The effects of beta-alanine supplementation and high-intensity interval training on neuromuscular fatigue and muscle function

Carbohydrate ingestion eliminates hypoglycemia and improves endurance exercise performance in triathletes adapted to very low- and high-carbohydrate isocaloric diets

Very-low-carbohydrate diets (LCHF; <50 g/day) have been debated for their potential to lower pre-exercise muscle and liver glycogen stores and metabolic efficiency, risking premature fatigue. It is also hypothesized that carbohydrate ingestion during prolonged exercise delays fatigue by increasing carbohydrate oxidation, thereby sparing muscle glycogen. Leveraging a randomized crossover design, we evaluated performance during strenuous time-to-exhaustion (70% V̇o2max) tests in trained triathletes following 6-wk high-carbohydrate (HCLF, 380 g/day) or very-low-carbohydrate (LCHF, 40 g/day) diets to determine 1) if adoption of the LCHF diet impairs time-to-exhaustion performance, 2) whether carbohydrate ingestion (10 g/h) 6-12× lower than current CHO fueling recommendations during low glycogen availability (>15-h pre-exercise overnight fast and/or LCHF diet) improves time to exhaustion by preventing exercise-induced hypoglycemia (EIH; <3.9 mmol/L; <70 mg/dL), and 3) the "keto-adaptation" time course through continuous substrate monitoring while caloric intake, physical activity, and fat-free mass are maintained. Time-to-exhaustion performance was similar across both dietary interventions. Minimal carbohydrate supplementation prevented EIH and significantly increased time to exhaustion equivalently in LCHF and HCLF interventions (22%). The LCHF diet significantly lowered 24-h glucose concentrations, which normalized after 4 wk, at the same timepoint peak blood ketone (R-β-hydroxybutyrate) concentrations normalized. These findings 1) demonstrate that an LCHF diet sustains strenuous endurance performance, 2) establish that minimal carbohydrate supplementation was sufficient to enhance exercise performance on LCHF and HCLF diets by mitigating EIH, and 3) indicate that a minimum 4-wk adaptation period to an LCHF diet is required to ensure normalization of metabolic homeostasis, glycemic control, and exercise performance.NEW & NOTEWORTHY This study examines the belief that very-low-carbohydrate diets (LCHF) impair prolonged exercise performance during strenuous exercise by comparing it with high-carbohydrate diets in competitive triathletes. After 6-wk diet adaptation, time-to-exhaustion (TTE) performance was similar across both diets. Minimal carbohydrate supplementation (10 g/h) during exercise eliminated exercise-induced hypoglycemia and improved TTE by 22% on both diets. These findings suggest that LCHF diets do not impair exercise performance and require a 4-wk adaptation period for metabolic homeostasis.

The Top 5 Can't-Miss Sport Supplements

Background/Objectives: Sports supplements have become popular among fitness enthusiasts for enhancing the adaptive response to exercise. This review analyzes five of the most effective ergogenic aids: creatine, beta-alanine, nitrates, caffeine, and protein. Methods: We conducted a narrative review of the literature with a focus on the sport supplements with the most robust evidence for efficacy and safety. Results: Creatine, one of the most studied ergogenic aids, increases phosphocreatine stores in skeletal muscles, improving ATP production during high-intensity exercises like sprinting and weightlifting. Studies show creatine supplementation enhances skeletal muscle mass, strength/power, and muscular endurance. The typical dosage is 3-5 g per day and is safe for long-term use. Beta-alanine, when combined with the amino acid histidine, elevates intramuscular carnosine, which acts as a buffer in skeletal muscles and delays fatigue during high-intensity exercise by neutralizing hydrogen ions. Individuals usually take 2-6 g daily in divided doses to minimize paresthesia. Research shows significant performance improvements in activities lasting 1-4 min. Nitrates, found in beetroot juice, enhance aerobic performance by increasing oxygen delivery to muscles, enhancing endurance, and reducing oxygen cost during exercise. The recommended dosage is approximately 500 milligrams taken 2-3 h before exercise. Caffeine, a central nervous system stimulant, reduces perceived pain while enhancing focus and alertness. Effective doses range from 3 to 6 milligrams per kilogram of body weight, typically consumed an hour before exercise. Protein supplementation supports muscle repair, growth, and recovery, especially after resistance training. The recommended intake for exercise-trained men and women varies depending on their specific goals. Concluions: In summary, creatine, beta-alanine, nitrates, caffeine, and protein are the best ergogenic aids, with strong evidence supporting their efficacy and safety.

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.

Enhanced production of β-alanine through co-expressing two different subtypes of L-aspartate-α-decarboxylase

β-Alanine (β-Ala) is an important intermediate with numerous applications in food and feed additives, pharmaceuticals, polymeric materials, and electroplating industries. Its biological production routes that employ L-aspartate-α-decarboxylase (ADC) as the key enzyme are attractive. In this study, we developed an efficient and environmentally safe method for β-Ala production by co-expressing two different subtypes of ADC. A bacterial ADC from Bacillus subtilis (BSADC) and an insect ADC from Tribolium castaneum (TCADC) use pyruvoyl and pyridoxal-5'-phosphate (PLP) as cofactor, respectively. 3050 mM (271.5 g/L) β-Ala was achieved from L-aspartic acid by using the whole-cell biocatalyst co-expressing BSADC and TCADC, corresponding to a conversion rate of 92.4%. Meanwhile, one-pot synthesis of β-Ala from fumaric acid through using a tri-enzyme cascade route with two different subtypes of ADC and L-aspartase (AspA) from Escherichia coli was established. 2250 mM (200.3 g/L) β-Ala was obtained from fumaric acid with a conversion rate of 90.0%. This work proposes a novel strategy that improves β-Ala production in the decarboxylation pathway of L-aspartic acid.

