Effects of beta-alanine supplementation and interval training on physiological determinants of severe exercise performance

Effects of Acute Beta-Alanine Ingestion and Immersion-Plus-Exercise on Connectedness to Nature and Perceived Pain

This double-blinded, placebo-controlled, crossover study examined the effect of induced painful sensation (via acute Beta Alanine (B-ALA) ingestion) on Love and Care of Nature (LCN), heart rate (HR), rating of perceived exertion (RPE), and McGill Pain Questionnaire (MPQ) during outdoor exercise. Twenty participants volunteered on consecutive days to complete a 0.8 km (0.5 mi) up-hill hike after consuming either B-ALA (6.4 g) or placebo. Immediately after consumption participants answered LCN, RPE, and MPQ questionnaires, immersed in a natural environment for 45 min, and then completed a hike as quickly as possible without running. No difference in HR (p = 0.846), or RPE (p = 0.606) were observed between treatments. Total MPQ scores increased with consumption of B-ALA (p = 0.001). An increased LCN score was observed following exercise regardless of condition (p = 0.035). The results demonstrate that acute B-ALA supplementation is effective in increasing perceived pain sensations. The results also demonstrate an increase in LCN in the presence of increased perceptions of pain sensations during exercise.

One-Week High-Dose β-Alanine Loading Improves World Tour Cyclists' Time-Trial Performance

Supplementation with β-alanine is becoming a common practice in high-performance athletes. The purpose of the present study was to investigate the effects of a one-week high-dose β-alanine loading phase employing a sustained-release powder on preserving the time-trial performance capacity of world tour cyclists during overreaching training. Per day, 20 g of sustained-release β-alanine was administered during one week (7 days) of intensive team training camp in a randomised balanced placebo-controlled parallel trial design, with six participants in each β-alanine (BA) or placebo (PLA) group. A 10-min time trial (10′ TT) was carried out to analyse performance and biochemical variables. Anthropometry, paresthesia, and adverse event data were also collected. Power-based relative training load was quantified. Compared to placebo, the BA improved mean power (6.21%, 37.23 W; 95% CI: 3.98–70.48 W, p = 0.046), distance travelled (2.16%, p = 0.046) and total work (4.85%, p = 0.046) without differences in cadence (p = 0.506) or RPE. Lactate (p = 0.036) and anion gap (p = 0.047) were also higher in the BA group, without differences in pH or Bicarbonate. High daily and single doses were well tolerated. One-week high-dose β-alanine loading with a sustained-release powder blend can help attenuate 10′ TT performance losses of world tour cyclists due to intensive training.

CORP: quantification of human skeletal muscle carnosine concentration by proton magnetic resonance spectroscopy

Noninvasive techniques to quantify metabolites in skeletal muscle provide unique insight into human physiology and enable the translation of research into practice. Proton magnetic resonance spectroscopy (¹H-MRS) permits the assessment of several abundant muscle metabolites in vivo, including carnosine, a dipeptide composed of the amino acids histidine and beta-alanine. Muscle carnosine loading, accomplished by chronic oral beta-alanine supplementation, improves muscle function and exercise capacity and has pathophysiological relevance in multiple diseases. Moreover, the marked difference in carnosine content between fast-twitch and slow-twitch muscle fibers has rendered carnosine an attractive candidate to estimate human muscle fiber type composition. However, the quantification of carnosine with ¹H-MRS requires technical expertise to obtain accurate and reproducible data. In this review, we describe the technical and physiological factors that impact the detection, analysis, and quantification of carnosine in muscle with ¹H-MRS. We discuss potential sources of error during the acquisition and preprocessing of the ¹H-MRS spectra and present best practices to enable the accurate, reliable, and reproducible application of this technique.

Dietary Carnitine and Carnosine Increase Body Lean in Healthy Cats in a Preliminary Study

Simple Summary

Cats, like mammals in general, experience lean body mass loss in later life. This study shows that two dietary interventions offset that loss: L-carnitine and carnosine. The combination did not change body lean. Interestingly, the combination resulted in an increased circulating concentration of 8 of the 10 cytokines measured, while L-carnitine alone resulted in decreased concentrations. Thus, L-carnitine could benefit the healthy cat while in some disease states it may be beneficial to increase both L-carnitine and carnosine.

Abstract

The need to maintain body lean as cats age is shown in both health and disease. In healthy cats, body lean is associated with enhanced movement and overall longevity. In many disease states (i.e., renal disease, obesity), an enhanced or minimally maximal support of body lean is associated with quality of life and is a nutritional goal in aiding in the management of the disease. This study was designed to investigate the effect of these two dietary components and their combination on body composition and circulating factors of health, including metabolomics analysis and cytokine concentration. The foods that were fed for 169 days to four groups of cats and consisted of control food (formulated to meet the nutritional needs of all adult cats), carnitine-enhanced food (control food plus 300 mg/kg L-carnitine), carnosine-enhanced food (control food plus 1000 mg/kg carnosine), and food enhanced with both (control plus 300 mg/kg carnitine and 1000 mg/kg carnosine). Dietary enhancement with L-carnitine and carnosine increased body lean at the end of the study compared to the cats consuming the control food or the combination food. The cats consuming L-carnitine alone had a decreased concentration of circulating cytokines, while those consuming the combination food had an increased concentration of glucose, pyruvate, succinate, and circulating cytokines.

