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The effect of branched chain amino acids on psychomotor performance during treadmill exercise of changing intensity simulating a soccer game
Abstract
The present study was designed to determine changes in the multiple-choice reaction time (MRT) during treadmill running simulating locomotor activity during a soccer game and to examine the effect of branched chain amino acids (BCAA) ingestion on psychomotor performance during the effort. Ten male soccer players were submitted to BCAA and placebo trials at 1-week intervals in a randomized order. BCAA (7 g) or placebo were given 1 h before exercise in a double blind manner. The running test consisted of two 45 min exercise bouts separated by a 15-min passive rest period and the whole test ended with 20-min active recovery. Running-walking speed changed from 0 to 6.4 m·s⁻¹ according to the time-motion analysis of soccer match. During the test, blood samples were taken for lactate, glucose, free fatty acid, and catecholamine determination. Following placebo treatment, MRT shortened from 320 ± 18 to 271 ± 11 ms (p < 0.001) during the first exercise bout then it increased during the resting break to 303 ± 138 ms (p < 0.05). During the second bout, MRT decreased to 280 ± 13 ms (p < 0.001). During active recovery, further shortening of MRT was noted. During BCAA trial, MRT was shorter than during placebo trial by ~10% (p < 0.05) before and during exercise. No significant differences were found between BCAA and placebo trials in biochemical indices. It is concluded that BCAA supplementation might be recommended in sport activities that change in intensity and require quick responses to external signals (e.g., soccer and other team games).
... BCAAs (leucine, isoleucine and valine), which form one-third of total muscle protein (Mero, 1999), are the only amino acids metabolised in skeletal muscle (Koo et al., 2014). Oral BCAAs ingestion is commonly used by athletes (Choi et al., 2013;Wisnik et al., 2011) as a nutritional supplement (Burke, 2001;Nemet and Eliakim, 2007) to reduce central fatigue by lowering 5-HT activity (Choi et al., 2013) and increasing dopamine synthesis and release (Bailey et al., 1993), to trigger neural signals (Zheng et al., 2013), and to enhance physical performance (Choi et al., 2013). Several studies have indicated that taking BCAAs before and during prolonged exercise can alleviate central fatigue (Bailey et al., 1993;Burke, 2001;Nemet and Eliakim, 2007) and muscular fatigue (Areces et al., 2015;Bailey et al., 1993;Nemet and Eliakim, 2007), but another study found that BCAAs administration had no effect on performance (Nemet and Eliakim, 2007). ...
... Improvements in time to exhaustion have been attributed to the effect of BCAAs on psychomotor performance (Burke, 2001). Our findings are consistent with those of Wisnik et al. (2011), who examined the effects of ingestion of 7 g of BCAAs in soccer players. The BCAAs were administered 1 hour prior to a multiple-choice reaction time test during treadmill exercise (running-walking speed varied from 0 to 6.4 ms to simulate a soccer game). ...
... This could explain why time to exhaustion was lower in the placebo trial. This finding agrees with that of Wisnik et al. (2011), who reported that FFA concentration during the first half of a soccer game was higher in a placebo trial than in a BCAA trial. Many researchers have demonstrated that exercising on a bicycle ergometer produces much more plasma FFAs levels post-exercise in endurance athletes than untrained individuals (Bailey et al., 1993;Men'shikov, 2004;Nemet and Eliakim, 2007;Presland et al., 2005;Romijn et al., 1993). ...
The aim of this study was to investigate the effects of oral branched-chain amino acids (BCAAs) intake on muscular (creatine kinase and myoglobin) and central (serotonin) fatigue during an incremental exercise protocol and to determine the time to exhaustion. Sixteen male long-distance runners (25.7 ± 2.0 yrs) performed two trials, 14 days apart. Using a double-blind, placebo-controlled, randomised crossover design, participants ingested either 20 g of BCAAs (BCAA trial) or a placebo 1 hour prior to performing an incremental exercise session on a treadmill. The starting speed was 8 km/h and this was increased by 1 km/h every 5 minutes until volitional exhaustion. Blood analysis indicated that plasma levels of serotonin were lower in the BCAA trial (259.3 ± 13.5 ng/ml) than the placebo trial (289.1 ± 14.5 ng/ml) (p < 0.05). There was a similar pattern of results for free fatty acid (p < 0.05). The creatine kinase level was higher in the BCAA trial (346.1 ± 33.7 U/L) than the placebo trial (307.3 ± 30.2 U/L). No significant difference between trials was observed regarding the level of myoglobin (p = 0.139). Time to exhaustion was longer in the BCAA trial (50.4 ± 2.3 min) than the placebo trial (46.6 ± 3.2 min). In conclusion, oral intake of 20 g of BCAAs 1 hour prior to an incremental treadmill exercise session increased time to exhaustion, probably due to the reduction in serotonin concentration. As myoglobin levels were within the normal range in both trials, we conclude that the participants did not reach muscular fatigue.
... BCAAs (leucine, isoleucine and valine), which form one-third of total muscle protein (Mero, 1999), are the only amino acids metabolised in skeletal muscle (Koo et al., 2014). Oral BCAAs ingestion is commonly used by athletes (Choi et al., 2013;Wisnik et al., 2011) as a nutritional supplement (Burke, 2001;Nemet and Eliakim, 2007) to reduce central fatigue by lowering 5-HT activity (Choi et al., 2013) and increasing dopamine synthesis and release (Bailey et al., 1993), to trigger neural signals (Zheng et al., 2013), and to enhance physical performance (Choi et al., 2013). Several studies have indicated that taking BCAAs before and during prolonged exercise can alleviate central fatigue (Bailey et al., 1993;Burke, 2001;Nemet and Eliakim, 2007) and muscular fatigue (Areces et al., 2015;Bailey et al., 1993;Nemet and Eliakim, 2007), but another study found that BCAAs administration had no effect on performance (Nemet and Eliakim, 2007). ...
... Improvements in time to exhaustion have been attributed to the effect of BCAAs on psychomotor performance (Burke, 2001). Our findings are consistent with those of Wisnik et al. (2011), who examined the effects of ingestion of 7 g of BCAAs in soccer players. The BCAAs were administered 1 hour prior to a multiple-choice reaction time test during treadmill exercise (running-walking speed varied from 0 to 6.4 ms to simulate a soccer game). ...
... This could explain why time to exhaustion was lower in the placebo trial. This finding agrees with that of Wisnik et al. (2011), who reported that FFA concentration during the first half of a soccer game was higher in a placebo trial than in a BCAA trial. Many researchers have demonstrated that exercising on a bicycle ergometer produces much more plasma FFAs levels post-exercise in endurance athletes than untrained individuals (Bailey et al., 1993;Men'shikov, 2004;Nemet and Eliakim, 2007;Presland et al., 2005;Romijn et al., 1993). ...
The aim of this study was to investigate the effects of oral branched-chain amino acids (BCAAs) intake on muscular (creatine kinase and myoglobin) and central (serotonin) fatigue during an incremental exercise protocol and to determine the time to exhaustion. Sixteen male long-distance runners (25.7 ± 2.0 yrs) performed two trials, 14 days apart. Using a double-blind, placebo-controlled, randomised crossover design, participants ingested either 20 g of BCAAs (BCAA trial) or a placebo 1 hour prior to performing an incremental exercise session on a treadmill. The starting speed was 8 km/h and this was increased by 1 km/h every 5 minutes until volitional exhaustion. Blood analysis indicated that plasma levels of serotonin were lower in the BCAA trial (259.3 ± 13.5 ng/ml) than the placebo trial (289.1 ± 14.5 ng/ml) (p < 0.05). There was a similar pattern of results for free fatty acid (p < 0.05). The creatine kinase level was higher in the BCAA trial (346.1 ± 33.7 U/L) than the placebo trial (307.3 ± 30.2 U/L). No significant difference between trials was observed regarding the level of myoglobin (p = 0.139). Time to exhaustion was longer in the BCAA trial (50.4 ± 2.3 min) than the placebo trial (46.6 ± 3.2 min). In conclusion, oral intake of 20 g of BCAAs 1 hour prior to an incremental treadmill exercise session increased time to exhaustion, probably due to the reduction in serotonin concentration. As myoglobin levels were within the normal range in both trials, we conclude that the participants did not reach muscular fatigue.
... This differs to our original hypothesis as it was expected the combined physical and mental demands of the match would have negative effects on cognitive performance. Comparable results have been found in previous studies 25,26 with football players in which psychomotor performance was found to improve after different running activities (low and high intensity). The explanation given was that different exercise activities (low and moderate) activate central nervous system functions and thus psychomotor performance can be improved. ...
... The explanation given was that different exercise activities (low and moderate) activate central nervous system functions and thus psychomotor performance can be improved. 25 Therefore, it is likely that the combined physical and mental stress of the match in the present study was not sufficiently demanding to have a negative effect on performance and may actually have been beneficial. ...
Context:
Referees' physical and cognitive performance are important for successful officiating in team sports. There is a lack of research on cognitive performance of referees in general, and none in futsal.
Purpose:
To assess referees' performance on the psychomotor vigilance task (PVT) before and after competitive futsal matches during the Football Association (FA) National Futsal League 2015/16.
Methods:
Fourteen futsal referees (mean [SD] age 34.3 [10.0] y) from the FA National Futsal group were included. The referees were required to undertake a 10-min PVT 60 min before the match kickoff time (pretest) and immediately after matches (posttest). They also completed the Brunel Mood Scale (BRUMS) questionnaire before the prematch PVT and after the postmatch PVT.
Result:
Data were analyzed by paired t tests comparing prematch and postmatch results. There was a significant difference in BRUMS parameters vigor (9.5 [2.5] prematch vs 6.3 [2.4] postmatch, P = .001) and fatigue (1.4 [1.3] prematch vs 5.6 [3.1] postmatch, P < .001). However, PVT performance was significantly improved (mean reaction time 248.3 [26.2] ms prematch vs 239.7 [22.4] ms postmatch, P = .023).