Nutrition and Altitude: Strategies to Enhance Adaptation, Improve Performance and Maintain Health: A Narrative Review

Training at low to moderate altitudes (~ 1600-2400 m) is a common approach used by endurance athletes to provide a distinctive environmental stressor to augment training stimulus in the anticipation of increasing subsequent altitude- and sea-level-based performance. Despite some scientific progress being made on the impact of various nutrition-related changes in physiology and associated interventions at mountaineering altitudes (> 3000 m), the impact of nutrition and/or supplements on further optimization of these hypoxic adaptations at low-moderate altitudes is only an emerging topic. Within this narrative review we have highlighted six major themes involving nutrition: altered energy availability, iron, carbohydrate, hydration, antioxidant requirements and various performance supplements. Of these issues, emerging data suggest that particular attention be given to the potential risk for poor energy availability and increased iron requirements at the altitudes typical of elite athlete training (~ 1600-2400 m) to interfere with optimal adaptations. Furthermore, the safest way to address the possible increase in oxidative stress associated with altitude exposure is via the consumption of antioxidant-rich foods rather than high-dose antioxidant supplements. Meanwhile, many other important questions regarding nutrition and altitude training remain to be answered. At the elite level of sport where the differences between winning and losing are incredibly small, the strategic use of nutritional interventions to enhance the adaptations to altitude training provides an important consideration in the search for optimal performance.

Acute citrulline-malate supplementation is ineffective during aerobic cycling and subsequent anaerobic performance in recreationally active males

Citrulline-malate (CM) purportedly increases exercise performance through increased nitric oxide production. The effects of CM on muscular strength performance are well-documented; however, the benefits of CM on aerobic and anaerobic biking performance are not well researched. Therefore, the present investigation examined the acute CM supplementation effects on aerobic and anaerobic cycling performance in recreationally active males. Methods: 28 recreationally active males (20.9 ± 2.8 years) completed randomized, double-blind, crossover trials consuming CM (12g dextrose + 8g CM) or a placebo (12g dextrose). Participants performed an aerobic cycling protocol (time-to-exhaustion [TTE]), followed by a subsequent 30-second Wingate cycling test, 60-minutes after supplement consumption. Results: Dependent t-tests showed no significant differences (p > 0.05) for TTE (PLA: 315.4 s ± 137.7 s; CM: 314.1 s ± 107.1 s) and Total Work Completed (TWC) (PLA: 74.7 ± 34.1 kilojoules (kJ); CM: 74.1 ± 26.4 kJ) during the aerobic cycling protocol. Dependent t-tests also showed no significant differences (p > 0.05) for mean watts (PLA: 586.1 ± 87.7 Watts (W); CM: 588.0 ± 93.0 W), peak watts (PLA: 773.0 ± 136.7 W; CM: 786.7 ± 133.0 W), and fatigue index (PLA: 12.9 ± 6.4 FI; CM: 14.3 ± 7.2 FI) during the Wingate protocol. Repeated-measures ANOVA results indicated a significant effect between each 5 s interval (p < 0.001), but no differences were observed between trials (p > 0.05). Conclusion: Acute CM supplementation in recreationally active males provides no ergogenic benefit in aerobic cycling performance followed by an anaerobic cycling test.

A Pilot Study to Examine the Impact of Beta-Alanine Supplementation on Anaerobic Exercise Performance in Collegiate Rugby Athletes

Beta-alanine (BA) is a precursor to carnosine which functions as a buffer assisting in the maintenance of intracellular pH during high-intensity efforts. Rugby is a sport characterized by multiple intermittent periods of maximal or near maximal efforts with short periods of rest/active recovery. The purpose of this pilot study was to evaluate the impact of six weeks of beta-alanine supplementation on anaerobic performance measures in collegiate rugby players. Twenty-one male, collegiate rugby players were recruited, while fifteen completed post-testing (Mean ± SD; Age: 21.0 ± 1.8 years, Height: 179 ± 6.3 cm, Body Mass: 91.8 ± 13.3 kg, % Body Fat: 21.3 ± 4.4). Supplementation was randomized in a double-blind, placebo-controlled manner between 6.4 g/d of beta-alanine and 6.4 g/d of maltodextrin placebo. Body composition, upper and lower-body maximal strength and muscular endurance, intermittent sprint performance, and post-exercise lactate, heart rate, and rating of perceived exertion were assessed before and after supplementation. Data were analyzed using a 2 × 2 (group × time) mixed factorial analysis of variance (ANOVA) with repeated measures on time. No significant interaction effects were noted for body mass, fat mass, fat-free mass, and percent bodyfat (p > 0.05). No performance effects resulting from beta-alanine supplementation were detected. Results from this initial pilot investigation suggest that BA exerts little to no impact on body composition parameters, muscular strength, muscular endurance, or intermittent sprinting performance. With the limited research exploring the impact of BA in this sporting context, these initial findings offer little support for BA use, but more research is needed to fully understand the potential impact of BA on various aspects of resistance exercise performance.

