Influence of β-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity

Amino acids regulating skeletal muscle metabolism: mechanisms of action, physical training dosage recommendations and adverse effects

Maintaining skeletal muscle mass is important for improving muscle strength and function. Hence, maximizing lean body mass (LBM) is the primary goal for both elite athletes and fitness enthusiasts. The use of amino acids as dietary supplements is widespread among athletes and physically active individuals. Extensive literature analysis reveals that branched-chain amino acids (BCAA), creatine, glutamine and β-alanine may be beneficial in regulating skeletal muscle metabolism, enhancing LBM and mitigating exercise-induced muscle damage. This review details the mechanisms of these amino acids, offering insights into their efficacy as supplements. Recommended dosage and potential side effects are then outlined to aid athletes in making informed choices and safeguard their health. Lastly, limitations within the current literature are addressed, highlighting opportunities for future research.

Acute effects of multi-ingredient pre-workout dietary supplement on anaerobic performance in untrained men: a randomized, crossover, single blind study

BACKGROUND

Multi-ingredient pre-workout dietary supplements (MIPS), which are combinations of different ingredients acting on different physiological mechanisms, can have a synergistic effect and improve performance. The aim of the study was to determine the acute effects of a multi-ingredient pre-workout supplement containing: beta-alanine, taurine, caffeine, L-tyrosine, and cayenne pepper (capsaicin) on anaerobic performance.

METHODS

A randomized, crossover, single-blind study was designed. Twelve young, healthy, untrained men aged 22.4 ± 1.44 years participated in the study. The participants performed a supramaximal all-out test (20 s Wingate test) twice, day by day, in random order: test after placebo or MIPS consumption. In both trials, the following variables were measured in the exercise test: total work performed, peak power, mean power, time to reach peak power, and power decrease.

RESULTS

MIPS was found to be effective in improving peak power (p = 0.009, ES = 0.77) and mean power (p = 0.04, ES = 0.62) in the Wingate test. However, the supplement consumption did not affect the amount of total work done (p = 0.10, ES = 0.48) in the test or power decrease (p = 0.07, ES = 0.53). The data indicate, that the improvement in anaerobic power was due to a significant improvement in pedaling speed, which was manifested in a significant improvement (i.e. shortening) in time to peak power (p = 0.003, ES = 0.88).

CONCLUSION

A multi-ingredient pre-workout dietary supplement was found to be effective in improving Wingate (anaerobic) performance.

TRIAL REGISTRATION

NCT06363669, retrospectively registered on 11.04.2024 (ClinicalTrials.gov).

Musculoskeletal crosstalk in chronic obstructive pulmonary disease and comorbidities: Emerging roles and therapeutic potentials

Chronic Obstructive Pulmonary Disease (COPD) is a multifaceted respiratory disorder characterized by progressive airflow limitation and systemic implications. It has become increasingly apparent that COPD exerts its influence far beyond the respiratory system, extending its impact to various organ systems. Among these, the musculoskeletal system emerges as a central player in both the pathogenesis and management of COPD and its associated comorbidities. Muscle dysfunction and osteoporosis are prevalent musculoskeletal disorders in COPD patients, leading to a substantial decline in exercise capacity and overall health. These manifestations are influenced by systemic inflammation, oxidative stress, and hormonal imbalances, all hallmarks of COPD. Recent research has uncovered an intricate interplay between COPD and musculoskeletal comorbidities, suggesting that muscle and bone tissues may cross-communicate through the release of signalling molecules, known as "myokines" and "osteokines". We explored this dynamic relationship, with a particular focus on the role of the immune system in mediating the cross-communication between muscle and bone in COPD. Moreover, we delved into existing and emerging therapeutic strategies for managing musculoskeletal disorders in COPD. It underscores the development of personalized treatment approaches that target both the respiratory and musculoskeletal aspects of COPD, offering the promise of improved well-being and quality of life for individuals grappling with this complex condition. This comprehensive review underscores the significance of recognizing the profound impact of COPD on the musculoskeletal system and its comorbidities. By unravelling the intricate connections between these systems and exploring innovative treatment avenues, we can aspire to enhance the overall care and outcomes for COPD patients, ultimately offering hope for improved health and well-being.

Generation and Characterization of Stable Small Colony Variants of USA300 Staphylococcus aureus in RAW 264.7 Murine Macrophages

Intracellular survival and immune evasion are typical features of staphylococcal infections. USA300 is a major clone of methicillin-resistant S. aureus (MRSA), a community- and hospital-acquired pathogen capable of disseminating throughout the body and evading the immune system. Carnosine is an endogenous dipeptide characterized by antioxidant and anti-inflammatory properties acting on the peripheral (macrophages) and tissue-resident (microglia) immune system. In this work, RAW 264.7 murine macrophages were infected with the USA300 ATCC BAA-1556 S. aureus strain and treated with 20 mM carnosine and/or 32 mg/L erythromycin. Stable small colony variant (SCV) formation on blood agar medium was obtained after 48 h of combined treatment. Whole genome sequencing of the BAA-1556 strain and its stable derivative SCVs when combining Illumina and nanopore technologies revealed three single nucleotide differences, including a nonsense mutation in the shikimate kinase gene aroK. Gene expression analysis showed a significant up-regulation of the uhpt and sdrE genes in the stable SCVs compared with the wild-type, likely involved in adaptation to the intracellular milieu.

Content of amino acids and biogenic amines in stored meat as a result of a broiler diet supplemented with β-alanine and garlic extract

Poultry meat is a highly esteemed product among consumers. However, the emphasis on increasing body weight has led to a rise in the proportion of rapidly shrinking fibers, adversely affecting the quality and shelf life of poultry meat. With a growing awareness of dietetics among consumers, there is an increasing challenge to produce chicken meat that is not only free of antibiotics but also beneficial for dietary and health reasons. Biogenic amines (BA) can serve as indicators of meat freshness and quality. While they play vital roles in the body, excessive consumption of BA can have toxic and carcinogenic effects. The objective of this study was to examine the impact of supplementing feed with garlic extract and β-alanine (β-Ala) on the formation of BA and amino acid (AA) levels in the breast and leg muscles of chickens stored under aerobic chilling conditions. The muscles were obtained from chickens fed with garlic extract and β-Ala in quantities of 0.5 and 2% for each additive, as well as 0.5 and 2% of their combination. Analyses were conducted on d 1, 3, 5, 7, and 10 of storage. β-Ala supplementation increased the proportion of this AA in breast (P < 0.01) and leg muscles (P < 0.01), along with a rise in the proportion of nonessential AA (NEAA; sum of aspartic, aspartic acid, glutamic, glutamic acid, serine, β-Ala, and proline) (P < 0.01). The levels of BA changed during storage in breast and leg muscles (P < 0.001). The applied diet significantly influenced the formation of putrescine (P = 0.030), phenylethylamine (P = 0.003), agmatine (P = 0.025), and total BA (P < 0.001) in breast muscles. On the 10 d of storage, the breast muscles exhibited the lowest BA index (BAI) in the group, with a diet supplemented with 0.5% garlic extract and 0.5% β-Ala (P < 0.05). The leg muscles showed a similar BA trend as the breast muscles. These supplements may be utilized in production to augment the protein content of chicken muscles and potentially decrease the BAI index during meat storage.

Food for thought: Physiological considerations for nutritional ergogenic efficacy

Top-class athletes have optimized their athletic performance largely through adequate training, nutrition, recovery, and sleep. A key component of sports nutrition is the utilization of nutritional ergogenic aids, which may provide a small but significant increase in athletic performance. Over the last decade, there has been an exponential increase in the consumption of nutritional ergogenic aids, where over 80% of young athletes report using at least one nutritional ergogenic aid for training and/or competition. Accordingly, due to their extensive use, there is a growing need for strong scientific investigations validating or invalidating the efficacy of novel nutritional ergogenic aids. Notably, an overview of the physiological considerations that play key roles in determining ergogenic efficacy is currently lacking. Therefore, in this brief review, we discuss important physiological considerations that contribute to ergogenic efficacy for nutritional ergogenic aids that are orally ingested including (1) the impact of first pass metabolism, (2) rises in systemic concentrations, and (3) interactions with the target tissue. In addition, we explore mouth rinsing as an alternate route of ergogenic efficacy that bypasses the physiological hurdles of first pass metabolism via direct stimulation of the central nervous system. Moreover, we provide real-world examples and discuss several practical factors that can alter the efficacy of nutritional ergogenic aids including human variability, dosing protocols, training status, sex differences, and the placebo effect. Taking these physiological considerations into account will strengthen the quality and impact of the literature regarding the efficacy of potential ergogenic aids for top-class athletes.