The role of chronic muscle (in)activity on carnosine homeostasis: a study with spinal cord-injured athletes

To examine the role of chronic (in)activity on muscle carnosine (MCarn) and how chronic (in)activity affects MCarn responses to β-alanine supplementation in spinal cord-injured athletes, 16 male athletes with paraplegia were randomized (2:1 ratio) to receive β-alanine (n = 11) or placebo (PL, n = 5). They consumed 6.4 g/day of β-alanine or PL for 28 days. Muscle biopsies of the active deltoid and the inactive vastus lateralis (VL) were taken before and after supplementation. MCarn in the VL was also compared with the VL of a group of individuals without paraplegia (n = 15). MCarn was quantified in whole muscle and in pools of individual fibers by high-performance liquid chromatography. MCarn was higher in chronically inactive VL vs. well-trained deltoid (32.0 ± 12.0 vs. 20.5 ± 6.1 mmol/kg DM; P = 0.018). MCarn was higher in inactive vs. active VL (32.0 ± 12.0 vs. 21.2 ± 7.5 mmol/kg DM; P = 0.011). In type-I fibers, MCarn was significantly higher in the inactive VL than in the active deltoid (38.3 ± 4.7 vs. 27.3 ± 11.8 mmol/kg DM, P = 0.014). MCarn increased similarly between inactive VL and active deltoid in the β-alanine group (VL: 68.9 ± 55.1%, P = 0.0002; deltoid: 90.5 ± 51.4%, P < 0.0001), with no changes in the PL group. MCarn content was higher in the inactive VL than in the active deltoid and the active VL, but this is probably a consequence of fiber type shift (type I to type II) that occurs with chronic inactivity. Chronically inactive muscle showed an increase in MCarn after BA supplementation equally to the active muscle, suggesting that carnosine accretion following β-alanine supplementation is not influenced by muscle inactivity.

The effect of β-alanine supplementation on high intensity cycling capacity in normoxia and hypoxia

The availability of dietary beta-alanine (BA) is the limiting factor in carnosine synthesis within human muscle due to its low intramuscular concentration and substrate affinity. Carnosine can accept hydrogen ions (H⁺), making it an important intramuscular buffer against exercise-induced acidosis. Metabolite accumulation rate increases when exercising in hypoxic conditions, thus an increased carnosine concentration could attenuate H⁺ build-up when exercising in hypoxic conditions. This study examined the effects of BA supplementation on high intensity cycling capacity in normoxia and hypoxia. In a double-blind design, nineteen males were matched into a BA group (n = 10; 6.4 g·d^-1) or a placebo group (PLA; n = 9) and supplemented for 28 days, carrying out two pre- and two post-supplementation cycling capacity trials at 110% of powermax, one in normoxia and one in hypoxia (15.5% O₂). Hypoxia led to a 9.1% reduction in exercise capacity, but BA supplementation had no significant effect on exercise capacity in normoxia or hypoxia (P > 0.05). Blood lactate accumulation showed a significant trial x time interaction post-supplementation (P = 0.016), although this was not significantly different between groups. BA supplementation did not increase high intensity cycling capacity in normoxia, nor did it improve cycling capacity in hypoxia even though exercise capacity was reduced under hypoxic conditions.

Reduced Dose of Beta-Alanine Is Sufficient to Maintain Performance in Repeated Sprints

Zandona, BA, Ramos, RA, de Oliveira, CdS, McAnulty, SR, Ferreira, LHB, Smolarek, AC, Enes, AAN, Urbinati, KMdSS, Aragon, AA, Schoenfeld, BJ, and de Souza Junior, TP. Reduced Dose of Beta-Alanine Is Sufficient to Maintain Performance in Repeated Sprints. J Strength Cond Res XX(X): 000-000, 2020-Beta-alanine (BA) supplementation has been shown to be effective in improving physical performance by increasing carnosine concentration. However, it is still necessary to know the effect of a maintenance dose on performance. Thus, this study aimed to investigate the effects of a maintenance dose of BA supplementation on performance. Forty-four anaerobically trained men with 23.9 ± 3.8 years of age, 176.0 ± 0.05 cm height, 81.2 ± 7.5 kg body mass, and 15.5 ± 2.9% of body fat performed a cycle ergometer test consisting of 4 sprints of 30 s with 4 minutes of active recovery. The study comprised 3 phases: (a) presupplementation, (b) supplementation with 6.4 g·d BA or placebo, and (c) postsupplementation with a maintenance dose of 1.2 g·d of BA or interruption of supplementation. Data were analyzed using generalized estimated equations with a priori 0.05 level of significance. The placebo group and interruption group presented a lower power (7.28 ± 0.66 and 7.71 ± 0.42 W·kg vs. 8.04 ± 0.84 and 9.25 ± 1.18 W·kg, respectively; p < 0.05) during the third sprint in postsupplementation, whereas the maintenance group maintained the required power (7.47 ± 1.03 vs. 8.74 ± 1.07 W·kg; p > 0.05). The placebo group also presented higher percentage of fatigue (44.5% ± 12.3 and 44.8% ± 7.7 vs. 37.6 ± 7.2%; p = 0.021) and higher subjective perception of exertion (8.92 ± 0.90 vs. 8.00 ± 1.60; p = 0.028). Therefore, the maintenance dose of 1.2 g·d BA was effective in maintaining performance, whereas a reduction in performance was observed after supplementation interruption.

