Physical and sports performance can benefit from various supplemental and nutritional intervention strategies. There is increasing interest in the ergogenic benefit of beta-alanine, which is the precursor to the histidine-containing dipeptide carnosine (β-alanyl-L-histidine), itself shown to have a key role in acid–base regulation during exercise, with other important health-linked roles (such as antioxidant and anti-glycation properties) also posited (Sale et al., 2013). Carnosine is one member of the histidine-containing dipeptides found in humans, with most animals also hosting one or both of its methylated variants, anserine (also expressed in human skeletal and cardiac muscle) or ophidine (Dolan, Saunders, et al., 2019; Toviwek et al., 2022). Already established as having a pH-buffering effect, the synthesis of carnosine in muscle tissue, where it is predominantly found, is rate-limited by the availability of beta-alanine (Perim et al., 2019; Stellingwerff et al., 2012).
Beta-alanine is a nonproteinogenic, nonessential amino acid which is synthesized in relatively small amounts in the liver (Trexler et al., 2015) and can be acquired in the diet from animal, but not plant sources. Supplementation strategies have been shown to significantly increase the amounts of beta-alanine found in blood plasma and subsequently elevate muscle carnosine content; specifically, dosages of beta-alanine ranging from 3.2 to 6.4 g per day given for 4 weeks have been shown to increase muscle carnosine levels by 42%–66% (Harris et al., 2006).
Meta-analyses by Hobson et al. (2012) and Saunders et al. (2017) demonstrated that the greatest ergogenic effects of beta-alanine were attained in exercise lasting 0.5–10 min, where the dominant contributor to energy production is the anaerobic-glycolytic pathway (Artioli et al., 2010). While the tests conducted in these meta-analyses differentiate between performance and capacity tests, they do not focus exclusively on maximal/supramaximal efforts as they also include tests which may contain significant bouts of submaximal output, particularly concerning performance tests. It was also recently shown that beta-alanine supplementation improved output during the second level of the Yo-Yo intermittent performance test (Grgic, 2021) and aerobic–anaerobic transition zones during performance testing (Ojeda et al., 2020). However, it was unclear whether beta-alanine was more effective at improving exercise capacity (i.e., work done and power) or performance (i.e., time to completion/exhaustion), likely due to a lack of studies focusing on performance at the time of their publication. Furthermore, the exercise testing protocols in some of the included studies may have biased the results; for example, studies measuring maximal oxygen capacity (
The aim of this study was to perform a systematic review and meta-analysis on the effects of beta-alanine supplementation on maximal intensity exercise output; specifically, strength and power as capacity measures, and performance time in young, male, trained individuals. Ergogenic supplements in general (muscle building and endurance enhancing) have a larger proportion of sales arising from men, as opposed to women, who generally gravitate more to weight loss supplements (Austin et al., 2017); taking this discrepancy into account, and in an effort to maintain a more homogeneous group to minimize bias, studies focusing on men were selected over those focusing on women or mixed groups, to be included in this study. Maximal intensity exercise is defined herein as efforts which reach muscular failure during strength and power tests at which no further, technically proficient, repetition can be executed, or efforts in which voluntary output of required (maximal/supramaximal) intensity must be sustained for a given duration. Thus, this study did not examine the effects of beta-alanine supplementation on submaximal exercise. The secondary aims of this study were to add resolution and nuance to the data sets, by applying subanalyses on supplementation duration and dosage, as well as the duration of the tests being performed.
Methods
This systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (Page et al., 2021), with the question determined according to PICO (Population, Intervention, Comparator, and Outcomes). The protocol of this systematic review was registered at the Open Science Framework (https://doi.org/10.17605/OSF.IO/AYZ5K).
Literature Search
Relevant articles were identified via electronic search using six databases (PubMed, Google Scholar, Cochrane Library of Science, Scopus, Web of Science, and ScienceDirect). Key search terms “beta-alanine” and “β-alanine” were concatenated with “trained male individuals,” “maximal intensity exercise,” and “athletic performance,” as well as (“trained males” OR “sports performance” OR “athletic performance” OR “maximal intensity”) AND (“beta-alanine” OR “β-alanine”). The terms were combined with the databases’ filter for controlled trials of interventions on humans. Screening was initiated with a title and abstract search against key search terms. Duplicates and nonpublished articles were removed after importing to Microsoft Excel. All remaining studies (titles and abstract) were screened against inclusion/exclusion criteria, with unclear studies remaining at this stage. The remaining articles were then retrieved and thoroughly assessed against criteria. All reviewers participated in this process and discussed any studies which needed further scrutiny before finalizing the studies being included.
Study Selection
The inclusion criteria of this systematic review were as follows: (a) human study; (b) placebo (PL)-controlled, double-blinded, randomized study; (c) male participants; (d) participants supplemented with beta-alanine; (e) participants who were physically active or recreationally active with consistent training more than three times per week for at least 6 months, and professional/semiprofessional/recreational athletes; (f) participants 18–40 years of age; (g) studies that investigated exercise involving maximal or supramaximal intensity efforts of 0.5–10 min duration, exercise tests involving a single bout of sustained effort, or shorter intervals of high-intensity effort interrupted by brief recovery periods; and (h) peer-reviewed studies published in English. The exclusion criteria were: (a) nonrandomized clinical studies; (b) untrained, inactive, or unhealthy participants; (c) participants under the age of 18 years or above the age of 40 years; (d) participants supplementing other dietary or ergogenic supplements with beta-alanine; (e) unspecified supplementation duration; (f) studies that investigated outcomes not relevant to exercise output; (g) Ph.D. theses, comments, editorials, or reviews; and (h) crossover designed studies that failed to report an appropriate washout period; studies have shown a decrease in supplemented levels of muscle carnosine at a rate of approximately 2% per week following cessation of supplementation protocol, with durations of up to 16 weeks being shown necessary for complete return to baseline levels (Baguet et al., 2009). Thus, 16 weeks was set as an appropriate washout period. Females were excluded due to the possibility of bias arising from the inherently lower levels of carnosine present in these participants (Derave et al., 2010), which can result in females experiencing a greater increase in intramuscular carnosine (Glenn et al., 2015).
Data Extraction
Three reviewers (K. Antoniou, Georgiou, and S. Antoniou) extracted the data from the eligible articles. The information extracted was as follows: study design, participant characteristics (number, sports, or physical activity), group characteristics (number of participants and age), beta-alanine group (dosage), PL/comparison group (form and dosage), study duration, outcome measures, testing protocol, load, and results.
Statistical Analysis
The overlap of CIs (95% CI) of outcome measurements from the included studies was used to determine statistical heterogeneity, represented by Cochran’s Q (chi-square test) and I2. The percentage of observed total variation between studies was indicated by the I2 statistic showing real heterogeneity as opposed to sampling error. I2 value is separated into three categories: low heterogeneity (25%–50%), moderate (50%–75%), and high (>75%; Grant & Hunter, 2006).
Quality and Risk of Bias Assessment
Quality assessment and the risk of bias were performed by all reviewers, in accordance with the Revised Cochrane Collaboration’s tool for assessing risk of bias in randomized trials (RoB2; Higgins et al., 2011). The tool comprises six domains: bias arising from the randomization process, bias arising from period and carryover effects, bias due to deviations from intended interventions, bias due to missing outcome data, bias in measurement of the outcome, and bias in selection of the reported result. For each domain, a possible risk of bias judgment was low risk, some concerns and high risk, as well as not applicable. A sensitivity test of the studies with highest bias is included (see Figure S4 in Supplementary Materials [available online]).
