Acta Physiol Scand 1991, 143, 225-226
Effect of branched-chain amino acid supplementation on mental performance E. B L O M S T R A N D , P. HASSMEN* and E. A. NEWSHOLME-f
Pripps Bryggerier, Research Laboratories, Bromma, * Department of Psychology, Stockholm University, Sweden and -f Department of Biochemistry, University of Oxford, U.K.
Several studies have indicated that physical exercise influences the synthesis and metabolism of brain monoamines, particularly 5-hydroxytryptamine (5H T ) (see Chaouloff 1989). An increase in the synthesis and concentration of 5-HT in the brain is suggested to contribute to the feeling of fatigue during sustained exercise (Blomstrand et a!. 1988, 1989). In these latter studies it was shown that the plasma concentration ratio of free tryptophan/other large neutral amino acids (LNAA) increased during exercise in both human subjects and rats. This increase should favour the transport of tryptophan into the brain and also the synthesis of 5-HT (see Newsholme & Leech 1983). If this ratio could be decreased, e.g. by increasing the plasma concentration of branched-chain amino acids (BCAA), this should decrease the transport of tryptophan into the brain, the synthesis of 5-HT and hence its concentration possibly in neurones that play a role in central fatigue. Six female subjects (age 22 1.6 yrs (mean SE), height 168 1.6 cm and weight 62 1.7 kg) were given either a 6% carbohydrate drink containing 7.5 g 1-l BCAA (40% valine, 35% leucine and 25% isoleucine) - the experimental drink, or a 6% carbohydrate solution -the placebo drink, during two games of soccer separated in time by 1 week. The experiment was carried out as a double-blind crossover design. The subjects were Swedish national standard soccer players and they were all field-players. The experiment was approved by the Ethics Committee at the Karolinska Institute, Stockholm. To assess the subjects’ mental performance the Stroop Colour and Word Test (CWT; Stroop 1935, Golden 1978) was used. The test was administered to the subjects 2-2.5 h before the game and within 45 min
+
Received 20 March 1991, accepted 27 June 1991. Key words : branched-chain amino acids, exercise, mental performance. Correspondence : Dr Eva Blomstrand, Pripps Bryggerier, Research Laboratories, S-161 86 Bromma, Sweden.
after the end of the game. At the same time blood samples were taken from an arm vein in five subjects. The blood samples were deproteinized with 57; trichloroacetic acid (1 :5) and plasma amino acid concentrations were determined by reversed-phase HPLC (Pfeifer et al. 1983). The plasma free tryptophan was separated from albumin-bound tryptophan as described previously (Blomstrand et al. 1988). Exercise caused an increase in the plasma concentration ratio of free tryptophan/other LNAA when the placebo was taken, while the ratio was decreased (due to the increased plasma concentration of BCAA), and at the end of exercise when the experimental drink was taken (Table 1). It should be noted that high values of free tryptophan were found in five blood samples that were taken at half-time, the average concentration being 9.3 pmol 1-l (range 6.513.3pmol I-’). The average amount of drink consumed per subject was 1.3 I, which was the same for both the experimental and placebo drink. The performance of the subjects in all parts of the CWT was improved after, in comparison to before, the game when the experimental drink was taken. No such effect was found when the subjects took the placebo (Table 2). Previously, improved performance in the CWT has been reported after physical exercise (Lichtman & Poser 1983). However, the present results do not agree with this as no improvement was found when the subjects took the placebo drink. However, this might be explained by the fact that 90 min of soccer is a more strenuous type of exercise than 45 min jogging which was the method employed by Lichtman & Poser (1983). On the other hand, when the subjects had taken the experimental drink during exercise, their performance in the CWT improved after in comparison to before the game, suggesting that an intake of BCAA during exercise can maintain the improved mental alertness caused by physical exercise. This effect of BCAA could be extremely important for mental performance in many types of sustained athletic events.
225
226
E. Blomstrand et al.
Table 1. Plasma concentrations of aromatic and branched-chain amino acids (BCAA) before and after a game of soccer The experimental drink consisted of a 6", carbohydrate solution with the addition of 7.5 g I-' of I3C4.i and the placebo of a 6",, carboh!drate solution Data are presented as meansfSE of means for file whlects Plasma concentrations (pmol 1 ') ~Valine Isoleucine Leucine ~
T \ p e of drinh
(,ondition -
~
-
Experimental ( n = i) Pre-exercise Post-exercirc Pre-exercise Placeho (ti = .5) Post-exercise
261 f 16 73 k9.3 143 k 16 647k63' 218+32* 310f37' 289f2.5 90f11 166+17 219f22" 58f7.Ix 112&13' Plasma concentrations (pmol It') ~_
.
T r ) ptophan T \ p e of drink
Condition
Free
Total
Tyrosine Phenylalanine
5.5kO.7 6.9k1.3 5.3f0.8 7.7*0.7*
64k3.6 58f5.8 64f7.6 63k4.7
76k1.6 66k6.3 86f13
.~
F.\perirnental ( n = .i) Pre-cxcrcisc Post-exercise Placebo ( 7 ~= 5) Pre-exercise Post-exercise
* P < 0.05 for post-
77f5.5
70k4.6 64f5.9 73k5.7 69k5.6
cs pre-exercise values (Student's t test).