Combined Exercise Training and Nutritional Interventions or Pharmacological Treatments to Improve Exercise Capacity and Body Composition in Chronic Obstructive Pulmonary Disease: A Narrative Review

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease that is associated with significant morbidity, mortality, and healthcare costs. The burden of respiratory symptoms and airflow limitation can translate to reduced physical activity, in turn contributing to poor exercise capacity, muscle dysfunction, and body composition abnormalities. These extrapulmonary features of the disease are targeted during pulmonary rehabilitation, which provides patients with tailored therapies to improve the physical and emotional status. Patients with COPD can be divided into metabolic phenotypes, including cachectic, sarcopenic, normal weight, obese, and sarcopenic with hidden obesity. To date, there have been many studies performed investigating the individual effects of exercise training programs as well as nutritional and pharmacological treatments to improve exercise capacity and body composition in patients with COPD. However, little research is available investigating the combined effect of exercise training with nutritional or pharmacological treatments on these outcomes. Therefore, this review focuses on exploring the potential additional beneficial effects of combinations of exercise training and nutritional or pharmacological treatments to target exercise capacity and body composition in patients with COPD with different metabolic phenotypes.

Effects of acute beta-alanine supplementation on post-exertion rating of per-ceived exertion, heart rate, blood lactate, and physical performance on the 6-minute race test in middle-distance runners

Introduction

Background: the use of beta-alanine (BA) to increase physical performance in the heavy-intensity domain zone (HIDZ) is widely documented. However, the effect of this amino acid on the post-exertion rating of perceived exertion (RPE), heart rate (HR), and blood lactate (BL) is still uncertain. Objectives: a) to determine the effect of acute BA supplementation on post-exertion RPE, HR, and BL in middle-distance athletes; and b) to determine the effect of acute BA supplementation on physical performance on the 6-minute race test (6-MRT). Material and methods: the study included 12 male middle-distance athletes. The de-sign was quasi-experimental, intrasubject, double-blind & crossover. It had two treat-ments (low-dose BA [30 mg·kg-1] and high-dose BA [45 mg·kg-1]) and a placebo, 72 hours apart. The effect of BA was evaluated at the end of the 6-MRT and post-exertion. The variables were RPE, HR and BL, and 6-MRT (m) distance. The statistical analysis included a repeated-measures ANOVA (p < 0.05). Results: the analysis evidenced no significant differences at the end of 6-MRT for all variables (p ˃ 0.05). However, both doses of BA generated a lower post-exertion RPE. The high dose of BA caused significant increases in post-exertion BL (p ˂ 0.05). Conclusion: acute supplementation with BA generated a lower post-exertion RPE. This decrease in RPE and the post-exertion BL increase could be related to an increase in physical performance in HIDZ.

Muscle typology influences the number of repetitions to failure during resistance training

This study examined whether muscle typology (muscle fibre type composition) is related to maximal strength and whether it can explain the high inter-individual variability in number of repetitions to failure during resistance training. Ninety-five resistance training novices (57 males) were assessed for their maximal isometric knee extension strength and muscle typology. Muscle typology was estimated by measuring carnosine in the soleus, gastrocnemius and/or vastus lateralis using proton magnetic resonance spectroscopy. Forty-four subjects (22 males) performed dynamic strength tests (1RM) and 3 sets of leg extensions and curls to failure (60%1RM) to determine the association between muscle typology and (total) number of repetitions. Twenty-one subjects performed additional biceps curls and triceps extensions (60%1RM) to assess influence of exercise, 23 subjects performed additional leg extensions and curls at 80% and 40%1RM to evaluate influence of training load. There was a weak but significant relationship between muscle typology and maximal isometric strength (r = 0.22, p = 0.03) favouring the fast typology individuals. Slow and fast typology individuals did not differ in upper arm and upper leg 1RM. Total number of repetitions was related to muscle typology at 80% (r = -0.42; p = 0.04) and 60% (p = -0.44; p = 0.003) but not at 40%1RM. Slow typology individuals performed more repetitions to failure at 60%1RM in the leg extension (p = 0.03), leg curl (p = 0.01) and biceps curl (p = 0.02). In conclusion, muscle typology has a small contribution to maximal isometric strength but not dynamic strength and partly determines the number of repetitions to failure during resistance training. This insight can help individualizing resistance training prescriptions.

Effect of muscle fibre types and carnosine levels on the expression of carnosine-related genes in pig skeletal muscle

It is generally accepted that carnosine (β-alanyl-L-histidine) content is higher in glycolytic than in oxidative muscle fibres, but the underlying mechanisms responsible for this difference remain to be elucidated. A first study to better understand potential mechanisms involved was undertaken (1) to determine whether differences in the expression of carnosine-related enzymes (CARNS1, CNDP2) and transporters (SLC6A6, SLC15A3, SLC15A4, SLC36A1) exist between oxidative and glycolytic myofibres and (2) to study the effect of carnosine on myoblast proliferative growth and on carnosine-related gene expression in cultured myoblasts isolated from glycolytic and oxidative muscles. Immunohistochemistry analyses were conducted to determine the cellular localization of carnosine-related proteins. Laser-capture microdissection and qPCR analyses were performed to measure the expression of carnosine-related genes in different myofibres isolated from the longissimus dorsi muscle of ten crossbred pigs. Myogenic cells originating from glycolytic and oxidative muscles were cultured to assess the effect of carnosine (0, 10, 25 and 50 mM) on their proliferative growth and on carnosine-related gene expression. The mRNA abundance of CNDP2 and of the studied carnosine transporters was higher in oxidative than in glycolytic myofibres. Since carnosine synthase (CARNS1) mRNA abundance was not affected by either the fibre type or the addition of carnosine to myoblasts, its transcriptional regulation would not be the main process by which carnosine content differences are determined in oxidative and glycolytic muscles. The addition of carnosine to myoblasts leading to a dose-dependent increase in SLC15A3 transcripts, however, suggests a role for this transporter in carnosine uptake and/or efflux to maintain cellular homeostasis.

Nutritional Considerations for the Vegan Athlete

Accepting a continued rise in the prevalence of vegan-type diets in the general population is also likely to occur in athletic populations, it is of importance to assess the potential impact on athletic performance, adaptation, and recovery. Nutritional consideration for the athlete requires optimization of energy, macronutrient, and micronutrient intakes, and potentially the judicious selection of dietary supplements, all specified to meet the individual athlete's training and performance goals. The purpose of this review is to assess whether adopting a vegan diet is likely to impinge on such optimal nutrition and, where so, consider evidence based yet practical and pragmatic nutritional recommendations. Current evidence does not support that a vegan-type diet will enhance performance, adaptation, or recovery in athletes, but equally suggests that an athlete can follow a (more) vegan diet without detriment. A clear caveat, however, is that vegan diets consumed spontaneously may induce suboptimal intakes of key nutrients, most notably quantity and/or quality of dietary protein and specific micronutrients (eg, iron, calcium, vitamin B12, and vitamin D). As such, optimal vegan sports nutrition requires (more) careful consideration, evaluation, and planning. Individual/seasonal goals, training modalities, athlete type, and sensory/cultural/ethical preferences, among other factors, should all be considered when planning and adopting a vegan diet.

Effect of long-term carnosine/anserine supplementation on iron regulation after a prolonged running session

PURPOSE

Exercise-induced hemolysis, which is caused by metabolic and/or mechanical stress during exercise, is considered a potential factor for upregulating hepcidin. Intramuscular carnosine has multiple effects including antioxidant activity. Therefore, this study aimed to determine whether long-term carnosine/anserine supplementation modulates exercise-induced hemolysis and subsequent hepcidin elevation.

METHODS

Seventeen healthy male participants were allocated to two different groups: participants consuming 1,500 mg/day of carnosine/anserine supplements (n = 9, C+A group) and participants consuming placebo powder supplements (n = 8, PLA group). The participants consumed carnosine/anserine or placebo supplements daily for 30.7 ± 0.4 days. They performed an 80-running session at 70% VO2peak pre-and post-supplementation. Iron regulation and inflammation in response to exercise were evaluated.

RESULTS

Serum iron concentrations significantly increased after exercise (p < 0.01) and serum haptoglobin concentrations decreased after exercise in both groups (p < 0.01). No significant differences in these variables were observed between pre-and post-supplementation. Serum hepcidin concentration significantly increased 180 min after exercise in both groups (p < 0.01). The integrated area under the curve of hepcidin significantly decreased after supplementation (p = 0.011) but did not vary between the C+A and PLA groups.

CONCLUSION

Long-term carnosine/anserine supplementation does not affect iron metabolism after a single endurance exercise session.