Results
Study Selection
After searching the six databases, 1,478 articles were identified, of which 328 were not randomized controlled trials. The remaining were filtered by title, and irrelevant (n = 594) and duplicated (n = 427) articles were excluded. All reviewers (Georgiou, K. Antoniou, S. Antoniou, and Michelekaki) took part in the screening process. The remaining 129 articles were retrieved, of which 70 were excluded because they failed to meet inclusion criteria. One report was not retrieved as it was written in Spanish. A total of 58 were then assessed for eligibility, of which 32 were excluded. Finally, a total of 26 articles were eligible for inclusion in the qualitative synthesis of this systematic review. Eight articles were not eligible for inclusion in the meta-analysis because the authors did not mention means and/or SDs of their data. The article selection process is shown in Figure 1. The characteristics of the included articles are summarized in Table 1.
—Preferred Reporting Items for Systematic Reviews and Meta-Analysis flow diagram.
Citation: International Journal of Sport Nutrition and Exercise Metabolism 34, 6; 10.1123/ijsnem.2024-0027
Summary of Randomized Controlled Trials Considering Supplementation of BA
| Study | Design | Participants | Groups and mean age (±SD) | Supplementation group | Placebo/comparison group | Duration | Outcomes measured | Testing protocol | Training load | Results |
|---|---|---|---|---|---|---|---|---|---|---|
| Derave et al. (2007) | Randomized, double-blind controlled trial | 15 track-and-field athletes | BA: n = 8, 23.8 (±4.2) years PL: n = 7, 18.4 (±1.5) years | 2.4 g/day (Days 1–4), 3.6 g/day (Days 5–9), and 4.8 g/day (Day 10–4 weeks) | Maltodextrin equivalent | 4 weeks | Performance time, isometric endurance, knee extension torque | Isokinetic and isometric muscle fatigue protocol, 400 m sprinting | N/A | Dynamic knee extension torque during the fourth and fifth bouts significantly improved with BA by 6.1% and 3.8%, respectively, with no effect on performance time |
| Brisola et al. (2018) | Randomized, double-blind controlled trial | 22 water polo players | BA: n = 11, 19 (±5) years PL: n = 11, 18 (±3) years | 4.8 g/day × 10 days and 6.4 g/day × 18 days | Dextrose equivalent | 4 weeks | Performance time | Repeated sprint ability swimming test | N/A | None of the results were significantly different between the BA and PL groups Likely beneficial effect for mean time (81%), worst time (78%), and total time (81%) Possible beneficial effect for total time (52%) |
| Milioni et al. (2019) | Randomized, double-blind controlled trial | 18 physically active males | BA: n = 9 PL: n = 9 Age: 25 (±5) years | 6.4 g/day | Dextrose 6.4 g/day | 4 weeks | VO2max, maximal aerobic velocity, performance time | Supramaximal running test at 115% of vVO2max, repeated sprint ability test | 4-week HIIT program | Improved performance time by −3.0% ± 2.0% |
| Bellinger and Minahan (2016b) | Randomized, double-blind controlled trial | 14 male trained cyclists | BA: n = 7 Placebo: n = 7 Age: 24.8 (±6.7) years | 6.4 g/day | Dextrose monohydrate equivalent | 4 weeks | Performance time and power output | 1-, 4- and 10-km cycling TTs, supramaximal cycling TTE | Subjects’ normal training regimen | Improvement in performance time by 17.6 ± 11.5 s, no statistically significant changes in power output |
| de Salles Painelli et al. (2014) | Randomized controlled trial | 40 trained and nontrained cyclists | TBA: n = 10 32 (±8) years TPL: n = 9 33 (±12) years NTBA: n = 10 25 (±4) years NTPL: n = 10 26 (±4) years | 6.4 g/day | Dextrose, 6.4 g/day | 4 weeks | Total work done and mean power output | Lower-body 30-s cycling Wingate test—four bouts | N/A | Significantly improved total work done and mean power output in both trained and nontrained participants in the BA group |
| Bellinger and Minahan (2016a) | Randomized controlled trial | 17 trained cyclists | BA: n = 9 PL: n = 8 Age: 24.5 (±6.2) years | 6.4 g/day | Dextrose monohydrate 6.4 g/day | 4 weeks | Time to exhaustion, performance time | Supramaximal cycling test 120% VO2max, 4,000-m cycling TT | N/A | Significant improvement in time to exhaustion (17.6 ± 11.5 s) in BA group No statistical difference in performance time |
| Saunders et al. (2012) | Randomized controlled trial | 16 elite hockey players and 20 nonelite players | BAE: n = 8 20 (±1) years PLE: n = 8 19 (±2) years BANE: n = 10 22 (±2) years PLNE: n = 10 22 (±3) years | 6.4 g/day | Maltodextrin equivalent | 4 weeks | Sprint performance | Loughborough Intermittent Shuttle Test | N/A | No effect of supplementation in sprint performance neither in the elite group nor the nonelite group |
| Ducker et al. (2013b) | Randomized controlled trial | 18 recreational runners | BA: n = 9 22 (±6) years PL: n = 9 22 (±5) years | 6.4 g/day | Glucose equivalent | 4 weeks | Time performance | 800-m run | N/A | Significant improvement in time performance with a very likely benefit (99%) in the BA group |
| Tobias et al. (2013) | Randomized double-blind, parallel group controlled trial | 37 Judo and Jiu Jitsu athletes | PL + PL: n = 09 26 (±5) years BA + PL: n = 10 26 (±4) years PL + SB: n = 9 23 (±4) years BA + SB: n = 9 26 (±5) years | 6.4 g/day | Dextrose equivalent or calcium carbonate or sodium bicarbonate | 4 weeks | Mean and peak power, total work done | Four 30-s upper body Wingate tests | N/A | BA improved total work done by +7%, however, nonsignificant |
| Hobson et al. (2013) | Randomized double-blind crossover controlled trial | 20 well-trained rowers | BA: n = 10 24 (±3) years PL: n = 10 23 (±4) years | 6.4 g/day | Maltodextrin equivalent ×28 days maltodextrin eq. and sodium bicarbonate ×2 days | 4 weeks | Time performance | 2,000-m rowing TT | Normal training regimen | Very likely beneficial effect (6.4 ± 8.1 s) of BA supplementation, however, not statistically significant |
| Freitas et al. (2019) | Randomized double-blind controlled trial | 23 recreationally trained males | BA: n = 12 PL: n = 11 Age: 23.7 (±3.9) years | 6.4 g/day | Maltodextrin equivalent | 4 weeks | Maximal strength maximal aerobic velocity | 45 leg press incremental treadmill running test | Resistance training protocol | No effect of BA supplementation |
| Ducker et al. (2013c) | Randomized double-blind controlled trial | 24 football hockey and soccer athletes | BA: n = 6 23 (±5) years SB: n = 6 21 (±3) years BA + SB: n = 6 23 (±4) years PL: n = 6 19 (±3) years | ∼6 g/day | Glucose 10 g/day | 4 weeks | Time performance | Repeated sprint test | N/A | No effect of BA supplementation |
| Ducker et al. (2013a) | Randomized controlled trial | 16 competitive male rowers | BA: n = 7, 26 (±9) years PL: n = 9, 26 (±9) years | 6–7 g/day | Sucrose, 10 g/day | 4 weeks | Total time, average power output | 2,000-m rowing ergometer test | N/A | Significant improvement in performance time at 750 m and at 1,000 m by 87% and power output at 750 m by 3.6% and at 1,000 m by 2.9% for BA group |