Conclusions:
The present results show, contrary to the authors' initial hypothesis, that psychomotor performance is improved as opposed to decreased after a single match. The postmatch improvement suggests that exercise can acutely enhance cognitive performance, which could be used to inform warm-up practices (eg, optimal duration and intensity) geared toward optimizing referees' cognitive performance during matches.
... However, the BCAA supplementation did not affect physical fatigue and was ineffective in preventing muscle power loss and perceived muscle pain during strenuous exercise such as in a marathon race [5,49]. Our previous studies in soccer players [39,54] showed a slight improvement in psychomotor performance after BCAA supplementation during both graded exercise until exhaustion and treadmill running simulating a football game. ...
... Administration of OA prevented the expected increase in blood ammonia concentration after the BCAA supplementation during the graded exhaustive exercise and therefore probably prevented the deterioration of multiple choice reaction time usually occurring in the final stage of the exhaustive exercise [20][21][22]39,54], which reflects improved psychomotor performance (Fig. 3). ...
Introduction:
Our previous studies showed only slight improvement in central fatigue, measured indirectly by psychomotor performance, after branched chain amino acids (BCAA) supplementation during various efforts in healthy men. It is hypothesised that hyperammonaemia resulting from amino acids metabolism may attenuate their beneficial effect on psychomotor performance; therefore, the L-ornithine L-aspartate (OA) as an ammonia decreasing agent was used. The aim of this study was to investigate the effectiveness of oral BCAA + OA supplementation to reduce plasma ammonia concentration and enhance psychomotor performance during exhaustive exercise in healthy men.
Material and methods:
Eleven endurance-trained men (mean age 32.6 ± 1.9 years) performed two sessions (separated by one week) of submaximal cycloergometer exercise for 90 minutes at 60% of maximal oxygen uptake followed by graded exercise until exhaustion with randomised, double-blind supplementation with a total of 16 g BCAA and 12 g OA (BCAA + OA trial) or flavoured water (placebo trial). Before exercise, during both efforts and after 20 minutes of recovery multiple choice reaction time (MCRT), perceived exertion, heart rate and oxygen uptake were measured and venous blood samples were taken for plasma leucine, valine, isoleucine, ornithine, aspartate, free tryptophan (fTRP), ammonia, lactate and glucose determination.
Results:
After ingestion, during both efforts and after 20 minutes of recovery the plasma concentrations of all supplemented amino acids were significantly increased, while the fTRP/BCAA ratio decreased in the BCAA + OA trial more than in the placebo trial. At the end of graded exercise plasma fTRP was lower and MCRT shorter in BCAA + OA than in the placebo trial (p < 0.05). At the end of prolonged exercise the plasma ammonia concentration was higher in BCAA + OA than in placebo trial (p < 0.05). Decreases in plasma ammonia during recovery were significantly higher in BCAA + OA than in the placebo trial. Plasma ammonia positively correlated with the total plasma BCAA and MCRT only in the BCAA + OA trial. The fTRP/BCAA ratio positively correlated with MCRT only in the placebo trial.
Conclusions:
Supplementation with BCAA and OA is a useful way to improve MCRT during high-intensity exercise and accelerate the elimination of ammonia at the recovery stage after exercise in healthy young men.
... In football, an increase in goal-scoring rate is observed in the latter stages of the match along with fatigue 42 , which may partly be due to the impairment in cognitive perception 3 . However, Wiśnik et al. 43 reported that the RT of cognitive task is shortened during treadmill exercise of changing intensity simulating a sport game. To the best of our knowledge, previous research could not detect why the cognitive-perceptive skills may often be poorer in the latter stage of the match. ...
The speed and accuracy of decision-making ( i.e. , executive function (EF) domains) is an integral factor in many sports. At rest, prolonged cognitive load (pCL) impairs reaction time (RT). In contrast, exercise improves RT and EF. We hypothesized that RT and EF during exercise would be diminished by prolonged ‘dual tasking’ as a consequence of pCL. To test the hypothesis, twenty healthy male participants performed four conditions [resting control (Rest), pCL only (pCL Rest ), exercise only (EX), and pCL + exercise (pCL EX )] in a randomized-crossover design. Both exercise conditions utilized a 50-min cycling exercise protocol (60% VO 2 peak) and the pCL was achieved via a 50-min colour-word Stroop task (CWST). Compared with Rest, pCL Rest caused a slowed CWST RT ( P < 0.05) and a large SD ( i.e. , intraindividual variability) of CWST RT ( P < 0.01). Similarly, compared with EX, the slowed CWST RT ( P < 0.05) and large SD of CWST RT ( P < 0.01) were also observed in pCL EX . Whereas the reverse-Stroop interference was not affected in pCL Rest ( P = 0.46), it was larger ( i.e. , declined EF) in pCL EX than EX condition ( P < 0.05). These observations provide evidence that the effort of pCL impairs RT and EF even during exercise.
... Branched chain amino acids (BCAA), including leucine, isoleucine and valine have all been shown to improve mental fatigue and physical performance responses to training and performance [5]. Similar results were also stated by Wiśnik et al [6] who indicated that soccer players with BCAA sup plementation had better psychomotor performance. Nowadays, chicken essence is considered as a nutritional supplement rich in BCAA with certain inhibitory effect on the occur rence of fatigue [3]. ...
Objective:
Chicken essence and branched chain amino acid (BCAA) supplementation has been recognized to significantly relieve fatigue. To obtain chicken essence with high amounts of BCAA, spent hens herein was used to prepare dripped chicken essence (SCE) and compared with commercial dripped chicken essence (CCE) for in vivo anti-fatigue effect.
Methods:
To determine the effect on anti-fatigue by dripped chicken essence, the exhaustive swimming was performed. Thirty-two 7-week ICR mice were divided into four groups, which included the control group (CG), CCE, SCE-1X and SCE-2X. The mice were given daily oral administration (0.012 mL/g bw/day). The fatigue index analysis was conducted weekly.
Results:
The results showed that SCE had a higher BCAA level as expected and mice treated with dripped chicken essence (CCE and SCE) could significantly improve exercise performance. The lower blood lactate level, blood urea nitrogen level and creatine kinase activity were found in the supplement of SCE group compared with the CCE group, which suggested that the SCE possessed strong anti-fatigue ability. This could possibly be due to the higher content of BCAA.
Conclusion:
In this study, SCE promoted recovery from physical fatigue in mice and elevated endurance ability. Among them, the double dose (SCE-2X) showed the strongest anti-fatigue ability. Taken together, spent chickens could be a good source of chicken essence to improve the effect of anti-fatigue.
... The 3 branched amino acids (leucine, valine and isoleucine) are among the most used ergogens, as they can alleviate the sense of fatigue [24], are beneficial to maintain the level of performance [25] and prevent muscle catabolism [26], immune system [27] biological regulator of skeletal muscle functioning [28], resulting overall beneficial in promoting maintenance, if not the increase of protein synthesis and lean mass [5]; in CSs they could be used in particular to reduce the sense of fatigue (in particular mental) that is experienced in matches, or in conjunction with particularly intense workouts; but we agree with the review by Simoncini et al. [29], explicitly made on Takwondo which does not consider an integration of bcaa as fundamental; the only study in favor of this practice is that of Fan-Chen et al. [30], operated on 12 athletes, for whom by simulating matches, with the integration of 0.17g per kg of body weight of BCAA together with arginine and citrulline an improvement in reaction times was recorded and confirmed the decrease in the plasma Tyr/BCAA ratio (linked to the lower perception of fatigue). ...
In recent years, nutrition applied to the sport has had a great response from technicians and science, justifying more and more the use of the support of food supplements, especially when considering elite athletes and/or professionals. The term combat sport refers to a varied and heterogeneous group of sporting activities, some recognized by the International Olympic Committee, others not; many aspects unite them. They are considered “minor” sports if compared to football, basketball, baseball, as they are less popular at a professional level, but with a great deal of participation at the amateur level; in this sense, everything concerning nutrition and food supplementation is often delegated to the practitioners themselves. This work would like to resume the current (however not abundant) literature and suggest a correct integration, based on the literature available even if not sport-specific, providing a tool for technicians and a starting point for specific works in the future.
... Taking BCAAs before exercise increases fatigue time, which may be due to the role of BCAAs in maintaining long-term physical activity. Multi-choice reaction time was performed during treadmill exercise, and it was found that after subjects ingested BCAA, it can enhanced attention and shorten reaction time [21]. Moreover, ginseng with BCAAs reduced muscle breakdown, preserved muscle in athletes and decreased delayed-onset muscle soreness in volleyball players [22]. ...
... In mammals, branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) are known as essential amino acids. BCAAs perform various functions beneficial to human health, including improving protein synthesis (Borgenvik et al. 2012;Howatson et al. 2012), reducing exercise-induced fatigue (Blomstrand et al. 1997;Wiśnik et al. 2011), and preventing progressive hepatic failure in advanced cirrhosis (Marchesini et al. 2003). BCAAs are important for the synthesis of the excitatory neurotransmitter glutamate and the inhibitory neurotransmitter γ-aminobutyric acid (GABA) in the brain . ...
Branched-chain amino acid aminotransferase (BCAT) catalyzes bidirectional transamination in the cell between branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) and branched-chain α-keto acids (BCKAs; α-ketoisovalerate, α-ketoisocaproate, and α-keto-β-methylvalerate). Eukaryotic cells contain two types of paralogous BCATs: mitochondrial BCAT (BCATm) and cytosolic BCAT (BCATc). Both isozymes have identical enzymatic functions, so they have long been considered to perform similar physiological functions in the cells. However, many studies have gradually revealed the differences in physiological functions and regulatory mechanisms between them. In this article, we present overviews of BCATm and BCATc in both yeast and human. We also introduce BCAT variants found natively or constructed artificially, which could have significant implications for research into the relationship between the primary structures and protein functions of BCATs.
Key points
• BCAT catalyzes bidirectional transamination in the cell between BCAAs and BCKAs.
• BCATm and BCATc are different in the metabolic roles and regulatory mechanisms.
• BCAT variants offer insight into a relationship between the structure and function.