Acute balenine supplementation in humans as a natural carnosinase-resistant alternative to carnosine

Balenine possesses some of carnosine's and anserine's functions, yet it appears more resistant to the hydrolysing CN1 enzyme. The aim of this study was to elucidate the stability of balenine in the systemic circulation and its bioavailability in humans following acute supplementation. Two experiments were conducted in which (in vitro) carnosine, anserine and balenine were added to plasma to compare degradation profiles and (in vivo) three increasing doses (1-4-10 mg/kg) of balenine were acutely administered to 6 human volunteers. Half-life of balenine (34.9 ± 14.6 min) was respectively 29.1 and 16.3 times longer than that of carnosine (1.20 ± 0.36 min, p = 0.0044) and anserine (2.14 ± 0.58 min, p = 0.0044). In vivo, 10 mg/kg of balenine elicited a peak plasma concentration (Cmax) of 28 µM, which was 4 and 18 times higher than with 4 (p = 0.0034) and 1 mg/kg (p = 0.0017), respectively. CN1 activity showed strong negative correlations with half-life (ρ = - 0.829; p = 0.0583), Cmax (r = - 0.938; p = 0.0372) and incremental area under the curve (r = - 0.825; p = 0.0433). Overall, balenine seems more resistant to CN1 hydrolysis resulting in better in vivo bioavailability, yet its degradation remains dependent on enzyme activity. Although a similar functionality as carnosine and anserine remains to be demonstrated, opportunities arise for balenine as nutraceutical or ergogenic aid.

Supplementation-induced change in muscle carnosine is paralleled by changes in muscle metabolism, protein glycation and reactive carbonyl species sequestering

Carnosine is a performance-enhancing food supplement with a potential to modulate muscle energy metabolism and toxic metabolites disposal. In this study we explored interrelations between carnosine supplementation (2 g/day, 12 weeks) induced effects on carnosine muscle loading and parallel changes in (i) muscle energy metabolism, (ii) serum albumin glycation and (iii) reactive carbonyl species sequestering in twelve (M/F=10/2) sedentary, overweight-to-obese (BMI: 30.0+/-2.7 kg/m2) adults (40.1+/-6.2 years). Muscle carnosine concentration (Proton Magnetic Resonance Spectroscopy; 1H-MRS), dynamics of muscle energy metabolism (Phosphorus Magnetic Resonance Spectroscopy; 31P-MRS), body composition (Magnetic Resonance Imaging; MRI), resting energy expenditure (indirect calorimetry), glucose tolerance (oGTT), habitual physical activity (accelerometers), serum carnosine and carnosinase-1 content/activity (ELISA), albumin glycation, urinary carnosine and carnosine-propanal concentration (mass spectrometry) were measured. Supplementation-induced increase in muscle carnosine was paralleled by improved dynamics of muscle post-exercise phosphocreatine recovery, decreased serum albumin glycation and enhanced urinary carnosine-propanal excretion (all p<0.05). Magnitude of supplementation-induced muscle carnosine accumulation was higher in individuals with lower baseline muscle carnosine, who had lower BMI, higher physical activity level, lower resting intramuscular pH, but similar muscle mass and dietary protein preference. Level of supplementation-induced increase in muscle carnosine correlated with reduction of protein glycation, increase in reactive carbonyl species sequestering, and acceleration of muscle post-exercise phosphocreatine recovery.

No Effect of Acute Balenine Supplementation on Maximal and Submaximal Exercise Performance in Recreational Cyclists

Carnosine (β-alanyl-L-histidine) and its methylated analogues anserine and balenine are highly concentrated endogenous dipeptides in mammalian skeletal muscle that are implicated in exercise performance. Balenine has a much better bioavailability and stability in human circulation upon acute ingestion, compared to carnosine and anserine. Therefore, ergogenic effects observed with acute carnosine and anserine supplementation may be even more pronounced with balenine. This study investigated whether acute balenine supplementation improves physical performance in four maximal and submaximal exercise modalities. A total of 20 healthy, active volunteers (14 males; six females) performed cycling sprints, maximal isometric contractions, a 4-km TT and 20-km TT following either preexercise placebo or 10 mg/kg of balenine ingestion. Physical, as well as mental performance, along with acid-base balance and glucose concentration were assessed. Balenine was unable to augment peak power (p = .3553), peak torque (p = .3169), time to complete the 4 km (p = .8566), nor 20 km time trial (p = .2660). None of the performances were correlated with plasma balenine or CN1 enzyme activity. In addition, no effect on pH, bicarbonate, and lactate was observed. Also, the supplement did not affect mental performance. In contrast, glucose remained higher during and after the 20 km time trial following balenine ingestion. In conclusion, these results overall indicate that the functionality of balenine does not fully resemble that of carnosine and anserine, since it was unable to elicit performance improvements with similar and even higher plasma concentrations.

The Effect of β-Alanine Supplementation on Performance, Cognitive Function and Resiliency in Soldiers

β-alanine is a nonessential amino acid that combines with the amino acid histidine to form the intracellular dipeptide carnosine, an important intracellular buffer. Evidence has been well established on the ability of β-alanine supplementation to enhance anaerobic skeletal muscle performance. As a result, β-alanine has become one of the more popular supplements used by competitive athletes. These same benefits have also been reported in soldiers. Evidence accumulated over the last few years has suggested that β-alanine can result in carnosine elevations in the brain, which appears to have broadened the potential effects that β-alanine supplementation may have on soldier performance and health. Evidence suggests that β-alanine supplementation can increase resilience to post-traumatic stress disorder, mild traumatic brain injury and heat stress. The evidence regarding cognitive function is inconclusive but may be more of a function of the stressor that is applied during the assessment period. The potential benefits of β-alanine supplementation on soldier resiliency are interesting but require additional research using a human model. The purpose of this review is to provide an overview of the physiological role of β-alanine and why this nutrient may enhance soldier performance.

Molecular Profiling of Athletes Performing High-Intensity Exercises in Extreme Environments

The aim of this study was to determine the influence of high-intensity training under extreme conditions (T = 40 °C) on the metabolism and immunological reactions of athletes. Male triathletes (n = 11) with a high level of sports training performed load testing to failure (17 ± 2.7 min) and maximum oxygen consumption (64.1 ± 6.4 mL/min/kg). Blood plasma samples were collected before and immediately after exercise. Mass spectrometric metabolomic analysis identified 30 metabolites and 6 hormones in the plasma, of which 21 and 4 changed after exercise, respectively. Changes in the intermediate products of tricarboxylic and amino acids were observed (FC > 1.5) after exercise. The obtained data can be associated with the effect of physical activity on metabolism in athletes. Therefore, constant monitoring of the biochemical parameters of athletes can help coaches identify individual shortcomings in a timely manner and track changes, especially as the volume of training increases. In addition, it was revealed that the immunological reaction (manifestation of a hyperactive reaction to food components) is personalized in nature. Therefore, it is important for coaches and sports doctors to analyze and control the eating behavior of athletes to identify food intolerances or food allergies in a timely manner and develop an individual elimination diet.

Acute Supplementation with Beta-Alanine Improves Performance in Aerobic-Anaerobic Transition Zones in Endurance Athletes

To determine the acute effect of low and high-dose BA trials on maximal aerobic speed (MAS) in endurance athletes. We hypothesized that high doses of BA have a greater effect than low doses, both compared to baseline.

Twelve male endurance athletes volunteered for the study (age = 21.8 ± 2.37 years, weight = 69.8 ± 4.36 kg, height = 174 ± 5.45 cm, maximal oxygen uptake = 59.6 ± 3.77 mLO₂·kg^-1·min^-1). The experimental design applied was randomized cross-over, double-blind. Treatment included three 6-minute run tests (6-MRT), the first as a baseline, then randomized 6-MRT with low (30 mg·kg^-1) and high (45 mg·kg^-1) dose BA trials. The 6-MRTs were separated by 72 hours. The main variable of the study was the distance (m) performed in the 6-MRT. Differences between tests were established through ANOVA and Tukey's multiple comparison tests (p < 0.05).

The analysis showed significant differences between baseline and both doses (p < 0.001). No significant differences were observed between low and high-dose BA trials (p > 0.05).

Both 30 and 45 mg·kg^-1 of BA increased physical performance at maximal aerobic speed in endurance athletes. The acute intake formats described in the present investigation may be helpful for endurance athletes training and competing in aerobic-anaerobic transition zones.

Secondary Metabolites in Nectar-Mediated Plant-Pollinator Relationships

In recent years, our understanding of the complex chemistry of floral nectar and its ecological implications for plant-pollinator relationships has certainly increased. Nectar is no longer considered merely a reward for pollinators but rather a plant interface for complex interactions with insects and other organisms. A particular class of compounds, i.e., nectar secondary compounds (NSCs), has contributed to this new perspective, framing nectar in a more comprehensive ecological context. The aim of this review is to draft an overview of our current knowledge of NSCs, including emerging aspects such as non-protein amino acids and biogenic amines, whose presence in nectar was highlighted quite recently. After considering the implications of the different classes of NSCs in the pollination scenario, we discuss hypotheses regarding the evolution of such complex nectar profiles and provide cues for future research on plant-pollinator relationships.