| Howe et al. (2013) | Randomized, double-blind controlled trial | 16 highly trained cyclists | BA: n = 8, 26 (±8) years PL: n = 8, 22 (±5) years | 65 mg–1 kg–1 day | Dextrose monohydrate equivalent | 4 weeks | Average power, average power/repetition, total work done | Maximal cycling test, isokinetic knee contraction (180°/s) | N/A | Isokinetic average power/repetition significantly increased with 85% likely benefit for BA group Total work done and average power were not statistically significant |
| Gross et al. (2014) | Randomized controlled trial | nine professional alpine skiers | BA: n = 5 PL: n = 4 Age: 19.5 (±1.1) years | 4.2 g/day | Maltodextrin equivalent | 5 weeks | Maximal power, average power | Countermovement jumps 90-s cycling 110% VO2max maximal 90-s box jump test | Strength and conditioning training | Significantly improved maximal (+7.0% ± 2.5%) and average power (+7.0% ± 2.4%) in BA group in countermovement jumps Tendency for improved overall performance (+2.6% ± 2.4%) in BA group |
| Jagim et al. (2013) | Randomized controlled trial | 21 rugby players, wrestlers, and strength-trained athletes | BA: n = 10 20.5 (±2.32) years PL: n = 11 20 (±2.45) years | 4 g/day × 1 week, and 6 g/day × 4 weeks | Rice flour equivalent | 5 weeks | Time to exhaustion | Running incremental tests at 115% and 140% of VO2max | Regular exercise habits | No effect of BA supplementation |
| Mate-Munoz et al. (2018) | Randomized controlled trial | 30 young, healthy resistance-trained men | BA: n = 15 PL: n = 15 Age: 21.85 (±1.6) years | 6.4 g/day | Sucrose equivalent | 5 weeks | Average and peak power | Back squat incremental load test, 1RM | Strength training | Significantly greater average power at 1RM by 42.65% and at maximum power output by 20.17% for BA group |
| Smith et al. (2019) | Randomized, double-blind controlled trial | 15 collegiate male rugby players | BA: n = 8 PL: n = 7 Age: 21.0 (±1.8) years | 6.4 g/day | 6.4 g/day of maltodextrin | 6 weeks | Upper- and lower-body maximal strength and muscular endurance, intermittent sprint performance | Bench press and back squat 1RM, five sets of bench press and back squat repetitions (70% of 1RM), Intermittent Running test | Six weeks of weight training and sport-specific training | No positive outcomes observed |
| Kern and Robinson (2011) | Randomized double-blind controlled trial | 37 collegiate wrestlers and football players | BAWR: n = 10, 20.1 (±2.06) years PLWR: n = 12, 19.8 (±1.83) years BAFB: n = 7, 18.4 (±0.59) years PLFB: n = 8, 18.9 (±2.1) years | 4 g/day | Dextrose equivalent | 8 weeks | Anaerobic power performance | 300-yard shuttle test, 90° flexed arm hang | Regular sport-specific resistance training and practice sessions | Both BA groups achieved better results than the PL groups, however, with no statistically significant difference |
| Askari and Rahmaninia (2018) | Randomized controlled trial | 20 healthy young men | BA: n = 10, 17.7(±1) years PL: n = 10 17.1(±0.6) years | 4.8 g/day | 4.8 g/day polydextrose | 8 weeks | Maximum strength, anaerobic power | 1RM bench press and leg press, RAST test, vertical jump test | 8-week resistance training | Significant differences in power performance and strength gains for the BA group |
| Turcu et al. (2022) | Randomized controlled trial | 20 basketball players | BA: n = 10 PL: n = 10 Age: 23 (±0.6) years | 6.4 g/day | Maltodextrin 6.4 g/day | 8 weeks | Lower-body power, anaerobic power, VO2max | Countermovement jump, anaerobic sprint test running incremental test | Regular basketball training | Increased anaerobic power, no significant differences in VO2max |
| de Camargo et al. (2023) | Randomized, double-blind, controlled trial | 19 resistance-trained men | BA: n = 9, 26.1 (±5.5) years PL: n = 10 28.5 (±5.5) years | 6.4 g/day | Maltodextrin equivalent | 8 weeks | Maximal strength | 1RM bench press and 1RM back squat | Resistance training protocol | BA supplementation did not maximize RT-induced adaptations |
| Hill et al. (2007) | Randomized, double-blind controlled trial | 25 physically active young males | BA: n = 13 25.4 (±2.1) years PL: n = 12 29.2 (±6.9) years | 4 g/day (Week 1) 4.8 g/day (Week 2) 5.6 g/day (Week 3) 6.4 g/day (Week 4) 6.4 g/day (Week 5–10) | Maltodextrin equivalent | 10 weeks | Total work done | Cycle capacity tests at 110% Wmax | N/A | Significantly improved total work done by 16.2% for the BA group |
| Kim et al. (2018) | Randomized, double-blind controlled trial | 19 amateur male boxers | BA: n = 9, 23.00 (±1.82) years PL: n = 10 22.20 (±2.21) years | 4.9 g/day for 49 kg −69 kg, and −5.4 g/day for −75 kg to + 91 kg | Maltodextrin in a similar manner | 10 weeks | Maximal and isokinetic strength (leg and trunk), peak, and mean power | Bench press and back squat dynamometer at an angular velocity of 30°/s and 60°/s 30 s Wingate test, Sargent jump test | 10-week training | Significant improvement in lower-body peak power (6.06%) and upper-body power drop (3.20%), as well as nonsignificant improvement in maximal strength (squat 4.21% and bench press 5.18%) in BA group |
| Saunders et al. (2017) | Randomized double-blind controlled trial | 25 active males | Two participants were allocated in BA for each participant in PL Age: 27 (±4) years | 6.4 g/day | Maltodextrin equivalent | 24 weeks | Time to exhaustion | Cycle capacity tests at 110% Wmax | N/A | Time to exhaustion significantly improved in BA group with possible to almost certain improvements across all weeks (96%–100%) but not in PL group |
Note. BA = beta-alanine; PL = placebo: N/A = not applicable: 1RM = one-repetition maximum: HIIT = high-intensity interval training: TT = time trial: TTE = time to exhaustion: TBA = trained + beta-alanine: TPL = trained + placebo: NTBA = nontrained + beta-alanine: NTPL = nontrained + placebo: BAE = beta-alanine elite participants: PLE = placebo elite participants: BANE = beta-alanine nonelite participants: PLNE = placebo nonelite participants: SB = sodium bicarbonate: BAWR = beta-alanine collegiate wrestlers/players: PLWR = placebo collegiate wrestlers/players: BAFB = beta-alanine football players: PLFB = placebo football players: Wmax = maximum power: RAST = radioallergosorbent.
Study Characteristics
A total of 331 participants were pooled together across the studies included in the meta-analysis, with similar numbers in the beta-alanine group (n = 166) and the PL group (n = 165). Sporting background of the participants varied: track and field (n = 25); cyclists (n = 47); runners (n = 18); team sports including football, soccer, basketball, hockey, and rugby (n = 68); recreationally active (n = 58); water polo (n = 22); amateur boxers (n = 19); resistance-trained (n = 49); alpine skiers (n = 9); and competitive rowers (n = 16).