Effects of Beta-Alanine Supplementation on Physical Performance in Aerobic-Anaerobic Transition Zones: A Systematic Review and Meta-Analysis

Beta-alanine supplementation (BA) has a positive impact on physical performance. However, evidence showing a benefit of this amino acid in aerobic-anaerobic transition zones is scarce and the results controversial. The aim of this systematic review and meta-analysis is to analyze the effects of BA supplementation on physical performance in aerobic-anaerobic transition zones. At the same time, the effect of different dosages and durations of BA supplementation were identified. The search was designed in accordance with the PRISMA^® guidelines for systematic reviews and meta-analyses and performed in Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2010 and 2020. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the Time Trial Test (TTT) and Time to Exhaustion (TTE) tests, the latter separated into the Limited Time Test (LTT) and Limited Distance Test (LDT). The analysis was carried out with a pooled standardized mean difference (SMD) through Hedges' g test (95% CI). Nineteen studies were included in the systematic review and meta-analysis, revealing a small effect for time in the TTT (SMD, -0.36; 95% CI, -0.87-0.16; I² = 59%; p = 0.010), a small effect for LTT (SMD, 0.25; 95% CI, -0.01-0.51; I² = 0%; p = 0.53), and a large effect for LDT (SMD, 4.27; 95% CI, -0.25-8.79; I² = 94%; p = 0.00001). BA supplementation showed small effects on physical performance in aerobic-anaerobic transition zones. Evidence on acute supplementation is scarce (one study); therefore, exploration of acute supplementation with different dosages and formats on physical performance in aerobic-anaerobic transition zones is needed.

Effects of Dietary Supplements on Adaptations to Endurance Training

Endurance training leads to a variety of adaptations at the cellular and systemic levels that serve to minimise disruptions in whole-body homeostasis caused by exercise. These adaptations are differentially affected by training volume, training intensity, and training status, as well as by nutritional choices that can enhance or impair the response to training. A variety of supplements have been studied in the context of acute performance enhancement, but the effects of continued supplementation concurrent to endurance training programs are less well characterised. For example, supplements such as sodium bicarbonate and beta-alanine can improve endurance performance and possibly training adaptations during endurance training by affecting buffering capacity and/or allowing an increased training intensity, while antioxidants such as vitamin C and vitamin E may impair training adaptations by blunting cellular signalling but appear to have little effect on performance outcomes. Additionally, limited data suggest the potential for dietary nitrate (in the form of beetroot juice), creatine, and possibly caffeine, to further enhance endurance training adaptation. Therefore, the objective of this review is to examine the impact of dietary supplements on metabolic and physiological adaptations to endurance training.

The Muscle Carnosine Response to Beta-Alanine Supplementation: A Systematic Review With Bayesian Individual and Aggregate Data E-Max Model and Meta-Analysis

Beta-alanine (BA) supplementation increases muscle carnosine content (MCarn), and has many proven, and purported, ergogenic, and therapeutic benefits. Currently, many questions on the nature of the MCarn response to supplementation are open, and the response to these has considerable potential to enhance the efficacy and application of this supplementation strategy. To address these questions, we conducted a systematic review with Bayesian-based meta-analysis of all published aggregate data using a dose response (Emax) model. Meta-regression was used to consider the influence of potential moderators (including dose, sex, age, baseline MCarn, and analysis method used) on the primary outcome. The protocol was designed according to PRISMA guidelines and a three-step screening strategy was undertaken to identify studies that measured the MCarn response to BA supplementation. Additionally, we conducted an original analysis of all available individual data on the MCarn response to BA supplementation from studies conducted within our lab (n = 99). The Emax model indicated that human skeletal muscle has large capacity for non-linear MCarn accumulation, and that commonly used BA supplementation protocols may not come close to saturating muscle carnosine content. Neither baseline values, nor sex, appeared to influence subsequent response to supplementation. Analysis of individual data indicated that MCarn is relatively stable in the absence of intervention, and effectually all participants respond to BA supplementation (99.3% response [95%CrI: 96.2–100]).

Supplements and Nutritional Interventions to Augment High-Intensity Interval Training Physiological and Performance Adaptations-A Narrative Review

High-intensity interval training (HIIT) involves short bursts of intense activity interspersed by periods of low-intensity exercise or rest. HIIT is a viable alternative to traditional continuous moderate-intensity endurance training to enhance maximal oxygen uptake and endurance performance. Combining nutritional strategies with HIIT may result in more favorable outcomes. The purpose of this narrative review is to highlight key dietary interventions that may augment adaptations to HIIT, including creatine monohydrate, caffeine, nitrate, sodium bicarbonate, beta-alanine, protein, and essential amino acids, as well as manipulating carbohydrate availability. Nutrient timing and potential sex differences are also discussed. Overall, sodium bicarbonate and nitrates show promise for enhancing HIIT adaptations and performance. Beta-alanine has the potential to increase training volume and intensity and improve HIIT adaptations. Caffeine and creatine have potential benefits, however, longer-term studies are lacking. Presently, there is a lack of evidence supporting high protein diets to augment HIIT. Low carbohydrate training enhances the upregulation of mitochondrial enzymes, however, there does not seem to be a performance advantage, and a periodized approach may be warranted. Lastly, potential sex differences suggest the need for future research to examine sex-specific nutritional strategies in response to HIIT.

