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ORIGINAL ARTICLE
The effect of L-arginine supplementation on body composition
and performance in male athletes: a double-blinded
randomized clinical trial
N Pahlavani
1,2
, MH Entezari
1
, M Nasiri
3
, A Miri
4
, M Rezaie
5
, M Bagheri-Bidakhavidi
6
and O Sadeghi
7
BACKGROUND/OBJECTIVE: Athletes used a lot of dietary supplements to achieve the more muscle mass and improve their
athletic performance. The objective of this study was to investigate the effect of L-arginine supplementation on sport performance
and body composition in male soccer players.
SUBJECTS/METHODS: This double-blinded, randomized and placebo-controlled trial was conducted on 56 male soccer players,
with age range of 1635, who referred to sport clubs in Isfahan, Iran. Subjects were randomly assigned to either L-arginine or
placebo groups. Athletes received daily either 2 g per day L-arginine supplement or the same amount of placebo (maltodextrin) for
45 days. Sport performance and also body mass index (BMI), body fat mass (BFM) and lean body mass (LBM) were measured at the
beginning and end of the study. Also, 3-day dietary records were collected at three different time points (before, in the middle of,
and at the end of the study).
RESULTS: The mean age of subjects was 20.85 ± 4.29 years. Sport performance (VO
2
max) signicantly increased in L-arginine
supplementation group (4.12 ± 6.07) compared with placebo group (1.23 ± 3.36) (P= 0.03). This increase remained signicant even
after adjustment of baseline values, physical activity and usual dietary intake of subjects throughout the study. No signicant effect
of L-arginine supplementation was found on weight, BMI, BFM and LBM.
CONCLUSIONS: L-arginine supplementation (2 g per day) could increase the sport performance in male athletes, but had no effect
on anthropometric measurements, including BMI, BFM and LBM. So, further studies are needed to shed light our ndings.
European Journal of Clinical Nutrition (2017) 71, 544548; doi:10.1038/ejcn.2016.266; published online 25 January 2017
INTRODUCTION
The consumption of nutritional supplements has been enhanced
in recent year.
1
Most dietary supplements are used to increase the
maintenance of muscle force during both short-term and high-
intensity practices. Recently, investigations have been shown that
some supplements such as creatine monohydrate and hydro-
xymethylbutyrate (HMB) cause ergogenic effects during high-
intensity exercises.
2
One of the most common supplements that
showed positive effects on muscle protein metabolism is amino
acids.
3
L-arginine is one of semi-essential amino acid that used by all
cells mostly,
4
and is responsible for normally 57% of the total
amount of amino acids in common human diet. The bio-
availability of arginine intake from dietary sources is 60%.
5
Evidences have shown that L-arginine supplement can improve
the endothelial function, insulin secretion, oxidative stress and
inammation related to diabetes mellitus (DM), cardiovascular
disease (CVD) and auto-immune disorders.
613
Moreover, it was
depicted that L-arginine supplementation can affect the sport
performance and body composition but the data in this regard is
inconsistent and limited to western countries. In a clinical trial,
intake of daily 3 g per day L-arginine supplement for 15 days
reduced muscle fatigue and increased the sport performance in
men,
14
but another similar study reported no signicant effect of
6 g per day L-arginine supplementation on athletesperformance
during 3 days.
15
In addition, Elam et al. revealed that consumption
of 2 g per day L-arginine in combination with ornithine during the
5 weeks increase both the muscle strength and lean body mass
(LBM).
16
However, the effects of L-arginine supplementation on
sport performance were not considered in the mentioned study.
On the basis of our knowledge, today no study examine the
effects of 2 g per day L-arginine supplementation on sport
performance. Therefore, based on the L-arginine dosage used in
Elam et al. study,
16
and due to they concluded that increase the
duration of L-arginine supplementation can to be more effective
than increase the dosage of L-arginine, this clinical trial aimed
to evaluate the effects of 6 weeks L-arginine supplementation
(2 g per day) on both sport performance and body composition in
male soccer players. In present study, we hypothesized that 2 g
per day L-arginine supplementation during 6 weeks provides
better effects on sport performance and body composition
compared with other dosage using in previous studies.
1
Food Security Research Center and Department of Clinical Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran;
2
Department of
Nutrition, Faculty of Medicine, Mashad University of Medical Sciences, Mashhad, Iran;
3
Department of Operating Room Technology, School of Paramedicine, Qom University of
Medical Sciences, Qom, Iran;
4
Department of Nutrition, School of Health, Zabol University of Medical Sciences, Zabol, Iran;
5
Department of Nursing, School of Nursing and
Midwifery, Isfahan University of Medical Sciences, Isfahan, Iran;
6
Department of Nutrition, School of Health, Kerman University of Medical Sciences, Kerman, Iran and
7
Department
of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Correspondence: Dr O Sadeghi, Department of
Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Keshavarz Street, School of Nutritional Sciences and Dietetics, Tehran,
1417933331, Iran.