Changes in the physicochemical parameters and microbial community of a new cultivar blue wheat cereal wholemeal during sourdough production

Changes in the characteristics of a new cultivar (DS8472-5) of blue wheat during wholemeal fermentation with Pediococcus acidilactici (LUHS29), Liquorilactobacillus uvarum (LUHS245), and Lactiplantibacillus plantarum (LUHS122), including acidity, microbiological and chromaticity parameters, free amino acid (FAA), gamma-aminobutyric acid (GABA), and biogenic amine (BA) contents, macro- and micro-element concentrations and fatty acid (FA) and volatile compounds (VC), were evaluated. In addition, a metagenomic analysis was performed. The lactic acid bacteria (LAB) strains used for fermentation was a significant factor in wholemeal fermentation sample pH, redness (a*) and LAB counts (p ≤ 0.05). In most of the samples, fermentation increased the FAA content in wheat wholemeal, and the highest concentration of GABA was found in DS8472-5 LUHS122 samples. Phenylethylamine (PHE) was found in all wheat wholemeal samples; however, spermidine was only detected in fermented samples and cadaverine only in DS8472-5 LUHS122. Fermented samples showed higher omega-3 and omega-6 contents and a higher number and variety of VC. Analysis of the microbial profile showed that LAB as part of the natural microbiota present in cereal grains also actively participates in fermentation processes induced by industrial bacterial cultures. Finally, all the tested LAB were suitable for DS8472-5 wheat wholemeal fermentation, and the DS8472-5 LUHS122 samples showed the lowest pH and the highest LAB viable counts (3.94, 5.80°N, and 8.92 log10 CFU/g, respectively).

Effect of 8-Week β-Alanine Supplementation on CRP, IL-6, Body Composition, and Bio-Motor Abilities in Elite Male Basketball Players

The purpose of this study was to evaluate the effect of 8-week β-alanine supplementation on C-Reactive Protein (CRP), interleukin-6 (IL-6), body composition, and bio-motor abilities in elite male basketball players. Twenty male basketball players (age: 23 + 0.6 years; body mass: 78.3 + 4.8 kg; height:185.3 + 5.4 cm, %BF, 15.2 ± 4.8) volunteered to participate in this study. They were divided into a β-alanine group (BG, N = 10) and a placebo group (PG, N = 10). All players were preparing for university competitions and had played for over five years. Players used 6.4 g/d of β-alanine in BG and maltodextrin in PG. The participants were involved in regular basketball training three months before the study. CRP, IL-6, body composition parameters, and bio-motor abilities were measured before starting the exercises and after completing the eight-week training period. The research findings showed a significant decrease in CRP and IL-6 and an increase in anaerobic peak power between the pre-test and post-test, as well as between BG and PG groups (p < 0.05). Although the other measured factors were a relative improvement compared to the pre-test and also compared to PG, these changes were not statistically significant (p < 0.05). Eight weeks of β-alanine supplementation ameliorated increases in IL-6 and CRP associated with in-season physical stressors in collegiate basketball players. These changes in pro-inflammatory cytokines suggest that β-alanine supplementation may be a useful nutritional strategy for immune regulation and can also improve anaerobic performance compared to PG.

Carnosine as a potential therapeutic for the management of peripheral vascular disease

AIMS

To evaluate the potential role of carnosine in the management of peripheral vascular disease.

DATA SYNTHESIS

Peripheral vascular disease is growing in its burden and impact; however it is currently under researched, and there are a lack of strong, non-invasive therapeutic options for the clinicians. Carnosine is a dipeptide stored particularly in muscle and brain tissue, which exhibits a wide range of physiological activities, which may be beneficial as an adjunct treatment for peripheral vascular disease. Carnosine's strong anti-inflammatory, antioxidant and antiglycating actions may aid in the prevention of plaque formation, through protective actions on the vascular endothelium, and the inhibition of foam cells. Carnosine may also improve angiogenesis, exercise performance and vasodilatory response, while protecting from ischemic tissue injury.

CONCLUSIONS

Carnosine may have a role as an adjunct treatment for peripheral vascular disease alongside typical exercise and surgical interventions, and may be used in high risk individuals to aid in the prevention of atherogenesis.

CLINICAL RECOMMENDATION

This review identifies a beneficial role for carnosine supplementation in the management of patients with peripheral vascular disease, in conjunction with exercise and revascularization. Carnosine as a supplement is safe, and associated with a host of beneficial effects in peripheral vascular disease and its key risk factors.

Effect of Beta-Alanine Supplementation on Exercise-Induced Cell Damage and Lactate Accumulation in Female Basketball Players: A Randomized, Double-Blind Study

Beta-alanine (BA) is a supplement that has received attention for its buffering potential among athletes. The aim of this study was to investigate the effects of BA supplementation on exercise performance and exercise-induced cell damage in female basketball players. Twenty-two female basketball players participated in a randomized, double-blind study. They ingested 6.4 g·day^-1 of BA or an isocaloric placebo (dextrose) over 4 weeks. Exercise performance including aerobic (Bruce test), anaerobic (Wingate test), intermittent (Yo-Yo test) and basketball performance (countermovement jump and free throw shots) was measured before and following the intervention. Exercise measures were performed at the lab and free throw shots were undertaken on a wooden indoor basketball court. Blood samples were also collected before and after the exhaustive exercise to assess lactate concentration, creatine kinase (CK), lactate dehydrogenase (LDH) and malondialdehyde (MDA) activity. The exhaustive exercise test induced an increase in lactate concentration and MDA, CK and LDH activity (all p < 0.05). BA supplementation significantly reduced the lactate response to exhaustive exercise (p = 0.001); however, it had no significant effect on exercise-induced MDA, CK and LDH activity (all p > 0.05). Furthermore, exercise performance measures improved from pre- to post-test regardless of supplement/placebo ingestion (all p < 0.05). BA consumption over 4 weeks significantly reduced lactate accumulation following exhaustive exercise, but had no ergogenic effect in female basketball players. Usual dosing of BA does not seem to exhibit protective effect against oxidative damage.

Effects of Four Weeks of Beta-Alanine Supplementation Combined with One Week of Creatine Loading on Physical and Cognitive Performance in Military Personnel

The purpose was to investigate the effects of a 7-day creatine (Cr) loading protocol at the end of four weeks of β-alanine supplementation (BA) on physical performance, blood lactate, cognitive performance, and resting hormonal concentrations compared to BA alone. Twenty male military personnel (age: 21.5 ± 1.5 yrs; height: 1.78 ± 0.05 m; body mass: 78.5 ± 7.0 kg; BMI: 23.7 ± 1.64 kg/m2) were recruited and randomized into two groups: BA + Cr or BA + placebo (PL). Participants in each group (n = 10 per group) were supplemented with 6.4 g/day of BA for 28 days. After the third week, the BA + Cr group participants were also supplemented with Cr (0.3 g/kg/day), while the BA + PL group ingested an isocaloric placebo for 7 days. Before and after supplementation, each participant performed a battery of physical and cognitive tests and provided a venous blood sample to determine resting testosterone, cortisol, and IGF-1. Furthermore, immediately after the last physical test, blood lactate was assessed. There was a significant improvement in physical performance and mathematical processing in the BA + Cr group over time (p < 0.05), while there was no change in the BA + PL group. Vertical jump performance and testosterone were significantly higher in the BA + Cr group compared to BA + PL. These results indicate that Cr loading during the final week of BA supplementation (28 days) enhanced muscular power and appears to be superior for muscular strength and cognitive performance compared to BA supplementation alone.

Nutritional Ergogenic Aids in Combat Sports: A Systematic Review and Meta-Analysis

Nutritional ergogenic aids (NEAs) are substances included within the group of sports supplements. Although they are widely consumed by athletes, evidence-based analysis is required to support training outcomes or competitive performance in specific disciplines. Combat sports have a predominant use of anaerobic metabolism as a source of energy, reaching peak exertion or sustained effort for very short periods of time. In this context, the use of certain NEAs could help athletes to improve their performance in those specific combat skills (i.e., the number of attacks, throws and hits; jump height; and grip strength, among others) as well as in general physical aspects (time to exhaustion [TTE], power, fatigue perception, heart rate, use of anaerobic metabolism, etc.). Medline/PubMed, Scopus and EBSCO were searched from their inception to May 2022 for randomised controlled trials (RCTs). Out of 677 articles found, 55 met the predefined inclusion criteria. Among all the studied NEAs, caffeine (5–10 mg/kg) showed strong evidence for its use in combat sports to enhance the use of glycolytic pathways for energy production during high-intensity actions due to a greater production of and tolerance to blood lactate levels. In this regard, abilities including the number of attacks, reaction time, handgrip strength, power and TTE, among others, were improved. Buffering supplements such as sodium bicarbonate, sodium citrate and beta-alanine may have a promising role in high and intermittent exertion during combat, but more studies are needed in grappling combat sports to confirm their efficacy during sustained isometric exertion. Other NEAs, including creatine, beetroot juice or glycerol, need further investigation to strengthen the evidence for performance enhancement in combat sports. Caffeine is the only NEA that has shown strong evidence for performance enhancement in combat sports.

