Single-Session Cerebellar Transcranial Direct Current Stimulation Improves Postural Stability and Reduces Ataxia Symptoms in Spinocerebellar Ataxia.

Spinocerebellar ataxia (SCA) results in balance and coordination impairment, and current treatments have limited efficacy. Recent evidence suggests that combining postural training with cerebellar transcranial direct current stimulation (ctDCS) can improve these symptoms. However, the combined effects of ctDCS and postural training on individuals with spinocerebellar ataxia remain underexplored. Ten volunteers with (SCA type 3) participated in a triple-blind, randomized, crossover study to receive a single session of ctDCS (2 mA for 20 min) and a sham ctDCS session separated by at least one week. The Biodex Balance System was used to assess balance at each session, measuring overall stability index, anteroposterior stability index, and medial-lateral stability index. As secondary outcomes, cerebellar ataxia symptoms were evaluated using the 8-item Scale for Assessment and Rating of Ataxia. The assessments were conducted before and after each session. The results indicated that ctDCS enhanced the overall stability index when compared to sham ctDCS (Z = -2.10, p = 0.03), although it did not significantly affect the anteroposterior or medial-lateral stability indices. Compared to the baseline, a single session of ctDCS reduced appendicular symptoms related to cerebellar ataxia, as evidenced by improvements in the nose-finger test (Z = -2.07, p = 0.04), fast alternating hand movements (Z = -2.15, p = 0.03), and heel-to-shin slide (Z = -1.91, p = 0.05). In conclusion, our study suggests that a single session of ctDCS, in combination with postural training, can enhance balance and alleviate ataxia symptoms in individuals with cerebellar ataxia. This study was approved by the local research ethics committee (No. 2.877.813) and registered on clinicaltrials.org (NCT04039048 - https://www.clinicaltrials.gov/study/NCT04039048 ) on 2019-07-28.

Sodium bicarbonate improved CrossFit® Benchmark Fran, but not subsequent 500 m rowing performance.

The aim of this study was to evaluate the influence of sodium bicarbonate (SB) supplementation on physical performance, neuromuscular and metabolic responses during CrossFit® exercise. Seventeen Advanced CrossFit®-trained athletes completed the randomized, double-blind, placebo-controlled crossover protocol consisting of four visits, including two familiarization sessions and two experimental trials separated by a 7-day washout period. Participants supplemented 0.3 g/kg body mass (BM) of SB or placebo 120-min prior to performing the CrossFit® benchmark Fran followed by 500 m of rowing. SB improved time to complete Fran compared to PLA (291.2 ± 71.1 vs. 303.3 ± 77.8 s, p = 0.047), but not 500 m rowing (112.1 s ± 7.9 vs. 113.2 s ± 8.9 s, p = 0.26). No substantial side-effects were reported during the trials. This study showed that SB improved CrossFit® benchmark Fran performance, but not subsequent 500-m rowing. These data suggest that SB might be an interesting supplementation strategy for CrossFit® athletes.

How Cool is That? The Effects of Menthol Mouth Rinsing on Exercise Capacity and Performance: A Systematic Review and Meta-analysis.