E-mail: omidsadeghi69@yahoo.com
Received 24 April 2016; revised 20 November 2016; accepted 1 December 2016; published online 25 January 2017
European Journal of Clinical Nutrition (2017) 71, 544548
© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved 0954-3007/17
www.nature.com/ejcn
MATERIAL AND METHODS
Design
This study as randomized, double-blinded, placebo-controlled trial was
registered in the Iranian Registry of Clinical Trials (IRCT, www.irct.ir) under
registration No: IRCT2013121515807N1. Study was approved by Ethics
Committee of Food Security Research Center, School of Nutrition and Food
Sciences, Isfahan University of Medical Sciences, Isfahan, Iran (registration
No: 392435), and a we obtained a written informed consent from all
subjects.
Subjects
This trial was done on male soccer players with age range of 1635 years in
Isfahan, Iran, during October to December 2013. Subjects were asked to
participate in the study by advertising at sports clubs of Isfahan University
of Medical Sciences, Isfahan, Iran. All soccer players were included in this
trial based on American College of Sports Medicine criteria.
17
Subjects with
a history of smoking or alcohol abuse during the last year, and acute or
chronic illness (including mental disorders, untreated hypothyroidism,
heart and kidney disease, hepatitis, infectious and inammatory diseases),
and those who used nutritional sport supplements during the last
2 months were excluded from the study.
To estimate sample size, we used formula suggested for randomized
clinical trial (n¼2Z
1þZ2
ðÞσ2
d2). The sample size calculated 28 subjects,
considering a study power of 80%, type I error of 5% (α= 0.05), type II
error of 20% (β= 0.20), and VO
2
max as a key variable. Totally, 70 soccer
players were selected at the baseline, which all were in a training program
for 45 days.
Subjects were randomly allocated to L-arginine supplement group
(n= 28) and placebo group (n= 28), after stratication for pre-intervention
body mass index (BMI) (in kg/m
2
;o30 and 430), by the rst research
assistant using computer-generated random numbers.
Measurements
Detailed information about age, anthropometric measurements, medical
history, medication and supplement use were collected. Anthropometric
measurements such as weight, height, BMI, lean body mass (LBM) and
body fat mass (BFM) were determined for each subjects at the beginning
and end of the study. We measured weights without shoes and with
minimal cloths to the nearest 0.5 kg. Height was measured by using a non-
stretched tape measure without shoes, while the shoulders had a normal
position. BMI was determined as weight in kilograms divided by height in
meters squared. LBM and BFM were measured by BC-418 Segmental Body
Composition Analyzer (TANITA CO USA). All subjects were asked to take
one glass of water before the measurements of body composition.
Sport performance (as an indirect method to measure VO
2
max) was
determined for each subject by Harvard Step Test at the baseline and end
of the trial (24 h after last tablet consumption).
18,19
In this test, athletes go
up and down on a step of 50 cm for 5 min with a rhythmic 30 up and
down per minute. Then, heart rate (HR) after 11.5 min resting is recorded
and scores are calculated by the following formula:
Performance score ¼Duration of activity ´100
ðResting heart rate after 1 to 1:5 minÞ´5=5
At the beginning and end of study, physical activity level was determined
by using International Physical Activity Questionnaire (IPAQ), which its
reliability and validity in Iran is accomplished.
20
This questionnaire assesses
walking time, moderate and vigorous intensity physical activities, and time
spent sitting across a common week. All athletes, participating in current
trial, had vigorous-intensity physical activity (soccer practice) on at least
4 days/session per week. Each session lasted at least 2 h. This routine
physical activity continued during the study. We asked all subjects not to
change the physical activity during the study. However, the discrepancies
between two groups in physical activity were adjusted in nal analysis.
Intervention
After assignment of subjects to L-arginine and placebo group, subjects in L-
arginine group received daily a tablet containing 2 g L-arginine (Karen
Pharmaceutical Co, Yazd-Iran), and those in placebo group received daily
the same amount of placebo (maltodextrin) for 45 days. Without
considering the exercise time in a day, subjects had been asked to
consume these tablets in the evening. The appearance of the placebo
tablets (including color, shape, size and packaging) was similar to the
L-arginine tablets. All subjects were recommended not to change the
common dietary intake during the study, and not to take any supplements
(vitamins, minerals, proteins charbohydrates and so on) except prescribed
supplement. We gave the supplement to subjects in two stages (week 1
and 3) in the sports clubs by the second researcher assistant who was
unaware of groupsassignment.
At the end of the study, we measured subjectscompliance through the
remaining tablets using following formula: number of used tablets/ all
given tablets × 100. To assess the dietary intake during the study, we
obtained 3-days dietary records at baseline, middle and end of the study.
