Download 1 Title page Effects of six weeks of β

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Title page
Effects of six weeks of β-alanine administration on VO2max, time to exhaustion and
lactate concentrations in male physical education students
Reza Ghiasvand 1, 2*
Gholamreza Askari 1, 2
Janmohamad Malekzadeh 3
Maryam Hajishafiee 1, 2
Pooya Daneshvar4
Fahimeh Akbari1, 2
Maryam Bahreynian 1, 2
*
Corresponding Author: Reza Ghiasvand, address: Department of Nutrition, School of Health, Isfahan
University of Medical Sciences, Hezar Jerib Street, Isfahan, Iran. Tel: 98-311-7922742, Fax: 98-3116682509, email: [email protected]
1. Department of Community Nutrition, School of Nutrition and Food Sciences, Isfahan
University of Medical Sciences, Isfahan, Iran
2. Food Security Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
3. Department of Nutrition, School of Health, Yasouj University of Medical Sciences,
Yasouj, Iran
4. Esfahan Sport Medicine Association, Isfahan, Iran
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Abstract
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Objectives
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Supplementation with β-alanine has been proposed to improve performance in some exercises
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such as cycling and running. Also, it has been demonstrated that great deals of proton ions are
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produced in the skeletal muscles during exercise that result in acidosis, whereas β-alanine may
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reduce this effect. Therefore, the aim of this study was to assess the effects of alanine
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supplementation on VO2max, time to exhaustion and lactate concentrations in male physical
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education students
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Methods
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Thirty nine male students volunteered for this study. Participants were supplemented orally for 6
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wk with either β-alanine or placebo (dextrose), randomly. VO2max, Time To Exhaustion (TTE)
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and lactate and glucose concentrations were measured before and after supplementation.
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Results
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Supplementation with β-alanine showed a significant increase in VO2max (p < 0.05) but a
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significant decrease in TTE and lactate concentrations (p < 0.05). A significant elevation in
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lactate concentrations, but a non significant increase in TTE was shown in placebo group.
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Plasma glucose concentrations didn’t change significantly in two groups after intervention.
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Conclusion
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It can be concluded that β-alanine supplementation can reduce lactate concentrations during
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exercise and thus can improve exercise performance in endurance athletes.
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Keywords
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β-alanine, supplementation, performance
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Running Title
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β-alanine and performance
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Introduction
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Ingestion of some amino acids have the presumably roles in performance improvement in
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athletes (Ivy et al. 2003; Koopman et al. 2004; Niles et al. 2001). Among them, β-alanine
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supplementation has been suggested to improve performance in high intensity exercises (Harris
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et al., 2003; Hill et al., 2005). On the other hand, it has been shown that large amounts of H+ are
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produced in the muscles during high-intensity exercise and result in pH reduction (Hultman and
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Sahlin 1980). There are many cellular pH buffers defend against exercise-induced acidosis
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(Parkhouse et al., 1985) include phosphocreatine, inorganic phosphates and histidine-
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containing dipeptides. Carnosine (β-alanyl-L-histidine) is the main histidine-containing dipeptide
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in humans (Quinn et al. 1992). Additionally, Hill et al. (2005) and Harris et al. (2005) showed
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that 28 days of β-alanine supplementation increased intramuscular levels of carnosine by nearly
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60%. Antioxidant function (Boldyrev et al., 1987), muscle contractility regulation (Batrukova and
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Rubstov, 1997) and pH buffering (Begum et al., 2005; Harris et al., 1990) are the possible
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physiological roles of carnosine in skeletal muscle. Thus, preventing of skeletal muscle acidity
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could be a possible role of carnosine in improving exercise performance (Suzuki et al., 2002;
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Harris et al., 2003).
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Doing exercise results in oxidative stress and muscle fatigue (Powers and Jackson 2008) that
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may be prevented by carnosine, due to its antioxidative properties (Kohen et al. 1988). On the
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other hand, β-alanine administration could increase carnosine content of skeletal muscles by
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40–80% (Harris et al. 2006; Hill et al. 2007; Derave et al. 2007). Increase of Carnosine
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concentrations in muscle, results in altered buffering capacity (Harris et al., 2006; Hill et al.,
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2007) and thus performance. Furthermore, some studies have shown that carnosine act as a
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Ca++ sensitizer for the sarcomeres in muscles, too (Dutka and Lamb 2004; Lamont and Miller
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1992) and thus could prevent of fatigue (Rubtsov 2001). However, synthesis of carnosine in
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muscle is limited by the availability rate of β-alanine that can be influenced by β-alanine
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supplementation (Bakardjiev and Bauer 1994; Dunnett and Harris 1999; Hill et al., 2007).