Effect of β-alanine supplementation during high-intensity interval training on repeated sprint ability performance and neuromuscular fatigue

The study investigated the influence of β-alanine supplementation during a high-intensity interval training (HIIT) program on repeated sprint ability (RSA) performance. This study was randomized, double-blinded, and placebo controlled. Eighteen men performed an incremental running test until exhaustion (TINC) at baseline and followed by 4-wk HIIT (10 × 1-min runs 90% maximal TINCvelocity [1-min recovery]). Then, participants were randomized into two groups and performed a 6-wk HIIT associated with supplementation of 6.4 g/day of β-alanine (Gβ) or dextrose (placebo group; GP). Pre- and post-6-wk HIIT + supplementation, participants performed the following tests: 1) TINC; 2) supramaximal running test; and 3) 2 × 6 × 35-m sprints (RSA). Before and immediately after RSA, neuromuscular function was assessed by vertical jumps, maximal isometric voluntary contractions of knee extension, and neuromuscular electrical stimulations. Muscle biopsies were performed to determine muscle carnosine content, muscle buffering capacity in vitro (βmin vitro), and content of phosphofructokinase (PFK), monocarboxylate transporter 4 (MCT4), and hypoxia-inducible factor-1α (HIF-1α). Both groups showed a significant time effect for maximal oxygen uptake (Gβ: 6.2 ± 3.6% and GP: 6.5 ± 4.2%; P > 0.01); only Gβ showed a time effect for total (−3.0 ± 2.0%; P = 0.001) and best (−3.3 ± 3.0%; P = 0.03) RSA times. A group-by-time interaction was shown after HIIT + Supplementation for muscle carnosine (Gβ: 34.4 ± 2.3 mmol·kg−1·dm−1and GP: 20.7 ± 3.0 mmol·kg−1·dm−1; P = 0.003) and neuromuscular voluntary activation after RSA (Gβ: 87.2 ± 3.3% and GP: 78.9 ± 12.4%; P = 0.02). No time effect or group-by-time interaction was shown for supramaximal running test performance, βm, and content of PFK, MCT4, and HIF-1α. In summary, β-alanine supplementation during HIIT increased muscle carnosine and attenuated neuromuscular fatigue, which may contribute to an enhancement of RSA performance.

NEW & NOTEWORTHY β-Alanine supplementation during a high-intensity interval training program increased repeated sprint performance. The improvement of muscle carnosine content induced by β-alanine supplementation may have contributed to an attenuation of central fatigue during repeated sprint. Overall, β-alanine supplementation may be a useful dietary intervention to prevent fatigue.

Can the Skeletal Muscle Carnosine Response to Beta-Alanine Supplementation Be Optimized?

Carnosine is an abundant histidine-containing dipeptide in human skeletal muscle and formed by beta-alanine and L-histidine. It performs various physiological roles during exercise and has attracted strong interest in recent years with numerous investigations focused on increasing its intramuscular content to optimize its potential ergogenic benefits. Oral beta-alanine ingestion increases muscle carnosine content although large variation in response to supplementation exists and the amount of ingested beta-alanine converted into muscle carnosine appears to be low. Understanding of carnosine and beta-alanine metabolism and the factors that influence muscle carnosine synthesis with supplementation may provide insight into how beta-alanine supplementation may be optimized. Herein we discuss modifiable factors that may further enhance the increase of muscle carnosine in response to beta-alanine supplementation including, (i) dose; (ii) duration; (iii) beta-alanine formulation; (iv) dietary influences; (v) exercise; and (vi) co-supplementation with other substances. The aim of this narrative review is to outline the processes involved in muscle carnosine metabolism, discuss theoretical and mechanistic modifiable factors which may optimize the muscle carnosine response to beta-alanine supplementation and to make recommendations to guide future research.

High-Intensity Interval Training Augments Muscle Carnosine in the Absence of Dietary Beta-alanine Intake

PURPOSE

Cross-sectional studies suggest that training can increase muscle carnosine (MCarn), although longitudinal studies have failed to confirm this. A lack of control for dietary β-alanine intake or muscle fiber type shifting may have hampered their conclusions. The purpose of the present study was to investigate the effects of high-intensity interval training (HIIT) on MCarn.

METHODS

Twenty vegetarian men were randomly assigned to a control (CON) (n = 10) or HIIT (n = 10) group. High-intensity interval training was performed on a cycle ergometer for 12 wk, with progressive volume (6-12 series) and intensity (140%-170% lactate threshold [LT]). Muscle carnosine was quantified in whole-muscle and individual fibers; expression of selected genes (CARNS, CNDP2, ABAT, TauT, and PAT1) and muscle buffering capacity in vitro (βmin vitro) were also determined. Exercise tests were performed to evaluate total work done, V˙O2max, ventilatory thresholds (VT) and LT.

RESULTS

Total work done, VT, LT, V˙O2max, and βmin vitro were improved in the HIIT group (all P < 0.05), but not in CON (P > 0.05). MCarn (in mmol·kg dry muscle) increased in the HIIT (15.8 ± 5.7 to 20.6 ± 5.3; P = 0.012) but not the CON group (14.3 ± 5.3 to 15.0 ± 4.9; P = 0.99). In type I fibers, MCarn increased in the HIIT (from 14.4 ± 5.9 to 16.8 ± 7.6; P = 0.047) but not the CON group (from 14.0 ± 5.5 to 14.9 ± 5.4; P = 0.99). In type IIa fibers, MCarn increased in the HIIT group (from 18.8 ± 6.1 to 20.5 ± 6.4; P = 0.067) but not the CON group (from 19.7 ± 4.5 to 18.8 ± 4.4; P = 0.37). No changes in gene expression were shown.