Neuromuscular adaptations to sixteen weeks of whole-body high-intensity interval training compared to ergometer-based interval and continuous training

The neuromuscular adaptations between ergometer-based high-intensity interval training (HIIT-T; n = 15), whole-body high-intensity interval training (HIIT-WB; n = 12) and moderate-intensity continuous training (MICT; n = 14) were compared in forty-one healthy men randomized to 16 weeks of training (3x per week). Two-way repeated measures analysis of variance (ANOVA) showed countermovement (CMJ) and squat (SJ) jump height (HIIT-T: 8.5 ± 13.3%; 3.1 ± 9.7%, HIIT-WB: 6.4 ± 9.8%, 10.4 ± 16.1% and MICT: 2.2 ± 9.5%; 4.4 ± 12.1%, respectively), SJ peak power (HIIT-T: 1.7 ± 3.9%; HIIT-WB : 6.4 ± 7.9%; MICT: 0.5 ± 6.5%) and CMJ rate of force development (HIIT-T: 58.1 ± 50.5%; HIIT-WB: 36.9 ± 54.2%; MICT: 38.4 ± 64.3%) improved similarly in all training groups (all p < 0.05). CMJ peak power increased only after HIIT-T (4.3 ± 5.5%) and HIIT-WB (4.5 ± 5.2%), while no differences were observed in both the rectus femoris and vastus lateralis maximal electromyographic amplitude. Finally, marked improvements were also observed in the number of repetitions in the HIIT-WB protocol at the eighth week, with no further improvement at the sixteenth week. These data suggest that 16 weeks of HIIT-WB is capable to improve neuromuscular function to a similar extent as HIIT-T and MICT.

Creatine supplementation can improve impact control in high-intensity interval training

OBJECTIVES

This study aimed to investigate the effects of creatine (Cr) supplementation on biomechanical parameters related to shock attenuation during a session of high-intensity interval training (HIIT).

METHODS

A single-blinded, placebo-controlled, crossover design was adopted to test eight male elite soccer players during HIIT sessions under two conditions: after placebo supplementation and after Cr supplementation. HIIT test sessions consisted of an intermittent test (five bouts of running) with a constant load applied until exhaustion was reached. The vertical component of ground reaction force and electromyography data were recorded by Gaitway and Lynx-EMG Systems, respectively. Heart rate, rated perceived exertion (Borg's Scale) and lactate concentration information were also obtained.

RESULTS

Cr supplementation did not affect heart rate, rated perceived exertion, and lactate concentration. Decreased values of magnitude of the first peak of the vertical component of ground reaction force (17.2-24.2%) and impulse of the first 50 ms (Imp50; 34.3%) were observed for Cr, but higher values of time to reach the first peak were detected for Cr compared with placebo. Significant modifications in muscle activation were also observed, mainly in the pre-activation phase, and changes were observed in intermediary bouts.

CONCLUSIONS

Cr supplementation has the potential to influence biomechanical parameters related to impact control during a single session of HIIT based on running. In particular, the findings of the current study indicate possible improvements in shock attenuation and a safer practice of HIIT under Cr supplementation.

Examining work-to-rest ratios to optimize upper body sprint interval training

The objective was to compare the metabolic influence of varying work-to-rest ratios during upper body sprint interval training (SIT). Forty-two recreationally-trained men were randomized into a training group [10 s work - 2 min of rest (10:2) or 4 min of rest (10:4), or 30 s work - 4 min of rest (30:4)] or a control group (CON). Participants underwent six training sessions over two weeks. Assessments consisted of a graded exercise test [maximal oxygen consumption (VO₂peak) and peak power output (PPO)], four constant-work rate trials [critical power, anaerobic working capacity, and electromyographic fatigue threshold], and an upper body Wingate test (mean/peak power and total work). Post-training absolute and relative VO₂peak was greater than pre-training for 30:4 (p = .005 and p = .009, respectively), but lower for CON (p = .001 and p = .006, respectively). Post-training PPO was greater in 30:4 (p < .001). No differences were observed during the constant-work rate trials or Wingate test. Traditional SIT appears to have enhanced VO₂peak in the upper body over a short-term two-week intervention.

Examination of a Multi-ingredient Preworkout Supplement on Total Volume of Resistance Exercise and Subsequent Strength and Power Performance

Bergstrom, HC, Byrd, MT, Wallace, BJ, and Clasey, JL. Examination of a multi-ingredient preworkout supplement on total volume of resistance exercise and subsequent strength and power performance. J Strength Cond Res 32(6): 1479-1490, 2018-This study examined the acute effects of a multi-ingredient preworkout supplement on (a) total-, lower-, and upper-body volume of resistance exercise and (b) the subsequent lower-body strength (isokinetic leg extension and flexion), lower-body power (vertical jump [VJ] height), upper-body power (bench throw velocity [BTv]), and cycle ergometry performance (critical power and anaerobic work capacity). Twelve men completed baseline strength and power measures before 2 experimental visits, supplement (SUP) and placebo (PL). The experimental visits involved a fatiguing cycling protocol 30 minutes after ingestion of the SUP or PL and 15 minutes before the beginning of the resistance exercise protocol, which consisted of 4 upper-body and 4 lower-body resistance exercises performed for 4 sets to failure at 75% 1 repetition maximum. The exercise volume for the total, lower, and upper body was assessed. The VJ height and BTv were measured immediately after the resistance exercise. Postexercise isokinetic leg extension and flexion strength was measured 15 minutes after the completion of a second cycling protocol. There was a 9% increase in the total-body volume of exercise and a 14% increase in lower-body volume of exercise for the SUP compared with the PL, with no effect on exercise volume for the upper body between the SUP and PL. The increased lower-body volume for the SUP did not result in greater lower-body strength and power performance decrements after exhaustive exercise, compared with the PL. These findings suggested the potential for the SUP to increase resistance exercise volume, primarily related to an increased lower-body volume of exercise.