T a b l e 2. Scores in the Stroop Colour and N'ord Test before and after a game of soccer. T h e test was repeated sewn rimes and the results are given as the average scores in the last six repetitions. For description of the drinks see Table I . Data are presented as means fSE of means for six subjects. Colour LVord Test Type of' drink
Condition
\Vord sheet
Colour sheet
Colour-word sheet
Experimental ( n = 6)
Pre-exercise Post-exercise Pre-exercise Post-exercise
154+7.7 164 k 7.5* l60k7.3 164k7.1
81.5f2.4 8.5.7 f 3.2' 85.9f4.4 85.9+5.3
60.9i3.4 65.1 i:3.7* 63.7k3.6 64.8k3.2
Placeho ( n = 6)
* P < 0.05 for
post-
1's
pre-exercise values (Student's t-test)
R E FE R EN CE S BI.OMSlRAUD, E., C ~ L S I N G ,F. & NEWSHOLME, E.A. 1988. Changes in plasma concentrations of aromatic and branched-chain amino acids during sustained esercise in man and their possible role in fatigue. -l(.L,t Ph.ysioI Sccinil 133, 115-121. BL.OMSTR411), E., PERRETT, D., PARRY-BILI.INGS, .\I. & \k.\\siioi,sw., E...i. 1989. Effect of sustained exercise on plasma amino acid concentrations and on 5 hydroxytryptamine metabolism in six different brain regions in the rat. Artu Physiol Scand 136, 473 481. Ct4.Ioi I A W F , F. 1Y89. Physical exercise and brain monoamincs. .4cti/ Physiol Srand 137, 1-13.
GOLDEN,C.J. 1978. The Stroop Color and Word Test: A .Manual for Clinical and Experimental uses. Stoelting, Chicago. LICHTMAK,S. & POSER,E.G. 1983. The effects of exercise on mood and cognitive functioning. J Psychosomatic Res 27, 43-52. NEWHOLM, E.,4. & LEECH,A.R. 1983. Biochemistry &r the Medical Sciences, pp. 78G-787. John Wiley, I Chichester. PFEIFER,R., KAROL,R., KORPI,J., BURGOYNE, R. & MCCOURT,D. 1983. Practical application of H P L C to amino acid analysis. A7n Lab (March), 77-84. STROOP,J.R. 1935. Studies of interference in serial verbal reactions. J ESP Psycho1 6, 643-661.
Effect of branched-chain amino acid supplementation on mental performance E. B L O M S T R A N D , P. HASSMEN* and E. A. NEWSHOLME-f
Pripps Bryggerier, Research Laboratories, Bromma, * Department of Psychology, Stockholm University, Sweden and -f Department of Biochemistry, University of Oxford, U.K.
Several studies have indicated that physical exercise influences the synthesis and metabolism of brain monoamines, particularly 5-hydroxytryptamine (5H T ) (see Chaouloff 1989). An increase in the synthesis and concentration of 5-HT in the brain is suggested to contribute to the feeling of fatigue during sustained exercise (Blomstrand et a!. 1988, 1989). In these latter studies it was shown that the plasma concentration ratio of free tryptophan/other large neutral amino acids (LNAA) increased during exercise in both human subjects and rats. This increase should favour the transport of tryptophan into the brain and also the synthesis of 5-HT (see Newsholme & Leech 1983). If this ratio could be decreased, e.g. by increasing the plasma concentration of branched-chain amino acids (BCAA), this should decrease the transport of tryptophan into the brain, the synthesis of 5-HT and hence its concentration possibly in neurones that play a role in central fatigue. Six female subjects (age 22 1.6 yrs (mean SE), height 168 1.6 cm and weight 62 1.7 kg) were given either a 6% carbohydrate drink containing 7.5 g 1-l BCAA (40% valine, 35% leucine and 25% isoleucine) - the experimental drink, or a 6% carbohydrate solution -the placebo drink, during two games of soccer separated in time by 1 week. The experiment was carried out as a double-blind crossover design. The subjects were Swedish national standard soccer players and they were all field-players. The experiment was approved by the Ethics Committee at the Karolinska Institute, Stockholm. To assess the subjects’ mental performance the Stroop Colour and Word Test (CWT; Stroop 1935, Golden 1978) was used. The test was administered to the subjects 2-2.5 h before the game and within 45 min
+
Received 20 March 1991, accepted 27 June 1991. Key words : branched-chain amino acids, exercise, mental performance. Correspondence : Dr Eva Blomstrand, Pripps Bryggerier, Research Laboratories, S-161 86 Bromma, Sweden.