The mean values from all three time points were considered as usual
dietary intake of subjects during the intervention. Subjects were asked to
record everything they consumed during the day, including the
supplement, between-meal and late-evening snacks as accurately as
possible. For dietary records, we used values in household
measurements.
21
To obtain nutrient intakes of the subjects on the basis
of these 3-days food records, we used Nutritionist IV software (based on US
National Nutrient Databank) modied for Iranian foods. The reliability and
validity of 3-day food record for Iranian adults had been conrmed
previously.
22,23
Statistical analysis
We analyzed all data by means of SPSS software version 18 (SPSS, Inc.,
Chicago, IL, USA). We used the KolmogrovSmirnov test to examine the
normal distribution of variables. Log transformation was conducted for
non-normally distributed variables. Independent-samples t-test was
applied for homogeneity of general characteristics, anthropometric
measurements, and dietary intakes in two groups. We used paired-
samples t-test to assess the effects of both L-arginine and placebo
supplements on sport performance and anthropometric measurements. To
compare the changes between groups, we applied independent-samples
t-test. To nd if the magnitude of the change depended on baseline
values, physical activity and usual dietary intake, we adjusted these
variables by using Analysis of covariance (ANCOVA) to obtain independent
effect of L-arginine supplementation on sport performance and body
composition. P-value o0.05 was considered as signicant level.
RESULT
Of 70 males screened for this study, 56 subjects were selected
based on inclusion and exclusion criteria. From 56 subjects in the
baseline, three in L-arginine group (due to skin dermatitis and
stomach problems) and one in placebo group (due to personal
reasons) were excluded from study. Therefore, 52 subjects
(L-arginine (n= 25) and placebo (n= 27)) completed the trial
(Figure 1). In this trial, 100% of tablets were consumed in both
groups and the rate of compliance in our study was high.
Mean age of subjects was 20.85 ± 4.29 years. The baseline data
of subjects is shown in Table 1. There was no statistically
signicant difference in age, weight, BMI, BFM, LBM and VO
2
max between two groups. Moreover, physical activity level was
not different during the study.
The usual dietary intakes of subjects throughout the interven-
tion on the basis of 3-day dietary records is presented in Table 2.
No signicant differences were found in usual intake of energy,
protein, carbohydrate, fat, calcium, iron, zinc, magnesium, vitamin
C and E, arginine, and caffeine between L-arginine and placebo
groups.
In comparison with the baseline values, a signicant increase in
VO
2
max and a signicant reduction in weight and BMI was seen
in L-arginine group at the end of study, but these changes was just
signicant for VO
2
max compared with changes in placebo group.
L-arginine and placebo supplementation resulted in no signicant
changes in BFM and LBM (Table 3). In addition, analyses with
adjustment of baseline values, physical activity and usual dietary
intake throughout the study revealed no signicant changes in
our observed ndings (Table 4).
L-arginine and athletic performance
N Pahlavani et al
545
© 2017 Macmillan Publishers Limited, part of Springer Nature. European Journal of Clinical Nutrition (2017) 544 548
DISCUSSION
To the best of our knowledge, this study is one of few studies to
examine the effect of L-arginine supplementation on sport
performance and anthropometric measurements in Iranian male
athletes. Previous studies have evaluated the effect of different
dosage of L-arginine on sport performance during the 3 or 15
or 35 days. It seems that consumption of L-arginine in a longer
time is more effective than increasing the dosage on sport
performance.
1416
According to our ndings, intake of 2 g per day
L-arginine during the 45 days could improve the sport perfor-
mance in male soccer players. This increase remained signicant
even after adjustment of baseline values, physical activity and
usual dietary intake of subjects throughout the study. This nding
is in line of previous studies. In an advanced strength training
program, in which subjects were given combined L-arginine-
ornithine or placebo, an increase was found in muscle power, LBM
and sport performance after 5 weeks supplementation.
16
In
another study, combined administration of arginine/glycine
enhanced the performance of skeletal muscle during exercise,
and glycinearginine mixture decreased signicantly muscle
fatigue during exercise.
24
In a study which the effect of 3-days
supplementation with 6 g per day L-arginine on sport performance
was assessed, results did not show any improvement in athletic
performance.
15
These results are inconsistent with our ndings
probably due to differences in study duration and tness level of
athletes. Also, it has been shown that supplementation of arginine
aspartate for 14 days before to marathon run had no effect on the
performance in trained runners.
25
This result is not in line with our
ndings because the pure form of L-arginine supplements are not
used in foresaid study. Totally, conicting results might be
explained by differences in the study design, subjectsconditions,
dosage of L-arginine supplements, and duration of the study.
Body composition is an important factor that contributes to
optimal sport performance. Body weight can affect an athletes
speed, endurance and power, while body composition can
inuence an athletes strength, agility and appearance.