BACKGROUND: Menthol (MEN) mouth rinsing (MR) has gained considerable interest in the athletic population for exercise performance; however, the overall magnitude of effect is unknown. OBJECTIVE: The aim of this systematic review and meta-analysis was to determine the efficacy of menthol MEN MR and the impact it has on exercise capacity and performance. METHODS: Three databases were searched with articles screened according to the inclusion/exclusion criteria. Three-level meta-analyses were used to investigate the overall efficacy of MEN MR and the impact it has on exercise capacity and performance. Meta-regressions were then performed with 1) mean VO2peak, 2) MEN swilling duration; 3) the MEN concentration of MR solution, 4) the number of executed swills throughout a single experiment, 5) the use of flavoured sweetened, non-caloric, or non-flavoured neutral solutions as controls, 6) mean environmental temperature at the time of exercise tests, and 7) exercise type as fixed factors to evaluate their influence on the effects of MEN MR. RESULTS: Ten MEN MR studies included sufficient information pertaining to MEN MR and exercise performance and capacity. MR with MEN resulted in no significant change in capacity and performance (SMD = 0.12; 95% CI - 0.08, 0.31; p = 0.23, n = 1, tau21 < 0.0001, tau22 = < 0.0001, I2 = 0%). No significant influence was detected in meta-regressions for VO2peak, (estimate: 0.03; df = 8; 95% CI - 0.03, 0.09; p = 0.27), swilling duration (5 vs. 10 s: 0.00; df = 16; 95% CI - 0.41, 0.41; p = 1.0), MEN concentration (low [0.01%] vs. high [0.1%]: - 0.08; df = 15; 95% CI - 0.49, 0.32; p = 0.67), number of swills (estimate: 0.02; df = 13; 95% CI - 0.05, 0.09; p = 0.56), the use of flavoured sweetener or non-caloric as control (non-flavoured vs. flavoured: 0.12; df = 16; 95% CI - 0.30, 0.55; p = 0.55) or mean room temperature during exercise tests (estimate: 0.01; df = 16; 95% CI - 0.02, 0.04; p = 0.62). CONCLUSION: MEN MR did not significantly improve overall exercise capacity and performance, though those involved in endurance exercise may see benefits.

Caffeine, CYP1A2 Genotype, and Exercise Performance: A Systematic Review and Meta-analysis.

PURPOSE: This study aimed to summarize and meta-analyze existing evidence regarding the influence of CYP1A2 genotypes on the acute effects of caffeine for exercise performance and to investigate the interaction between genotype, dosage, and timing of caffeine supplementation. METHODS: Six databases were searched for studies determining the effect of caffeine (except mouth rinsing) on exercise performance between CYP1A2 genotypes. Three-level meta-analyses were performed using standardized mean differences (SMD; Hedge's g ) to determine the effect of caffeine on exercise outcomes within and between CYP1A2 genotypes (AA, AC, and CC). Meta-regressions were performed for dose, timing, and presence of reported conflict of interests (RCOI). A meta-analysis was also performed with placebo values to assess for imbalances between genotypes. RESULTS: Thirteen studies, totaling 119 outcomes and 440 participants, were included (233 AA, 175 AC, ad 34 CC). Caffeine improved performance for AA (SMD = 0.30, 95% confidence interval [CI] = 0.21-0.39, P < 0.0001) and AC (SMD = 0.16, 95% CI = 0.06-0.25, P = 0.022) but worsened performance for CC (SMD = -0.22, 95% CI = -0.44 to -0.01, P < 0.0001). Dose affected only CC, with greater doses generating more positive SMD (CC-dose estimate: +0.19/1 mg·kg -1 body mass, 95% CI = 0.04-0.33, P = 0.01). Timing influenced only CC, with better performance with later onset of exercise after supplementation (CC-timing estimate: +0.01/min, 95% CI = 0.00-0.02, P = 0.02). RCOI only affected SMD of CC (CC-RCOI estimate: -0.57, 95% CI = -1.02 to -0.12, P = 0.01). After excluding studies with RCOI, no influence of genotype was seen (all P ≥ 0.19). Small, nonsignificant differences were seen in placebo between genotypes (SMD AA vs CC: -0.13; AA vs AC: -0.12; AC vs CC: -0.05; all P ≥ 0.26). CONCLUSIONS: Caffeine improved performance for AA and AC but worsened performance for CC. Dose and timing moderated the efficacy of caffeine for CC only. Caution is advised because baseline differences and studies with RCOI could have influenced these results.

Caffeine and sport.

Caffeine is a trimethylxanthine found in coffee and several other foods and beverages. Its stimulatory effects make it an interesting strategy to boost performance for athletic populations. Scientific evidence supports its efficacy to improve high-intensity endurance exercise, explosive and high-intensity efforts, resistance exercise, team sports and combat sports, though individual variation in the ergogenic response to caffeine exists. Supplementation can be taken in many forms including dissolved in water, via capsules, coffee, energy drinks and caffeinated gum; ingestion via capsules, dissolved in water or in caffeinated gum appear to be most effective. Variability in the exercise response following caffeine supplementation may be explained by genetic factors or habitual caffeine consumption. Caffeine is an excellent supplement for athletes looking to improve their exercise performance, though some consideration of side-effects and impact on sleep are warranted.