CONCLUSIONS

In the absence of any dietary intake of β-alanine, HIIT increased MCarn content. The contribution of increased MCarn to the total increase in βmin vitro appears to be small.

Ergogenic Effects of β-Alanine Supplementation on Different Sports Modalities: Strong Evidence or Only Incipient Findings?

Brisola, GMP and Zagatto, AM. Ergogenic effects of β-alanine supplementation on different sports modalities: strong evidence or only incipient findings? J Strength Cond Res 33(1): 253-282, 2019-β-Alanine supplementation is a popular nutritional ergogenic aid among the sports community. Due to its efficacy, already proven in the literature, to increase the intramuscular carnosine content (β-alanyl-L-histidine), whose main function is intramuscular buffering, β-alanine supplementation has become a nutritional strategy to improve performance, mainly in high-intensity efforts. However, although many studies present evidence of the efficacy of β-alanine supplementation in high-intensity efforts, discrepancies in outcomes are still present and the performance enhancing effects seem to be related to the specificities of each sport discipline, making it difficult for athletes/coaches to interpret the efficacy of β-alanine supplementation. Thus, this study carried out a review of the literature on this topic and summarized, analyzed, and critically discussed the findings with the objective of clarifying the current evidence found in the literature on different types of efforts and sport modalities. The present review revealed that inconsistencies are still found in aerobic parameters determined in incremental tests, except for physical working capacity at the neuromuscular fatigue threshold. Inconsistencies are also found for strength exercises and intermittent high-intensity efforts, whereas in supramaximal continuous mode intermittent exercise, the beneficial evidence is strong. In sports modalities, the evidence should be analyzed separately for each sporting modality. Thus, sports modalities that have strong evidence of the ergogenic effects of β-alanine supplementation are: cycling race of 4 km, rowing race of 2,000 m, swimming race of 100 and 200 m, combat modalities, and water polo. Finally, there is some evidence of slight additional effects on physical performance from cosupplementation with sodium bicarbonate.

Time of VO(2)max plateau and post-exercise oxygen consumption during incremental exercise testing in young mountain bike and road cyclists

The purpose of this study was to compare markers of glycolytic metabolism in response to the Wingate test and the incremental test in road and mountain bike cyclists, who not different performance level and aerobic capacity. All cyclists executed the Wingate test and incremental test on a cycle ergometer. Maximal power and average power were determined during the Wingate test. During the incremental test the load was increased by 50 W every 3 min, until volitional exhaustion and maximal aerobic power (APmax), maximal oxygen uptake (VO2max), and time of VO(2)max plateau (Tplateau) were determined. Post-exercise measures of oxygen uptake (VO(2)post), carbon dioxide excretion, (VCO(2)post), and the ratio between VCO(2)/VO(2) (RERpost) were collected for 3 min immediately after incremental test completion. Arterialized capillary blood was drawn to measure lactate (La-) and hydrogen (H+) ion concentrations in 3 min after each test. The data demonstrated significant differences between mountain bike and road cyclists for Tplateau, VO(2)post, VCO(2)post, La- which was higher-, and RERpost which was lower-, in mountain bike cyclists compare with road cyclists. No differences were observed between mountain bike and road cyclists for APmax, VO(2)max, H(+) and parameters measured in the Wingate test. Increased time of VO2max plateau concomitant to larger post-exercise La- and VO(2) values suggests greater anaerobic contribution during incremental testing efforts by mountain bike cyclists compared with road cyclists.

The Effects of β-Alanine Supplementation on Muscle pH and the Power-Duration Relationship during High-Intensity Exercise

Purpose: To investigate the influence of β-alanine (BA) supplementation on muscle carnosine content, muscle pH and the power-duration relationship (i.e., critical power and W′).

Methods: In a double-blind, randomized, placebo-controlled study, 20 recreationally-active males (22 ± 3 y, V°O_2peak 3.73 ± 0.44 L·min⁻¹) ingested either BA (6.4 g/d for 28 d) or placebo (PL) (6.4 g/d) for 28 d. Subjects completed an incremental test and two 3-min all-out tests separated by 1-min on a cycle ergometer pre- and post-supplementation. Muscle pH was assessed using ³¹P-magnetic resonance spectroscopy (MRS) during incremental (INC KEE) and intermittent knee-extension exercise (INT KEE). Muscle carnosine content was determined using ¹H-MRS.

Results: There were no differences in the change in muscle carnosine content from pre- to post-intervention (PL: 1 ± 16% vs. BA: −4 ± 25%) or in muscle pH during INC KEE or INT KEE (P > 0.05) between PL and BA, but blood pH (PL: −0.06 ± 0.10 vs. BA: 0.09 ± 0.13) during the incremental test was elevated post-supplementation in the BA group only (P < 0.05). The changes from pre- to post-supplementation in critical power (PL: −8 ± 18 W vs. BA: −6 ± 17 W) and W′ (PL: 1.8 ± 3.3 kJ vs. BA: 1.5 ± 1.7 kJ) were not different between groups. No relationships were detected between muscle carnosine content and indices of exercise performance.

Conclusions: BA supplementation had no significant effect on muscle carnosine content and no influence on intramuscular pH during incremental or high-intensity intermittent knee-extension exercise. The small increase in blood pH following BA supplementation was not sufficient to significantly alter the power-duration relationship or exercise performance.