Dosage of beta-alanine varied between studies, from 3.9 g per day to 6.4 g per day. Studies were grouped as low (3.9–4.6 g per day, n = 4), medium (4.7–5.5 g per day, n = 2), and high dose (5.6–6.4 g per day, n = 12). These groupings (low/medium/high) are arbitrary, serving to differentiate between dose magnitudes for this review only, and are not representative of the general dose considerations found in the literature, although these groupings may be useful in practical terms, as they often approximate dose ranges available for commercial use. Supplementation protocols lasted from 4 to 10 weeks for the studies analyzed, grouped into duration of 4 weeks (n = 9) and 5–10 weeks (n = 9). For the test durations, studies analyzed were grouped as 0–1 (n = 8), 1–4 (n = 7), and 4–10 min (n = 3).
Effect of Beta-Alanine on Maximal Intensity Exercise
The main analysis of this review included 18 studies. Five studies measured power output (Brisola et al., 2018; Ducker et al., 2013a; Gross et al., 2014; Howe et al., 2013; Turcu et al., 2022), five measured muscle strength (Askari & Rahmaninia, 2018; de Camargo et al., 2023; Freitas et al., 2019; Kim et al., 2018; Smith et al., 2019), one measured work done (Hill et al., 2007), six measured time taken to complete an exercise task (Bellinger & Minahan, 2016a, 2016b; Derave et al., 2007; Ducker et al., 2013b, 2013c; Jagim et al., 2013), and one measured total work sets completed (Maté-Muñoz et al., 2018). Since outcomes were measured using different methods and units of measurement, utilizing mean differences (MD) would have been inappropriate; therefore, global output was expressed as the composite score of all measures using SMD.
Figure 2 shows that supplementation with beta-alanine had small to moderate but significant positive effects on maximal exercise (SMD: 0.39, 95% CI [0.09, 0.69]; p = .01), compared with PL. The studies reviewed in this analysis displayed low to moderate heterogeneity (I2 = 44%, p = .02). Fourteen of the 18 studies showed beta-alanine supplementation having a beneficial effect on maximal exercise (Bellinger & Minahan, 2016a, 2016b; Brisola et al., 2018; Derave et al., 2007; Ducker et al., 2013a, 2013b, 2013c; Freitas et al., 2019; Hill et al., 2007; Howe et al., 2013; Kim et al., 2018; Maté-Muñoz et al., 2018; Smith et al., 2019; Turcu et al., 2022) with the study by Hill et al. (2007) displaying a large effect size (3.59). The remaining four studies showed a neutral or small detrimental effect of supplementation (Askari & Rahmaninia, 2018; de Camargo et al., 2023; Gross et al., 2014; Jagim et al., 2013). As described in the Methods, a second meta-analysis using identical data, but assuming r to be .50, was also performed for comparison (Figure 3).
—Forest plot comparing the effects of beta-alanine supplementation on maximum intensity exercise.
Citation: International Journal of Sport Nutrition and Exercise Metabolism 34, 6; 10.1123/ijsnem.2024-0027
—Forest plot comparing the effects of beta-alanine supplementation on maximum intensity exercise assuming r to be .5.
Citation: International Journal of Sport Nutrition and Exercise Metabolism 34, 6; 10.1123/ijsnem.2024-0027
Subgroup Analysis: Supplementation Duration
To investigate the effect of duration of beta-alanine supplementation, a subgroup analysis was performed between studies in which supplementation lasted for 4 weeks (n = 9; Bellinger & Minahan, 2016a, 2016b; Brisola et al., 2018; Derave et al., 2007; Ducker et al., 2013a, 2013b, 2013c; Freitas et al., 2019; Howe et al., 2013) or 5–10 weeks (n = 9; Askari & Rahmaninia, 2018; de Camargo et al., 2023; Gross et al., 2014; Hill et al., 2007; Jagim et al., 2013; Kim et al., 2018; Maté-Muñoz et al., 2018; Smith et al., 2019; Turcu et al., 2022; Figure 4). The lower, 4-week, duration of supplementation showed a smaller but significant effect on maximal intensity exercise (SMD: 0.34, 95% CI [0.02, 0.67]; p = .04) when compared to PL, and displayed no heterogeneity (I2 = 0%, p = .99), compared with the higher, 5–10 weeks duration of supplementation which showed a larger but statistically insignificant effect (SMD: 0.47, 95% CI [−0.14, 1.07]; p = .13) compared with PL, and moderate to large homogeneity (I2 = 72%, p < .0004).
—Forest plot comparing the effects of beta-alanine supplementation duration on maximum intensity exercise.
Citation: International Journal of Sport Nutrition and Exercise Metabolism 34, 6; 10.1123/ijsnem.2024-0027
We performed further analysis on the 5–10 weeks group, splitting them into groups that provided beta-alanine for 5–6 weeks (n = 4) or 8–10 weeks (n = 5). This analysis showed a small (SMD: 0.18, 95% CI [−0.43, 0.79]; p = .57) and moderate (SMD: 0.79, 95% CI [−0.24, 1.82]; p = .13) effect when compared to PL, respectively, but was not significantly different. The 5–6 weeks group showed low heterogeneity (I2 = 38%, p = .18), and the 8–10 weeks group showed high heterogeneity (I2 = 83%, p = .0001).
All studies in the 4-week group reported that beta-alanine supplementation was beneficial, while five of the nine studies in the 5–10 weeks group showed beneficial effects. The remaining four studies showed neutral or small detrimental effects on maximal intensity exercise.
Subgroup Analysis: Exercise Test Duration
To investigate whether beta-alanine supplementation changed maximal exercise output relative to the duration of the test, a subgroup analysis was conducted, in which the studies were divided into those which used tests lasting 0–1 (n = 8), 1–4 (n = 7), and 4–10 min (n = 3) (Figure 5).
—Forest plot comparing the effects of beta-alanine supplementation on exercise test duration.
Citation: International Journal of Sport Nutrition and Exercise Metabolism 34, 6; 10.1123/ijsnem.2024-0027
The 0–1 min group showed a small insignificant effect on maximal output (SMD: 0.13, 95% CI [−0.22, 0.47]; p = .98) with no heterogeneity (I2 = 0%, p = .98). Despite a moderate effect size, there was no significant effect in the 1–4 min test duration group (SMD: 0.72, 95% CI [−0.03, 1.47]; p = .06), and heterogeneity was high (I2 = 75%, p = .0005). Finally, the 4–10 min group showed a moderate and significant effect of beta-alanine supplementation on maximal output (SMD: 0.55, 95% CI [0.07–1.04]; p = .03) with no heterogeneity (I2 = 0%, p = .58). All results are compared with PL.
Of the eight studies included in the 0–1 min group, five showed beneficial effects and the remaining three showed neutral or detrimental effects. Six of the seven studies in the 1–4 min group showed positive effects on maximal output, and all three studies in the 4–10 min group showed beneficial effects.