... BCAAs influence recovery from fatigue by controlling the increase in serotonin and 5-hydroxyindoleacetic acid levels after exercise 16) . In a clinical trial targeting athletes, BCAAs were reported to influence psychomotor performance, such as increased reaction time during exercise 17) . PycnoRacer™ also contains arginine (Table 1). ...
The performance and physical status of professional cyclists in Japan who train with pycnogenol-containing supplements have not been evaluated. This pilot study aimed to investigate how off-season training and ingesting PycnoRacer™ containing branched-chain amino acids (BCAAs) and pycnogenol can influence cycling performance in cyclists. Eight professional male cyclists (mean age, 24.0 ± 2.4 years) were included in this study. All athletes received and ingested PycnoRacer™ containing 60 mg of pycnogenol, 4,800 mg of BCAA, and 1,200 mg of arginine daily for 28 days. We evaluated the cycling performance and other parameters of each athlete before using PycnoRacer™ and after 28 days of training with the supplement. Measures of performance, such as maximum oxygen consumption, maximum aerobic power, and maximum heart rate, were evaluated with breath-by-breath exercise tolerance tests using a gas analyzer. Additionally, other parameters, including body composition, respiratory function, and degree of cycling training, were measured. The maximum oxygen consumption, maximum aerobic power, and caloric expenditure during cycling training increased significantly after 28 days of training with PycnoRacer™. However, no significant differences were found in the maximum heart rate, body composition, and respiratory function before and after using PycnoRacer™. Pycnogenol-containing supplements enhance off-season cycling performance and caloric expenditure during cycling training of professional cyclists.
... BCAAs affect recovery from fatigue by controlling the increase in serotonin and 5-hydroxyindoleacetic acid levels after exercise 30) . In clinical trials in athletes, BCAAs have been reported to affect psychomotor performance, such as increased reaction time during exercise 31) . The relationship between arginine intake, improved performance, and growth hormone secretion in athletes remains unclear 32,33) . ...
[Purpose] Changes in the muscle performance of professional motorized athletes using pycnogenol-containing supplements have not been clarified. The purpose of this study was to evaluate the changes in muscle strength and endurance of professional cyclists during 4 weeks of training with the use of PycnoRacerTM. [Participants and Methods] Eight professional cyclists were requested to consume PycnoRacerTM twice/day for 4 weeks. The muscle endurance test consisted of 50 consecutive knee flexion and extension exercises at 180°/sec using an isokinetic torque machine before and after PycnoRacerTM administration. The athletes’ body composition, including leg muscle mass, was also measured. [Results] The maximum flexor muscle torque and 41st–50th flexion muscle torque values significantly improved after supplement consumption (average improvement of 8.5%; range, 13.3–67.2%). The leg muscle mass and body composition did not differ significantly between the two conditions. The participants showed an average improvement of 31.8% (range, 0.9–67.8%) in their total work with cycling training. No adverse events were observed. [Conclusion] The use of PycnoRacerTM may improve training, muscle strength, and endurance, but not muscle mass.
... As a result of the study, BCAA could be effective in endurance athletes. Wisnik (2011) studied the effect of BCAA on psychomotor performance with the participation of 10 male professional football players. They applied the protocol of treadmill exercise that simulated a soccer game. ...
... Under particular conditions such as starvation, exercise, and lactation, the increase in BCAA oxidation function is an important energy source in vivo. Studies have reported that the ability of muscle to oxidize α-ketoglutaric acid (α-KG), the transamination product of BCAA, can increase three to five times when deprived of food (Hsu et al., 2011;Wiśnik et al., 2011). However, starvation is a severe deficiency in caloric energy intake needed to maintain an organism's life. ...
The branched-chain amino acids (BCAAs) play a key role in the energy metabolism of the muscle tissue and the Krüppel-like factor 15 (KLF15) as a transcription factor, which is a key regulator of BCAA metabolism in the skeletal muscle. This study assessed the effect of starvation for 0, 3, 7, and 15 days on BCAA metabolism in the skeletal muscle of Nile tilapia. The results showed that the expression of KLF15 showed a trend of increasing first and then decreasing during starvation, as well as the expression and activity of branched-chain aminotransferase 2 (BCAT2) and alanine aminotransferase (ALT). On the other hand, the content of BCAA was at first decreased and then upregulated, and it reached the lowest level after starvation for 3 days. In addition, through dual-luciferase reporter assay and injection experiments, it was found that KLF15 is the target gene of miR-125a-3p, which further verified that miR-125a-3p can regulate the BCAA metabolism by targeting KLF15 in the skeletal muscle. Thus, our work investigated the possible mechanisms of BCAA metabolism adapting to nutritional deficiency in the skeletal muscle of Nile tilapia and illustrated the regulation of BCAA metabolism through the miR-125a-3p-KLF15-BCAA pathway in the skeletal muscle.
... Scientific literature describes direct influence of different external factors on the level of cognitive-executive functions examined with various psychomotor tests including response time measurements. Considerable attention has been devoted to research on momentary changes in response time and activation of the sympathoadrenal response examined with the use of direct measurements after various physical efforts [14][15][16][17][18][19][20][21][22][23][24][25][26], after exposure to hard environmental conditions or lack of sleep [27][28][29][30][31]. Scientists have also determined the relationship between response time and age, physical activity and/or health [32][33][34][35] and in healthy subjects after administration of erogenic substance [36][37][38]. Numerous psychomotor tests have been conducted on competitive athletes, however judo competitors participated only in few [39][40][41]. ...
Background & Study Aim: Cognitive functions of combat sports contestants, such as visual perception, information processing, divisibility of attention and eye-limb coordination play an important role in solving the problems related to tactic and strategy during a fight. The purpose of this study was to answer the question: whether performance level of the two various psycho-motor tests is linked to the sport levels among male judo athletes. Material & methods: The psychomotor studies involved four groups of male judo athletes. Two groups were composed of highly skilled senior members of the Judo National Team (HSS, n = 18, age 22.7 +/- 3.0) and junior members of the Judo National Team (HSJ, n = 24, age 17.8 +/- 0.9), who were more successful than the others and therefore were called up to the Polish National Team. Two other groups were less successful and possessed lower skills, i.e. seniors (LSS, n = 24, age 23.2 +/- 3.3) and juniors (LSJ, n = 26, age 18.8 +/- 0.6), who were not selected into the national teams. All groups were examined at rest state in the forenoon at the same period of the training season. Results: The older groups (HSS+ LSS) showed better performance of the psychomotor tests than the younger ones (HSJ+ LSJ). Likewise, the highly skilled groups (HSS+ HSJ) obtained better scores than the lower skilled ones (LSS+ LSJ). Only highly skilled groups and the entire group showed significant correlations between age or training experience and psychomotor skills. Conclusions: The psychomotor abilities were better among older athletes allowing to formulate two competing hypotheses suggesting that: (1) long-term judo training (assuming the similarity of the characteristics of all subjects before the start of the training) has a positive effect on the development of cognitive functions of a human, which translates both into high athletic performance and improvement of motor safety during daily physical activity; (2) high athletic performance in judo is conditioned by an optimal level of psychomotor abilities.
... However, in that study there was no measurement of physical performance during the trials. Wisnik et al. (2011) provided male soccer players with 7 g of BCAA or a placebo before a multiple-choice reaction time during treadmill test and they found that BCAA administration shortened the time to complete the test by 10 %. ...
The aim of this study was to determine the effectiveness of a 7-day oral supplementation with branched-chain amino acids (BCAA) to prevent muscle damage during a marathon. Forty-six experienced runners were randomly divided into two groups, one with BCAA supplementation (n = 25, supplemented with 5 g day(-1) of powdered 1:0.5:0.5 leucine:isoleucine:valine, during the 7 days prior to the competition) and the other as a control group (n = 21, supplemented with an isocaloric placebo). Before the marathon race and within 3 min of finishing, leg muscle power was measured with a maximal countermovement jump and a urine sample was obtained. During the race, running pace was measured by means of a time-chip. Myoglobin concentration was determined in the urine samples as an indirect marker of muscle damage. A visual analog scale (0-10 points) was used to assess leg muscle pain during the race. In the BCAA group, the mean running pace during the marathon was similar to the control group (3.3 ± 0.4 vs. 3.3 ± 0.5 m s(-1), respectively, 0.98). The pre- to post-race reduction in muscle power was similar in both BCAA and control groups (-23.0 ± 16.1 vs. -17.3 ± 13.8 %, P = 0.13). Post-race urine myoglobin concentration was similar in both BCAA and control groups (5.4 ± 7.5 vs. 4.5 ± 8.6 μg mL(-1), P = 0.70). Finally, there were no differences between groups in the perceived muscle pain during the race (6 ± 1 vs. 5 ± 1 points, P = 0.80). A 7-day supplementation of BCAA (5 g day(-1)) did not increase the running performance during a marathon. Furthermore, BCAA supplementation was ineffective to prevent muscle power loss, muscle damage or perceived muscle pain during a marathon race.
This small pilot study used a double-blinded, between subject experimental design in an attempt to investigate the claim made my Magnum Nutraceuticals in regards to their newest supplement, DNA. The manufacturer has a three-day guarantee saying that if an individual takes this supplement for three days then they will experience an increase in strength (more repetitions to their normal weight lifting regiment). Two groups (placebo and experimental) performed three different weight lifting exercises (squats, chin-ups, bench press) while lifting ½ of their body weight per manufacturer’s instructions. The groups met on two different occasions separated by three days in between. The first meeting the participants completed the three aforementioned exercises and were assigned into the placebo or intervention group. After the baseline the participants were instructed to take their pills as directed for the next three days with the third day being a repeat of the three exercises to compare with baseline. Once all 13 participants (N=7 intervention, N=6 placebo) completed the final workout, the results were scored and significant differences were noted in all three exercises after excluding the numbers from the outlier in the experimental group. There was one minor adverse effect (dyspepsia) experienced with the use of the supplement though all ingredients contained within DNA had GRAS status as designated by the FDA. It was concluded that participants taking DNA had a significant increase in strength when compared against the placebo group for squats, bench, and pull-ups. DNA was shown to be reasonably safe and may help athletes increase repetitions when training with a similar exercise regiment.