No Effect of β-alanine on Muscle Function and Kayak Performance

PURPOSE

If β-alanine supplementation counteracts muscular fatigue development or improves athletic performance was investigated.

METHODS

Elite kayak rowers (10 men and 7 women) were supplemented with either 80 mg·kg body mass·d of β-alanine or placebo for 8 wk. Muscular fatigue development was investigated by applying a 2-min elbow flexor maximal voluntary contraction (MVC). EMG was recorded continuously, and voluntary activation was determined 30, 60, 90, and 115 s into the 2-min MVC. In addition, performance was evaluated as 1000-m and 5 × 250-m kayak ergometer rowing.

RESULTS

Force reduction during the 2-min MVC was similar before and after supplementation with β-alanine (30.9% ± 10.3% vs 36.0% ± 14.1%) and placebo (35.5% ± 7.7% vs 35.1% ± 8.0%). No time effect was apparent in voluntary activation during the 2-min MVC. In addition, there was no detectable effect of β-alanine supplementation on 1000-m kayak ergometer performance (β-alanine: 0.26% ± 0.02% vs placebo: -0.18% ± 0.02%) or accumulated 5 × 250-m time (β-alanine: -1.0% ± 0.3% vs placebo: -1.0% ± 0.2%). In 5 × 250 m, mean power output was reduced to a similar extent from first to fifth interval before and after supplementation with β-alanine (23% ± 11% vs 22% ± 10%) and placebo (26% ± 13% vs 20% ± 5%).

CONCLUSIONS

Two-minute MVC characteristics are unaffected by β-alanine supplementation in elite kayakers, and likewise, both a 1000-m kayak ergometer time trial lasting 4-5 min and a 5 × 250-m repeated sprint ability were unaltered by supplementation.

Additive Benefits of β-Alanine Supplementation and Sprint-Interval Training

PURPOSE

The present study investigated the effects of β-alanine supplementation only, and in combination with sprint-interval training (SIT), on training intensity, and energy provision and performance during exhaustive supramaximal-intensity cycling and a 4- and 10-km time trial (TT).

METHODS

Fourteen trained cyclists (V˙O2max = 4.5 ± 0.6 L·min) participated in this placebo-controlled, double-blind study. Subjects performed a supramaximal cycling test to exhaustion (equivalent to 120% V˙O2max) and a 4- and 10-km TT and 4 × 1-km sprints at three time points: before and after 28 d of supplementation loading (6.4 g·d) with β-alanine (n = 7) or a placebo (n = 7), and after a 5-wk supervised, SIT program performed twice weekly (repeated 1-km cycling sprints) while maintaining supplementation with β-alanine (1.2 g·d) or a placebo.

RESULTS

After the loading period, sprints 3 and 4 of the 4 × 1-km sprint intervals were improved with β-alanine supplementation (4.5% ± 3.4% and 7.0% ± 4.0%; P < 0.05, respectively). After 5 wk of SIT, training intensity increased in both groups but the change was greater with β-alanine supplementation (9.9% ± 5.0% vs 4.9% ± 5.0%; P = 0.04). β-alanine supplementation also improved supramaximal cycling time to exhaustion to a greater extent than placebo (14.9% ± 9.2% vs 9.0% ± 6.9%; P = 0.04), whereas 4- and 10-km TT performance improved to a similar magnitude in both groups. After SIT, β-alanine also increased anaerobic capacity (5.5% ± 4.2%; P = 0.04), whereas V˙O2peak increased similarly in each group (3.1% ± 2.9% vs 3.5% ± 2.9%; P < 0.05).

CONCLUSIONS

These findings indicate that β-alanine supplementation enhances training intensity during SIT and provides additional benefits to exhaustive supramaximal cycling compared with SIT alone.

Twenty-four Weeks of β-Alanine Supplementation on Carnosine Content, Related Genes, and Exercise

INTRODUCTION

Skeletal muscle carnosine content can be increased through β-alanine (BA) supplementation, but the maximum increase achievable with supplementation is unknown. No study has investigated the effects of prolonged supplementation on carnosine-related genes or exercise capacity.

PURPOSE

This study aimed to investigate the effects of 24 wk of BA supplementation on muscle carnosine content, gene expression, and high-intensity cycling capacity (CCT110%).

METHODS

Twenty-five active males were supplemented with 6.4 g·d of sustained release BA or placebo for a 24 wk period. Every 4 wk participants provided a muscle biopsy and performed the CCT110%. Biopsies were analyzed for muscle carnosine content and gene expression (CARNS, TauT, ABAT, CNDP2, PHT1, PEPT2, and PAT1).

RESULTS

Carnosine content was increased from baseline at every time point in BA (all P < 0.0001; week 4 = +11.37 ± 7.03 mmol·kg dm, week 8 = +13.88 ± 7.84 mmol·kg dm, week 12 = +16.95 ± 8.54 mmol·kg dm, week 16 = +17.63 ± 8.42 mmol·kg dm, week 20 = +21.20 ± 7.86 mmol·kg dm, and week 24 = +20.15 ± 7.63 mmol·kg dm) but not placebo (all P > 0.05). Maximal increases were +25.66 ± 7.63 mmol·kg dm (range = +17.13 to +41.32 mmol·kg dm), and absolute maximal content was 48.03 ± 8.97 mmol·kg dm (range = 31.79 to 63.92 mmol·kg dm). There was an effect of supplement (P = 0.002) on TauT; no further differences in gene expression were shown. Exercise capacity was improved in BA (P = 0.05) with possible to almost certain improvements across all weeks.