Subgroup Analysis: Dosage
A subgroup analysis on the influence of beta-alanine dosage on maximal intensity exercise revealed significant increases with a high dose (n = 12, 5.6–6.4 g per day; SMD: 0.35, 95% CI [0.09, 0.62]; p = .009). Low (n = 4, 3.9–4.6 g per day) and medium (n = 2, 4.7–5.5 g per day) dosages had no statistically significant effects, with large (SMD: 0.82, 95% CI [−0.78, 2.43]; p = .32) and small (SMD: 0.15, 95% CI [−0.48, 0.78]; p = .65) effect sizes, respectively (Figure 6). All results are compared with PL.
—Forest plot comparing the effects of beta-alanine supplementation dosages on maximum intensity exercise.
Citation: International Journal of Sport Nutrition and Exercise Metabolism 34, 6; 10.1123/ijsnem.2024-0027
One of the studies in the low-dosage group showed detrimental effects on output (Gross et al., 2014), one study (Askari & Rahmaninia, 2018) included in the medium dosage protocol displayed a neutral outcome, and two studies in the high-dosage protocol (de Camargo et al., 2023; Jagim et al., 2013) reported detrimental or neutral effects. The heterogeneity between subgroups was insignificant (I2 = 0%, p = .70).
Risk of Bias
Quality assessment and risk of bias performed according to the Revised Cochrane Collaboration’s tool for assessing risk of bias in randomized trials (RoB2; Higgins et al., 2019) demonstrated that the overall risk of bias of the included studies is low. Bias results are presented in Figure 7.
—Assessment of bias of the randomized studies according to RoB 2 tool: (a) traffic light plot and (b) summary plot.
Citation: International Journal of Sport Nutrition and Exercise Metabolism 34, 6; 10.1123/ijsnem.2024-0027
Discussion
Effect of Beta-Alanine on Maximal Intensity Exercise
This review aimed to evaluate the effects of beta-alanine supplementation on maximal intensity exercise. There was a small (0.39), significant effect in favor of beta-alanine supplementation on maximal intensity exercise. The duration of beta-alanine supplementation showing the greatest ergogenic benefits was 4 weeks, with the administered dosage ranging from 5.6 to 6.4 g per day. Beta-alanine supplementation was most effective for exercise lasting 4–10 min.
Our review’s results are in agreement with previous systematic reviews (Berti Zanella et al., 2017; Quesnele et al., 2014) that also found improvements in the same parameters. Beyond that, our results indicate that beta-alanine supplementation can enhance both exercise performance and capacity, agreeing with previous research (Saunders et al., 2017). An older systematic review and meta-analysis by Hobson et al. (2012) found that beta-alanine supplementation had a significant effect on capacity but did not improve performance-based measures. The difference in results could be due to the lack of studies incorporating performance measures at the time, as the authors have acknowledged (Saunders et al., 2017).
Several studies in this review showed that supplementation with beta-alanine improved short-term, high-intensity exercise. Specifically, studies reported significant improvements in total work done and power, which are capacity measures (Askari & Rahmaninia, 2018; De Salles Painelli et al., 2014; Derave et al., 2007; Ducker et al., 2013c; Gross et al., 2014; Hill et al., 2007; Kim et al., 2018; Maté-Muñoz et al., 2018; Turcu et al., 2022), and improvements in performance measures, such as time to completion/exhaustion (Bellinger & Minahan, 2016a, 2016b; Ducker et al., 2013a, 2013c; Milioni et al., 2019; Saunders et al., 2017). However, some studies reported no significant improvements in performance or capacity after beta-alanine supplementation. Ducker et al. (2013b) and Saunders et al. (2012) reported no changes in performance time in a repeated sprint test. No effect of beta-alanine supplementation was observed by Freitas et al. (2019) on maximal strength, and other authors also reported no effect (Hobson et al., 2013; Howe et al., 2013; Tobias et al., 2013). Potential explanations are discussed within their respective sections in the following paragraph.
From a mechanistic perspective, beta-alanine supplementation has been demonstrated to increase muscle carnosine levels (Culbertson et al., 2010; Varanoske et al., 2017). Carnosine is an important buffer of hydrogen ions (H+), a fatiguing metabolite which accumulates during high-intensity exercise, altering muscle pH from ∼7.05 to as low as ∼6.5 (Allen et al., 2008; Sweeney et al., 2010) negatively affecting exercise output (Culbertson et al., 2010; Ducker et al., 2013a). In addition, carnosine can increase calcium (Ca2+) release from the sarcoplasmic reticulum, increasing muscular contractility and delaying fatigue, thus enhancing output (Dutka et al., 2012; Ojeda et al., 2020).
Effect of Beta-Alanine Supplementation Duration on Maximal Intensity Exercise
Our analysis suggests that the duration of beta-alanine supplementation providing the greatest relative benefit to improving exercise output is 4 weeks. Indeed, a longer duration of supplementation did not appear to augment effects. Furthermore, when subjects were tested on a supramaximal cycling test, data suggested that the greatest enhancement in output was achieved at the end of 4 weeks of supplementation (Hill et al., 2007). Shorter supplementation periods (<4 weeks) did not significantly improve maximal intensity exercise; however, a trend toward improvements in exercise performance with smaller dosage periods has been suggested (Hoffman et al., 2008).
It is not yet clear what the optimal duration period is for increasing intramuscular carnosine concentrations (Trexler et al., 2015), but we can speculate why the 4 weeks duration may have led to the greatest benefits; beta-alanine shares the same transporter to the cell with taurine therefore prolonged supplementation with beta-alanine may affect homeostasis (Artioli et al., 2010; Dolan, Swinton, et al., 2019). This in turn can reverse beta-alanine’s influence, as reported in a study where participants were ingesting 6.4 g per day of beta-alanine for 24 weeks (Dolan, Swinton, et al., 2019).
Mediation of Beta-Alanine’s Effect by Test Duration
Meta-analysis results demonstrated that beta-alanine supplementation improved exercise output in tests lasting 4–10 min, but not for tests lasting 0–1 min or 1–4 min, although the SMD was moderate for the latter. These results are in contrast to previous research indicating that tests lasting from 1 to 4 min benefited most from beta-alanine supplementation (Hobson et al., 2012; Saunders et al., 2017). During exercise of this duration at high intensity, the predominant energetic pathway is the anaerobic-glycolytic pathway, where H+ is generated, leading to a decrease in pH, that can precipitate fatigue (Ojeda et al., 2020).
A possible explanation for our findings could be the nature of the tests employed in studies. Performance tests were intermittent, relying upon pacing strategies. They included short periods of maximal intensity exercise followed by light-intensity recovery periods, possibly masking beta-alanine’s ergogenic effect at the early stages of the tests. Maximal blood H+ accumulation occurs after approximately 4 min of intense exercise (Saunders et al., 2017). When maximal exercise is intermittent, it takes longer for H+ to accumulate, extending the time needed for beta-alanine supplementation to manifest its effects.
Beta-alanine supplementation did not enhance performance in shorter tests lasting 0–1 min, possibly because exercise of this duration is not limited by acidosis (Artioli et al., 2010). According to (Saunders et al., 2017), a 0.5- to 10-min time frame could be more applicable for carnosine’s acid buffering role since physical activity lasting 7–8 min still relies heavily on energy from glycolysis. Total anaerobic energy contribution during a 4-km cycling test lasting around 6 min is about 25%, while total energy contribution from glycolysis during 2,000 m rowing, lasting >7 min, is about 12% (Saunders et al., 2017).