هدفت الدراسة للتعرّف إلى تأثير تناول مكملات الأحماض الأمينيّة ذات السلسلة المتفرعة على مسافة الجري خلال اختبار كوبر وبعض علامات التعب العضليّ عند طلبة التفوّق الرياضيّ بجامعة اليرموك. استخدِم التصميم الأعمى العشوائيّ لمجموعة واحدة ضمَّت 11 طالب بعمر (20.73±1.39 سنة) خضعوا لتجربتيْن (بفاصل زمني أسبوعان). تضمن بروتوكول الدراسة قيام كل لاعب بتناول 25 غم BCAAs مذاباً في 500 مللتر قبل ساعتيْن من بدء التجربة (تجربة الأحماض الامينيّة) أو 500 مللتر ماء فقط (التجربة الضابطة). تضمنت كل تجربة إحماء لمدّة 5 دقائق، ومن ثمَّ إطالة لعضلات الذراعيْن والرجليْن لمدة 4 دقائق. بعد ذلك، خضع كل مشترك لاختبار كوبر (12 دقيقة جري). وبعد الانتهاء من كل تجربة تمَّ حساب المسافة المقطوعة وسحب عينة دم من كل مشترك لقياس متغيرات الدراسة. أظهرت النتائج أن مسافة الجري كانت أطول/أفضل في تجربة الأحماض الأمينيّة (3607 متر) مقارنة بالتجربة الضابطة (3501 متر) وبشكلٍ دالٍّ إحصائياً (α ≤ 0.05). أمَّا تركيز إنزيم ألدوليز ومستوى لاكتيت الدم كان أقل (أفضل) في تجربة الأحماض الأمينيّة مقارنة بالضابطة وبشكلٍ دالٍّ إحصائياً، بينما لم تظهر فروق إحصائيّة في سكر الدم ومعدّل ضربات القلب بين التجربتيْن. تمّ الاستنتاج أنَّ BCAAs عامل مُنتج للطاقة وتقلِّل من علامات التعب العضليّ.
The branched-chain amino acids (BCAA) play an important role in muscle energy metabolism, and Krüppel-like factor 15 (KLF15) is an essential regulator of BCAA metabolism in muscle under nutritional deficiency. In this study, we analyzed the effect of normal feeding (starvation for 0 day), starvation for 3, 7, 10, 15 days, and refeeding for 7 days after 15 days of starvation on the expression of KLF15 and BCAA metabolism in muscle of Chinese soft-shelled turtles by a fasting-refeeding trial. The results showed that the level of KLF15 transcription was increased first and then decreased in muscle during short-term starvation, and the protein level was gradually increased. Both the mRNA and protein level of the KLF15 returned to normal feeding level after refeeding for 7 days. The changing trend of the activities of branched-chain aminotransferase (BCAT) and alanine aminotransferase (ALT) was consistent to that of KLF15 mRNA, but at the transcription level, the expression of BCAT mRNA was consistent with the change of enzyme activity as well as ALT continued to increase in muscle under starvation. In addition, BCAA content showed a trend that decreased first and then increased under starvation, while the alanine (Ala) was the contrary. The above results indicated that the regulatory role of KLF15 in BCAA catabolism of muscle in Chinese soft-shelled turtles under nutritional deficiency, which might be activated the catabolism of BCAA in muscle to provide energy and maintain the homeostasis by KLF15-BACC signaling axis.
Background and aims: Current state of evidence recommends beneficial effects of branched chain amino acids (BCAAs) on exercise performance; however, randomized controlled trials (RCTs) of BCAA supplementation yield discordant results. The objective of this study was to clarify the effects of BCAA supplementation in exercise through meta-analysis of all relevant RCTs.
Methods: A comprehensive search of PubMed, Embase, ISI web of science, and the Cochrane library has been conducted from inception to September 2016. This meta-analysis includes 31 primary trials of the effect of BCAA supplementation on central fatigue, fatigue substances (lactate and ammonia), energy metabolites (glucose and free fatty acids) and, muscle damage substances (LDH and CK). The estimates were either obtained from a fixed-effects model or a random-effects model. The studies’ heterogeneity was calculated by Cochrane’s test and I² index.
Results: BCAA had no effect on central fatigue (SMD − 0.31, 95% CI − 0.72 to 0.09; p = 0.1; heterogeneity I² = 0%, p = 0.9). However, a significant reduction was detected in the lactate levels (WMD − 0.16, 95% CI − 0.26 to − 0.53; p = 0.003; heterogeneity I² = 47.9%, p = 0.023). Moreover, BCAA supplementation had beneficial effects on ammonia, glucose, FFA, and CK, but had no effects on LDH.
Conclusion: BCAA supplementation did not have any effect on the feeling of fatigue; however, it led to a favorable effect on fatigue substances, energy metabolites and muscle soreness substances. Therefore, it can be concluded that the ingestion of the BCAA can play a helpful role in the enhancement of the exercise performance.
Nitric oxide (NO) is a gaseous signaling molecule with a short half-life that's known to exert its biological functions through cyclic guanosine monophosphate. In our system, nitric oxide is produced by nitric oxide synthase enzymes, which use substrates l-arginine, reduced nicotinamide adenine dinucleotide phosphate (NADPH), and oxygen by producing citrulline, nicotinamide adenine dinucleotide phosphate (NADP⁺), and NO. Nitric oxide can react with superoxide to produce peroxynitrite (ONOO?), which can cause irreversible modification and inhibition of different biological molecules, including mitochondrial membrane complexes and antioxidant defense enzymes through oxidizing reactions. This chapter focuses on the direct and indirect role of NO in terms of energy metabolism. Nitric oxide in this context governs and regulates metabolism, heat production, and body composition, which overall change the tissue distribution of oxygen, adenosine triphosphate production, blood flow, glucose utilization, and supply of other nutrients by resulting in altered tissue functions and physical activities.
الملخص
هدفت الدراسة للتعرّف إلى تأثير تناول مكملات الأحماض الأمينيّة ذات السلسلة المتفرعة على مسافة الجري خلال اختبار كوبر وبعض علامات التعب العضليّ عند طلبة التفوّق الرياضيّ بجامعة اليرموك. استخدِم التصميم الأعمى العشوائيّ لمجموعة واحدة ضمَّت 11 طالب بعمر (20.73±1.39 سنة) خضعوا لتجربتيْن (بفاصل زمني أسبوعان). تضمن بروتوكول الدراسة قيام كل لاعب بتناول 25 غم BCAAs مذاباً في 500 مللتر قبل ساعتيْن من بدء التجربة (تجربة الأحماض الامينيّة) أو 500 مللتر ماء فقط (التجربة الضابطة). تضمنت كل تجربة إحماء لمدّة 5 دقائق، ومن ثمَّ إطالة لعضلات الذراعيْن والرجليْن لمدة 4 دقائق. بعد ذلك، خضع كل مشترك لاختبار كوبر (12 دقيقة جري). وبعد الانتهاء من كل تجربة تمَّ حساب المسافة المقطوعة وسحب عينة دم من كل مشترك لقياس متغيرات الدراسة. أظهرت النتائج أن مسافة الجري كانت أطول/أفضل في تجربة الأحماض الأمينيّة (3607 متر) مقارنة بالتجربة الضابطة (3501 متر) وبشكلٍ دالٍّ إحصائياً (α ≤ 0.05). أمَّا تركيز إنزيم ألدوليز ومستوى لاكتيت الدم كان أقل (أفضل) في تجربة الأحماض الأمينيّة مقارنة بالضابطة وبشكلٍ دالٍّ إحصائياً، بينما لم تظهر فروق إحصائيّة في سكر الدم ومعدّل ضربات القلب بين التجربتيْن. تمّ الاستنتاج أنَّ BCAAs عامل مُنتج للطاقة وتقلِّل من علامات التعب العضليّ.
الكلمات المفتاحية: أحماض أمينيّة ذات سلسلة متفرعة، اختبار كوبر، جري، تعب عضلي، مكملات.
Psychomotor skill is the human ability to respond with maximal speed and accuracy to external events or goals. It depends on several brain functions, including cognitive functions, attention, concentration, verbal and spatial working memory and information processing speed. The psychomotor performance is assessed by lots of neuropsychological tests, which are directed to evaluate either the single brain function or the global accuracy and time of the response. These tests, especially combined with functional magnetic resonance of the brain provide the useful tool for evaluation of the status of patient with neurological and psychiatric diseases and to investigate the effects of some agents, such as food components, on the brain functions in patients and healthy subjects.
The onset of exercise facilitates an improvement in psychomotor performance until the second ventilatory threshold, after which performance is reduced. This inverted-U relationship appears valid for incremental and steady-state exercise, however, not for intermittent exercise. This study examined changes in psychomotor performance of team sport officials during a laboratory-based match simulation. Twelve elite Australian football (n = 5) and rugby league (n = 7) officials (32.5 ± 5.5 years; 180.0 ± 6.8 cm; 78.8 ± 7.6 kg) completed the match simulation on a non-motorised treadmill. Physiological measures were routinely taken, while psychomotor performance was assessed using the Eriksen flanker task (multiple-choice response time). Significant reductions (P < 0.05) were observed in distance covered and high-speed running during the second half when compared to the first. No significant differences (P > 0.05) in psychomotor performance at different time points were observed. Response time was significantly improved when running above 65% of maximal sprinting speed (P < 0.01). This data questions the application of the inverted-U hypothesis for intermittent exercise and suggests that the short high-intensity efforts may not result in the same physiological events that limit psychomotor performance during sustained high-intensity exercise. More so, the high-intensity efforts during the match protocol appeared to promote psychomotor performance during the intermittent exercise.