26
In the
present study, no signicant effect of L-arginine supplemen-
tation was found on weight, BMI, BFM and LBM. This result is in
line of previous ndings. Piatti et al.
27
showed that L-arginine
Figure 1. Summary of athletes ow.
Table 1. General baseline characteristics of male athletes who
received either L-arginine or placebo
Variables L-arginine group
a
(n = 25)
Placebo group
b
(n = 27)
P-value
c
Age (y) 21.32 ±4.59 20.40 ±4.04 0.44
Weight (kg) 73.82 ±14.02 72.90 ±16.32 0.830
BMI (kg/m
2
) 24.01±4.53 23.34 ±4.02 0.574
BFM (kg) 15.49 ±8.59 14.07 ±7.56 0.52
LBM (kg) 58.32 ±6.6 58.82 ±9.96 0.82
VO
2
max (ml/min/kg) 52.28 ±10.26 51.31 ±3.89 0.66
Physical activity
(MET-minutes/week)
3941.44 ±987.70 3810.09 ±1199.69 0.670
Abbreviations: BFM, body fat mass; BMI, body mass index; LBM, lean
body mass. All values are mean ±s.d.
a
Received 2000 mg L-arginine per day
during study.
b
Received 2000 mg placebo per day during the study.
c
Obtained from independent-samples t-test.
L-arginine and athletic performance
N Pahlavani et al
546
European Journal of Clinical Nutrition (2017) 544 548 © 2017 Macmillan Publishers Limited, part of Springer Nature.
supplementation (9 g per day) in 4 weeks had no effect on weight
in patients with diabetes mellitus. In another study on patients
undergoing coronary bypass surgery, L-arginine intake (6.4 g
per day) had no effect on weight, fat mass, fat-free mass and waist
circumference.
6
In contrast to our ndings, some study showed a
signicant effect of L-arginine supplementation on body composi-
tion. Paul Flakoll et al.
28
revealed that supplementation with
mixture of HMB (β-hydroxy-β-methylbutyrate), arginine and lysine
for 12 week, can increase the fat-free mass and protein synthesis
in elderly women. In one study performed by Luccoti et al.,
7
intake
of 8.3 g per day L-arginine supplement in 3 weeks reduced waist
circumference and fat mass signicantly in obese type 2 diabetic
patients, but did not have signicant effect on weight. Differences
in study design, dosage of L-arginine supplements and duration of
the study may be reasons for conicting results in previous
studies.
The exact mechanism explaining the effect of L-arginine on
sport performance is unknown. It can improve the sport
performance by enhancing protein synthesis and tissue repair.
29
L-arginine is also the precursor of nitric oxide used to increase
muscular power, endurance and improvement in blood ow.
30,31
It could be benecial for subjects with resistance exercises.
Furthermore, an increasing in blood ow could improve sport
performance theoretically by increasing nutrient delivery and/or
waste-product removal from exercising skeletal muscles.
32
We found no main side effects on L-arginine supplementation
except skin dermatitis in two subjects and stomach problem in
one. We cut the supplementation in these subjects and excluded
them from the study.
Some limitations in this study should be considered. The sample
size of this study was low and also this trial was done just in male
athletes. Therefore, further studies with larger sample size are
needed to examine the effect of L-arginine supplementation on
both genders. Furthermore, we could not evaluate the appropriate
dosage of L-arginine in this study. As a result of limited funding,
we did not measure the plasma arginine and nitric oxide levels in
baseline and at the end of the trial. Thus, these limitations should
be paid attention in future studies.
Table 2. Usual dietary intake of participants who received either L-arginine or placebo during the study
Variables L-arginine group
a
(n = 25) Placebo group
b
(n = 27) P-value
c
Energy Intake (Kcal) 2251.46 ±362.01 2232.65 ±341.48 0.84
Protein Intake (g per day) 83.04 ±14.13 80.66 ±7.52 0.45
Carbohydrate (g per day) 327.51 ±40.85 317.47 ±27.78 0.31
Fat (g per day) 66.43 ±12.43 69.24 ±8.92 0.35
Calcium (g per day) 1.02 ±0.4 1.03 ±0.49 0.89
Iron (mg per day) 16.55 ±2.73 37.62 ±99.81 0.29
Zinc (mg per day) 9.79 ±3.16 10.27 ±6.04 0.72
Magnesium (mg per day) 309.27 ±128.04 314.83 ±115.44 0.87
Vitamin C (mg per day) 102.33 ±78.19 95.48 ±76.4 0.75
Vitamin E (mg per day) 21.8 ±17.85 19.42 ±7.42 0.52
Arginine (mg per day) 388.73 ±464.33 437.96 ±458.29 0.7
Caffeine (mg per day) 100.04 ±51.35 71.69 ±67.65 0.09
All values are mean ±s.d.
a
Received 2000 mg L-arginine per day during study.
b
Received 2000 mg placebo per day during the study.
c
Obtained from
independent-samples ttest
Table 3. Athletic performance and Anthropometric measurements at study baseline and 45 days after the intervention in athletes who received
either L-arginine or placebo.