In addition, it is worth mentioning that duration of the tests itself may have an effect on the reliability of precision of the assessments. Hopkins et al. (2001) showed that measures of reliability can vary based on the nature of the tests being conducted (i.e., field test of sprint running vs. mean power on isokinetic ergometers) as a function of measurement error, expressed as coefficient of variation. It stands to reason that similar effects may be observed as the duration of a test varies, and more research on this topic is required.
Effect of Beta-Alanine Dosage
Dosages were categorized into three groups, low (3.9–4.6 g per day), medium (4.7–5.5 g per day), and high (5.6–6.4 g per day). The most significant changes in exercise output were observed with high dosages of beta-alanine supplementation, at 5.6–6.4 g per day. This dosage range has been shown to increase muscle carnosine concentrations by up to 64% and 80% at 4 weeks and 10 weeks, respectively (Trexler et al., 2015).
This is in line with research that demonstrated carnosine synthesis in human skeletal muscle is dependent on beta-alanine availability (Sale et al., 2010). Additionally, in the absence of a known threshold of intramuscular carnosine storage, it is reasonable to assume that higher beta-alanine dosages result in higher muscle carnosine concentrations, and this equates to greater muscle buffering capacity during high-intensity exercise (Hobson et al., 2012). Estimations suggest that carnosine contributes up to 10% of the total buffering capacity in muscle (Artioli et al., 2010). After beta-alanine supplementation, total buffering capacity can reach up to 15%, and if only Type II muscle fibers are taken into consideration, carnosine contribution can be >25% (Artioli et al., 2010).
However, Ojeda et al. (2020) found in their systematic review and meta-analysis that even dosages as low as 1.5 g per day could result in changes in physical output. This variability in results regarding beta-alanine dosage could be due to the exercise test or outcomes measured and requires further research. Ducker et al. (2013a) state that a range of 3–6 g per day of beta-alanine supplementation for a duration of 4 weeks can increase intramuscular carnosine concentrations from 30% to 80%, with the range of dosage supplementation likely being proportional to carnosine concentration increase.
Strengths and Limitations
To date, this is the most comprehensive meta-analysis on the effects of beta-alanine supplementation, covering a generalized analysis as well as various subgroupings including supplementation duration, exercise test duration, and dosage. A major strength of this research is the high quality of the studies included. Overall, the included studies had a low risk of bias, with only one study exhibiting a high risk of bias, in just two domains. Almost all of the studies mention that they controlled for nutritional supplementation and ergogenic aid use during the intervention period, and excluded participants that consumed any supplement that could affect the results of the intervention 3 months prior to the study.
Females may have been excluded because they inherently have lower levels of carnosine (Baguet et al., 2010); therefore, mixed gender groups could bias results. Furthermore, all studies excluded vegetarians, as they may have lower basal carnosine stores (Baguet et al., 2010). The findings of this review are therefore only applicable to omnivorous males. A limitation is the low number of studies available for review that provided beta-alanine, without the addition of other ingredients. Additionally, any conclusions from this investigation only pertain to maximal intensity outcomes, such as strength, power, and performance time, as this review did not focus on submaximal outcomes, or exercise lasting 0.5 min or >10 min in duration.
Practical Applications
Based on our findings, beta-alanine supplementation could be used by coaches, strength and conditioning trainers, and athletes across a broad spectrum of sports and activities as an ergogenic aid to enhance physical exercise output. Supplementation is likely to be most beneficial for athletes in high-intensity sports lasting from 4 to 10 min, such as middle-distance runners, rowers, swimmers, and combat sports’ athletes. For maximal benefits, the dosage should range from 5.6 to 6.4 g per day, for a supplementation period of 4 weeks. In order to avoid paresthesia that may occur after beta-alanine supplementation, it is recommended to ingest beta-alanine in smaller doses of 1.6 g throughout the day (Trexler et al., 2015) and to consume 2 g/kg of carbohydrates an hour before beta-alanine supplementation (Ojeda et al., 2020). This study can also serve as a foundation for further research into those areas of beta-alanine supplementation which still need clarification, such as acute dosing protocols, and whether or not upper limits to cellular carnosine saturation exist, and their subsequent effects on exercise/sports performance and physiology.
Conclusions and Future Perspectives
This systematic review and meta-analysis demonstrated that beta-alanine supplementation can significantly enhance maximal intensity exercise, as measured by changes in power, strength, work done, performance time, and total sets performed. Our analysis suggests that such effects are observed with a dosage of 5.6 g–6.4 g per day for 4 weeks, when exercise performance lasts 4–10 min. This highlights the need for more high-quality, newer systematic reviews since the 4–10 min time frame is not in agreement with previous systematic reviews (Hobson et al., 2012; Saunders et al., 2017).
Nevertheless, heterogeneous results from individual studies necessitate the need for further research. Also, some studies suggest that beta-alanine supplementation can enhance maximal intensity exercise with lower, acute doses (Ducker et al., 2013a; Ojeda et al., 2020) even when ingested 1 hr prior to testing (Ojeda et al., 2020). Therefore, dosage and duration of beta-alanine supplementation need to be further investigated, as well as the minimal effective acute dose. More research should be conducted with female participants, both athletes and sports enthusiasts, since studies concerning beta-alanine supplementation in females are currently scarce compared with those in males.
Acknowledgments
The authors would like to thank the Cambridge University ReachSci Society for their support and assistance. This project was an outcome of the Mini-Ph.D. Programme 2023: Food Science and Nutrition. Availability of Data and Material: Data available within the article or its Supplementary Materials (available online). Author Contributions: Conceptualization: Zare, Ali Redha. Methodology, investigation, data curation, and formal analysis–writing of the original draft: Georgiou, K. Antoniou, S. Antoniou, Michelekaki. Writing, review, and editing: Zare, Ali Redha, Prokopidis, and Clifford. Project administration: Ali Redha, Georgiou. Supervision: Clifford and Christodoulides. Read and approved the final version: All authors.
References
Allen, D.G., Lamb, G.D., & Westerblad, H. (2008). Skeletal muscle fatigue: Cellular mechanisms. Physiological Reviews, 88(1), 287–332.
Artioli, G.G., Gualano, B., Smith, A., Stout, J., & Lancha, A.H. (2010). Role of β-alanine supplementation on muscle carnosine and exercise performance. Medicine & Science in Sports & Exercise, 42(6), 1162–1173.
Askari, F., & Rahmaninia, F. (2018). The effect of 8 weeks beta-alanine supplementation and resistance training on maximal-intensity exercise performance adaptations in young males. Physical Education of Students, 23(1), 4–8.
Austin, S.B., Yu, K., Liu, S.H., Dong, F., & Tefft, N. (2017). Household expenditures on dietary supplements sold for weight loss, muscle building, and sexual function: Disproportionate burden by gender and income. Preventive Medicine Reports, 6, 236–241.
Baguet, A., Bourgois, J., Vanhee, L., Achten, E., & Derave, W. (2010). Important role of muscle carnosine in rowing performance. Journal of Applied Physiology, 109(4), 1096–1101.
Baguet, A., Reyngoudt, H., Pottier, A., Everaert, I., Callens, S., Achten, E., & Derave, W. (2009). Carnosine loading and washout in human skeletal muscles. Journal of Applied Physiology, 106(3), 837–842.
Bellinger, P.M., & Minahan, C.L. (2016a). Metabolic consequences of beta-alanine supplementation during exhaustive supramaximal cycling and 4000-m time-trial performance. Applied Physiology, Nutrition, and Metabolism, 41(8), 864–871.