The ergogenic effect of acute carnosine and anserine supplementation: dosing, timing, and underlying mechanism

Background

Recent studies suggest that acute-combined carnosine and anserine supplementation has the potential to improve the performance of certain cycling protocols. Yet, data on optimal dose, timing of ingestion, effective exercise range, and mode of action are lacking. Three studies were conducted to establish dosing and timing guidelines concerning carnosine and anserine intake and to unravel the mechanism underlying the ergogenic effects.

Methods

First, a dose response study A was conducted in which 11 men randomly received placebo, 10, 20, or 30 mg.kg⁻¹ of both carnosine and anserine. They performed 3x maximal voluntary isometric contractions (MVC), followed by a 5 x 6 s repeated cycling sprint ability test (RSA), once before the supplement and 30 and 60 minutes after. In a second study, 15 men performed 3x MVCs with femoral nerve electrical stimulation, followed by an RSA test, once before 30 mg.kg⁻¹ carnosine and anserine and 60 minutes after. Finally, in study C, eight men performed a high intensity cycling training after randomly ingesting 30 mg.kg⁻¹ of carnosine and anserine, a placebo or antihistamines (reduce post-exercise blood flow) to investigate effects on muscle perfusion.

Results

Study A showed a 3% peak power (p = 0.0005; 95% CI = 0.07 to 0.27; ES = 0.91) and 4.5% peak torque (p = 0.0006; 95% CI = 0.12 to 0.50; ES = 0.87) improvement on RSA and MVC, with 30 mg.kg⁻¹ carnosine + anserine ingestion 60 minutes before the performance yielding the best results. Study B found no performance improvement on group level; however, a negative correlation (r = −0.54; p = 0.0053; 95% CI = −0.77 to −0.19) was found between carnosinase enzyme activity (responsible for carnosine and anserine breakdown) and performance improvement. No effect of the supplement on neuromuscular function nor on muscle perfusion was found.

Conclusions

These studies reveal that acute ingestion of 30 mg.kg⁻¹ of both carnosine and anserine, 60 minutes before a high intensity exercise, can potentially improve performance, such as short cycling sprints or maximal muscle contractions. Subjects with lower carnosinase activity, and thus a slower breakdown of circulating dipeptides, appear to benefit more from this ergogenic effect. Finally, neither the involvement of a direct effect on neuromuscular function, nor an indirect effect on recovery through increased muscle perfusion could be confirmed as potential mechanism of action. The ergogenic mechanism therefore remains elusive.

Endogenous dipeptide-carnosine supplementation ameliorates hypobaric hypoxia-induced skeletal muscle loss via attenuating endoplasmic reticulum stress response and maintaining proteostasis

High altitude is an environmental stress that is accompanied with numerous adverse biological responses, including skeletal muscle weakness and muscle protein loss. Skeletal muscle wasting is an important clinical problem, progressing to critical illness, associated with increased morbidity and mortality. The present study explores the protective efficacy of endogenous dipeptide, carnosine (CAR), supplementation in ameliorating skeletal muscle protein loss under hypobaric hypoxia (HH). Male Sprague-Dawley rats (n = 5) were randomly divided into control group, HH-exposed group (3 days HH exposure equivalent to 7,620 m), and HH-exposed rats supplemented with carnosine (3 days; 150 mg/kg b.w, orally) (HH + CAR). HH-exposed rats supplemented with CAR ameliorated HH-induced oxidative protein damage, lipid peroxidation, and maintained pro-inflammatory cytokines levels. HH-associated muscle protein degradative pathways, including calpain, ubiquitination, endoplasmic reticulum stress, autophagy, and apoptosis were also regulated in carnosine-supplemented rats. Further, the muscle damage marker, the levels of serum creatine phosphokinase were also reduced in HH + CAR co-supplemented rats which proved the protective efficacy of CAR against hypobaric hypoxia-induced muscle protein loss. Altogether, CAR supplementation ameliorated HH-induced skeletal muscle protein loss via performing multifaceted ways, mainly by maintaining redox homeostasis and proteostasis in skeletal muscle.

Aging-related metabolic changes in the extensor digitorum longus muscle of senescence-accelerated mouse-prone 8

Aim

Sarcopenia – aging‐related loss of muscle mass and muscle strength – is a key feature of the frailty model. In the present study, we aimed to elucidate the molecular biological changes associated with aging in the extensor digitorum longus muscle of senescence‐accelerated mouse prone 8 mouse model by capillary electrophoresis–mass spectrometry.

Methods

Three groups of senescence‐accelerated mouse prone 8 mice were used, namely, 12‐week‐old (young; n = 5), 40‐week‐old (elderly; n = 5) and 55‐week‐old mice (late elderly; n = 5). The extensor digitorum longus muscle was collected. After preliminary analyses, metabolome analysis was carried out by capillary electrophoresis–mass spectrometry. Additionally, we examined whether the activity of enzymes in the metabolic pathway fluctuated with aging, by real‐time polymerase chain reaction.

Results

Among the 116 water‐soluble metabolites associated with the central energy metabolism pathway, changes were observed in 19 metabolites between 12‐ and 40 ‐weeks‐old, in 40 metabolites between 40‐ and 55‐weeks‐old, and in 57 metabolites between 12‐ and 55‐weeks‐old. The fluctuated metabolites that were common among the groups were Val, putrescine and His. The levels of putrescine, associated with cell proliferation, protein synthesis and nucleic acid synthesis, and β‐Ala and His, a component of carnosine that is characterized by its anti‐oxidant and anti‐fatigue effects, decreased with age.

Conclusions

We confirmed that there were two aging‐related metabolic changes in the extensor digitorum longus muscle of senescence‐accelerated mouse prone 8 mice. Based on the changes in metabolites, cell senescence and fatigue in the extensor digitorum longus muscle might increase in old mice compared with those in young mice, showing molecular biological changes with aging. Geriatr Gerontol Int 2022; 22: 160–167.

Evaluation of spatial memory and anti-fatigue function of long-term supplementation of <i>β</i>-alanine and confirmation through cAMP-PKA and apoptosis pathways in mice

With an aim to explore the effects of <i>β</i>-alanine (<i>β</i>-A) on spatial memory and fatigue resistance, Kunming mice were treated with different concentrations of β-A (418, 836, and 2090 mg·kg^-1·day^-1). After gavage feeding with <i>β</i>-A for 10 weeks, results of the maze and MWM tests showed that <i>β</i>-A can enhance spatial learning and memory in mice. After evaluating the fatigue resistance, biochemical parameters (LG, GG, BUN, SOD, and MDA) showed significant differences in the low concentration treatment group compared to control group. Our data demonstrated that the appropriate dose of <i>β</i>-A can alleviate the oxidative stress and muscle fatigue in mice. Subsequently, expression of mRNA of key genes involved in cAMP-PKA pathway (PDE4A, MAPK1, adcy1, cAMP and CREB) was up regulated. Also, expression levels of apoptotic pathway genes were significantly affected as confirmed by qPCR and Western blotting. Our results demonstrated that <i>β</i>-A can enhance spatial learning and memory in mice via regulation of cAMP-PKA and apoptotic pathway.

Nutritional optimization for female elite football players-topical review

Women's football is an intermittent sport characterized by frequent intense actions throughout the match. The high number of matches with limited recovery time played across a long competitive season underlines the importance of nutritional strategies to meet these large physical demands. In order to maximize sport performance and maintain good health, energy intake must be optimal. However, a considerable proportion of female elite football players does not have sufficient energy intake to match the energy expenditure, resulting in low energy availability that might have detrimental physiologic consequences and impair performance. Carbohydrates appear to be the primary fuel covering the total energy supply during match-play, and female elite football players should aim to consume sufficient carbohydrates to meet the requirements of their training program and to optimize the replenishment of muscle glycogen stores between training bouts and matches. However, several macro- and micronutrients are important for ensuring sufficient energy and nutrients for performance optimization and for overall health status in female elite football players. The inadequacy of macro-and micronutrients in the diet of these athletes may impair performance and training adaptations, and increase the risk of health disorders, compromising the player's professional career. In this topical review, we present knowledge and relevant nutritional recommendations for elite female football players for the benefit of sports nutritionists, dietitians, sports scientists, healthcare specialists, and applied researchers. We focus on dietary intake and cover the most pertinent topics in sports nutrition for the relevant physical demands in female elite football players as follows: energy intake, macronutrient and micronutrient requirements and optimal composition of the everyday diet, nutritional and hydration strategies to optimize performance and recovery, potential ergogenic effects of authorized relevant supplements, and future research considerations.