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While it has been estimated that carnosine is responsible for near ten percent of the total
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buffering capacity in human muscle (Hill et al., 2007), the importance of acidosis control in
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exercise performance is still controversial. There are few studies on β-alanine supplementation
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and its possible effects on endurance exercise; therefore, the purpose of this study was to
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assess the effects of β-alanine administration on VO2max, time to exhaustion and lactate
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concentrations in male physical education students.
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Materials and methods
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Thirty nine male physical education students volunteered for this investigation. These students
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were fit and active, but not involved in professional sports. Characteristics of the participants
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include age, weight and height were 21.1 ± 0.7 years, 71.8 ± 8.8 kg and 178 ± 7 cm for β-
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alanine (n = 20) and 21.9 ± 1.5 years, 74.9 ± 8.3 kg and 180 ± 5 cm for placebo group (n = 19),
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respectively (NS). Before initiating the study, all participants were informed of all procedures of
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the study and signed an informed consent. None of the participants had ingested β-alanine, or
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any other nutritional supplements, for a minimum of 3 months prior the initiation of the study.
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Participants were asked to abstain from exercise 24 h before trial initiation and to maintain their
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current physical activity and dietary patterns. Participants were asked to fill a “food record” for
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the 2 days before intervention. After pre-testing, the participants were randomly assigned to one
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of two groups: a) β-alanine (2 g/day), b) placebo (2 g dextrose per day). The supplements were
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same in appearance, and ingested four times per day for 42 consecutive days before post-
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testing. All participants completed all experiments, and there were no complaints of side-effects
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of the supplements.
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This study was a placebo-controlled, double-blind clinical trial. Participants were supplemented
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orally for 6 wk with either β-alanine (Ajinomoto, USA, Inc) or placebo (dextrose). The study was
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approved by the Ethics Committee (Esfahan Sport Medicine Association, Iran). Supplements
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were provided in capsules of 400 mg and were administered each day as five divided single
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doses, with at least 2 h in between ingestions. Thus, daily doses consisted of 2 g/day during the
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study. Venous blood samples were obtained from all participants between 5:00 and 6:00 p.m.,
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after intensive endurance exercising, at the baseline and after intervention. All measurements
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were done before the start of the supplementation (Pre) and after the intervention (Post).
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Prior to and following the supplementation protocol, participants performed a continuous graded
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exercise test (GXT) on an electronically braked cycle ergometer (Lode, The Netherlands) to
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determine VO2max and time to exhaustion (TTE).
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For each GXT, the primary power output was set at 30 watts and elevated 30 watts every two
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minutes until the participant couldn’t maintain the required power output at a pedaling rate of 70
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rpm due to fatigue.
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Plasma samples were obtained for the determination of plasma lactate and glucose
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concentrations immediately prior to each GXT and two minutes post-exercise.
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Glucose and lactate were analyzed using YSI auto-analyzer (Yellow Springs, OH).
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Dietary analyses were performed using Nutritionist IV software.
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Statistical analyses were conducted using the Statistical Program for the Social Sciences
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(SPSS version 13, Inc., Chicago, IL) computer software package. Data are presented as
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means ± standard deviation. Independent t test was used to analyze the differences in
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performance between the trials. Paired t test was used to analyze before and after test data for
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each group differences. An alpha level of p < 0.05 was considered statistically significant.
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Results
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Table 1 shows the mean±SD values of exercise performance indices for the pre- and post-
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supplementation. Supplementation with β-alanine demonstrated a significant increase in
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VO2max (p < 0.05) .On the other hand, TTE and lactate concentrations decreased after 6 weeks
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of supplementation with β-alanine (p < 0.05). The placebo group showed a significant increase
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in lactate concentrations (p < 0.05), but a non significant increase in TTE. No significant
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changes in plasma glucose concentrations were detected after exercise in two groups.
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The post-exercise concentrations of plasma lactate were significantly higher (p < 0.05) than
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baseline in two groups. However, the post-exercise concentrations of lactate were significantly
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lower (p < 0.05) during the alanine supplementation compared to the placebo group. Dietary
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intake before each trial was similar for energy and macronutrients (Table 2).