There is an interdependent relationship between insomnia and fatigue in the medical literature, but both remain distinct entities. Insomnia entails problematic sleep initiation, maintenance, or restoration with an accompanying decrease in perceived daytime function. Lethargy is a symptom that has a wide differential diagnosis that heavily overlaps with cancer-related fatigue; however, insomnia may contribute to worsened fatigue and lethargy in cancer patients. Insomnia is a major risk factor for mood disturbances such as depression, which may also contribute to lethargy in this at-risk population. The pathophysiology of fatigue and insomnia is discussed in this review, including their differential diagnoses as well as the emerging understanding of the roles of neurotransmitters, branched-chain amino acids, and inflammatory cytokines. Treatment approaches for insomnia and fatigue are also discussed and reviewed, including the role of hypnotics, psychotropics, hormonal agents, and alternative therapies.
The immediate and short-term after effects of a bout of aerobic exercise on young adults’ information processing were investigated. Seventeen participants performed an auditory two-choice reaction time (RT) task before, during, and after 40 min of ergometer cycling. In a separate session, the same sequence of testing was completed while seated on an ergometer without pedalling. Results indicate that exercise (1) improves the speed of reactions by energizing motor outputs; (2) interacts with the arousing effect of a loud auditory signal suggesting a direct link between arousal and activation; (3) gradually reduces RT and peaks between 15 and 20 min; (4) effects on RT disappear very quickly after exercise cessation; and (5) effects on motor processes cannot be explained by increases in body temperature caused by exercise. Taken together, these results support a selective influence of acute aerobic exercise on motor adjustment stage.
The purpose of this study was to investigate whether short-term amino acid supplementation could maintain a short-term net anabolic hormonal profile and decrease muscle cell damage during a period of high-intensity resistance training (overreaching), thereby enhancing recovery and decreasing the risk of injury and illness. Eight previously resistance trained males were randomly assigned to either a high branched chain amino acids (BCAA) or placebo group. Subjects consumed the supplement for 3 weeks before commencing a fourth week of supplementation with concomitant high-intensity total-body resistance training (overreaching) (3 x 6-8 repetitions maximum, 8 exercises). Blood was drawn prior to and after supplementation, then again after 2 and 4 days of training. Serum was analyzed for testosterone, cortisol, and creatine kinase. Serum testosterone levels were significantly higher (p < 0.001), and cortisol and creatine kinase levels were significantly lower (p < 0.001, and p = 0.004, respectively) in the BCAA group during and following resistance training. These findings suggest that short-term amino acid supplementation, which is high in BCAA, may produce a net anabolic hormonal profile while attenuating training-induced increases in muscle tissue damage. Athletes' nutrient intake, which periodically increases amino acid intake to reflect the increased need for recovery during periods of overreaching, may increase subsequent competitive performance while decreasing the risk of injury or illness.
Previous studies have shown that sustained exercise in human subjects causes an increase in the plasma concentration ratio of free tryptophan: other large neutral amino acids [including the branched-chain amino acids (BCAA)]. This should favour the transport of tryptophan into the brain and also the synthesis of 5-hydroxytryptamine, which is thought to contribute to fatigue during prolonged exercise. A mixture of the three BCAA was given to subjects during a 30-km cross-country race or a marathon (42.2 km) and the effects on mental and physical performances were measured. The mental performance, measured as the performance in the Stroop Colour and Word Test (CWT), was improved after, as compared to before the 30-km cross-country race when a BCAA supplement was given during the race, whereas the CWT scores were similar before and after in the placebo group. The running performance in the marathon was improved for the "slower" runners (3.05 h-3.30 h) when BCAA was taken during the race; however, there was no significant effect on the performance in the "faster" runners (less than 3.05 h). The results showed that both mental and physical performance was improved by an intake of BCAA during exercise. In addition, the effects of exercise on the plasma concentration of the aromatic amino acids were altered when a BCAA supplement was given during the marathon.
It has been suggested that an elevated concentration of the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) in specific areas of the brain may contribute to the development of central/mental fatigue during and after sustained exercise. Supplementation with branched-chain amino acids (BCAAs) should prevent the exercise-induced increase in the plasma concentration ratio of free tryptophan to other large neutral amino acids (including BCAAs) and thereby prevent an elevation in the level of 5-HT in the brain. In this study, subjects were given either a mixture of BCAAs in a carbohydrate solution or a placebo drink that contained only carbohydrates during a 30-km cross-country race. Several tasks to measure cognitive performance were performed before and after the race. When subjects were supplied with BCAAs, their performance in the different parts of the color-word test (words, colors and color words) was improved by an average of 3-7% (p < 0.05) after exercise, whereas there was no difference in performance before and after exercise in the subjects who were given the placebo. Furthermore, the experimental group, supplied with BCAAs, maintained their performance in the shape-rotation and figure-identification tasks, whereas an impairment in performance in these tests by 25% (p < 0.05) and 15% (p < 0.05), respectively, was found in the subjects who received the placebo. Thus, BCAA supplementation seemed to have an effect on the more complex tasks, whereas no effect could be detected on the less demanding tasks. However, an intake of BCAAs during exercise modified only slightly the exercise-induced changes in mood.
Two experiments were carried out to examine the effect of moderate and maximal exercise on the cognitive performance of experienced soccer players. Experiment 1 examined the speed and visual search in familiar (game) and unfamiliar (non-game) contexts. Participants had to detect, as quickly as possible, the presence or absence of a ball in tachistoscopically presented slides. Participants were tested at rest and while exercising at 70 and 100% maximum power output. A main effect of exercise intensity was demonstrated and Tukey post-hoc tests showed that performance during maximal exercise was significantly better than in the other two conditions. We concluded that exercise significantly improves speed of visual search. Experiment 2 examined the effects of exercise on speed of search, speed of decision following ball detection, overall speed of decision and accuracy of decision at rest and while exercising at 70 and 100% maximum power output. A repeated-measures multivariate analysis of variance and Tukey post-hoc tests showed that performance during exercise was significantly better than at rest. Observation of the separate univariate analyses of variance demonstrated that most of the variance could be accounted for by overall speed of decision and speed of decision after ball detection. We concluded that exercise induces not only an improvement in a simple task, like speed of visual search, but also an overall increase in speed of information processing. Theories concerning the effect of emotionally induced arousal on cognitive performance do not accurately predict the effect of physically induced arousal on cognitive tasks.
Previous investigations from this laboratory have demonstrated that during graded exercise with exercise intensities increasing every 3 min until exhaustion the multiple choice reaction time (RT) decreased until the intensity exceeded the lactate threshold (LT) by approximately 25%, and then rapidly increased. The aim of this study was to follow up changes in RT during prolonged exercise at constant intensities above and below LT and to relate these changes to changes in venous blood lactate [La-]b, and plasma catecholamine [CA]pl concentration responses to the exercise. For this purpose eight young soccer players exercised for 20-min on a cycle ergometer at 10% above LT, and nine exercised for 60 min at an intensity 30% below LT. During both tests RT, heart rate (HR), as well as [La-]b, and [CA]pl were measured. Above LT, RT decreased from the 5th min until the end of exercise, whilst HR, [La-]b, and [CA]pl increased progressively. Significant inverse correlations were ascertained between RT and plasma adrenaline (r = -0.651) and noradrenaline concentrations (r = -0.678). During exercise below LT, RT decreased up to approximately 40 min, then it reached a nadir, and stabilized at this level. This was accompanied by only small changes in [La-]b and [CA]pl. The present findings would indicate that young athletes are able to maintain for a relatively long time, or even increase, their psychomotor performance during endurance exercise both below and above the LT.
The aim of the present study was to examine the effects of prolonged exercise at the ventilatory threshold and carbohydrate ingestion on single (SRT) and choice (CRT) reaction time. Eight well-trained triathletes completed three testing sessions within a 3-week period. Maximal oxygen uptake was determined in the first test, whereas the second and the third sessions were composed of a 100-min run (treadmill 15 min, overground 70 min, treadmill 15 min) performed at the velocity associated with the ventilatory threshold. During these submaximal tests, the subjects ingested (in random order) 8 ml x kg(-1) body weight of either a placebo (Pl) or 5.5% carbohydrate (CHO) solution prior to the first submaximal run and 2 ml x kg(-1) body weight every 15 min after that. The cognitive tasks were performed before and after exercise for CRT, and before, during each submaximal run and after exercise for SRT. Furthermore, at the end of each submaximal test subjects were asked to report their rating of perceived exertion (RPE). Results showed a significant positive effect of CHO ingestion on RPE and CRT performance at the end of exercise, while no effect of exercise duration was found in the Pl condition. After a 100-min run, during the CHO condition, CRT mean (SD) group values decreased from 688.5 (51) ms to 654 (63) ms, while during the Pl condition, RPE mean group values increased from 11 (2) to 16 (1.02) and CRT mean values remained stable [688 (104) ms vs 676 (73.4) ms, P > 0.05]. No similar effect was observed for SRT. These results suggest that CHO-electrolyte ingestion during a 100-min run results in an improvement in the complex cognitive performance measured at the end of that run.
BCAAs (leucine, isoleucine, and valine), particularly leucine, have anabolic effects on protein metabolism by increasing the rate of protein synthesis and decreasing the rate of protein degradation in resting human muscle. Also, during recovery from endurance exercise, BCAAs were found to have anabolic effects in human muscle. These effects are likely to be mediated through changes in signaling pathways controlling protein synthesis. This involves phosphorylation of the mammalian target of rapamycin (mTOR) and sequential activation of 70-kD S6 protein kinase (p70 S6 kinase) and the eukaryotic initiation factor 4E-binding protein 1. Activation of p70 S6 kinase, and subsequent phopsphorylation of the ribosomal protein S6, is associated with enhanced translation of specific mRNAs. When BCAAs were supplied to subjects during and after one session of quadriceps muscle resistance exercise, an increase in mTOR, p70 S6 kinase, and S6 phosphorylation was found in the recovery period after the exercise with no effect of BCAAs on Akt or glycogen synthase kinase 3 (GSK-3) phosphorylation. Exercise without BCAA intake led to a partial phosphorylation of p70 S6 kinase without activating the enzyme, a decrease in Akt phosphorylation, and no change in GSK-3. It has previously been shown that leucine infusion increases p70 S6 kinase phosphorylation in an Akt-independent manner in resting subjects; however, a relation between mTOR and p70 S6 kinase has not been reported previously. The results suggest that BCAAs activate mTOR and p70 S6 kinase in human muscle in the recovery period after exercise and that GSK-3 is not involved in the anabolic action of BCAAs on human muscle.