ISSN exercise & sports nutrition review update: research & recommendations

Background

Sports nutrition is a constantly evolving field with hundreds of research papers published annually. In the year 2017 alone, 2082 articles were published under the key words ‘sport nutrition’. Consequently, staying current with the relevant literature is often difficult.

Methods

This paper is an ongoing update of the sports nutrition review article originally published as the lead paper to launch the Journal of the International Society of Sports Nutrition in 2004 and updated in 2010. It presents a well-referenced overview of the current state of the science related to optimization of training and performance enhancement through exercise training and nutrition. Notably, due to the accelerated pace and size at which the literature base in this research area grows, the topics discussed will focus on muscle hypertrophy and performance enhancement. As such, this paper provides an overview of: 1.) How ergogenic aids and dietary supplements are defined in terms of governmental regulation and oversight; 2.) How dietary supplements are legally regulated in the United States; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of nutritional approaches to augment skeletal muscle hypertrophy and the potential ergogenic value of various dietary and supplemental approaches.

Conclusions

This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.

Post-Game High Protein Intake May Improve Recovery of Football-Specific Performance during a Congested Game Fixture: Results from the PRO-FOOTBALL Study

The effects of protein supplementation on performance recovery and inflammatory responses during a simulated one-week in-season microcycle with two games (G1, G2) performed three days apart were examined. Twenty football players participated in two trials, receiving either milk protein concentrate (1.15 and 0.26 g/kg on game and training days, respectively) (PRO) or an energy-matched placebo (1.37 and 0.31 g/kg of carbohydrate on game and training days, respectively) (PLA) according to a randomized, repeated-measures, crossover, double-blind design. Each trial included two games and four daily practices. Speed, jump height, isokinetic peak torque, and muscle soreness of knee flexors (KF) and extensors (KE) were measured before G1 and daily thereafter for six days. Blood was drawn before G1 and daily thereafter. Football-specific locomotor activity and heart rate were monitored using GPS technology during games and practices. The two games resulted in reduced speed (by 3–17%), strength of knee flexors (by 12–23%), and jumping performance (by 3–10%) throughout recovery, in both trials. Average heart rate and total distance covered during games remained unchanged in PRO but not in PLA. Moreover, PRO resulted in a change of smaller magnitude in high-intensity running at the end of G2 (75–90 min vs. 0–15 min) compared to PLA (P = 0.012). KE concentric strength demonstrated a more prolonged decline in PLA (days 1 and 2 after G1, P = 0.014–0.018; days 1, 2 and 3 after G2, P = 0.016–0.037) compared to PRO (days 1 after G1, P = 0.013; days 1 and 2 after G2, P = 0.014–0.033) following both games. KF eccentric strength decreased throughout recovery after G1 (PLA: P=0.001–0.047—PRO: P =0.004–0.22) in both trials, whereas after G2 it declined throughout recovery in PLA (P = 0.000–0.013) but only during the first two days (P = 0.000–0.014) in PRO. No treatment effect was observed for delayed onset of muscle soreness, leukocyte counts, and creatine kinase activity. PRO resulted in a faster recovery of protein and lipid peroxidation markers after both games. Reduced glutathione demonstrated a more short-lived reduction after G2 in PRO compared to PLA. In summary, these results provide evidence that protein feeding may more efficiently restore football-specific performance and strength and provide antioxidant protection during a congested game fixture.

A novel method for muscle fatigue assessment during robot-based tracking tasks

In this work we propose a novel method based on sEMG signals, easy and fast to perform, administered with a robotic device to maximize repeatability and objectivity. Muscle fatigue, which is frequently experienced by healthy subjects, can be a highly debilitating symptom in case of neuromuscular disorders. Its assessment provides crucial information on the progression of the disability itself, on patient's muscular function and on the efficacy of the eventual clinical intervention. Hence, a robust and objective protocol for fatigue assessment is fundamental in rehabilitation practice. Therefore, the aim of this work was twofold. Firstly, we aimed to test the proposed method and highlight its strengths and drawbacks for a future optimization and implementation in a clinical context. Secondly, we meant to identify which are the most sensitive and reliable measures of muscles' performance that can quickly and optimally predict subjects' behavior. sEMG signals were collected from right Extensor and Flexor Carpi Radialis of 9 healthy subjects during a flexion-extension robotic task consisting in a haptic tracking in a viscous field. Three indicators of fatigue (Mean Frequency, Dimitrov Index, Root Mean Square) were obtained and we proposed a novel sensitive parameter which determines the Onset of Fatigue.

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.

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.

Effects of 4 Weeks of High-Intensity Interval Training and β-Hydroxy-β-Methylbutyric Free Acid Supplementation on the Onset of Neuromuscular Fatigue