Increased Bioavailability of β-Alanine by a Novel Controlled-Release Powder Blend Compared to a Slow-Release Tablet

BACKGROUND

β-Alanine is a sport supplement with increasing popularity due to its consistent ability to improve physical performance, with the downside of requiring several weeks of supplementation as imposed to the maximum daily and single dose tolerated without side effects (i.e., paresthesia). To date, the only alternative to overcome this problem has been use of a sustained-release tablet, while powders are the most commonly used format to deliver several grams of amino acids in a single dose. In this study we assessed the bioavailability, pharmacokinetics and paresthesia effect of β-alanine after administration in a novel controlled-released powder blend (test) versus a sustained-release tablet (reference).

METHODS

Twelve subjects (25.6 ± 3.2 y, 50% female) participated in a randomized, single-blind, crossover study. Each participant was administered orally the test (β-alanine 8 g, l-histidine 300 mg, carnosine 100 mg) or the reference product (10 tablets to reach β-alanine 8 g, Zinc 20 mg) with a 1-week washout period. β-Alanine plasma concentrations (0-8 h) were determined by LC-MS/MS and model-independent pharmacokinetic analysis was carried out. Paresthesia intensity was evaluated using a Visual Analog Score (VAS) and the categorical Intensity Sensory Score (ISS).

RESULTS

The CMAX and AUC0→∞ increased 1.6- and 2.1-fold (both p < 0.001) in the test product, respectively, which yielded 2.1-fold higher bioavailability; Ka decreased in the test (0.0199 ± 0.0107 min-1) versus the reference (0.0299 ± 0.0121 min-1) product (p = 0.0834) as well as V/F and Cl/F (both p < 0.001); MRT0→last increased in the test (143 ± 19 min) versus reference (128 ± 16 min) formulation (p = 0.0449); t1/2 remained similar (test: 63.5 ± 8.7 min, reference: 68.9 ± 9.8 min). Paresthesia EMAX increased 1.7-fold using the VAS (p = 0.086) and the ISS (p = 0.009). AUEC increased 1.9-fold with the VAS (p = 0.107) and the ISS (p = 0.019) reflecting scale intrinsic differences. Pharmacokinetic-pharmacodynamic analysis showed a clockwise hysteresis loop without prediction ability between CMAX, AUC0→∞ and EMAX or AUEC. No side effects were reported (except paresthesia).

CONCLUSIONS

The novel controlled-release powder blend shows 100% higher bioavailability of β-alanine, opening a new paradigm that shifts from chronic to short or mid-term supplementation strategies to increase carnosine stores in sports nutrition.

Anti-cancer actions of carnosine and the restoration of normal cellular homeostasis

Carnosine is a naturally occurring dipeptide found in meat. Alternatively it can be formed through synthesis from the amino acids, β-alanine and L-histidine. Carnosine has long been advocated for use as an anti-oxidant and anti-glycating agent to facilitate healthy ageing, and there have also been reports of it having anti-proliferative effects that have beneficial actions against the development of a number of different cancers. Carnosine is able to undertake multiple molecular processes, and it's mechanism of action therefore remains controversial - both in healthy tissues and those associated with cancer or metabolic diseases. Here we review current understanding of its mechanistic role in different physiological contexts, and how this relates to cancer. Carnosine turns over rapidly in the body due to the presence of both serum and tissue carnosinase enzymes however, so its use as a dietary supplement would require ingestion of multiple daily doses. Strategies are therefore being developed that are based upon either resistance of carnosine analogs to enzymatic turnover, or else β-alanine supplementation, and the development of these potential therapeutic agents is discussed.

Connections between Different Sports and Ergogenic Aids-Focusing on Salivary Cortisol and Amylase

Athletes are exposed to a tremendous amount of stress, both physically and mentally, when performing high intensity sports with frequent practices, pushing numerous athletes into choose to use ergogenic aids such as caffeine or β-alanine to significantly improve their performance and ease the stress and pressure that is put onto the body. The beneficial or even detrimental effects of these so-called ergogenic aids can be appreciated through the use of numerous diagnostic tools that can analyze various body fluids. In the recent years, saliva samples are gaining more ground in the field of diagnostic as it is a non-invasive procedure, contains a tremendous amount of analytes that are subject to pathophysiological changes caused by diseases, exercises, fatigue as well as nutrition and hydration. Thus, we describe here the current progress regarding potential novel biomarkers for stress and physical activity, salivary α-amylase and salivary cortisol, as well as their use and measurement in combination with different already-known or new ergogenic aids.

Muscle Ionic Shifts During Exercise: Implications for Fatigue and Exercise Performance

Exercise causes major shifts in multiple ions (e.g., K⁺ , Na⁺ , H⁺ , lactate^- , Ca²⁺ , and Cl^- ) during muscle activity that contributes to development of muscle fatigue. Sarcolemmal processes can be impaired by the trans-sarcolemmal rundown of ion gradients for K⁺ , Na⁺ , and Ca²⁺ during fatiguing exercise, while changes in gradients for Cl^- and Cl^- conductance may exert either protective or detrimental effects on fatigue. Myocellular H⁺ accumulation may also contribute to fatigue development by lowering glycolytic rate and has been shown to act synergistically with inorganic phosphate (Pi) to compromise cross-bridge function. In addition, sarcoplasmic reticulum Ca²⁺ release function is severely affected by fatiguing exercise. Skeletal muscle has a multitude of ion transport systems that counter exercise-related ionic shifts of which the Na⁺ /K⁺ -ATPase is of major importance. Metabolic perturbations occurring during exercise can exacerbate trans-sarcolemmal ionic shifts, in particular for K⁺ and Cl^- , respectively via metabolic regulation of the ATP-sensitive K⁺ channel (K_ATP ) and the chloride channel isoform 1 (ClC-1). Ion transport systems are highly adaptable to exercise training resulting in an enhanced ability to counter ionic disturbances to delay fatigue and improve exercise performance. In this article, we discuss (i) the ionic shifts occurring during exercise, (ii) the role of ion transport systems in skeletal muscle for ionic regulation, (iii) how ionic disturbances affect sarcolemmal processes and muscle fatigue, (iv) how metabolic perturbations exacerbate ionic shifts during exercise, and (v) how pharmacological manipulation and exercise training regulate ion transport systems to influence exercise performance in humans. © 2021 American Physiological Society. Compr Physiol 11:1895-1959, 2021.

Carnosine, Small but Mighty-Prospect of Use as Functional Ingredient for Functional Food Formulation

Carnosine is a dipeptide synthesized in the body from β-alanine and L-histidine. It is found in high concentrations in the brain, muscle, and gastrointestinal tissues of humans and is present in all vertebrates. Carnosine has a number of beneficial antioxidant properties. For example, carnosine scavenges reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes created by peroxidation of fatty acid cell membranes during oxidative stress. Carnosine can oppose glycation, and it can chelate divalent metal ions. Carnosine alleviates diabetic nephropathy by protecting podocyte and mesangial cells, and can slow down aging. Its component, the amino acid beta-alanine, is particularly interesting as a dietary supplement for athletes because it increases muscle carnosine, and improves effectiveness of exercise and stimulation and contraction in muscles. Carnosine is widely used among athletes in the form of supplements, but rarely in the population of cardiovascular or diabetic patients. Much less is known, if any, about its potential use in enriched food. In the present review, we aimed to provide recent knowledge on carnosine properties and distribution, its metabolism (synthesis and degradation), and analytical methods for carnosine determination, since one of the difficulties is the measurement of carnosine concentration in human samples. Furthermore, the potential mechanisms of carnosine's biological effects in musculature, metabolism and on immunomodulation are discussed. Finally, this review provides a section on carnosine supplementation in the form of functional food and potential health benefits and up to the present, neglected clinical use of carnosine.