L-arginine group
a
(n = 25) P-value
b
Placebo group
b
(n = 27) P-value
c
Pvalue
d
Baseline After Change Baseline After Change
(VO2max (ml/min/kg) 52.28 ±10.27 56.40 ±9.07 4.12 ±6.07 0.02 51.31 ±3.90 52.54 ±5.55 1.23±3.36 0.06 0.03
Weight (Kg) 73.82 ±14.02 73.19 ±14.07 0.71 ±1.62 0.03 72.90 ±16.32 72.74 ±15.83 0.16 ±1.41 0.56 0.19
BMI (kg/m
2
) 24.01 ±4.53 23.73 ±4.57 0.28 ±0.61 0.03 23.34 ±4.03 23.25 ±3.97 .09 ±0.36 0.21 0.18
BFM (Kg) 15.49 ±8.60 15.28 ±8.36 0.21 ±1.31 0.42 14.07 ±7.56 13.99 ±7.63 0.07 ±1.04 0.7 0.68
LBM (kg) 58.32 ±6.60 58.68 ±6.91 0.35 ±1.03 0.1 58.83 ±9.97 58.86 ±9.62 0.03 ±0.91 0.85 0.24
Abbreviations: BMI, body mass index; BFM, body fat mass; LBM, lean body mass. All values are means±SDs.
a
Received 2000 mg L-arginine per day
during study.
b
Received 2000 mg placebo per day during the study.
c
Obtained from independent-samples ttest.
d
Obtained from paired-samples ttest.
Table 4. Adjusted changes in the athletic performance and
anthropometric measurements in athletes who received either
L-arginine or placebo
Variables L-arginine group
a
(n = 25)
Placebo group
b
(n = 27)
P-value
c
Sport performance 4.26 ±0.98 1.09 ±0.94 0.03
Weight (kg) 0.6 ±0.29 0.25 ±0.28 0.42
BMI (kg/m2) 0.27 ±0.09 0.096 ±0.09 0.22
BFM 0.24 ±0.23 0.04 ±0.22 0.56
LBM 0.42 ±0.19 0.02 ±0.18 0.12
Abbreviations: BFM, body fat mass; BMI, body mass index; LBM, lean
body mass. All values are mean s ±SDs. All analyses were adjusted for
baseline values, physical activity and usual dietary intake.
a
Received
2000 mg L-arginine per day during study.
b
Received 2000 mg placebo
per day during the study.
c
Obtained from ANCOVA.
L-arginine and athletic performance
N Pahlavani et al
547
© 2017 Macmillan Publishers Limited, part of Springer Nature. European Journal of Clinical Nutrition (2017) 544 548
CONCLUSION
Two grams per day L-arginine intake during 45 days could increase
the sport performance in male athletes, but have no effect on
anthropometric measurements, including BMI, BFM and LBM.
Further studies based on determination of L-arginine dose and
with a larger sample size are needed to shed light our ndings.
CONFLICT OF INTEREST
The authors declare no conict of interest.
ACKNOWLEDGEMENTS
This paper was adapted from MSc dissertation, which was supported by School of
Nutrition & Food Sciences, Isfahan University of Medical Sciences (code: 392435). So,
we thank the authorities of this university for their cooperation. Also, we appreciate
the athletes who participated in the study.
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... 13 Two studies showed that chronic arginine supplementation (i.e., 4 or 45 days) is effective for improving aerobic exercise performance lasting more than 5 min in duration. 14,15 Conversely, three studies did not observe favourable effects of chronic arginine supplementation on aerobic exercise performance. 16e18 The dose (amount of absolute or relative), the timing of the intake before the exercise (i.e., acute effect), and the duration of the intake (i.e., chronic effect) of the arginine supplementation are possible reasons for the inconsistent findings among studies. ...