Performing moderate to severe activity is safe and tolerable for healthy youth while wearing a cloth facemask.

OBJECTIVE: To investigate if a cloth facemask could affect physiological and perceptual responses to exercise at distinct exercise intensities in healthy young individuals. METHODS: Nine participants (sex, female/male: 6/3; age: 13±1 years; VO2peak: 44.5±5.5 mL/kg/min) underwent a progressive square-wave test at four intensities: (1) 80% of ventilatory anaerobic threshold (VAT), (2) VAT, and (3) 40% between VAT and [Formula: see text] wearing a triple-layered cloth facemask or not. Participants then completed a final stage to exhaustion at a running speed equivalent to the maximum achieved during the cardio-respiratory exercise test (Peak). Physiological, metabolic, and perceptual measures were measured. RESULTS: Mask did not affect spirometry (forced vital capacity, peak expiratory flow, forced expiratory volume; all p≥0.27), respiratory (inspiratory capacity, end-expiratory volume [EELV] to functional vital capacity ratio, EELV, respiratory frequency [Rf], tidal volume [VT], Rf/VT, end-tidal carbo dioxide pressure, ventilatory equivalent to carbon dioxide ratio; all p≥0.196), hemodynamic (heart rate, systolic and diastolic blood pressure; all p>0.41), ratings of perceived exertion (p = 0.04) or metabolic measures (lactate; p = 0.78) at rest or at any exercise intensity. CONCLUSIONS: This study shows that performing moderate to severe activity is safe and tolerable for healthy youth while wearing a cloth facemask. TRIAL REGISTRATION: ClinicalTrials.gov: NCT04887714.

The Influence of n-3PUFA Supplementation on Muscle Strength, Mass, and Function: A Systematic Review and Meta-Analysis.

The effects of omega 3 polyunsaturated fatty acids (n-3PUFA) supplementation on skeletal muscle are currently unclear. The purpose of this systematic review was to synthesize all available evidence regarding the influence of n-3PUFA supplementation on muscle mass, strength, and function in healthy young and older adults. Four databases were searched (Medline, Embase, Cochrane CENTRAL, and SportDiscus). Predefined eligibility criteria were determined according to Population, Intervention, Comparator, Outcomes, and Study Design. Only peer-reviewed studies were included. The Cochrane RoB2 Tool and the NutriGrade approach were used to access risk of bias and certainty in evidence. Effect sizes were calculated using pre-post scores and analyzed using a three-level, random-effects meta-analysis. When sufficient studies were available, subanalyses were performed in the muscle mass, strength, and function outcomes according to participant's age (<60 or ≥60 years), supplementation dosage (<2 or ≥2 g/day), and training intervention ("resistance training" vs. "none or other"). Overall, 14 individual studies were included, total 1443 participants (913 females; 520 males) and 52 outcomes measures. Studies had high overall risk of bias and consideration of all NutriGrade elements resulted in a certainty assessment of moderate meta-evidence for all outcomes. n-3PUFA supplementation had no significant effect on muscle mass (standard mean difference [SMD] = 0.07 [95% CI: -0.02, 0.17], P = 0.11) and muscle function (SMD = 0.03 [95% CI: -0.09, 0.15], P = 0.58), but it showed a very small albeit significant positive effect on muscle strength (SMD = 0.12 [95% CI: 0.006, 0.24], P = 0.04) in participants when compared with placebo. Subgroup analyses showed that age, supplementation dose, or cosupplementation alongside resistance training did not influence these responses. In conclusion, our analyses indicated that n-3PUFA supplementation may lead to very small increases in muscle strength but did not impact muscle mass and function in healthy young and older adults. To our knowledge, this is the first review and meta-analysis investigating whether n-3PUFA supplementation can lead to increases in muscle strength, mass, and function in healthy adults. Registered protocol: doi.org/10.17605/OSF.IO/2FWQT.