CONCLUSIONS

Twenty-four weeks of BA supplementation increased muscle carnosine content and improved high-intensity cycling capacity. The downregulation of TauT suggests it plays an important role in muscle carnosine accumulation with BA supplementation, whereas the variability in changes in muscle carnosine content between individuals suggests that other determinants other than the availability of BA may also bear a major influence on muscle carnosine content.

Influence of training intensity on adaptations in acid/base transport proteins, muscle buffer capacity, and repeated-sprint ability in active men

McGinley C, Bishop DJ. Influence of training intensity on adaptations in acid/base transport proteins, muscle buffer capacity, and repeated-sprint ability in active men. J Appl Physiol 121: 1290–1305, 2016. First published October 14, 2016; doi: 10.1152/japplphysiol.00630.2016 .—This study measured the adaptive response to exercise training for each of the acid-base transport protein families, including providing isoform-specific evidence for the monocarboxylate transporter (MCT)1/4 chaperone protein basigin and for the electrogenic sodium-bicarbonate cotransporter (NBCe)1. We investigated whether 4 wk of work-matched, high-intensity interval training (HIIT), performed either just above the lactate threshold (HIITΔ20; n = 8), or close to peak aerobic power (HIITΔ90; n = 8), influenced adaptations in acid-base transport protein abundance, nonbicarbonate muscle buffer capacity (βmin vitro), and exercise capacity in active men. Training intensity did not discriminate between adaptations for most proteins measured, with abundance of MCT1, sodium/hydrogen exchanger (NHE) 1, NBCe1, carbonic anhydrase (CA) II, and CAXIV increasing after 4 wk, whereas there was little change in CAIII and CAIV abundance. βmin vitro also did not change. However, MCT4 protein content only increased for HIITΔ20 [effect size (ES): 1.06, 90% confidence limits × / ÷ 0.77], whereas basigin protein content only increased for HIITΔ90 (ES: 1.49, × / ÷ 1.42). Repeated-sprint ability (5 × 6-s sprints; 24 s passive rest) improved similarly for both groups. Power at the lactate threshold only improved for HIITΔ20 (ES: 0.49; 90% confidence limits ± 0.38), whereas peak O2 uptake did not change for either group. Detraining was characterized by the loss of adaptations for all of the proteins measured and for repeated-sprint ability 6 wk after removing the stimulus of HIIT. In conclusion, 4 wk of HIIT induced improvements in each of the acid-base transport protein families, but, remarkably, a 40% difference in training intensity did not discriminate between most adaptations.

β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis of the evidence on the effects of β-alanine supplementation on exercise capacity and performance.

DESIGN

This study was designed in accordance with PRISMA guidelines. A 3-level mixed effects model was employed to model effect sizes and account for dependencies within data.

DATA SOURCES

3 databases (PubMed, Google Scholar, Web of Science) were searched using a number of terms ('β-alanine' and 'Beta-alanine' combined with 'supplementation', 'exercise', 'training', 'athlete', 'performance' and 'carnosine').

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Inclusion/exclusion criteria limited articles to double-blinded, placebo-controlled studies investigating the effects of β-alanine supplementation on an exercise measure. All healthy participant populations were considered, while supplementation protocols were restricted to chronic ingestion. Cross-over designs were excluded due to the long washout period for skeletal muscle carnosine following supplementation. A single outcome measure was extracted for each exercise protocol and converted to effect sizes for meta-analyses.

RESULTS

40 individual studies employing 65 different exercise protocols and totalling 70 exercise measures in 1461 participants were included in the analyses. A significant overall effect size of 0.18 (95% CI 0.08 to 0.28) was shown. Meta-regression demonstrated that exercise duration significantly (p=0.004) moderated effect sizes. Subgroup analyses also identified the type of exercise as a significant (p=0.013) moderator of effect sizes within an exercise time frame of 0.5-10 min with greater effect sizes for exercise capacity (0.4998 (95% CI 0.246 to 0.753)) versus performance (0.1078 (95% CI -0.201 to 0.416)). There was no moderating effect of training status (p=0.559), intermittent or continuous exercise (p=0.436) or total amount of β-alanine ingested (p=0.438). Co-supplementation with sodium bicarbonate resulted in the largest effect size when compared with placebo (0.43 (95% CI 0.22 to 0.64)).

SUMMARY/CONCLUSIONS

β-alanine had a significant overall effect while subgroup analyses revealed a number of modifying factors. These data allow individuals to make informed decisions as to the likelihood of an ergogenic effect with β-alanine supplementation based on their chosen exercise modality.

Metabolic consequences of β-alanine supplementation during exhaustive supramaximal cycling and 4000-m time-trial performance