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Objective This study examined the effects of a single and chronic oral intake of l-arginine supplementation on blood ammonia concentration and exercise performance. Methods Sixteen healthy young men (mean ± standard deviation, 23 ± 3 years) participated in a randomised, double-blind, cross-over, placebo-controlled study. For the acute trials, the participants consumed 200 mL of water containing either l-arginine (5 g) or placebo (dextrin; 5.5 g) and performed cycling exercise at 75% of heart rate reserve for 60 min, followed by a 15-min cycling performance test. For the chronic trials, the participants continued to consume each designated supplement twice a day for another 13 days, and then repeated the same protocol as the acute trials at day 15. After a 14-day washout period, the participants changed the supplement and repeated the same protocol as above. Results Plasma ammonia concentrations were lower in the chronic arginine trial than those in both acute placebo (mean difference - 4.5 μmol/L) and acute arginine (mean difference - 5.1 μmol/L) trials (p < 0.05). There was no difference in plasma ammonia concentration between the chronic arginine and chronic placebo trials (mean difference - 1.2 μmol/L). No differences were found in mean power output during the performance test between the chronic arginine and chronic placebo trials (mean difference 0.5 W) or between the acute arginine and acute placebo trials (mean difference 0.0 W). Conclusions An acute and chronic oral intake of l-arginine supplementation did not attenuate exercise-induced increases in ammonia accumulation or had not significant impact on cycling performance.
... In a randomised, doubleblind, placebo-controlled design, the effect of chronic arginine supplementation (i.e., from 7 days to 45 days) on exercise performance was examined, and the ndings were inconsistent [13]. Two studies showed that chronic arginine supplementation (i.e., 4 or 45 days) is effective for improving aerobic exercise performance lasting more than 5 minutes in duration [14,15]. Conversely, three studies did not observe favourable effects of chronic arginine supplementation on aerobic exercise performance [16][17][18]. ...
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Background This study examined the effects of a single and continuous oral intake of L-arginine supplementation on blood metabolites and exercise performance. Methods Sixteen healthy young men (mean ± standard deviation, 23 ± 3 years) participated in a randomised, double-blind, cross-over, placebo-controlled study. For the acute trials, the participants consumed 200 mL of water containing either L-arginine (5 g) or placebo (L-arginine was replaced with dextrin) and performed cycling exercise at 75 % of heart rate reserve for 60 min, followed by a 15-min cycling performance test. The participants continued to consume each designated supplement twice a day for 13 days. For the chronic trials, the participants repeated the same protocol as the acute trials at day 15. After a 14-day washout period, the participants changed the supplement and repeated the same protocol as above. The linear mixed model was used to examine between-trial differences over the 1-day or 2-week intervention for outcome variables. Results Plasma ammonia concentrations were lower in the chronic arginine (43.5 ± 27.6 µmol/L) trial than in both acute arginine (52.1 ± 36.3 µmol/L, 95% confidence interval − 15.907 to − 1.318 µmol/L, Effect size = 0.262) and placebo (51.1 ± 32.7 µmol/L, 95% confidence interval − 14.932 to − 0.343 µmol/L, Effect size = 0.249) trials (p < 0.05). No differences were found in mean power output during the performance test between the chronic arginine (169.3 ± 8.6 W) and placebo (168.8 ± 2.3 W) trials (p > 0.05). Conclusions These results indicate that a continuous oral intake of L-arginine supplementation attenuated ammonia accumulation, but this did not influence cycling performance.
... However, a double-blind, controlled, randomized study tested the effectiveness of 2 g arginine supplementation on performance of 56 soccer players during 45 days and found significant improvements in maximum oxygen consumption (VO2max) with subsequent performance increase [69]. Twenty-eight soccer players were selected and supplemented with 6 g arginine during 14 days, and their performance in the RAST protocol on six 35-m consecutive sprints with 10 s of active rest was tested. ...
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Background: Soccer is an extremely competitive sport, where the most match important moments can be defined in detail. Use of ergogenic supplements can be crucial to improve the performance of a high-performance athlete. Therefore, knowing which ergogenic supplements are important for soccer players can be an interesting strategy to maintain high level in this sport until final and decisive moments of the match. In addition, other supplements, such as dietary supplements, have been studied and increasingly referenced in the scientific literature. But, what if ergogenic supplements were combined with dietary supplements? This review brings some recommendations to improve performance of soccer athletes on the field through dietary and/or ergogenic supplements that can be used simultaneously. Summary: Soccer is a competitive sport, where the match important moments can be defined in detail. Thus, use of ergogenic supplements covered in this review can improve performance of elite soccer players maintaining high level in the match until final moments, such as creatine 3-5 g day-1, caffeine 3-6 mg kg-1 BW around 60 min before the match, sodium bicarbonate 0.1-0.4 g kg-1 BW starting from 30 to 180 min before the match, β-alanine 3.2 and 6.4 g day-1 provided in the sustained-release tablets divided into 4 times a day, and nitrate-rich beetroot juice 60 g in 200 mL of water (6 mmol of NO3- L) around 120 min before match or training, including a combination possible with taurine 50 mg kg-1 BW day-1, citrulline 1.2-3.4 g day-1, and arginine 1.2-6 g day-1. Key Messages: Soccer athletes can combine ergogenic and dietary supplements to improve their performance on the field. The ergogenic and dietary supplements used in a scientifically recommended dose did not demonstrate relevant side effects. The use of various evidence-based supplements can add up to further improvement in the performance of the elite soccer players.
