dose of leucine utilized in our study was slightly higher than that used in studies that evaluated either lean mass accretion or stimulation of muscle protein anabolism without weight loss, ranging from 3-to 4-g per day provided in one dose (20,21). A weight loss study conducted by Verreijen et al. (24), utilizing a whey protein supplement containing 3 g of leucine, found that participants in the intervention group gained lean mass during weight loss (0.4 ± 1.2 kg) while those in the placebo group lost lean mass (0.5 ± 2.1 kg). ...
Article
Objective: This study evaluated the effect of leucine supplementation coupled with a calorie-restricted diet over a 12-week period in mid-life overweight and obese women on body composition and resting metabolic rate (RMR). Method: This study was a randomized, single-blind, placebo-controlled trial in which 34 women were randomly assigned to either 10 g leucine (LEU) or placebo daily, while following a calorie-restricted diet A dual energy x-ray absorptiometry (DXA) analysis, metabolic rate assessment via a BodyGem® and anthropometrics were performed at baseline and after the 12-week study to determine changes in fat mass, lean mass and RMR. Main variables were analyzed using 2 (condition) by 2 (time) mixed design ANOVAs with repeated measures. Odds ratio was calculated by counting the number of individuals gaining or maintaining lean mass (p ≤ .05). Results: Both groups lost a significant amount of weight due to both fat and lean mass loss, but there was no significant difference between groups, with RMR remaining unchanged over the course of the study and not significantly different between groups. The loss in lean mass was noticeably less, though not statistically significant (p = 0.644) for the women in the LEU group, with 38% vs. 6%, gaining or retaining lean mass during the intervention relative to the placebo. Conclusions: Our findings demonstrate that a greater proportion of mid-life overweight or obese women taking LEU supplements gained or maintained lean mass during intentional weight loss, though it did not reach a level of statistical significance.
... Katsanos et al. (23) evaluated the acute effects of leucine supplementation without exercise and reported that a higher level of leucine ingestion was needed among older versus younger adults to promote postprandial muscle protein synthesis (1.7 vs 2.8 g). In a 12-week RT plus leucine intervention, young male participants who consumed 4 g leucine daily and trained twice per week had significantly greater gains in strength compared to participants in the placebo group, as well as non-significant gains and losses in FFM and fat mass (FM), respectively (25). In an acute resistance exercise study in young males, investigators compared the anabolic response following resistance exercise with the administration of three different beverages (26). ...
... The 5-g daily dose of leucine utilized in our study is supported by other studies demonstrating the effectiveness of a similar dosage (16,18,20,24). The fact that we observed no significant increase in FFM with the 5-g daily dose of leucine supplementation is in contrast to studies of both young men and older men and women that utilized similar doses of leucine supplementation (25,27). Thus, the routine dietary intake and dosing protocol of the participants in the present study may have played a role. ...
Article
Objective: This study investigated the effects of leucine supplementation with resistance training (RT) in untrained peri- and postmenopausal women on fat free mass, strength, and select anabolic-related hormones. Method: This was a randomized, double-blind, placebo-controlled trial, in which 36 untrained women were randomly assigned to either a leucine or placebo supplement group coupled with 10 weeks of RT, performed thrice weekly, while ingesting either 5 g of placebo or leucine. Before and after RT, body composition and muscle strength were assessed and venous blood samples obtained to determine the levels of estradiol, testosterone, insulin-like growth factor-1, growth hormone, and cortisol. Data were analyzed by utilizing separate 2 × 2 [group × time (pretest and posttest)] factorial analyses of variance with repeated measures (p ≤ .05). Results: There were no significant changes or differences between groups in fat free mass or with any of the serum hormones assessed in response to supplementation. However, there were significant increases in strength in both groups in response to RT, but not supplementation. Conclusions: Peri- and postmenopausal women had significant increases in strength following 10 weeks of RT, with no additional effects from supplementing with leucine. There were no significant changes in either group regarding fat free mass or serum hormones.
... 28 Therefore, future studies are necessary to investigate the mechanism for the reduction in abdominal fat area observed with A-mix supplementation combined with physical activity promotion. Although many trials have reported that the long-term supplementation of amino acids, combined with exercise, increased fat mobilization and/or weight loss, [29][30][31][32][33][34][35][36] this study focused on the promotion of physical activity, rather than a specific exercise training program. For example, Lucotti et al focused on the effects of 8.3 g arginine supplementation combined with two 45 min sessions per day of whole body exercise five times per week for 5 weeks. ...
... 33 Ispoglou et al focused on the effects of 4.0 g leucine supplementation combined with a resistance training program using eight standard exercise machines twice per week for 12 weeks. 35 These prescribed exercise programs were more intensive than that used in this study. Low-to-moderate intensity exercise may be better than vigorous exercise for the promotion of fat mass reduction, because the substrate oxidation achieved during high-intensity exercise primarily involves carbohydrate oxidation. ...
... Lean body mass and muscle power are also related to genetic control and growth factors such as hormone and hormone like compound that enhances the cells to produce gains in muscle fibre size. This may have caused variations in progress [12] . ...