Bellinger, P.M., & Minahan, C.L. (2016b). The effect of β-alanine supplementation on cycling time trials of different length. European Journal of Sport Science, 16(7), 829–836.
Berti Zanella, P., Donner Alves, F., & Guerini De Souza, C. (2017). Effects of beta-alanine supplementation on performance and muscle fatigue in athletes and non-athletes of different sports: A systematic review. Journal of Sports Medicine and Physical Fitness, 57(9), 1132–1141.
Brisola, G.M.P., Redkva, P.E., Pessôa Filho, D.M., Papoti, M., & Zagatto, A.M. (2018). Effects of 4 weeks of β-alanine supplementation on aerobic fitness in water polo players. PLoS One, 13(10), Article 205129.
Culbertson, J.Y., Kreider, R.B., Greenwood, M., & Cooke, M. (2010). Effects of Beta-alanine on muscle carnosine and exercise performance: A review of the current literature. Nutrients, 2(1), 75–98.
de Camargo, J.B.B., Brigatto, F.A., Zaroni, R.S., Germano, M.D., Souza, D., Bacurau, R.F., Marchetti, P.H., Braz, T.V., Aoki, M.S., & Lopes, C.R. (2023). Does beta-alanine supplementation enhance adaptations to resistance training? A randomized, placebo-controlled, double-blind study. Biology of Sport, 40(1), 217–224.
De Salles Painelli, V., Saunders, B., Sale, C., Harris, R.C., Solis, M.Y., Roschel, H., Gualano, B., Artioli, G.G., & Lancha, A.H., Jr. (2014). Influence of training status on high-intensity intermittent performance in response to beta-Alanine supplementation. Amino Acids, 46(5), 1207–1215.
Derave, W., Everaert, I., Beeckman, S., & Baguet, A. (2010). Muscle carnosine metabolism and β-Alanine supplementation in relation to exercise and training. Sports Medicine, 40(3), 247–263.
Derave, W., Ozdemir, M.S., Harris, R.C., Pottier, A., Reyngoudt, H., Koppo, K., Wise, J.A., & Achten, E. (2007). Beta-alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters. Journal of Applied Physiology, 103(5), 1736–1743.
Dolan, E., Saunders, B., Harris, R.C., Bicudo, J.E.P.W., Bishop, D.J., Sale, C., & Gualano, B. (2019). Comparative physiology investigations support a role for histidine-containing dipeptides in intracellular acid–base regulation of skeletal muscle. Comparative Biochemistry and Physiology -Part A: Molecular and Integrative Physiology, 234, 77–86.
Dolan, E., Swinton, P.A., Painelli, V.D.S., Hemingway, B.S., Mazzolani, B., Smaira, F.I., Saunders, B., Artioli, G.G., & Gualano, B. (2019). A systematic risk assessment and meta-analysis on the use of oral β-alanine supplementation. Advances in Nutrition, 10(3), 452–463.
Ducker, K.J., Dawson, B., & Wallman, K.E. (2013a). Effect of beta-alanine supplementation on 2000-m rowing-ergometer performance. International Journal of Sport Nutrition and Exercise Metabolism, 23(4), 336–343.
Ducker, K.J., Dawson, B., & Wallman, K.E. (2013b). Effect of beta-alanine supplementation on 800-m running performance. International Journal of Sport Nutrition and Exercise Metabolism, 23(6), 554–561.
Ducker, K.J., Dawson, B., & Wallman, K.E. (2013c). Effect of beta alanine and sodium bicarbonate supplementation on repeated-sprint performance. Journal of Strength and Conditioning Research, 27(12), 3450–3460.
Dutka, T.L., Lamboley, C.R., McKenna, M.J., Murphy, R.M., & Lamb, G.D. (2012). Effects of carnosine on contractile apparatus Ca2+ sensitivity and sarcoplasmic reticulum Ca2+ release in human skeletal muscle fibers. Journal of Applied Physiology, 112(5), 728–736.
Freitas, M.C., Cholewa, J., Panissa, V., Quizzini, G., de Oliveira, J.V., Figueiredo, C., Gobbo, L.A., Caperuto, E., Zanchi, N.E., Lira, F., & Rossi, F.E. (2019). Short-time β-alanine supplementation on the acute strength performance after high-intensity intermittent exercise in recreationally trained men. Sports, 7(5), Article 108.
Glenn, J.M., Smith, K., Moyen, N.E., Binns, A., & Gray, M. (2015). Effects of acute beta-alanine supplementation on anaerobic performance in trained female cyclists. Journal of Nutritional Science and Vitaminology, 61(2), 161–166.
Grant, J., & Hunter, A. (2006). Measuring inconsistency in knowledgebases. Journal of Intelligent Information Systems, 27(2), 159–184.
Grgic, J. (2021). Effects of beta-alanine supplementation on Yo–Yo test performance: A meta-analysis. Clinical Nutrition ESPEN, 43, 158–162.
Gross, M., Bieri, K., Hoppeler, H., Norman, B., & Vogt, M. (2014). Beta-alanine supplementation improves jumping power and affects severe-intensity performance in professional alpine skiers. International Journal of Sport Nutrition and Exercise Metabolism, 24(6), 665–673.
Harris, R.C., Tallon, M.J., Dunnett, M., Boobis, L., Coakley, J., Kim, H.J., Fallowfield, J.L., Hill, C.A., Sale, C., & Wise, J.A. (2006). The absorption of orally supplied β-alanine and its effect on muscle carnosine synthesis in human vastus lateralis. Amino Acids, 30(3), 279–289.
Higgins, J.P., Savović, J., Page, M.J., Elbers, R.G., & Sterne, J.A. (2019). Cochrane handbook for systematic reviews of interventions. Chapter 8: Assessing risk of bias in a randomized trial (pp. 205–228). Wiley Online Library. www.riskofbias.info
Higgins, J.P.T., Altman, D.G., Gøtzsche, P.C., Jüni, P., Moher, D., Oxman, A.D., Savović, J., Schulz, K.F., Weeks, L., & Sterne, J.A.C. (2011). The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials. British Medical Journal, 343(7829), Article 928.
Hill, C.A., Harris, R.C., Kim, H.J., Harris, B.D., Sale, C., Boobis, L.H., Kim, C.K., & Wise, J.A. (2007). Influence of β-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity. Amino Acids, 32(2), 225–233.
Hobson, R.M., Harris, R.C., Martin, D., Smith, P., Macklin, B., Gualano, B., & Sale, C. (2013). Effect of Beta-Alanine with and without sodium bicarbonate on 2,000-m rowing performance. International Journal of Sport Nutrition and Exercise Metabolism, 23(5), 480–487.
Hobson, R.M., Saunders, B., Ball, G., Harris, R.C., & Sale, C. (2012). Effects of β-alanine supplementation on exercise performance: A meta-analysis. Amino Acids, 43(1), 25–37.
Hoffman, J.R., Ratamess, N.A., Faigenbaum, A.D., Ross, R., Kang, J., Stout, J.R., & Wise, J.A. (2008). Short-duration beta-alanine supplementation increases training volume and reduces subjective feelings of fatigue in college football players. Nutrition Research, 28(1), 31–35.
Hopkins, W.G., Schabort, E.J., & Hawley, J.A. (2001). Reliability of power in physical performance tests. Sports Medicine, 31(3), 211–234.