... The consumption of amino acid supplements carrying vasodilatory properties is increasing in the sports field, due to the positive additional effect of vasodilation on muscle blood supply and athletic performance [24,25]. In this scenario, the L-Arginine vasodilator effect has gained the favor of the athletes to improve their physical performance [14,21,26]. The perceived benefit of L-Arginine assumption, though, ailments the described arginine paradox, which has been described by Ignarro and coworkers; indeed, L-Arginine is a nonessential amino acid, synthesized in the small intestine from proline, glutamate, and glutamine, which is also abundant in diets with apparently no need for supplementation [27][28][29]. ...
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Background: Ergogenic nutritional supplementation is sought by professional athletes for improving physical performance; nevertheless, scientific evidence to support the chronic use of L-Arginine among water polo players is missing. Methods: Seventeen male professional water polo players were randomly assigned to assume 5 grams per day of L-Arginine (n = 9) or placebo (n = 8) for 4 weeks. The players' fitness level was assessed in the maximal speed swimming test. Ear lobe blood samples taken before and after the effort for serum lactate content were analyzed. A speed-to-lactate ratio was generated at the baseline and after 4 weeks of treatment. We also tested the effects of L-Arginine in vitro, measuring NO production, mitochondrial respiration, and gene expression in human fibroblasts. Results: L-Arginine did not modify BMI, muscle strength, and maximal speed at 200 meters after 4 weeks. However, L-Arginine ameliorated oxidative metabolism to exercise as suggested by the statistically significant lower lactate-to-speed ratio, which was not observed in placebo-treated controls. In vitro, L-Arginine induced the expression of a key regulator of mitochondrial biogenesis (PGC1α) and genes encoding for complex I and increased the production of nitric oxide and the maximal oxygen consumption rate. Conclusions: Chronic L-Arginine is safe and effective in ameliorating the oxidative metabolism of professional water polo players, through a mechanism of enhanced mitochondrial function.
... L-arginine is a semi essential amino acid and it is the natural precursor of NO, which has a various regulatory mechanisms such as stimulation of thermogenesis (Petrović et al., 2005;Vasilijević et al., 2010), increasing mitochondrial biogenesis (Nisoli et al., 2003;Fu et al., 2005), growth of brown adipose tissue (Jobgen et al., 2009;Monti et al., 2008;Satterfield et al., 2012) and regulating fat metabolic gene expression (Tan et al., 2011;, xxxx;Hu et al., 2017) that all of these can affect weight control processes (Patel et al., 2017). Based on prior studies L-arginine plays important roles in human metabolism and is protective nutrient against some chronic diseases such as obesity, oxidative stress and inflammation derived from diabetes mellitus (DM), cardiovascular disease (CVD), endothelial dysfunction, auto-immune disorders and some types of cancers (Wu et al., 2009;Pahlavani et al., 2017;. Nevertheless, anti-obesity effects of supplementation with L-arginine is controversial. ...
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Background: Animal studies have shown that L-Arginine can affect anthropometric and body composition indices favorably, while results of human studies are contradictory. Objective: This is a meta-analysis of human studies in which L-arginine was provided as a dietary supplement to test its effects on anthropometric indices. Design: We searched the Cochrane library, PubMed, Embase and Scopus databases to identify studies in which Larginine was provided to humans in randomized clinical trials. Results: Of 4784 publications, 12 trials were included for the meta-analysis. Pooled effect sizes indicated that Larginine significantly reduced body mass index (BMI), waist circumference (WC), and fat mass (FM), and also increased fat-free mass (FFM) compared to the placebo group. However, the effects of L-arginine on body weight (BW) was not significant. Subgroup analysis could not identify factors significantly influencing BW. Conclusion: We found a beneficial effect of L-arginine supplementation on anthropometric indices in overweight and obese subjects.
... Other studies also showed decreased obesity with linseed products: young rats fed a linseed flour intervention for the first 90 days showed higher lean mass, lower fat mas, and a smaller adipocyte area [21] and linseed dietary fiber reduced apparent energy and fat digestibility leading to decreased abdominal fat and body weight [22]. Linseed contains 20 to 30% globulin-rich proteins with a high content of arginine [23,24] which has been associated with increases in lean mass [25,26] thereby providing a possible mechanism for lean mass increase as well as fat mass decrease [27]. In high-fat diet-fed mice, SDG decreased abdominal fat and body weight by inducing adiponectin expression at a much higher dose of 0.5 or 1% in diet [28] and inhibiting adipogenesis at a dose of 50 mg/kg/day [29]. ...