The present study investigated the effects of β-alanine supplementation on the resultant blood acidosis, lactate accumulation, and energy provision during supramaximal-intensity cycling, as well as the aerobic and anaerobic contribution to power output during a 4000-m cycling time trial (TT). Seventeen trained cyclists (maximal oxygen uptake = 4.47 ± 0.55 L·min(-1)) were administered 6.4 g of β-alanine (n = 9) or placebo (n = 8) daily for 4 weeks. Participants performed a supramaximal cycling test to exhaustion (equivalent to 120% maximal oxygen uptake) before (PreExh) and after (PostExh) the 4-week supplementation period, as well as an additional postsupplementation supramaximal cycling test identical in duration and power output to PreExh (PostMatch). Anaerobic capacity was quantified and blood pH, lactate, and bicarbonate concentrations were measured pre-, immediately post-, and 5 min postexercise. Subjects also performed a 4000-m cycling TT before and after supplementation while the aerobic and anaerobic contributions to power output were quantified. β-Alanine supplementation increased time to exhaustion (+12.8 ± 8.2 s; P = 0.041) and anaerobic capacity (+1.1 ± 0.7 kJ; P = 0.048) in PostExh compared with PreExh. Performance time in the 4000-m TT was reduced following β-alanine supplementation (-6.3 ± 4.6 s; P = 0.034) and the mean anaerobic power output was likely to be greater (+6.2 ± 4.5 W; P = 0.035). β-Alanine supplementation increased time to exhaustion concomitant with an augmented anaerobic capacity during supramaximal intensity cycling, which was also mirrored by a meaningful increase in the anaerobic contribution to power output during a 4000-m cycling TT, resulting in an enhanced overall performance.

Physiological and health-related adaptations to low-volume interval training: influences of nutrition and sex

Interval training refers to the basic concept of alternating periods of relatively intense exercise with periods of lower-intensity effort or complete rest for recovery. Low-volume interval training refers to sessions that involve a relatively small total amount of exercise (i.e. ≤10 min of intense exercise), compared with traditional moderate-intensity continuous training (MICT) protocols that are generally reflected in public health guidelines. In an effort to standardize terminology, a classification scheme was recently proposed in which the term 'high-intensity interval training' (HIIT) be used to describe protocols in which the training stimulus is 'near maximal' or the target intensity is between 80 and 100 % of maximal heart rate, and 'sprint interval training' (SIT) be used for protocols that involve 'all out' or 'supramaximal' efforts, in which target intensities correspond to workloads greater than what is required to elicit 100 % of maximal oxygen uptake (VO2max). Both low-volume SIT and HIIT constitute relatively time-efficient training strategies to rapidly enhance the capacity for aerobic energy metabolism and elicit physiological remodeling that resembles changes normally associated with high-volume MICT. Short-term SIT and HIIT protocols have also been shown to improve health-related indices, including cardiorespiratory fitness and markers of glycemic control in both healthy individuals and those at risk for, or afflicted by, cardiometabolic diseases. Recent evidence from a limited number of studies has highlighted potential sex-based differences in the adaptive response to SIT in particular. It has also been suggested that specific nutritional interventions, in particular those that can augment muscle buffering capacity, such as sodium bicarbonate, may enhance the adaptive response to low-volume interval training.

Effects of beta-alanine supplementation on brain homocarnosine/carnosine signal and cognitive function: an exploratory study

Objectives

Two independent studies were conducted to examine the effects of 28 d of beta-alanine supplementation at 6.4 g d^-1 on brain homocarnosine/carnosine signal in omnivores and vegetarians (Study 1) and on cognitive function before and after exercise in trained cyclists (Study 2).

Methods

In Study 1, seven healthy vegetarians (3 women and 4 men) and seven age- and sex-matched omnivores undertook a brain 1H-MRS exam at baseline and after beta-alanine supplementation. In study 2, nineteen trained male cyclists completed four 20-Km cycling time trials (two pre supplementation and two post supplementation), with a battery of cognitive function tests (Stroop test, Sternberg paradigm, Rapid Visual Information Processing task) being performed before and after exercise on each occasion.

Results

In Study 1, there were no within-group effects of beta-alanine supplementation on brain homocarnosine/carnosine signal in either vegetarians (p = 0.99) or omnivores (p = 0.27); nor was there any effect when data from both groups were pooled (p = 0.19). Similarly, there was no group by time interaction for brain homocarnosine/carnosine signal (p = 0.27). In study 2, exercise improved cognitive function across all tests (P<0.05), although there was no effect (P>0.05) of beta-alanine supplementation on response times or accuracy for the Stroop test, Sternberg paradigm or RVIP task at rest or after exercise.

Conclusion

28 d of beta-alanine supplementation at 6.4g d^-1 appeared not to influence brain homocarnosine/carnosine signal in either omnivores or vegetarians; nor did it influence cognitive function before or after exercise in trained cyclists.

Beta-alanine supplementation, muscle carnosine and exercise performance

PURPOSE OF REVIEW

The use of dietary supplements in sports is widespread as athletes are continuously searching for strategies to increase performance at the highest level. Beta-alanine is such a supplement that became increasingly popular during the past years. This review examines the available evidence regarding the optimization of supplementation, the link between beta-alanine and exercise performance and the underlying ergogenic mechanism.

RECENT FINDINGS

It has been repeatedly demonstrated that chronic beta-alanine supplementation can augment intramuscular carnosine content. Yet, the factors that determine the loading process, as well as the mechanism by which this has an ergogenic effect, are still debated. On the basis of its biochemical properties, several functions are ascribed to carnosine, of which intramuscular pH buffer and calcium regulator are the most cited ones. In addition, carnosine has antiglycation and antioxidant properties, suggesting it could have a therapeutic potential.

SUMMARY

On the basis of the millimolar presence of carnosine in mammalian muscles, it must play a critical role in skeletal muscle physiology. The recent number of studies shows that this is related to an improved exercise homeostasis and excitation-contraction coupling. Recent developments have led to the optimization of the beta-alanine supplementation strategies to elevate muscle carnosine content, which are helpful in its application in sports and to potential future therapeutic applications.