This study investigated the effects of high-intensity interval training (HIIT) and β-hydroxy-β-methylbutyric free acid (HMB) supplementation on physical working capacity at the onset of neuromuscular fatigue threshold (PWC(FT)). Thirty-seven participants (22 men, 15 women; 22.8 ± 3.4 years) completed an incremental cycle ergometer test (graded exercise test [GXT]); electromyographic amplitude from the right vastus lateralis was recorded. Assessments occurred preceding (PRE) and after 4 weeks of supplementation (POST). Participants were randomly assigned to control (C, n = 9), placebo (P, n = 14), or supplementation (S, n = 14) groups. Both P and S completed 12 HIIT sessions, whereas C maintained normal diet and activity patterns. The PWC(FT) (W) was determined using the maximal perpendicular distance (D(MAX)) method. Electromyographic amplitude (μVrms) over time was used to generate a cubic regression. Onset of fatigue (TF) was the x-value of the point on the regression that was at D(MAX) from a line between the first and last data points. The PWC(FT) was estimated using TF and GXT power-output increments. The 2-way analysis of variance (ANOVA) (group × time) resulted in a significant interaction for PWC(FT) (F = 6.69, p = 0.004). Post hoc analysis with 1-way ANOVA resulted in no difference in PWC(FT) among groups at PRE (F = 0.87, p = 0.43); however, a difference in PWC(FT) was shown for POST (F = 5.46, p = 0.009). Post hoc analysis among POST values revealed significant differences between S and both P (p = 0.034) and C (p = 0.003). No differences (p = 0.226) were noted between P and C. Paired samples t-tests detected significant changes after HIIT for S (p < 0.001) and P (p = 0.016), but no change in C (p = 0.473). High-intensity interval training increased PWC(FT), but HMB with HIIT was more effective than HIIT alone. Furthermore, it seems that adding HMB supplementation with HIIT in untrained men and women may further improve endurance performance measures.

International society of sports nutrition position stand: Beta-Alanine

The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of beta-alanine supplementation. Based on the current available literature, the conclusions of the ISSN are as follows: 1) Four weeks of beta-alanine supplementation (4-6 g daily) significantly augments muscle carnosine concentrations, thereby acting as an intracellular pH buffer; 2) Beta-alanine supplementation currently appears to be safe in healthy populations at recommended doses; 3) The only reported side effect is paraesthesia (tingling), but studies indicate this can be attenuated by using divided lower doses (1.6 g) or using a sustained-release formula; 4) Daily supplementation with 4 to 6 g of beta-alanine for at least 2 to 4 weeks has been shown to improve exercise performance, with more pronounced effects in open end-point tasks/time trials lasting 1 to 4 min in duration; 5) Beta-alanine attenuates neuromuscular fatigue, particularly in older subjects, and preliminary evidence indicates that beta-alanine may improve tactical performance; 6) Combining beta-alanine with other single or multi-ingredient supplements may be advantageous when supplementation of beta-alanine is high enough (4-6 g daily) and long enough (minimum 4 weeks); 7) More research is needed to determine the effects of beta-alanine on strength, endurance performance beyond 25 min in duration, and other health-related benefits associated with carnosine.

β-Alanine supplementation for athletic performance: an update

β-alanine supplementation has become a common practice among competitive athletes participating in a range of different sports. Although the mechanism by which chronic β-alanine supplementation could have an ergogenic effect is widely debated, the popular view is that β-alanine supplementation augments intramuscular carnosine content, leading to an increase in muscle buffer capacity, a delay in the onset of muscular fatigue, and a facilitated recovery during repeated bouts of high-intensity exercise. β-alanine supplementation appears to be most effective for exercise tasks that rely heavily on ATP synthesis from anaerobic glycolysis. However, research investigating its efficacy as an ergogenic aid remains equivocal, making it difficult to draw conclusions as to its effectiveness for training and competition. The aim of this review was to update, summarize, and critically evaluate the findings associated with β-alanine supplementation and exercise performance with the most recent research available to allow the development of practical recommendations for coaches and athletes. A critical review of the literature reveals that when significant ergogenic effects have been found, they have been generally shown in untrained individuals performing exercise bouts under laboratory conditions. The body of scientific data available concerning highly trained athletes performing single competition-like exercise tasks indicates that this type of population receives modest but potentially worthwhile performance benefits from β-alanine supplementation. Recent data indicate that athletes may not only be using β-alanine supplementation to enhance sports performance but also as a training aid to augment bouts of high-intensity training. β-alanine supplementation has also been shown to increase resistance training performance and training volume in team-sport athletes, which may allow for greater overload and superior adaptations compared with training alone. The ergogenic potential of β-alanine supplementation for elite athletes performing repeated high-intensity exercise bouts, either during training or during competition in sports which require repeated maximal efforts (e.g., rugby and soccer), needs scientific confirmation.

Effects of 28 days of beta-alanine and creatine supplementation on muscle carnosine, body composition and exercise performance in recreationally active females

BACKGROUND

The purpose of this study was to examine the short-term and chronic effects of β-ALA supplementation with and without creatine monohydrate on body composition, aerobic and anaerobic exercise performance, and muscle carnosine and creatine levels in college-aged recreationally active females.

METHODS

Thirty-two females were randomized in a double-blind, placebo-controlled manner into one of four supplementation groups: β-ALA only (BA, n = 8), creatine only (CRE, n = 8), β-ALA and creatine combined (BAC, n = 9) and placebo (PLA, n = 7). Participants supplemented for four weeks included a loading phase for the creatine for week 1 of 0.3 g/kg of body weight and a maintenance phase for weeks 2-4 of 0.1 g/kg of body weight, with or without a continuous dose of β-ALA of 0.1 g/kg of body weight with doses rounded to the nearest 800 mg capsule providing an average of 6.1 ± 0.7 g/day of β-ALA. Participants reported for testing at baseline, day 7 and day 28. Testing sessions consisted of obtaining a resting muscle biopsy of the vastus lateralis, body composition measurements, performing a graded exercise test on the cycle ergometer for VO2peak with lactate threshold determination, and multiple Wingate anaerobic capacity tests.