It is clear that the cause of fatigue is complex, influenced by events occurring in both the periphery and the central nervous system. Work conducted over the last 20 years has focused on the role of brain serotonin and catecholamines in the development of fatigue, and the possibility that manipulation of neurotransmitter precursors may delay the onset of fatigue. While there is some evidence that branched-chain amino acid and tyrosine ingestion can influence perceived exertion and some measures of mental performance, the results of several apparently well-controlled laboratory studies have not demonstrated a positive effect on exercise capacity or performance under temperate conditions. As football is highly reliant upon the successful execution of motor skills and tactics, the possibility that amino acid ingestion may help to attenuate a loss in cognitive function during the later stages of a game would be desirable, even in the absence of no apparent benefit to physical performance. There are several reports of enhanced performance of high-intensity intermittent exercise with carbohydrate ingestion, but at present it is difficult to separate the peripheral effects from any potential impact on the central nervous system. The possibility that changes in central neurotransmission play a role in the aetiology of fatigue when exercise is performed in high ambient temperatures has recently been examined, although the significance of this in relation to the pattern of activity associated with football has yet to be determined.
Brain serotonin has been suggested to play an important role in the central fatigue. Synthesis of this neurotransmitter is stimulated by increased availability of tryptophan (TR). During exercise plasma level of free TR increases, whilst that of BCAA decreases. Since BCAA competitively inhibit TR transport through the blood-brain barrier, attempts have been made to attenuate central fatigue during prolonged exercise by BCAA supplementation. The aim of this study was to find out whether BCAA supplementation influences psychomotor performance, determined by the multiple choice reaction time (MRT), during a short-term exercise. Sixteen male subjects performed twice graded exercise till volitional exhaustion with the work load increasing by 50 W every 3 rain starting from 50 W. Oxygen uptake and heart rate were continuously recorded. One hour before exercise the subjects received either 7 g of BCAA or placebo in a double blind manner. MRT was measured immediately before exercise, at each exercise load and during recovery period. BCAA ingestion shortened MRT at rest in comparison with placebo (277±9 vs. 296±10 ms, P<0.05). Both after BCAA and placebo, MRT was decreasing during exercise until work load of 60-80% of maximal load and then it rapidly increased. After BCAA the shortest MRT occurred at higher exercise load than after placebo (253±9 vs. 216±10 W, P<0.001). Maximal work load attained during the test, oxygen uptake and heart rate were not affected by BCAA. In conclusion, supplementation with BCAA improves psychomotor performance at rest and delays its decrement at high exercise intensities.
The authors examined the effect of branched-chain amino acid (BCAA) supplementation on squat-exercise-induced delayed-onset muscle soreness (DOMS) using 12 young, healthy, untrained female participants. The experiment was conducted with a crossover double-blind design. In the morning on the exercise-session day, the participants ingested either BCAA (isoleucine:leucine:valine = 1:2.3:1.2) or dextrin at 100 mg/kg body weight before the squat exercise, which consisted of 7 sets of 20 squats/set with 3-min intervals between sets. DOMS showed a peak on Days 2 and 3 in both trials, but the level of soreness was significantly lower in the BCAA trial than in the placebo. Leg-muscle force during maximal voluntary isometric contractions was measured 2 d after exercise (Day 3), and the BCAA supplementation suppressed the muscle-force decrease (to ~80% of the value recorded under the control conditions) observed in the placebo trial. Plasma BCAA concentrations, which decreased after exercise in the placebo trial, were markedly elevated during the 2 hr postexercise in the BCAA trial. Serum myoglobin concentration was increased by exercise in the placebo but not in the BCAA trial. The concentration of plasma elastase as an index of neutrophil activation appeared to increase after the squat exercise in both trials, but the change in the elastase level was significant only in the placebo trial. These results suggest that muscle damage may be suppressed by BCAA supplementation.
The purpose of this study was to determine whether branched-chain amino acid (BCAA) supplementation affects aerobic performance, ratings of perceived exertion (RPE), or substrate utilization as compared with an isocaloric, carbohydrate (CHO) beverage or a noncaloric placebo (PLAC) beverage. Nine untrained males performed three 90-minute cycling bouts at 55% VO₂ peak followed by 15-minute time trials. Subjects, who were blinded to beverage selection, ingested a total of 200 kcal via the CHO or BCAA beverage before and at 60 minutes of exercise or the PLAC beverage on the same time course. RPE and metabolic measurements were taken every 15 minutes during steady-state exercise, and each of the trials was separated by 8 weeks. Plasma glucose and BCAA concentrations were measured pre- and post-exercise. A greater distance (4.6 ± 0.6 km) was traveled in the time-trial during the CHO trial than the PLAC trial (3.9 ± 0.4 km) (p < 0.05). There was no difference between the BCAA (4.4 ± 0.5 km) and PLAC trials. RPE was reduced at the 75-minute and 90-minute mark during the BCAA trial as compared with the PLAC trial. There were no significant differences found for the trial vs. time interaction in regard to respiratory exchange ratio. Thus, CHO supplementation improves performance in a loaded time-trial as compared with a PLAC beverage. BCAA supplementation, although effective at increasing blood concentrations of BCAA, did not influence aerobic performance but did attenuate RPE as compared with a PLAC beverage.
During aerobic exercise with increasing intensities choice reaction time (CRT) progressively shortens up to 60-80% of maximal workload, and then it rapidly increases. The aim of this study was to determine whether workload associated with the shortest CRT operationally called "the psychomotor fatigue threshold" is related to the metabolic response to exercise. Thirteen male soccer players (aged 23.3 + or - 1.0 yrs) participated in this study. Before and after 6 weeks of training in the pre-competition period they underwent treadmill test at 0 grade with running speed increasing every 3 min by 2 km/h starting from 6 km/h until exhaustion. At each stage of exercise CRT, heart rate, respiratory gas exchange and blood lactate [LA] were measured and the workload corresponding to [LA] of 4 mmol/l (OBLA) was recorded. After training, CRT was significantly shortened at rest (from m + or - SEM = 345 + or - 12 to 317 + or - 12 ms) and during exercise (from 304 + or - 10 to 285 + or - 11 ms at the psychomotor fatigue threshold and from 359 + or - 13 to 331 + or - 13 ms, p<0.001 at the last stage). Both OBLA and the psychomotor fatigue threshold were shifted towards greater running velocities (by 0.92 + or - 0.26 and 0.85 + or - 0.22 km/h, respectively). The psychomotor fatigue threshold exceeded OBLA both before and after training. Significant correlations were ascertained between OBLA and psychomotor fatigue threshold (r = 0.97) and between the changes in OBLA occurring during training and those in psychomotor fatigue threshold (r = 0.88). It is concluded that endurance training not only increases exercise tolerance due to its influence on metabolism but also facilitates psychomotor performance during heavy exercise.
The purpose of this study was to examine the role of branched-chain amino acid (BCAA) supplementation during recovery from intense eccentric exercise.
Twenty-four non-weight-trained males were assigned to one of two groups: one group (supplementary, SUP) ingested BCAA beverages (n = 12); the second group (placebo, PLA) ingested artificially flavored water (n = 12). Diet was controlled throughout the testing period to match habitual intake. The eccentric exercise protocol consisted of 12 x 10 repetitions of unilateral eccentric knee extension exercise at 120% concentric one repetition maximum. On the day of the exercise, supplements were consumed 30 min before exercise, 1.5 h after exercise, between lunch and dinner, and before bed. On the following 2 d, four supplements were consumed between meals. Muscle soreness, muscle function, and putative blood markers of muscle damage were assessed before and after (1, 8, 24, 48, and 72 h) exercise.
Muscle function decreased after the eccentric exercise (P < 0.0001), but the degree of force loss was unaffected by BCAA ingestion (51% +/- 3% with SUP vs -48% +/- 7% with PLA). A decrease in flexed muscle soreness was observed in SUP compared with PLA at 48 h (21 +/- 3 mm vs 32 +/- 3 mm, P = 0.02) and 72 h (17 +/- 3 mm vs 27 +/- 4 mm, P = 0.038). Flexed muscle soreness, expressed as area under the curve, was lower in SUP than in PLA (P = 0.024).
BCAA supplementation may attenuate muscle soreness, but it does not ameliorate eccentric exercise-induced decrements in muscle function or increases in reputed blood markers of muscle damage, when consumed before exercise and for 3 d after an eccentric exercise bout.
Some researchers have reported that moderate physical exercise improves cognitive function, and that exercise at high intensity beyond the optimal point attenuates performance, in an inverted U-relationship. The optimal intensity of physical exercise for cognitive function might be related closely to the anaerobic threshold. It has been regarded as an extremely useful index for effective training intensity in cardiorespiratory fitness. This review specifically addresses acute physical exercise around the anaerobic threshold in healthy subjects and its effects on task performance during or after exercise. We discuss physiological factors for the facilitating effect of moderate exercise on cognitive function, which indicates the initial basis in complicated mechanisms of the benefits of physical exercise on cognitive performance.
Although a generally positive effect of acute exercise on cognitive performance has been demonstrated, the specific nature of the relationship between exercise-induced arousal and cognitive performance remains unclear This study was designed to identify the relationship between exercise-induced arousal and cognitive performance for the central and peripheral components of a response time task at two different levels of task difficulty. Sixteen male participants performed both simple and choice response time tasks at eight different arousal levels (from 20% to 90% heart rate reserve). Performance on the simple and choice response time tasks was examined after fractionating the response time into its central component, premotor time, and peripheral components, motor, and movement time. A priori trend analysis was used to test both linear and quadratic relationships. Results indicated that exercise-induced arousal has a positive influence on the peripheral components of response time tasks; however it has a limited impact on the central components of these tasks.