Beta-alanine did not improve high-intensity performance throughout simulated road cycling

This study investigated the effect of beta-alanine supplementation on short-duration sprints and final 4-km simulated uphill cycling time-trial performance during a comprehensive and novel exercise protocol representative of the demands of road-race cycling, and determined if changes were related to increases in muscle carnosine content. Seventeen cyclists (age 38 ± 9 y, height 1.76 ± 0.07 m, body mass 71.4 ± 8.8 kg, V̇O_2max 52.4 ± 8.3 ml·kg^-1·min^-1) participated in this placebo-controlled, double-blind study. Cyclists undertook a prolonged intermittent cycling protocol lasting 125 min, with a 10-s sprint every 20 min, finishing with a 4-km time-trial at 5% simulated incline. Participants completed two familiarization sessions, and two main sessions, one pre-supplementation and one post-supplementation following 28 days of 6.4 g·day^-1 of beta-alanine (N=11) or placebo (N=6; maltodextrin). Muscle biopsies obtained pre- and post-supplementation were analysed for muscle carnosine content. There were no main effects on sprint performance throughout the intermittent cycling test (all P>0.05). There was no group (P=0.69), time (P=0.50) or group x time interaction (P=0.26) on time-to-complete the 4-km time-trial. Time-to-completion did not change from pre- to post-supplementation for BA (-19.2 ± 45.6 s, P=0.43) or PL (+2.8 ± 31.6 s, P=0.99). Beta-alanine supplementation increased muscle carnosine content from pre- to post-supplementation (+9.4 ± 4.0 mmol·kg^-1dm; P<0.0001) but was not related to performance changes (r=0.320, P=0.37). Chronic beta-alanine supplementation increased muscle carnosine content but did not improve short-duration sprint performance throughout simulated road race cycling, nor 4-km uphill time-trial performance conducted at the end of this cycling test.Highlights Performance during prolonged cycling events often depends on the ability to maintain an increased power output during higher intensity periods. Thus, cyclists are likely heavily dependent on their ability to resist fatigue during these periods of high-intensity activity.Meta-analytical data show beta-alanine to be an effective supplement to improve exercise outcomes, but little work exists on its efficacy during dynamic actions that are common during prolonged cycling.Beta-alanine supplementation increased muscle carnosine content but did not generate improvements in the performance of high-intensity cycling (10-s sprints or 4-km uphill time-trial) during a simulated road race cycling protocol.These data suggest that short duration sprints (≤10 s) and longer duration (>10 min) high-intensity activity throughout endurance cycling may not be improved with beta-alanine supplementation despite increases in muscle carnosine content.

The effect of multi-ingredient intra- versus extra-cellular buffering supplementation combined with branched-chain amino acids and creatine on exercise-induced ammonia blood concentration and aerobic capacity in taekwondo athletes

Background

This study aimed to investigate the effect of multi-ingredient intra- (BA) versus extra- (ALK) cellular buffering factor supplementation, combined with the customary intake of branched-chain amino acids (BCAA) and creatine malate (TCM), on body composition, exercise variables, and biochemical and hematological parameters in 9 elite taekwondo athletes.

Methods

Eight-week randomized double-blind crossover BA (5.0 g·day⁻¹ of β-alanine) versus ALK (0.07 g·kg_FFM⁻¹·day⁻¹ of sodium bicarbonate) supplementation combined with BCAA (0.2 g·kg_FFM⁻¹·day⁻¹) and TCM (0.05 g·kg_FFM⁻¹·day⁻¹) during a standard 8-week taekwondo training period was implemented. In the course of the experiment, body composition (dual X-ray absorptiometry), aerobic capacity (ergospirometric measurements during an incremental treadmill test until exhaustion), and exercise blood biomarkers concentrations were measured. Data were analyzed using repeated measures within-between interaction analysis of variance with the inclusion of experimental supplementation order.

Results

The maximum post-exercise blood ammonia concentration decreased in both groups after supplementation (from 80.3 ± 10.6 to 72.4 ± 10.2 µmol∙L⁻¹, p = 0.013 in BA; from 81.4 ± 8.7 to 74.2 ± 8.9 µmol∙L⁻¹, p = 0.027 in ALK), indicating reduced exercise-related adenosine triphosphate degradation. However, no differences were found in body composition, aerobic capacity, blood lactate concentration, and hematological parameters after neither BA (combined with BCAA and TCM) nor ALK (combined with BCAA and TCM) supplementation.

Conclusions

In highly trained taekwondo athletes, neither extra- nor intracellular buffering enhancement resulting from BA and ALK supplementation, combined with BCAA and TCM treatment, affects body mass and composition, maximum oxygen uptake, and hematological indices, even though certain advantageous metabolic adaptations can be observed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12970-021-00451-3.

Individual Participant Data Meta-Analysis Provides No Evidence of Intervention Response Variation in Individuals Supplementing With Beta-Alanine

Currently, little is known about the extent of interindividual variability in response to beta-alanine (BA) supplementation, nor what proportion of said variability can be attributed to external factors or to the intervention itself (intervention response). To investigate this, individual participant data on the effect of BA supplementation on a high-intensity cycling capacity test (CCT110%) were meta-analyzed. Changes in time to exhaustion (TTE) and muscle carnosine were the primary and secondary outcomes. Multilevel distributional Bayesian models were used to estimate the mean and SD of BA and placebo group change scores. The relative sizes of group SDs were used to infer whether observed variation in change scores were due to intervention or non-intervention-related effects. Six eligible studies were identified, and individual data were obtained from four of these. Analyses showed a group effect of BA supplementation on TTE (7.7, 95% credible interval [CrI] [1.3, 14.3] s) and muscle carnosine (18.1, 95% CrI [14.5, 21.9] mmol/kg DM). A large intervention response variation was identified for muscle carnosine (σIR = 5.8, 95% CrI [4.2, 7.4] mmol/kg DM) while equivalent change score SDs were shown for TTE in both the placebo (16.1, 95% CrI [13.0, 21.3] s) and BA (15.9, 95% CrI [13.0, 20.0] s) conditions, with the probability that SD was greater in placebo being 0.64. In conclusion, the similarity in observed change score SDs between groups for TTE indicates the source of variation is common to both groups, and therefore unrelated to the supplement itself, likely originating instead from external factors such as nutritional intake, sleep patterns, or training status.

Evaluation of High-Intensity Interval Training and Beta-Alanine Supplementation on Efficiency of Electrical Activity and Electromyographic Fatigue Threshold

ABSTRACT

Herda, AA, Smith-Ryan, AE, Kendall, KL, Cramer, JT, and Stout, JR. Evaluation of high-intensity interval training and beta-alanine supplementation on efficiency of electrical activity and electromyographic fatigue threshold. J Strength Cond Res 35(6): 1535-1541, 2021-The purpose of this study was to determine the effects of high-intensity interval training (HIIT) with or without β-alanine (BA) supplementation on the electromyographic fatigue threshold (EMGFT) and efficiency of electrical activity (EEA) in young women. Forty-four women (mean ± SD; age [yrs]: 21.7 ± 3.7; height [cm]: 166.3 ± 6.4; body mass [kg]: 66.1 ± 10.3) were randomly assigned to one of 3 treatment groups. The supplement groups performed HIIT on the cycle ergometer 3 times·wk-1 for 6 weeks. Electromyographic fatigue threshold and EEA were assessed at baseline (PRE), after 3 weeks of training (MID), and after 6 weeks of HIIT (POST). Two 2-way mixed factorial analyses of variance (time [PRE vs. MID vs. POST] × treatment (BA vs. PL vs. CON)] were used to analyze EMGFT and EEA with a predetermined level of significance α of 0.05. For EMGFT, there was no interaction (p = 0.26) and no main effect for time (p = 0.28) nor treatment (p = 0.86); thus, there were no changes in EMGFT regardless of training or supplementation status. For EEA, there was no interaction (p = 0.70) nor treatment (p = 0.79); however, there was a main effect for time (p < 0.01). Our findings indicated that neither training nor supplementation was effective in improving EMGFT in women. Efficiency of electrical activity was altered, potentially because of a learning effect. Coaches and practitioners may not use these tests to monitor training status; however, they may find EEA as a useful tool to track cycling efficiency.