A Cloth Facemask Causes No Major Respiratory or Cardiovascular Perturbations During Moderate to Heavy Exercise.

PURPOSE: Investigate whether a cloth facemask could affect physiological and perceptual responses to exercise at distinct exercise intensities in untrained individuals. METHODS: Healthy participants (n = 35; 17 men, age 30 [4] y, and 18 women, age 28 [5] y) underwent a progressive square wave test at 4 intensities: (1) 80% of ventilatory anaerobic threshold; (2) ventilatory anaerobic threshold; (3) respiratory compensation point; and (4) exercise peak (Peak) to exhaustion, 5-minute stages, with or without a triple-layered cloth facemask (Mask or No-Mask). Several physiological and perceptual measures were analyzed. RESULTS: Mask reduced inspiratory capacity at all exercise intensities (P < .0001). Mask reduced respiratory frequency (P = .001) at Peak (-8.3 breaths·min-1; 95% confidence interval [CI], -5.8 to -10.8), respiratory compensation point (-6.9 breaths·min-1; 95% CI, -4.6 to -9.2), and ventilatory anaerobic threshold (-6.5 breaths·min-1; 95% CI, -4.1 to -8.8), but not at Baseline or 80% of ventilatory anaerobic threshold. Mask reduced tidal volume (P < .0001) only at respiratory compensation point (-0.5 L; 95% CI, -0.3 to -0.6) and Peak (-0.8 L; 95% CI, -0.6 to -0.9). Shallow breathing index was increased with Mask only at Peak (11.3; 95% CI, 7.5 to 15.1). Mask did not change HR, lactate, ratings of perceived exertion, blood pressure, or oxygen saturation. CONCLUSIONS: A cloth facemask reduced time to exhaustion but had no major impact on cardiorespiratory parameters and had a slight but clinically meaningless impact on respiratory variables at higher intensities. Moderate to heavy activity is safe and tolerable for healthy individuals while wearing a cloth facemask. CLINICALTRIALS: gov: NCT04887714.

Effects of Capsaicin and Capsiate on Endurance Performance: A Meta-Analysis.

Several studies have explored the effects of capsaicin and capsiate on endurance performance, with conflicting findings. This systematic review aimed to perform a meta-analysis examining the effects of capsaicin and capsiate vs. placebo on endurance performance in humans. Seven databases were searched to find eligible studies. The effects of capsaicin and capsiate on aerobic endurance (e.g., time-trials or time-to-exhaustion tests), muscular endurance (e.g., repetitions performed to muscular failure), and rating of perceived exertion (RPE) were examined in a random-effects meta-analysis. Fourteen studies (n = 183) were included in the review. Most studies provided capsaicin or capsiate in the dose of 12 mg, 45 min before exercise. In the meta-analysis for aerobic endurance, there was no significant difference between the placebo and capsaicin/capsiate conditions (Cohen's d: 0.04; 95% confidence interval: -0.16, 0.25; p = 0.69). In subgroup meta-analyses, there were no significant differences between the placebo and capsaicin/capsiate conditions when analyzing only studies that used time-trials (p = 0.20) or time-to-exhaustion tests (p = 0.80). In the meta-analysis for muscular endurance, a significant ergogenic effect of capsaicin/capsiate was found (Cohen's d: 0.27; 95% confidence interval: 0.10, 0.43; p = 0.002). When analyzing set-specific effects, an ergogenic effect of capsaicin/capsiate was found in set 1, set 2, and set 3 (Cohen's d: 0.21-29). Capsaicin/capsiate ingestion reduced RPE following muscular endurance (p = 0.03) but not aerobic endurance tests (p = 0.58). In summary, capsaicin/capsiate supplementation acutely enhances muscular endurance, while the effects on aerobic endurance are less clear.