Research
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The present study was conducted with an aim to investigate the effect of leucine supplementation in muscle growth of gym goers. 15 healthy male gym-goers ingested with 3 g/d of leucine and 15 healthy male gym goers were considered as test and placebo group, respectively. Their daily dietary intake was assessed and was told to stay on same diet and exercise routine till the completion of study period. Anthropometric measurements, body measurements and body composition were assessed on the initial day and at the end of the study period. A significant difference (p≤0.01) was observed between pre and post value of supplemented group for WHR. Medium effect size (0.7) for WHR between two groups was observed significantly which indicates that the change was moderate between the groups after supplementation. Independent t-test showed small value of effect size for visceral fat (0.3) and medium for bone mass (0.4) between two groups. These results states that 3 g/d of leucine supplementation for 45 days can enhance muscle growth and increases the strength performance of the gym persons.
... In fact, another meta-analysis detected a beneficial effect of leucine on LBM, although not on muscle strength [136]. In addition, the combination of leucine plus RT gives rise to greater MPS and myofibrillar muscle hypertrophy than leucine supplementation alone [137], and also leads to additional strength gains in untrained men [138]. ...
Article
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Purpose Several supplements are purported to promote muscle hypertrophy and strength gains in healthy subjects, or to prevent muscle wasting in atrophying situations (e.g., ageing or disuse periods). However, their effectiveness remains unclear. Methods This review summarizes the available evidence on the beneficial impacts of several popular supplements on muscle mass or strength. Results Among the supplements tested, nitrate and caffeine returned sufficient evidence supporting their acute beneficial effects on muscle strength, whereas the long-term consumption of creatine, protein and polyunsaturated fatty acids seems to consistently increase or preserve muscle mass and strength (evidence level A). On the other hand, mixed or unclear evidence was found for several popular supplements including branched-chain amino acids, adenosine triphosphate, citrulline, β-Hydroxy-β-methylbutyrate, minerals, most vitamins, phosphatidic acid or arginine (evidence level B), weak or scarce evidence was found for conjugated linoleic acid, glutamine, resveratrol, tribulus terrestris or ursolic acid (evidence level C), and no evidence was found for other supplements such as ornithine or α-ketoglutarate (evidence D). Of note, although most supplements appear to be safe when consumed at typical doses, some adverse events have been reported for some of them (e.g., caffeine, vitamins, α-ketoglutarate, tribulus terrestris, arginine) after large intakes, and there is insufficient evidence to determine the safety of many frequently used supplements (e.g., ornithine, conjugated linoleic acid, ursolic acid). Conclusion In summary, despite their popularity, there is little evidence supporting the use of most supplements, and some of them have been even proven ineffective or potentially associated with adverse effects.
... It has been suggested that a possible action for HMB to reduce BF may be through Sirt1 and 3 (Silent information transcripts 1 and 3) and AMPK (adenosine monophosphate kinase)a mechanism that has also been reported with leucine (Wilson et al., 2014)however, these mechanisms are derived from in vitro and/or animal investigations (Bruckbauer et al., 2012;Stancliffe & Zemel, 2012), while human investigations for 12 weeks, in novice trainees, show no effect of leucine in reducing BF (Ispoglou, King, Polman, & Zanker, 2011). Another argument used to support previously reported extraordinary results (Kraemer et al., 2009;Wilson et al., 2014) is the addition of other ostensibly ergogenic amino acids (arginine, glutamine and taurine) or ATP. ...
Article
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... Thus, leucine supplementation during meals could optimize whole-day MPS in this current population. In literature, leucine supplementation induced higher gains in strength, but not in lean body mass, in novice trainees during 12 weeks of a weight training program [40]. Indeed, the ingestion of branched chain amino acids alone increased but did not maximally stimulate the MPS following exercise, as the lack of other EAAs limits the response of myofibrillar-MPS following exercise [41]. ...
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A higher protein intake is recommended for athletes compared to healthy non-exercising individuals. Additionally, the distribution and quality (i.e., leucine content) of the proteins consumed throughout the day should be optimized. This study aimed to determine the nitrogen balance and distribution of protein and amino acid intakes in competitive swimmers during the general preparation phase. Thirteen swimmers (age: 19.7 ± 1.0 years; VO2max: 63.9 ± 3.7 mL·kg−1·min−1, mean ± standard deviation) participated in a five-day experimental training period. Nutrient intakes were assessed using dietary records. Nitrogen balance was calculated from the daily protein intake and urinary nitrogen excretion. The intake amounts of amino acids and protein at seven eating occasions were determined. The average and population-safe intakes for zero nitrogen balance were estimated at 1.43 and 1.92 g·kg−1·day−1, respectively. The intake amounts of protein and leucine at breakfast, lunch, and dinner satisfied current guidelines for the maximization of muscle protein synthesis, but not in the other four occasions. The population-safe protein intake level in competitive swimmers was in the upper range (i.e., 1.2–2.0 g·kg−1·day−1) of the current recommendations for athletes. The protein intake distribution and quality throughout the day may be suboptimal for the maximization of the skeletal muscle adaptive response to training.
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Several dietary supplements have been proposed as a means of improving muscle strength and hypertrophy when combined with resistance training. However, few have received sufficient attention from sports scientists to produce robust evidence for being well recommended. A growing body of literature has emerged for several dietary ingredients with the potential to promote muscular adaptations. Therefore, the aim of this review is to provide an evidence-based review of the efficacy of emerging nutritional supplements to allow athletes, coaches, and practitioners to make an informed decision when considering their use as a means of improving muscle strength and hypertrophy.
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