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Discussion
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Findings of our study suggest that supplementation with β-alanine may improve the endurance
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exercise performance as measured by the VO2max, TTE and plasma lactate concentrations.
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Several studies support our findings (Zoeller et al., 2007, Klein et al., 2009, Baguet et al., 2010,
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Derave et al. 2007).
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Also, Harris et al. (2006) showed that supplementation with creatine+β-alanine, resulted in
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significant increases (P<0.01) in muscle carnosine content. So that, the increased muscle
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carnosine content was accompanied with an improvement in VO2max and TTE in response to a
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maximal graded exercise test performed on a cycle ergometer. Their results were agreed with
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ours.
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Another study demonstrated that supplementation with both β-alanine and creatine improved
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cycling performance (TTE), too (Hill et al. (2005)).
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However, β-alanine administration alone improved performance just in the first minute of
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exercise (Harris et al., 2003). They concluded that this was due to H+ buffering by carnosine
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during this transitional period.
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Our data demonstrate that the significant improvements in the performance indices with β-
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alanine supplementation were due to pH reduction, too.
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The improvement in TTE seen in the placebo group participants appears to be related to their
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encouragement by our staff or due to psychological status.
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Also, the findings of the present study may have been influenced by the fluctuations in the
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skeletal muscle response to oral supplementation with β-alanine.
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Our data suggest that supplementation with β-alanine especially may delay the onset of fatigue
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and thus improve performance during incremental cycle exercise in men.
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The glucose concentrations didn’t change significantly in our study, maybe due to different
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individual response and insufficient dose or duration. The participants in this study, however,
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were male physical education students rather than untrained participants.
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Although we did not measure the muscle carnosine content, but according to the hypothesis, β-
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alanine supplementation would prevent the drop in intracellular pH during high-intensity
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contractions and results in less circulating acidosis finally due to elevation of myocellular
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carnosine content. It has long been suggested that the acidosis limits muscle contractility
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(Dennig et al., 1931). Furthermore, several studies have shown the pH regulation importance on
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performance during endurance exercise, by a pre-exercise alkalosis intervention (Messonnier et
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al., 2007).
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This suggests that the difference between groups is related to the presumable enhancement of
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muscle carnosine content (Harris et al. 2006; Baguet et al. 2009).
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Future studies should examine muscle carnosine levels along with VO2max and plasma lactate
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concentration during strenuous exercise with variable quantities of β-alanine supplementation.
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Also, further investigations are necessary to determine the effects of β-alanine supplementation
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during more prolonged and submaximal exercise.
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Conclusion
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Overall, it can be concluded from this study that β-alanine administration can reduce acidosis
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during high-intensity exercise and thus can improve exercise performance in endurance athletes
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and that 6 weeks of supplementation with β-alanine at the mentioned prescribed dose did not
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result in significant changes in glucose concentrations.
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Acknowledgments
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This study was financially supported by grants from the “Esfahan Sport Medicine Association”.
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There is not any conflict of interest for authors. The contribution of Mr. Mohammad
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Khoshnevisan, Mr. Ehsan Bayat and Mrs. Fatemeh Shahryarzadeh is greatly acknowledged.
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Table 1. Comparison of exercise performance indices, pre- and post-supplementation (mean
±SD)
β-alanine
variables
VO2max
Placebo
Pre
Post
Pre
Post
2.62 ± 0.82
2.79 ± 0.73a, b
2.85 ± 0.67
2.81 ± 0.79
(L.min-1)
TTE (sec)
923.6 ±237.5 992.4 ± 225.5 a, b 917.5 ± 243.8 926.5 ± 240.5 a
Lactate (mg/dl)
15.5 ± 6.2
Glucose (mg/dl) 79 ± 14
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a
b
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14.8 ± 7.1
36.0 ± 12.6 a, b
83 ± 11
84 ± 8
80 ± 14
Shows significant differences after exercise between two groups
Shows significant differences after exercise within a group
Table 2. Dietary intake of subjects for 2 days before intervention (Mean ± SD)
Trial
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27.9 ± 14.4a,b
Energy (kcal) Protein (g) Carbohydrates (g) Fat (g)
β-alanine 2,625 ± 820
105 ± 32
326 ± 185
105 ± 82
Placebo
99 ± 27
312 ± 154
102 ± 93
2,577 ± 625