A reliable, simple, and rapid enzymatic method is described for the microdetermination of serum free fatty acids. The principle of the method is based on the activation of free fatty acids by a bacterial acyl-CoA synthetase (EC 6.2.1.3). The reaction is followed as production of AMP using the myokinase-pyruvate kinase-lactate dehydrogenase system as an indicator reaction. Results on the determination using human and rabbit sera showed a close correlation with the chemical colorimetric method.
Seven healthy subjects exercised to exhaustion on a bicycle ergometer at a power output corresponding to 70% of maximum oxygen uptake after administration of either a placebo or 20 mg of paroxetine, a serotonin re-uptake inhibitor. Exercise time after paroxetine (median 94 min; range 84-127 min) was less (P < 0.05) than after placebo (median 116 min; range 86-133 min). The metabolic and cardiorespiratory responses to exercise were the same in both trials. This result supports the suggestion that there is a central component to fatigue which is mediated by the activity of serotoninergic neurones.
Arterial concentrations and substrate exchange across the leg and splanchnic vascular beds were determined for glucose, lactate, pyruvate, glycerol, individual acidic and neutral amino acids, and free fatty acids (FFA) in 6 subjects at rest and during 4 hr of exercise at approximately 30% of maximal oxygen uptake. FFA turnover and regional exchange were evaluated using 14C labeled oleic acid. It is concluded that during prolonged exercise at a low work intensity blood glucose levels fall because hepatic glucose output fails to keep up with augmented glucose utilization by the exercising legs, a large portion of hepatic glycogen stores is mobilized and an increasing fraction of the splanchnic glucose output is derived from gluconeogenesis, blood borne substrates in the form of glucose and FFA account for a major part of leg muscle metabolism, the relative contribution from FFA increasing progressively, and augmented secretion of glucagon may play an important role in the metabolic adaptation to prolonged exercise by its stimulatory influence on hepatic glycogenolysis and gluconeogenesis.
1. An increased uptake of tryptophan in the brain may increase serotoninergic activity and recently has been suggested to be a cause of fatigue during prolonged exercise. The present study, therefore, investigates whether ingestion of tryptophan or the competing branched-chain amino acids (BCAAs) affect performance. Ten endurance-trained male athletes were studied during cycle exercise at 70-75% maximal power output, while ingesting, ad random and double-blind, drinks that contained 6% sucrose (control) or 6% sucrose supplemented with (1) tryptophan (3 g l-1), (2) a low dose of BCAA (6 g l-1) or (3) a high dose of BCAA (18 g l-1). 2. These treatments greatly increased the plasma concentration of the respective amino acids. Using the kinetic parameters of transport of human brain capillaries, BCAA supplements were estimated to reduce brain tryptophan uptake at exhaustion by 8-12%, while tryptophan ingestion caused a 7- to 20-fold increase. Exercise time to exhaustion was not different between treatments (122 +/- 3 min). 3. The data suggest that manipulation of tryptophan supply to the brain either has no additional effect upon serotoninergic activity during prolonged exhaustive exercise or that manipulation of serotoninergic activity functionally does not contribute to mechanisms of fatigue.
Twenty-two male soccer players (mean age 21.3 yrs) performed an incremental, multistage bicycle ergometer exercise test with work load increasing by 50 W, until volitional exhaustion. The exercise stages lasted 3 min and were separated by 1 min resting periods. Before exercise and during each load an audio-visual five-choice reaction task was administered to assess subjects' psychomotor performance. During resting intervals venous blood samples were taken for lactate (LA), adrenaline (A) and noradrenaline (NA) determinations. It was found that reaction time (RT) decreased gradually during exercise reaching its minimum (approx. 87% of pre-exercise value) at load 236 W (approx. 75% VO2max, HR 164 beats/min). Then, it increased rapidly, exceeding the resting level by 18%. The work load and heart rate (HR) associated with the minimal RT were higher (p < 0.001) than work load and HR associated with the LA threshold (by 46 W and 17 beats/min, respectively). Plasma A and NA showed an exponential increase during exercise with thresholds at 204 and 208 W, respectively (HR 149 and 154 beats/min). Work load at which plasma NA threshold occurred was significantly higher than the LA threshold but it did not differ from the work load associated with the minimal RT. Conversely, plasma A threshold was lower than the load of the minimal RT but did not differ significantly from LA threshold. It is concluded that young athletes continue to improve their psychomotor performance during exercise even at heavy work loads exceeding anaerobic, and plasma adrenaline thresholds. A relationship between reaction time and plasma catecholamines fits the U-shape curve.
In prolonged exercise the plasma level of branched-chain amino acids (BCAA) may fall and that of fatty acid increases: the latter increases the free tryptophan level, so that the plasma concentration ratio, free tryptophan/BCAA may increase leading to higher levels of tryptophan and therefore of 5-hydroxytryptamine (5-HT) in brain. The latter increases the activity of some 5-HT neurons in the brain which can cause sleep and which could, therefore, increase the mental effort necessary to maintain athletic activity. Drinks containing branched-chain amino acids should restore vigor to athletes whose performance is depressed by an excess of cerebral 5-HT. Recent work suggests that intake of branched-chain amino acids may improve performance in slower runners in the marathon and decrease perceived physical and mental exertion in laboratory experiments. This suggestion is supported by pharmacological manipulations that result in either increased or decreased physical performance.
On two occasions, seven male endurance-trained cyclists performed exhaustive exercise on a cycle ergometer in the morning after they had performed a bout of exercise the preceding evening in an attempt to lower the muscle glycogen stores. The subjects exercised at a work rate corresponding to approximately 70% of their maximal oxygen uptake for 60 min, followed by another 20 min of maximal exercise. During exercise the subjects were given either a solution of branched-chain amino acids (BCAAs) or flavoured water (placebo). Every 10 min during exercise the subjects rated their perceived exertion and mental fatigue on two different Borg scales. During the 60 min exercise at a given work rate the subjects ratings of perceived exertion when they were given BCAAs were 7% lower, and their ratings of mental fatigue were 15% lower than when they were given placebo. In addition, the performance in the colour task of Stroops Colour Word Test performed after exercise was improved when BCAAs had been ingested during exercise, compared with the results from the placebo trial. There was no difference in the physical performance between the two trials measured as the amount of work done during the last 20 min of exercise when the subjects performed at their maximum. The plasma concentration ratio of free tryptophan/BCAAs, which increased by 45% during exercise and by 150% 5 min after exercise in the placebo trial, remained unchanged or even decreased when BCAAs were ingested.
Effects of a serotonin re-uptake inhibitor and oral amino acid supplementations on physical and mental performance as well as neuroendocrine variables were investigated. 10 male subjects cycled in four trials until exhaustion. Participants ingested a placebo in trial (T) I, 20 mg paroxetine in T II, 21 g branched-chain amino acids (BCAA) in T III and 20g tyrosine (TYR) in T IV. Heart rate, capillary lactate, plasma insulin, free fatty acids, glucose, serotonin and beta-endorphin did not differ in trials. Plasma ammonia increments during exercise were higher in T III. Plasma BCAA in T III and plasma TYR in T IV were increased after 30 min of exercise according to the supplemented substances. In contrast to all other trials, the ratio of plasma free TRP/BCAA did not increase in T III. Plasma TYR/BCAA was augmented in T IV and decreased in T III after 30 min of exercise, whereas it did not change in T I and II. Plasma prolactin (PRL), growth hormone, cortisol, adrenocorticotropic hormone, norepinephrine and epinephrine increased during all trials. Plasma PRL increments were higher in T IV. Exhaustion was reached earlier in T II. No significant differences were found between other trials. Drive during psychometric testing subsequent to exercise was improved in T III and IV. The results indicate that fatigue during endurance exercise was increased by pharmacological augmentation of the brain serotonergic activity. However, a reduction of 5-HT synthesis via BCAA supplementation did not affect physical fatigue. TYR administration did not alter physical performance either although plasma PRL increments suggest that changes in the monoaminergic system were induced. Precaution is necessary before assuming an ergogenic value of amino acids.
Fatigue from voluntary muscular effort is a complex phenomenon involving the central nervous system (CNS) and muscle. An understanding of the mechanisms within muscle that cause fatigue has led to the development of nutritional strategies to enhance performance. Until recently, little was known about CNS mechanisms of fatigue, even though the inability or unwillingness to generate and maintain central activation of muscle is the most likely explanation of fatigue for most people during normal daily activities. A possible role of nutrition in central fatigue is receiving more attention with the development of theories that provide a clue to its biological mechanisms. The focus is on the neurotransmitter serotonin [5-hydroxytryptamine (5-HT)] because of its role in depression, sensory perception, sleepiness, and mood. Nutritional strategies have been designed to alter the metabolism of brain 5-HT by affecting the availability of its amino acid precursor. Increases in brain 5-HT concentration and overall activity have been associated with increased physical and perhaps mental fatigue during endurance exercise. Carbohydrate (CHO) or branched-chain amino acid (BCAA) feedings may attenuate increases in 5-HT and improve performance. However, it is difficult to distinguish between the effects of CHO on the brain and those on the muscles themselves, and most studies involving BCAA show no performance benefits. It appears that important relations exist between brain 5-HT and central fatigue. Good theoretical rationale and data exist to support a beneficial role of CHO and BCAA on brain 5-HT and central fatigue, but the strength of evidence is presently weak.
The aim of this study was to examine the effects of branched-chain amino acid (BCAA) supplementation on serum indicators of muscle damage after prolonged exercise. We hypothesized that BCAA supplementation would reduce the serum activities of intramuscular enzymes associated with muscle damage.
To test this hypothesis, sixteen male subjects were assigned to one of two groups: the supplemental group (consuming 12 g x d(-1) BCAA for 14 d in addition to their normal diet) or the control group (normal diet only). Baseline serum creatine kinase (CK) and lactate dehydrogenase (LDH), shown to be accurate indicators of muscle damage, were determined during the week before the exercise test. The exercise test was administered on day seven and required the subjects to cycle for 120 min on an ergometer at approximately 70% VO2max. Blood samples were taken prior to and immediately following exercise and at 1 hr, 2 hrs, 3 hrs, 4 hrs, 1 d, 3 d, 5 d and 7 d postexercise. All subjects were required have their diets analyzed daily during the 14 d.