Can the Brazilian Caffeine Expectancy Questionnaires Differentiate the CYP1A2 and ADORA2A Gene Polymorphisms?-An Exploratory Study with Brazilian Athletes.

This study investigated the ability of the Brazilian Caffeine Expectancy Questionnaire (CaffEQ-BR), full and brief versions, to differentiate genetic profiles regarding the polymorphisms of the CYP1A2 (rs 762551) and ADORA2A (rs 5751876) genes in a cohort of Brazilian athletes. One-hundred and fifty participants were genotyped for CYP1A2 and ADORA2A. After the recruitment and selection phase, 71 (90% male and 10% female, regular caffeine consumers) completed the CaffEQ-BR questionnaires and a self-report online questionnaire concerning sociodemographic data, general health status, and frequency of caffeine consumption. The order of completion of the CaffEQ-BR questionnaires was counterbalanced. The concordance between the full and brief versions of the CaffEQ-BR was analyzed using the intraclass correlation coefficient (ICC). To determine the discriminatory capacity of the questionnaires for genotype, the receiver operating characteristic (ROC) curve was applied for sensitivity and specificity (significance level of 5%). Mean caffeine intake was 244 ± 161 mg·day−1. The frequency of AA genotypes for CYP1A2 was 47.9% (n = 34) and 52.1% (n = 37) for C-allele carriers (AC and CC). The frequencies of TT genotypes for ADORA2A were 22.7% (n = 15) and 77.3% (n = 51) for C-allele carriers (TC and CC). All CaffEQ-BR factors, for the full and brief versions, were ICCs > 0.75, except for factor 6 (anxiety/negative effects; ICC = 0.60), and presented ROC curve values from 0.464 to 0.624 and 0.443 to 0.575 for CYP1A2 and ADORA2A. Overall, the CaffEQ-BR (full and brief versions) did not show discriminatory capacity for CYP1A2 and ADORA2A gene polymorphisms. In conclusion, the CaffEQ-BR was not able to differentiate genotypes for the CYP1A2 or ADORA2A genes in this group of Brazilian athletes.

Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine.

OBJECTIVE: The aim was to quantify the proportion of the literature on caffeine supplementation that reports habitual caffeine consumption, and determine the influence of habitual consumption on the acute exercise response to caffeine supplementation, using a systematic review and meta-analytic approach. METHODS: Three databases were searched, and articles screened according to inclusion/exclusion criteria. Three-level meta-analyses and meta-regression models were used to investigate the influence of habitual caffeine consumption on caffeine's overall ergogenic effect and within different exercise types (endurance, power, strength), in men and women, and in trained and untrained individuals. Sub-analyses were performed according to the following: acute relative dose (< 3, 3-6, > 6 mg/kg body mass [BM]); whether the acute caffeine dose provided was lower or higher than the mean daily caffeine dose; and the caffeine withdrawal period prior to the intervention (< 24, 24-48, > 48 h). RESULTS: Sixty caffeine studies included sufficient information on habitual consumption to be included in the meta-analysis. A positive overall effect of caffeine was shown in comparison to placebo (standard mean difference [SMD] = 0.25, 95% confidence interval [CI] 0.20-0.30; p < 0.001) with no influence of relative habitual caffeine consumption (p = 0.59). Subgroup analyses showed a significant ergogenic effect when the caffeine dose was < 3 mg/kg BM (SMD = 0.26, 95% CI 0.12-0.40; p = 0.003) and 3-6 mg/kg BM (SMD = 0.26, 95% CI 0.21-0.32; p < 0.0001), but not > 6 mg/kg BM (SMD = 0.11, 95% CI - 0.07 to 0.30; p = 0.23); when the dose was both higher (SMD = 0.26, 95% CI 0.20-0.31; p < 0.001) and lower (SMD = 0.21, 95% CI 0.06-0.36; p = 0.006) than the habitual caffeine dose; and when withdrawal was < 24 h, 24-48 h, and > 48 h. Caffeine was effective for endurance, power, and strength exercise, with no influence (all p ≥ 0.23) of relative habitual caffeine consumption within exercise types. Habitual caffeine consumption did not modify the ergogenic effect of caffeine in male, female, trained or untrained individuals. CONCLUSION: Habitual caffeine consumption does not appear to influence the acute ergogenic effect of caffeine.