Howe, S.T., Bellinger, P.M., Driller, M.W., Shing, C.M., & Fell, J.W. (2013). The effect of beta-alanine supplementation on isokinetic force and cycling performance in highly trained cyclists. International Journal of Sport Nutrition and Exercise Metabolism, 23(6), 562–570.
Jagim, A.R., Wright, G.A., Brice, A.G., & Doberstein, S.T. (2013). Effects of beta-alanine supplementation on sprint endurance. Journal of Strength and Conditioning Research, 27(2), 526–532.
Kern, B.D., & Robinson, T.L. (2011). Effects of β-alanine supplementation on performance and body composition in collegiate wrestlers and football players. Journal of Strength and Conditioning Research, 25(7), 1804–1815.
Kim, K.J., Song, H.S., Yoon, D.H., Fukuda, D.H., Kim, S.H., & Park, D.H. (2018). The effects of 10 weeks of β-alanine supplementation on peak power, power drop, and lactate response in Korean national team boxers. Journal of Exercise Rehabilitation, 14(6), 985–992.
Maté-Muñoz, J.L., Lougedo, J.H., Garnacho-Castaño, M.V., Veiga-Herreros, P., Lozano-Estevan, M.D.C., García-Fernández, P., de Jesús, F., Guodemar-Pérez, J., San Juan, A.F., & Domínguez, R. (2018). Effects of β-alanine supplementation during a 5-week strength training program: A randomized, controlled study. Journal of the International Society of Sports Nutrition, 15(1), Article 224.
Milioni, F., de Poli, R.A.B., Saunders, B., Gualano, B., da Rocha, A.L., Sanchez Ramos da Silva, A., Muller, P.T.G., & Zagatto, A.M. (2019). Effect of β-alanine supplementation during high-intensity interval training on repeated sprint ability performance and neuromuscular fatigue. Journal of Applied Physiology, 127(6), 1599–1610.
Ojeda, Á.H., Cerda, C.T., Salvatierra, M.F.P., Barahona-Fuentes, G., & Aguilera, C.J. (2020). Effects of beta-alanine supplementation on physical performance in aerobic–anaerobic transition zones: A systematic review and meta-analysis. Nutrients, 12(9), Article 490.
Page, M.J., McKenzie, J.E., Bossuyt, P.M., Boutron, I., Hoffmann, T.C., Mulrow, C.D., Shamseer, L., Tetzlaff, J.M., Akl, E.A., Brennan, S.E., Chou, R., Glanville, J., Grimshaw, J.M., Hróbjartsson, A., Lalu, M.M., Li, T., Loder, E.W., Mayo-Wilson, E., McDonald, S., ... Moher, D. (2021). The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. BMJ, 372, Article 71.
Perim, P., Marticorena, F.M., Ribeiro, F., Barreto, G., Gobbi, N., Kerksick, C., Dolan, E., & Saunders, B. (2019). Can the skeletal muscle carnosine response to beta-Alanine supplementation be optimized? Frontiers in Nutrition, 6, Article 135.
Quesnele, J.J., Laframboise, M.A., Wong, J.J., Kim, P., & Wells, G.D. (2014). The effects of beta-alanine supplementation on performance: A systematic review of the literature. International Journal of Sport Nutrition and Exercise Metabolism, 24(1), 14–27.
Rosenthal, R. (1991). Meta-analytic procedures for social research. SAGE Publications, Inc.
Sale, C., Artioli, G.G., Gualano, B., Saunders, B., Hobson, R.M., & Harris, R.C. (2013). Carnosine: From exercise performance to health. Amino Acids, 44(6), 1477–1491.
Sale, C., Saunders, B., & Harris, R.C. (2010). Effect of beta-alanine supplementation on muscle carnosine concentrations and exercise performance. Amino Acids, 39(2), 321–333.
Saunders, B., DE Salles Painelli, V., DE Oliveira, L.F., DA Eira Silva, V., DA Silva, R.P., Riani, L., Franchi, M., Gonçalves, L.S., Harris, R.C., Roschel, H., & Al, E. (2017). Twenty-four weeks of β-alanine supplementation on carnosine content, related genes, and exercise. Medicine & Science in Sports & Exercise, 49(5), 896–906.
Saunders, B., Elliott-Sale, K., Artioli, G.G., Swinton, P.A., Dolan, E., Roschel, H., Sale, C., & Gualano, B. (2017). β-Alanine supplementation to improve exercise capacity and performance: A systematic review and meta-Analysis. British Journal of Sports Medicine, 51(8), 658–669.
Saunders, B., Sale, C., Harris, R.C., & Sunderland, C. (2012). Effect of beta-alanine supplementation on repeated sprint performance during the Loughborough Intermittent Shuttle Test. Amino Acids, 43(1), 39–47.
Smith, C.R., Harty, P.S., Stecker, R.A., & Kerksick, C.M. (2019). A pilot study to examine the impact of beta-alanine supplementation on anaerobic exercise performance in collegiate rugby athletes. Sports, 7(11), Article 231.
Stellingwerff, T., Decombaz, J., Harris, R.C., & Boesch, C. (2012). Optimizing human in vivo dosing and delivery of β-alanine supplements for muscle carnosine synthesis. Amino Acids, 43(1), 57–65.
Sweeney, K.M., Wright, G.A., Glenn Brice, A., & Doberstein, S.T. (2010). The effect of beta-alanine supplementation on power performance during repeated sprint activity. Journal of Strength and Conditioning Research, 24(1), 79–87.
Tobias, G., Benatti, F.B., de Salles Painelli, V., Roschel, H., Gualano, B., Sale, C., Harris, R.C., Lancha, A.H., & Artioli, G.G. (2013). Additive effects of beta-alanine and sodium bicarbonate on upper-body intermittent performance. Amino Acids, 45(2), 309–317.
Toviwek, B., Koonawootrittriron, S., Suwanasopee, T., & Pongprayoon, P. (2022). Molecular insights into the binding of carnosine and anserine to human serum carnosinase 1 (CN1). PeerJ Physical Chemistry, 4, Article 25.
Trexler, E.T., Smith-Ryan, A.E., Stout, J.R., Hoffman, J.R., Wilborn, C.D., Sale, C., Kreider, R.B., Jäger, R., Earnest, C.P., Bannock, L., Campbell, B., Kalman, D., Ziegenfuss, T.N., & Antonio, J. (2015). International Society of Sports Nutrition position stand: Beta-alanine. Journal of the International Society of Sports Nutrition, 12(1), 1–14.
Turcu, I., Oancea, B., Chicomban, M., Simion, G., Simon, S., Negriu Tiuca, C.I., Ordean, M.N., Petrovici, A.G., Nicolescu Seusan, N.A., Haisan, P.L., & Al, E. (2022). Effect of 8-week β-alanine supplementation on CRP, IL-6, body composition, and bio-motor abilities in elite male basketball players. International Journal of Environmental Research and Public Health, 19(20), Article 700.
Varanoske, A.N., Hoffman, J.R., Church, D.D., Coker, N.A., Baker, K.M., Dodd, S.J., Oliveira, L.P., Dawson, V.L., Wang, R., Fukuda, D.H., & Stout, J.R. (2017). β-Alanine supplementation elevates intramuscular carnosine content and attenuates fatigue in men and women similarly but does not change muscle L-histidine content. Nutrition Research, 48, 16–25.