RESULTS

Although mean changes were consistent with prior studies and large effect sizes were noted, no significant differences were observed among groups in changes in muscle carnosine levels (BA 35.3 ± 45; BAC 42.5 ± 99; CRE 0.72 ± 27; PLA 13.9 ± 44%, p = 0.59). Similarly, although changes in muscle phosphagen levels after one week of supplementation were consistent with prior reports and large effect sizes were seen, no statistically significant effects were observed among groups in changes in muscle phosphagen levels and the impact of CRE supplementation appeared to diminish during the maintenance phase. Additionally, significant time × group × Wingate interactions were observed among groups for repeated sprint peak power normalized to bodyweight (p = 0.02) and rate of fatigue (p = 0.04).

CONCLUSIONS

Results of the present study did not reveal any consistent additive benefits of BA and CRE supplementation in recreationally active women.

Evidence-based evaluation of potential benefits and safety of beta-alanine supplementation for military personnel

This Department of Defense-sponsored evidence-based review evaluates the safety and putative outcomes of enhancement of athletic performance or improved recovery from exhaustion in studies involving beta-alanine alone or in combination with other ingredients. Beta-alanine intervention studies and review articles were collected from 13 databases, and safety information was collected from adverse event reporting portals. Due to the lack of systematic studies involving military populations, all the available literature was assessed with a subgroup analysis of studies on athletes to determine if beta-alanine would be suitable for the military. Available literature provided only limited evidence concerning the benefits of beta-alanine use, and a majority of the studies were not designed to address safety. Overall, the strength of evidence in terms of the potential for risk of bias in the quality of the available literature, consistency, directness, and precision did not support the use of beta-alanine by military personnel. The strength of evidence for a causal relation between beta-alanine and paresthesia was moderate.

The role and effects of carnosine and β-alanine on exercise: an updated mini review

Purpose

– The paper aims to describe the role and effects of carnosine and β-alanine on exercise.

Design/methodology/approach

– The review includes the most updated studies found in Pub-Med all of which are in relation to carnosine and β-alanine on exercise performance.

Findings

– The use of β-alanine in recent research has shown to increase muscle carnosine concentrations in as short as two weeks, with increasing levels with longer supplementation periods. Although there is strong support that β-alanine supplementation during training possesses ergogenic value, the specific mechanism of action and ergogenic value remains to be fully examined.

Originality/value

– The paper gives information to nutritionists, clinical dietitians and sports nutritionists on the newest data about the role and effects of carnosine and β-alanine on exercise performance.

Carnosine: from exercise performance to health

Carnosine was first discovered in skeletal muscle, where its concentration is higher than in any other tissue. This, along with an understanding of its role as an intracellular pH buffer has made it a dipeptide of interest for the athletic population with its potential to increase high-intensity exercise performance and capacity. The ability to increase muscle carnosine levels via β-alanine supplementation has spawned a new area of research into its use as an ergogenic aid. The current evidence base relating to the use of β-alanine as an ergogenic aid is reviewed here, alongside our current thoughts on the potential mechanism(s) to support any effect. There is also some emerging evidence for a potential therapeutic role for carnosine, with this potential being, at least theoretically, shown in ageing, neurological diseases, diabetes and cancer. The currently available evidence to support this potential therapeutic role is also reviewed here, as are the potential limitations of its use for these purposes, which mainly focusses on issues surrounding carnosine bioavailability.

International Society of Sports Nutrition position stand: energy drinks

Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on a critical analysis of the literature on the safety and efficacy of the use of energy drinks (ED) or energy shots (ES). The ISSN has concluded the following. 1. Although ED and ES contain a number of nutrients that are purported to affect mental and/or physical performance, the primary ergogenic nutrients in most ED and ES appear to be carbohydrate and/or caffeine. 2. The ergogenic value of caffeine on mental and physical performance has been well-established but the potential additive benefits of other nutrients contained in ED and ES remains to be determined. 3. Consuming ED 10-60 minutes before exercise can improve mental focus, alertness, anaerobic performance, and/or endurance performance. 4. Many ED and ES contain numerous ingredients; these products in particular merit further study to demonstrate their safety and potential effects on physical and mental performance. 5. There is some limited evidence that consumption of low-calorie ED during training and/or weight loss trials may provide ergogenic benefit and/or promote a small amount of additional fat loss. However, ingestion of higher calorie ED may promote weight gain if the energy intake from consumption of ED is not carefully considered as part of the total daily energy intake. 6. Athletes should consider the impact of ingesting high glycemic load carbohydrates on metabolic health, blood glucose and insulin levels, as well as the effects of caffeine and other stimulants on motor skill performance. 7. Children and adolescents should only consider use of ED or ES with parental approval after consideration of the amount of carbohydrate, caffeine, and other nutrients contained in the ED or ES and a thorough understanding of the potential side effects. 8. Indiscriminant use of ED or ES, especially if more than one serving per day is consumed, may lead to adverse events and harmful side effects. 9. Diabetics and individuals with pre-existing cardiovascular, metabolic, hepatorenal, and neurologic disease who are taking medications that may be affected by high glycemic load foods, caffeine, and/or other stimulants should avoid use of ED and/or ES unless approved by their physician.