Reduced Endurance Capacity and Suboptimal Energy Availability in Top-Level Female Cyclists.

PURPOSE: Women's professional cycling has grown in popularity, and this increase is also apparent in Brazil, which has increased its female cycling calendar in recent years. The aim of this observational study was to (1) determine training and competition loads of a top-level Brazilian female cycling team, (2) evaluate nutrition and clinical health, and (3) measure whether exercise capacity changed throughout the season. METHODS: Training and competition data were collected over the season using global positioning system monitors, while laboratory-based physiological and performance measures (incremental cycling test, 30-s Wingate, 4-km time trial) and clinical and nutritional analyses were performed at time points throughout the season. RESULTS: Total distance covered over the year was 11,124 (2895) km (7382-14,698 km). Endurance capacity was reduced over the season (P = .005) but not anaerobic power (all P > .05). Nutrition and stress markers remained largely unchanged throughout the season, although there were some individual fluctuations in some measures, and testosterone concentration was low for some. Median estimated energy availability ranged between 32.3 and 56.8 kcal·kgLBM-1·d-1 during training and 26.4 and 53.8 kcal·kgLBM-1·d-1 during competition. Percentage of training spent in optimal estimated energy availability was generally low, with 3 athletes spending <35% within the optimal intake. CONCLUSIONS: Substantial training and competition loads of the monitored professional Brazilian female cyclists may have reduced exercise capacity toward the end of the season, indicative of a grueling yearlong schedule. Several athletes may have had suboptimal energy availability during the season, potentially affecting testosterone concentration. These data demonstrate the difficulties in maintaining optimal nutrition, health, and performance throughout a season in professional female cycling and highlight the need for quality sport-science support for this type of top-level athlete.

Novel insights on caffeine supplementation, CYP1A2 genotype, physiological responses and exercise performance.

Caffeine is a popular ergogenic aid due to its primary physiological effects that occur through antagonism of adenosine receptors in the central nervous system. This leads to a cascade of physiological reactions which increases focus and volition, and reduces perception of effort and pain, contributing to improved exercise performance. Substantial variability in the physiological and performance response to acute caffeine consumption is apparent, and a growing number of studies are implicating a single-nucleotide polymorphism in the CYP1A2 gene, responsible for caffeine metabolism, as a key factor that influences the acute responses to caffeine ingestion. However, existing literature regarding the influence of this polymorphism on the ergogenic effects of caffeine is controversial. Fast caffeine metabolisers (AA homozygotes) appear most likely to benefit from caffeine supplementation, although over half of studies showed no differences in the responses to caffeine between CYP1A2 genotypes, while others even showed either a possible advantage or disadvantage for C-allele carriers. Contrasting data are limited by weak study designs and small samples sizes, which did not allow separation of C-allele carriers into their sub-groups (AC and CC), and insufficient mechanistic evidence to elucidate findings. Mixed results prevent practical recommendations based upon genotype while genetic testing for CYP1A2 is also currently unwarranted. More mechanistic and applied research is required to elucidate how the CYP1A2 polymorphism might alter caffeine's ergogenic effect and the magnitude thereof, and whether CYP1A2 genotyping prior to caffeine supplementation is necessary.

Correction to: Is Open-Label Placebo a New Ergogenic Aid? A Commentary on Existing Studies and Guidelines for Future Research.

Page 4, Figure 1.

"I put it in my head that the supplement would help me": Open-placebo improves exercise performance in female cyclists.