Acute preexercise supplementation of combined carnosine and anserine enhances initial maximal power of Wingate tests in humans

Classic in vitro experiments (Severin's phenomenon) demonstrated that acute carnosine supplementation may potentiate muscle contractility. However, upon oral ingestion, carnosine is readily degraded in human plasma by the highly active serum carnosinase-1 (CN1). We developed a novel strategy to circumvent CN1 by preexercise ingestion of combined carnosine (CARN) and anserine (ANS), the methylated analog with similar biochemical properties but more resistant to CN1. First, in vitro hydrolysis was tested by adding carnosine and anserine to human plasma, alone or in combination. Second, five subjects were supplemented with 25 mg/kg anserine or 25 mg/kg of each anserine and carnosine to test in vivo bioavailability. Third, two double-blind, placebo-controlled, crossover studies investigated the effect of preexercise ANS + CARN (20 mg/kg body wt of each) supplementation on performance during a single all-out Wingate test following 6-min high-intensity cycling (study A) or three repeated Wingate tests (study B). In vitro experiments demonstrated slower degradation of anserine versus carnosine, which was further slowed by simultaneously adding carnosine. In vivo bioavailability of plasma anserine was more prominent [2.5-fold increased area under the curve (AUC)] when ANS + CARN versus ANS was ingested. Study A showed significantly higher (+6% ± 11%; P = 0.04) power in the first 5 s of the Wingate test following ANS + CARN (12.8 ± 2.4 W/kg) versus placebo (12.1 ± 2.2 W/kg). Study B demonstrated increased peak power (+3%) throughout three consecutive Wingate tests (ANS + CARN 10.5 ± 0.6 W/kg vs. placebo 10.2 ± 9.9 W/kg). These experiments reveal a novel acute nutritional method to effectively raise plasma anserine and carnosine by high-dose combined supplementation. This approach led to improved initial cycling power, revealing a new nutritional strategy to increase exercise performance.NEW & NOTEWORTHY Current results reveal that carnosine and anserine competitively bind to the highly active carnosinase enzyme in human plasma. Acute combined carnosine and anserine supplementation is therefore described as novel strategy to raise plasma anserine and carnosine. We report that indices of maximal exercise/muscle power during the initial stage of a Wingate test were significantly improved by preexercise 20-25mg/kg body wt anserine and carnosine supplementation, pointing toward a novel acute nutritional strategy to improve high-intensity exercise performance.

Beta-Alanine Supplementation and Sport Climbing Performance

BACKGROUND

Supplementing β-alanine (BA) improves exercise performance in efforts that are highly dependent on anaerobic glycolysis. As it has not yet been established whether it relates to climbing, the current study aimed to investigate the effects of BA on climbing-specific performance.

METHODS

Fifteen elite climbers performed intermittent high-force high-velocity campus board exercise, and two bouldering traverses, hard and easy. They ingested 4.0 g·d^-1 BA or placebo for four weeks in a double-blind, pre/post experimental design.

RESULTS

In the campus board trial, ANOVA revealed a tendency toward significance (p = 0.066). Post hoc analysis revealed that there was a significant (p = 0.002) and "large" (d = 1.55) increase in the total number of "slaps" in the BA group. No significant supplementation × group interaction was found in "hard" traverse and a significant interaction for mean changes in number of moves (p = 0.025) and in time to failure (p = 0.044) on an "easy" traverse. Post hoc analysis revealed that only the BA group significantly improved from baseline in number of moves (+9.5) and time to failure (+32 s). Effect sizes were d = 1.73 and d = 1.44, respectively.

CONCLUSIONS

Four weeks of BA supplementation can improve performance during continuous climbing lasting about 1 min and repeated bouts of upper body campus-like movements. However, it failed to enhance climbing of a shorter duration.

Proton magnetic resonance spectroscopy in skeletal muscle: Experts' consensus recommendations

1 H-MR spectroscopy of skeletal muscle provides insight into metabolism that is not available noninvasively by other methods. The recommendations given in this article are intended to guide those who have basic experience in general MRS to the special application of 1 H-MRS in skeletal muscle. The highly organized structure of skeletal muscle leads to effects that change spectral features far beyond simple peak heights, depending on the type and orientation of the muscle. Specific recommendations are given for the acquisition of three particular metabolites (intramyocellular lipids, carnosine and acetylcarnitine) and for preconditioning of experiments and instructions to study volunteers.

Kinetics of Muscle Carnosine Decay after β-Alanine Supplementation: A 16-wk Washout Study

PURPOSE

This study aimed to describe the kinetics of carnosine washout in human skeletal muscle over 16 wk.

METHODS

Carnosine washout kinetics were studied in 15 young, physically active omnivorous men randomly assigned to take 6.4 g·d-1 of β-alanine (n = 11) or placebo (n = 4) for 8 wk. Muscle carnosine content (M-Carn) was determined before (PRE), immediately after (POST), and 4, 8, 12, and 16 wk after supplementation. High-intensity exercise tests were performed at these same time points. Linear and exponential models were fitted to the washout data, and the leave-one-out method was used to select the model with the best fit for M-Carn decay data. Repeated-measures correlation analysis was used to assess the association between changes in M-Carn and changes in performance.

RESULTS

M-Carn increased from PRE to POST in the β-alanine group only (+91.1% ± 29.1%; placebo, +0.04% ± 10.1%; P < 0.0001). M-Carn started to decrease after cessation of β-alanine supplementation and continued to decrease until week 16 (POST4, +59% ± 40%; POST8, +35% ± 39%; POST12, +18% ± 32%; POST16, -3% ± 24% of PRE M-Carn). From week 12 onward, M-Carn was no longer statistically different from PRE. Both linear and exponential models displayed very similar fit and could be used to describe carnosine washout, although the linear model presented a slightly better fit. The decay in M-Carn was mirrored by a similar decay in high-intensity exercise tolerance; M-Carn was moderately and significantly correlated with total mechanical work done (r = 0.505; P = 0.032) and time to exhaustion (r = 0.72; P < 0.001).

CONCLUSIONS

Carnosine washout takes 12-16 wk to complete, and it can be described either by linear or exponential curves. Changes in M-Carn seem to be mirrored by changes in high-intensity exercise tolerance. This information can be used to optimize β-alanine supplementation strategies.

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.

Ergogenic effect of pre-exercise chicken broth ingestion on a high-intensity cycling time-trial

Background

chicken meat extract is a popular functional food in Asia. It is rich in the bioactive compounds carnosine and anserine, two histidine-containing dipeptides (HCD). Studies suggest that acute pre-exercise ingestion of chicken extracts has important applications towards exercise performance and fatigue control, but the evidence is equivocal. This study aimed to evaluate the ergogenic potential of the pre-exercise ingestion of a homemade chicken broth (CB) vs a placebo soup on a short-lasting, high-intensity cycling exercise.

Methods

fourteen men participated in this double-blind, placebo-controlled, crossover intervention study. Subjects ingested either CB, thereby receiving 46.4 mg/kg body weight of HCD, or a placebo soup (similar in taste without HCD) 40 min before an 8 min cycling time trial (TT) was performed. Venous blood samples were collected at arrival (fasted), before exercise and at 5 min recovery. Plasma HCD were measured with UPLC-MS/MS and glutathione (in red blood cells) was measured through HPLC. Capillary blood samples were collected at different timepoints before and after exercise.

Results

a significant improvement (p = 0.033; 5.2%) of the 8 min TT mean power was observed after CB supplementation compared to placebo. Post-exercise plasma carnosine (p <  0.05) and anserine (p <  0.001) was significantly increased after CB supplementation and not following placebo. No significant effect of CB supplementation was observed either on blood glutathione levels, nor on capillary blood analysis.

Conclusions

oral CB supplementation improved the 8 min TT performance albeit it did not affect the acid-base balance or oxidative status parameters. Further research should unravel the potential role and mechanisms of HCD, present in CB, in this ergogenic approach.

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.

Effects of Pre-Workout Multi-Ingredient Supplement on Anaerobic Performance: Randomized Double-Blind Crossover Study

BACKGROUND

The purpose of this research was to investigate the acute effects of a pre-workout supplement on anaerobic performance in resistance-trained men.

METHODS

Twenty-three men underwent three randomized, double-blind testing sessions separated by a seven-day break. The participants performed three tests: isokinetic strength, three repetition maximum (3-RM) strength and Wingate. Statistical analysis was conducted in R environment. Linear mixed models were estimated via R package lme4.

RESULTS

Mean T@0.2 s was significantly greater in supplemented condition for right and left knee flexors (PL: 103.2 ± 37.6 Nm; supplemented condition: 131.8 ± 29.3 Nm (p = 0.001)), and PL: 103.7 ± 39.3; supplemented condition: 129.4 ± 28.4 (p = 0.001)). T@0.2 s for right and left knee extensors (PL: 202.6 ± 58.6 Nm; supplemented condition: 237.2 ± 54.7 Nm (p = 0.001); PL: 203.3 ± 63.2 Nm, supplemented condition: 229.8 ± 50.8 Nm (p = 0.002)). Significant difference was in mean anaerobic power between supplemented and PL condition for right and left knee flexors (p = 0.002, p = 0.005) and for right and left knee extensors (p = 0.001 and p = 0.002). TTP was significantly shorter in supplemented condition for both sides knee flexors (p = 0.002). There was a significant difference for mean power in the Wingate test (placebo: 8.5 ± 0.6 W/kg; supplemented condition: 8.7 ± 0.5 W/kg (p = 0.038)). Mean 3-RM was significantly greater in supplemented condition (p = 0.001).

CONCLUSIONS

The supplement significantly improves upper and lower body strength and power output in resistance-trained men.