Effects of β-alanine supplementation on exercise performance: a meta-analysis

Due to the well-defined role of β-alanine as a substrate of carnosine (a major contributor to H⁺ buffering during high-intensity exercise), β-alanine is fast becoming a popular ergogenic aid to sports performance. There have been several recent qualitative review articles published on the topic, and here we present a preliminary quantitative review of the literature through a meta-analysis. A comprehensive search of the literature was employed to identify all studies suitable for inclusion in the analysis; strict exclusion criteria were also applied. Fifteen published manuscripts were included in the analysis, which reported the results of 57 measures within 23 exercise tests, using 18 supplementation regimes and a total of 360 participants [174, β-alanine supplementation group (BA) and 186, placebo supplementation group (Pla)]. BA improved (P = 0.002) the outcome of exercise measures to a greater extent than Pla [median effect size (IQR): BA 0.374 (0.140–0.747), Pla 0.108 (−0.019 to 0.487)]. Some of that effect might be explained by the improvement (P = 0.013) in exercise capacity with BA compared to Pla; no improvement was seen for exercise performance (P = 0.204). In line with the purported mechanisms for an ergogenic effect of β-alanine supplementation, exercise lasting 60–240 s was improved (P = 0.001) in BA compared to Pla, as was exercise of >240 s (P = 0.046). In contrast, there was no benefit of β-alanine on exercise lasting <60 s (P = 0.312). The median effect of β-alanine supplementation is a 2.85% (−0.37 to 10.49%) improvement in the outcome of an exercise measure, when a median total of 179 g of β-alanine is supplemented.

The electromyographic fatigue threshold is not a valid tool to assess muscle function

The present study aimed at determining the electromyographic fatigue threshold (EMG(FT)) from the EMG activity level and the EMG frequency content of the First Dorsal Interosseous. Thirty-seven healthy subjects performed seven isometric index abductions at randomly ordered percentages of maximal voluntary contraction (i.e., 20%, 25%, 30%, 35%, 40%, 50% and 60%). During these bouts, surface EMG was measured using a linear electrodes array (i.e., seven EMG channels) in the First Dorsal Interosseous. For each subject the EMG(FT) was determined from both Root Mean Square (RMS) and Mean Power Frequency (MPF) values, only if the following criteria were met: (i) significant positive linear regression (P<0.05) between force and slope coefficient, (ii) an adjusted coefficient of determination for force versus slope coefficient relationship greater than 0.85, and (iii) a standard error for the EMG(FT) below 5% of MVC. The results showed the inability to determine an EMG(FT) in all of the 37 subjects from both RMS (9 out of 37 subjects) and MPF (27 out of 37 subjects). In addition, for the 12 subjects tested twice, the reproducibility of the EMG(FT) determination was weak (ICC=-0.029 and SEM=7.5% of MVC for EMG(FT) determined from MPF). The present results suggest that the EMG(FT) is not a valid tool to assess muscle function.

Role of beta-alanine supplementation on muscle carnosine and exercise performance

In this narrative review, we present and discuss the current knowledge available on carnosine and beta-alanine metabolism as well as the effects of beta-alanine supplementation on exercise performance. Intramuscular acidosis has been attributed to be one of the main causes of fatigue during intense exercise. Carnosine has been shown to play a significant role in muscle pH regulation. Carnosine is synthesized in skeletal muscle from the amino acids l-histidine and beta-alanine. The rate-limiting factor of carnosine synthesis is beta-alanine availability. Supplementation with beta-alanine has been shown to increase muscle carnosine content and therefore total muscle buffer capacity, with the potential to elicit improvements in physical performance during high-intensity exercise. Studies on beta-alanine supplementation and exercise performance have demonstrated improvements in performance during multiple bouts of high-intensity exercise and in single bouts of exercise lasting more than 60 s. Similarly, beta-alanine supplementation has been shown to delay the onset of neuromuscular fatigue. Although beta-alanine does not improve maximal strength or VO2max, some aspects of endurance performance, such as anaerobic threshold and time to exhaustion, can be enhanced. Symptoms of paresthesia may be observed if a single dose higher than 800 mg is ingested. The symptoms, however, are transient and related to the increase in plasma concentration. They can be prevented by using controlled release capsules and smaller dosing strategies. No important side effect was related to the use of this amino acid so far. In conclusion, beta-alanine supplementation seems to be a safe nutritional strategy capable of improving high-intensity anaerobic performance.

The effects of a pre-workout supplement containing caffeine, creatine, and amino acids during three weeks of high-intensity exercise on aerobic and anaerobic performance

Background

A randomized, single-blinded, placebo-controlled, parallel design study was used to examine the effects of a pre-workout supplement combined with three weeks of high-intensity interval training (HIIT) on aerobic and anaerobic running performance, training volume, and body composition.

Methods

Twenty-four moderately-trained recreational athletes (mean ± SD age = 21.1 ± 1.9 yrs; stature = 172.2 ± 8.7 cm; body mass = 66.2 ± 11.8 kg, VO₂max = 3.21 ± 0.85 l·min^-1, percent body fat = 19.0 ± 7.1%) were assigned to either the active supplement (GT, n = 13) or placebo (PL, n = 11) group. The active supplement (Game Time^®, Corr-Jensen Laboratories Inc., Aurora, CO) was 18 g of powder, 40 kcals, and consisted of a proprietary blend including whey protein, cordyceps sinensis, creatine, citrulline, ginseng, and caffeine. The PL was also 18 g of powder, 40 kcals, and consisted of only maltodextrin, natural and artificial flavors and colors. Thirty minutes prior to all testing and training sessions, participants consumed their respective supplements mixed with 8-10 oz of water. Both groups participated in a three-week HIIT program three days per week, and testing was conducted before and after the training. Cardiovascular fitness (VO₂max) was assessed using open circuit spirometry (Parvo-Medics TrueOne^® 2400 Metabolic Measurement System, Sandy, UT) during graded exercise tests on a treadmill (Woodway, Pro Series, Waukesha, WI). Also, four high-speed runs to exhaustion were conducted at 110, 105, 100, and 90% of the treadmill velocity recorded during VO₂max, and the distances achieved were plotted over the times-to-exhaustion. Linear regression was used to determine the slopes (critical velocity, CV) and y-intercepts (anaerobic running capacity, ARC) of these relationships to assess aerobic and anaerobic performances, respectively. Training volumes were tracked by summing the distances achieved during each training session for each subject. Percent body fat (%BF) and lean body mass (LBM) were assessed with air-displacement plethysmography (BOD POD^®, Life Measurement, Inc., Concord, CA).