after the end of the game. At the same time blood samples were taken from an arm vein in five subjects. The blood samples were deproteinized with 57; trichloroacetic acid (1 :5) and plasma amino acid concentrations were determined by reversed-phase HPLC (Pfeifer et al. 1983). The plasma free tryptophan was separated from albumin-bound tryptophan as described previously (Blomstrand et al. 1988). Exercise caused an increase in the plasma concentration ratio of free tryptophan/other LNAA when the placebo was taken, while the ratio was decreased (due to the increased plasma concentration of BCAA), and at the end of exercise when the experimental drink was taken (Table 1). It should be noted that high values of free tryptophan were found in five blood samples that were taken at half-time, the average concentration being 9.3 pmol 1-l (range 6.513.3pmol I-’). The average amount of drink consumed per subject was 1.3 I, which was the same for both the experimental and placebo drink. The performance of the subjects in all parts of the CWT was improved after, in comparison to before, the game when the experimental drink was taken. No such effect was found when the subjects took the placebo (Table 2). Previously, improved performance in the CWT has been reported after physical exercise (Lichtman & Poser 1983). However, the present results do not agree with this as no improvement was found when the subjects took the placebo drink. However, this might be explained by the fact that 90 min of soccer is a more strenuous type of exercise than 45 min jogging which was the method employed by Lichtman & Poser (1983). On the other hand, when the subjects had taken the experimental drink during exercise, their performance in the CWT improved after in comparison to before the game, suggesting that an intake of BCAA during exercise can maintain the improved mental alertness caused by physical exercise. This effect of BCAA could be extremely important for mental performance in many types of sustained athletic events.
225
226
E. Blomstrand et al.
Table 1. Plasma concentrations of aromatic and branched-chain amino acids (BCAA) before and after a game of soccer The experimental drink consisted of a 6", carbohydrate solution with the addition of 7.5 g I-' of I3C4.i and the placebo of a 6",, carboh!drate solution Data are presented as meansfSE of means for file whlects Plasma concentrations (pmol 1 ') ~Valine Isoleucine Leucine ~
T \ p e of drinh
(,ondition -
~
-
Experimental ( n = i) Pre-exercise Post-exercirc Pre-exercise Placeho (ti = .5) Post-exercise
261 f 16 73 k9.3 143 k 16 647k63' 218+32* 310f37' 289f2.5 90f11 166+17 219f22" 58f7.Ix 112&13' Plasma concentrations (pmol It') ~_
.
T r ) ptophan T \ p e of drink
Condition
Free
Total
Tyrosine Phenylalanine
5.5kO.7 6.9k1.3 5.3f0.8 7.7*0.7*
64k3.6 58f5.8 64f7.6 63k4.7
76k1.6 66k6.3 86f13
.~
F.\perirnental ( n = .i) Pre-cxcrcisc Post-exercise Placebo ( 7 ~= 5) Pre-exercise Post-exercise
* P < 0.05 for post-
77f5.5
70k4.6 64f5.9 73k5.7 69k5.6
cs pre-exercise values (Student's t test).
T a b l e 2. Scores in the Stroop Colour and N'ord Test before and after a game of soccer. T h e test was repeated sewn rimes and the results are given as the average scores in the last six repetitions. For description of the drinks see Table I . Data are presented as means fSE of means for six subjects. Colour LVord Test Type of' drink
Condition
\Vord sheet
Colour sheet
Colour-word sheet
Experimental ( n = 6)
Pre-exercise Post-exercise Pre-exercise Post-exercise
154+7.7 164 k 7.5* l60k7.3 164k7.1
81.5f2.4 8.5.7 f 3.2' 85.9f4.4 85.9+5.3
60.9i3.4 65.1 i:3.7* 63.7k3.6 64.8k3.2
Placeho ( n = 6)
* P < 0.05 for
post-
1's
pre-exercise values (Student's t-test)
R E FE R EN CE S BI.OMSlRAUD, E., C ~ L S I N G ,F. & NEWSHOLME, E.A. 1988. Changes in plasma concentrations of aromatic and branched-chain amino acids during sustained esercise in man and their possible role in fatigue. -l(.L,t Ph.ysioI Sccinil 133, 115-121. BL.OMSTR411), E., PERRETT, D., PARRY-BILI.INGS, .\I. & \k.\\siioi,sw., E...i. 1989. Effect of sustained exercise on plasma amino acid concentrations and on 5 hydroxytryptamine metabolism in six different brain regions in the rat. Artu Physiol Scand 136, 473 481. Ct4.Ioi I A W F , F. 1Y89. Physical exercise and brain monoamincs. .4cti/ Physiol Srand 137, 1-13.
GOLDEN,C.J. 1978. The Stroop Color and Word Test: A .Manual for Clinical and Experimental uses. Stoelting, Chicago. LICHTMAK,S. & POSER,E.G. 1983. The effects of exercise on mood and cognitive functioning. J Psychosomatic Res 27, 43-52. NEWHOLM, E.,4. & LEECH,A.R. 1983. Biochemistry &r the Medical Sciences, pp. 78G-787. John Wiley, I Chichester. PFEIFER,R., KAROL,R., KORPI,J., BURGOYNE, R. & MCCOURT,D. 1983. Practical application of H P L C to amino acid analysis. A7n Lab (March), 77-84. STROOP,J.R. 1935. Studies of interference in serial verbal reactions. J ESP Psycho1 6, 643-661.