Dietary analyses indicated that all subjects consumed the recommended daily intake of BCAA (0.64 g x kg(-1)) in their normal diets. Baseline serum values for CK and LDH were not different between groups in the 7 d prior to the test (p>0.05). However there were significant increases (p<0.05) between the pre-exercise and postexercise values for LDH and CK until 5 d postexercise test. Importantly, the BCAA supplementation significantly reduced this change in LDH from 2hrs to 5 d posttest, and CK from 4 hrs to 5 d post-test (p<0.05).
These results indicate that supplementary BCAA decreased serum concentrations of the intramuscular enzymes CK and LDH following prolonged exercise, even when the recommended intake of BCAA was being consumed. This observation suggests that BCAA supplementation may reduce the muscle damage associated with endurance exercise.
A novel hypothesis for the role of branched-chain amino acids (BCAA) in regulating levels of the major excitatory neurotransmitter glutamate in the central nervous system is described. It is postulated that the branched-chain aminotransferase (BCAT) isoenzymes (mitochondrial BCATm and cytosolic BCATc) are localized in different cell types and operate in series to provide nitrogen for optimal rates of de novo glutamate synthesis. BCAA enter the astrocyte where transamination is catalyzed by BCATm, producing glutamate and branched-chain alpha-keto acids (BCKA). BCKA, which are poorly oxidized in astrocytes, exit and are taken up by neurons. Neuronal BCATc catalyzes transamination of the BCKA with glutamate. The products, BCAA, exit the neuron and return to the astrocyte. The alpha-ketoglutarate product in the neurons may undergo reductive amination to glutamate via neuronal glutamate dehydrogenase. Operation of the shuttle in the proposed direction provides a mechanism for efficient nitrogen transfer between astrocytes and neurons and synthesis of glutamate from astrocyte alpha-ketoglutarate. Evidence in favor of the hypothesis is: 1) The two BCAT isoenzymes appear to be localized separately in the neurons (BCATc) or in the astroglia (BCATm). 2) Inhibition of the shuttle in the direction of glutamate synthesis can be achieved by inhibiting BCATc using the neuroactive drug gabapentin. Although gabapentin does not inhibit BCATm, it does block de novo glutamate synthesis from alpha-ketoglutarate. 3) Conversely, gabapentin stimulates oxidation of glutamate. Inhibition of BCATc may allow BCKA to accumulate in the astroglia, thus facilitating conversion of glutamate to alpha-ketoglutarate.
There is an increasing interest in the mechanisms behind central fatigue, particularly in relation to changes in brain monoamine metabolism and the influence of specific amino acids on fatigue. Several studies in experimental animals have shown that physical exercise increases the synthesis and metabolism of brain 5-hydroxytryptamine (5-HT). Support for the involvement of 5-HT in fatigue can be found in studies where the brain concentration of 5-HT has been altered by means of pharmacological agents. When the 5-HT level was elevated in this way the performance was impaired in both rats and human subjects, and in accordance with this a decrease in the 5-HT level caused an improvement in running performance in rats. The precursor of 5-HT is the amino acid tryptophan and the synthesis of 5-HT in the brain is thought to be regulated by the blood supply of free tryptophan in relation to other large neutral amino acids (including the branched-chain amino acids, BCAA) since these compete with tryptophan for transport into the brain. Studies in human subjects have shown that the plasma ratio of free tryptophan/BCAA increases during and, particularly, after sustained exercise. This would favour the transport of tryptophan into the brain and also the synthesis and release of 5-HT which may lead to central fatigue. Attempts have been made to influence the 5-HT level by giving BCAA to human subjects during different types of sustained heavy exercise. The results indicate that ingestion of BCAA reduces the perceived exertion and mental fatigue during exercise and improves cognitive performance after the exercise. In addition, in some situations ingestion of BCAA might also improve physical performance; during exercise in the heat or in a competitive race when the central component of fatigue is assumed to be more pronounced than in a laboratory experiment. However, more experiments are needed to further clarify the effect of BCAA and also of tryptophan ingestion on physical performance and mental fatigue.
As shown in the first part of this review, well equilibrated neurotransmission in which 5-HT plays a dominant role is important for proper neuromodulation and adjustment of neuronal network elements. Adequate 5-HT system function supports regulation of intercommunicative neuronal transmission in the brain, which optimizes behavioral neuromodulation during and after different forms of exertions, thereby preventing transient dysregulation. Impairment of neuromodulation and neuronal network in the brain with transient dysfunctions or permanent substantial deficits at manifestation of various types of depression results from prevalent impairment of 5-HT neurotransmission and its central interaction with other neurotransmitter systems. Exercise-induced increase of free tryptophan (TRP) in blood occurs due to liberation from albumin, which is caused by adrenergically induced lipolysis of free fatty acids and results in higher free TRP uptake into the brain. Consecutively enhanced serotonin (5-HT) biosynthesis does not per se initiate mood impairment or central fatigue. It is suggested that in overtrained athletes central fatigue, mental deficiency and behavioral alterations with depressive mood are probably not primarily caused by metabolic and neuromuscular alterations. The primary trigger of these transient behavioural alterations might instead be initiated by a central exhaustive exercise stress which elicits impairment of complex neuromodulation, also afflicting the interaction of central neurotransmitters or hypothalamic neuropeptides and releasing factors. In a consecutive correction of the variation, the implication of the serotonergic system on the central neuromodular disturbance might improve or prevent the progressive course both in transient and in permanent mental disorders. However, an unsuccessful attempt to improve the depressive symptomatology leads mostly to an overproportional exaggeration of the behavioral changes.
We have previously shown in healthy volunteers that an amino acid mixture lacking tyrosine and phenylalanine reduces tyrosine availability to the brain and produces cognitive and neuroendocrine effects consistent with reduced dopamine function. This could provide a potential nutritional approach to disorders such as mania and schizophrenia, which are characterised by overactivity of dopamine pathways. The amino acid mixture we tested previously is unpalatable, whereas mixtures containing only branch chain amino acids can be made more palatable. However, the effects of such mixtures on dopamine function in humans have not been studied.
To assess the tolerability of different doses of branch chain amino acids and to measure their effects on neuroendocrine and cognitive measures sensitive to changes in dopamine function.
We used a randomised, double-blind, cross-over design in 12 healthy volunteers to assess the effect of single oral doses of 10 g, 30 g and 60 g branch chain amino acids on plasma prolactin and a test of spatial recognition memory
The branch chain amino acids were well tolerated. The availability of tyrosine for brain catecholamine synthesis decreased in a dose-related manner. As hypothesised, the drink increased both the plasma prolactin and the latency to respond on the spatial recognition memory task.
A drink containing branch chain amino acids is well tolerated in healthy volunteers and produces effects consistent with lowered dopamine function.
Branched-chain amino acids (BCAAs) influence brain function by modifying large, neutral amino acid (LNAA) transport at the blood-brain barrier. Transport is shared by several LNAAs, notably the BCAAs and the aromatic amino acids (ArAAs), and is competitive. Consequently, when plasma BCAA concentrations rise, which can occur in response to food ingestion or BCAA administration, or with the onset of certain metabolic diseases (e.g., uncontrolled diabetes), brain BCAA concentrations rise, and ArAA concentrations decline. Such effects occur acutely and chronically. Such reductions in brain ArAA concentrations have functional consequences: biochemically, they reduce the synthesis and the release of neurotransmitters derived from ArAAs, notably serotonin (from tryptophan) and catecholamines (from tyrosine and phenylalanine). The functional effects of such neurochemical changes include altered hormonal function, blood pressure, and affective state. Although the BCAAs thus have biochemical and functional effects in the brain, few attempts have been made to characterize time-course or dose-response relations for such effects. And, no studies have attempted to identify levels of BCAA intake that might produce adverse effects on the brain. The only "model" of very high BCAA exposure is a very rare genetic disorder, maple syrup urine disease, a feature of which is substantial brain dysfunction but that probably cannot serve as a useful model for excessive BCAA intake by normal individuals. Given the known biochemical and functional effects of the BCAAs, it should be a straightforward exercise to design studies to assess dose-response relations for biochemical and functional effects and, in this context, to explore for adverse effect thresholds.
Several factors have been identified to cause peripheral fatigue during exercise, whereas the mechanisms behind central fatigue are less well known. Changes in the brain 5-hydroxytryptamine (5-HT) level is one factor that has been suggested to cause fatigue. The rate-limiting step in the synthesis of 5-HT is the transport of tryptophan across the blood-brain barrier. This transport is influenced by the fraction of tryptophan available for transport into the brain and the concentration of the other large neutral amino acids, including the BCAAs (leucine, isoleucine, and valine), which are transported via the same carrier system. Studies in human subjects have shown that the plasma ratio of free tryptophan (unbound to albumin)/BCAAs increases and that tryptophan is taken up by the brain during endurance exercise, suggesting that this may increase the synthesis of 5-HT in the brain. Ingestion of BCAAs increases their concentration in plasma. This may reduce the uptake of tryptophan by the brain and also 5-HT synthesis and thereby delay fatigue. Accordingly, when BCAAs were supplied to human subjects during a standardized cycle ergometer exercise their ratings of perceived exertion and mental fatigue were reduced, and, during a competitive 30-km cross-country race, their performance on different cognitive tests was improved after the race. In some situations the intake of BCAAs also improves physical performance. The results also suggest that ingestion of carbohydrates during exercise delays a possible effect of BCAAs on fatigue since the brain's uptake of tryptophan is reduced.
Under resting conditions, the brain is protected against hypoxia because cerebral blood flow increases when the arterial oxygen tension becomes low. However, during strenuous exercise, hyperventilation lowers the arterial carbon dioxide tension and blunts the increase in cerebral blood flow, which can lead to an inadequate oxygen delivery to the brain and contribute to the development of fatigue.
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