Results

Both GT and PL groups demonstrated a significant (p = 0.028) increase in VO₂max from pre- to post-training resulting in a 10.3% and 2.9% improvement, respectively. CV increased (p = 0.036) for the GT group by 2.9%, while the PL group did not change (p = 0.256; 1.7% increase). ARC increased for the PL group by 22.9% and for the GT group by 10.6%. Training volume was 11.6% higher for the GT versus PL group (p = 0.041). %BF decreased from 19.3% to 16.1% for the GT group and decreased from 18.0% to 16.8% in the PL group (p = 0.178). LBM increased from 54.2 kg to 55.4 kg (p = 0.035) for the GT group and decreased from 52.9 kg to 52.4 kg in the PL group (p = 0.694).

Conclusion

These results demonstrated improvements in VO₂max, CV, and LBM when GT is combined with HIIT. Three weeks of HIIT alone also augmented anaerobic running performance, VO₂max and body composition.

Effects of beta-alanine on muscle carnosine and exercise performance: a review of the current literature

Muscle carnosine has been reported to serve as a physiological buffer, possess antioxidant properties, influence enzyme regulation, and affect sarcoplasmic reticulum calcium regulation. Beta-alanine (β-ALA) is a non-essential amino acid. β-ALA supplementation (e.g., 2-6 grams/day) has been shown to increase carnosine concentrations in skeletal muscle by 20-80%. Several studies have reported that β-ALA supplementation can increase high-intensity intermittent exercise performance and/or training adaptations. Although the specific mechanism remains to be determined, the ergogenicity of β-ALA has been most commonly attributed to an increased muscle buffering capacity. More recently, researchers have investigated the effects of co-ingesting β-ALA with creatine monohydrate to determine whether there may be synergistic and/or additive benefits. This paper overviews the theoretical rationale and potential ergogenic value of β-ALA supplementation with or without creatine as well as provides future research recommendations.

The effects of four weeks of creatine supplementation and high-intensity interval training on cardiorespiratory fitness: a randomized controlled trial

Background

High-intensity interval training has been shown to be a time-efficient way to induce physiological adaptations similar to those of traditional endurance training. Creatine supplementation may enhance high-intensity interval training, leading to even greater physiological adaptations. The purpose of this study was to determine the effects of high-intensity interval training (HIIT) and creatine supplementation on cardiorespiratory fitness and endurance performance (maximal oxygen consumption (VO_2PEAK), time-to-exhaustion (VO_2PEAKTTE), ventilatory threshold (VT), and total work done (TWD)) in college-aged men.

Methods

Forty-three recreationally active men completed a graded exercise test to determine VO_2PEAK, VO_2PEAKTTE, and VT. In addition, participants completed a time to exhaustion (TTE) ride at 110% of the maximum workload reached during the graded exercise test to determine TWD (TTE (sec) × W = J). Following testing, participants were randomly assigned to one of three groups: creatine (creatine citrate) (Cr; n = 16), placebo (PL; n = 17), or control (n = 10) groups. The Cr and PL groups completed four weeks of HIIT prior to post-testing.

Results

Significant improvements in VO_2PEAK and VO_2PEAKTTE occurred in both training groups. Only the Cr group significantly improved VT (16% vs. 10% improvement in PL). No changes occurred in TWD in any group.

Conclusion

In conclusion, HIIT is an effective and time-efficient way to improve maximal endurance performance. The addition of Cr improved VT, but did not increase TWD. Therefore, 10 g of Cr per day for five days per week for four weeks does not seem to further augment maximal oxygen consumption, greater than HIIT alone; however, Cr supplementation may improve submaximal exercise performance.

Can the electromyographic fatigue threshold be determined from superficial elbow flexor muscles during an isometric single-joint task?

The purpose of this study was to compare the electromyographic fatigue threshold (EMG(FT)) values determined simultaneously from superficial elbow flexor muscles during an isometric single-joint task. Eight subjects performed isometric elbow flexions at randomly ordered percentages of maximal voluntary contraction (20, 30, 40, 50 and 60%). During these bouts, electromyographic (EMG) activity was measured in the anterior head of Deltoïd, lateral head of Triceps brachii, Brachioradialis and both short and long head of Biceps brachii. For each subject and each muscle, the EMG amplitude data were plotted as function of time for the five submaximal bouts. The slope coefficient of the EMG amplitude versus time linear relationships were plotted against force level. EMG(FT) was determined as the y-intercept of this relationship and considered as valid only if the following criteria were met: (1) significant positive linear regression (P < 0.05) between force and slope coefficient, (2) an adjusted coefficient of determination for force versus slope coefficient relationship greater than 0.85, and (3) a standard error for the EMG(FT) below 5% of maximal voluntary contraction. The EMG(FT) could only be determined for one muscle (the long head of Biceps brachii) and only in three out of the eight subjects (mean value = 24.9 +/- 1.1% of maximal voluntary contraction). The lack of EMG(FT) in most of the subjects (5/8) could be explained by putative compensations between elbow muscles which were indirectly observed in some subjects. In this way, EMG(FT) should be studied from a more simple movement i.e., ideally a movement implying mainly one muscle.