This study investigated the effect of open-placebo on cycling time-trial (TT) performance. Twenty-eight trained female cyclists completed a 1-km cycling TT following a control session or an open-placebo intervention. The intervention consisted of an individual presentation, provided by a medic, in which the concept of open-placebo was explained to the participant, before she ingested two red and white capsules containing flour; 15 min later, they performed the TT. In the control session, the participant sat quietly for 20 min. Heart rate and ratings of perceived exertion (RPE) were monitored throughout exercise, while blood lactate was determined pre- and post-exercise. Post-exercise questionnaires were employed to gain insight into the perceived influence of the supplement on performance. Open-placebo improved time-to-completion (P = 0.039, 103.6±5.0 vs. 104.4±5.1 s, -0.7±1.8 s, -0.7±1.7%) and mean power output (P = 0.01, 244.8±34.7 vs. 239.7±33.2, +5.1±9.5 W) during the TT. Individual data analysis showed that 11 individuals improved, 13 remained unchanged and 4 worsened their performance with open-placebo. Heart rate, RPE and blood lactate were not different between sessions (all P>0.05). Positive expectation did not appear necessary to induce performance improvements, suggesting unconscious processes occurred, although a lack of an improvement appeared to be associated with a lack of belief. Open-placebo improved 1-km cycling TT performance in trained female cyclists. Although the intervention was successful for some individuals, individual variation was high, and some athletes did not respond or even performed worse. Thus, open-placebo interventions should be carefully considered by coaches and practitioners, while further studies are warranted.

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

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

Sanitary and physiological quality of 'purple' corn (Zea mays L. ) seeds submitted to thermotherapy / Qualidade sanitária e fisiológica de sementes de milho 'Roxo' (Zea mays L. ) submetidas à termoterapia

The use of seeds with good sanitary and physiological potential ensures the establishment of the crop, with a uniform, vigorous and disease-free seedling stand, which will result in good productivity levels. Seen that, the objective was to evaluate the sanitary and physiological quality of purple corn seeds (Zea mays L.) submitted to thermotherapy. They were subjected to heat treatment with immersion in sterile distilled water (SDW) heated at 50, 60 and 70 °C for 1, 2, and 3 minutes. The control (0 min) correspondens only to immersing the seeds in SDW, which were submitted to sanitary and germination tests in a completely randomized experimental design, in a factorial arrangement 3 × 3 + 1 (exposure time × temperature + additional control). Data were subjected to analysis of variance, and the means were compared with the Scott-Knott test up to 5% of probability, with the aid of the statistical program SISVAR®. Immersing Zea mays seeds in hot water at 50, 60 and 70 °C for 1, 2, and 3 minutes is efficient to prevent the increased incidence of Aspergillus sp., Penicillium sp., and Fusarium sp. The heat treatment at 60 °C for 1 and 2 minutes of immersion reduces the incidence of fungal mycoflora without impairing the physiological quality of seeds.(AU)

O uso de sementes com bom potencial sanitário e fisiológico garante o estabelecimento da cultura, com estande de plântulas uniformes, vigorosas e livres de doenças, que consequentemente resultará em bons níveis de produtividade. Diante do exposto, objetivou-se avaliar a qualidade sanitária e fisiológica de sementes de milho roxo (Zea mays L.) submetidas à termoterapia, por meio de tratamento térmico com imersão em água destilada esterilizada (ADE), aquecida à temperatura de 50, 60 e 70 °C por 1, 2 e 3 minutos. O controle (0 min) correspondeu apenas à imersão das sementes em ADE. As sementes foram submetidas aos testes de sanidade e germinação em delineamento experimental inteiramente randomizado em esquema fatorial 3 × 3 + 1 (tempo de exposição × temperatura + controle adicional). Os dados foram submetidos à análise de variância e as médias foram comparadas pelo teste de Scott-Knott até 5% de probabilidade, com o auxílio do programa estatístico SISVAR®. A imersão das sementes de Zea mays em água quente a 50, 60 e 70 °C durante 1, 2 e 3 minutos é eficiente para impedir o aumento da incidência de Aspergillus sp., Penicillium sp. e Fusarium sp. O tratamento térmico a 60 °C por 1 e 2 minutos de imersão reduz a incidência da micoflora fúngica, sem prejudicar a qualidade fisiológica das sementes.(AU)