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Linseed is a dietary source of plant-based ω–3 fatty acids along with fiber as well as lignans including secoisolariciresinol diglucoside (SDG). We investigated the reversal of signs of metabolic syndrome following addition of whole linseed (5%), defatted linseed (3%), or SDG (0.03%) to either a high-carbohydrate, high-fat or corn starch diet for rats for the final eight weeks of a 16–week protocol. All interventions reduced plasma insulin, systolic blood pressure, inflammatory cell infiltration in heart, ventricular collagen deposition, and diastolic stiffness but had no effect on plasma total cholesterol, nonesterified fatty acids, or triglycerides. Whole linseed did not change the body weight or abdominal fat in obese rats while SDG and defatted linseed decreased abdominal fat and defatted linseed increased lean mass. Defatted linseed and SDG, but not whole linseed, improved heart and liver structure, decreased fat vacuoles in liver, and decreased plasma leptin concentrations. These results show that the individual components of linseed produce greater potential therapeutic responses in rats with metabolic syndrome than whole linseed. We suggest that the reduced responses indicate reduced oral bioavailability of the whole seeds compared to the components.
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Background & Aims Skeletal muscle losses (both quantitative and qualitative) and the consequent risk of sarcopenia are important issues in people living with HIV (PLWH), even when treated with antiretroviral therapies (ART). We aimed to conduct a systematic review (SR) investigating the effects of dietary interventions with proteins, amino acids, and other nitrogenated compounds on the skeletal muscle of PLWH. Methods We searched the published literature until August 24th, 2020, including clinical trials predominantly with AIDS-free PLWH treated with ART. Results From the 82 studies initially selected, 75 were excluded for the following reasons: nutritional interventions different from nitrogenated compounds; non-nutritional interventions; lack of information on body composition; and studies with most participants with AIDS. From the publications included (n = 7), the majority were performed with small and heterogeneous samples. None of the studies included any new-generation ART or pre- or post-exposition drugs. Two studies found benefits of supplementation on muscle mass; one was performed in a very unfavorable socioeconomic setting, and the supplementation was based on food-derived substances. The other study supplemented creatine, and its benefits were found only when combined with physical exercise training and only by one of the methods of body composition analysis (DXA). Conclusions Our results showed that nutritional interventions with proteins, amino acids, or other nitrogenated compounds could not improve the skeletal muscle mass in PLWH. Further studies are needed, with bigger sample sizes and more precise control of ART schemes. Systematic Review Registration PROSPERO registration number CRD42019139981.
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Sodium fluoride (NaF) is one of the neglected environmental toxicants that has continued to silently cause toxicity to both humans and animals. NaF is universally present in water, soil and the atmosphere. The persistent and alarming rate of increase in cardiovascular and renal diseases and disorders caused by chemicals such as sodium fluoride (NaF) in mammalian tissues have led to the use of various drugs for the treatment of these diseases. This study aims at evaluating the renoprotective and antihypertensive effects of L- Arginine on NaF-induced nephrotoxicity. Thirty male Wistar rats (150 – 180 g) were used in this study. The rats were randomly divided into five groups of six rats each as Control, NaF (300 ppm), NaF + L- Arginine (100 mg/kg), NaF + L- Arginine (200 mg/kg), and NaF + Lisinopril (10 mg/kg), respectively; orally for eight days. Histopathological examination and immunohistochemistry of renal angiotensin converting enzyme (ACE) and mineralocorticoid receptor (MCR) were performed. Markers of renal damage, oxidative stress, antioxidant defence system, and blood pressure parameters were determined. L- Arginine significantly (p <0.05) ameliorated the hypertensive effects of NaF. The systolic, diastolic and mean arterial blood pressure of the treated groups were significantly (p< 0.05) reduced compared with the hypertensive group. This finding was concurrent with significantly increased serum bioavailability of nitric oxide in the hypertensive treated groups. Also, there was significant reduction in the level of blood urea nitrogen (BUN) and creatinine in the serum of the hypertensive rats treated with L- arginine. There was significant (p<0.05) reduction in markers of oxidative stress such as hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA) and protein carbonyl (PCO) and concurrent increase in the levels of antioxidant enzymes in the kidney of hypertensive rats treated with L arginine. The results of this study suggest that L- Arginine normalized high blood pressure, reduced oxidative stress, reduced the expression of renal ACE and MCR, and improved nitric oxide production. Thus, L- Arginine holds promise as a potential therapy against hypertension and renal damage.
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Due to the special training conditions and lifestyle athletes require an antioxidant system that is more efficient than others. To keep this system optimal, many of them use antioxidant supplements. This study aimed to investigate the effects of vitamins C and E supplementation on muscle damage, performance, and body composition in athlete women. The study was a 4-week randomized, double-blind clinical trial conducted on 64 trained female athletes recruited in Isfahan sports club. They were randomly assigned to one of the following four groups; A: vitamin C (250 mg/day), B: vitamin E (400 IU), C: vitamin C + vitamin E and control (placebo). Harvard Step Test was used to measure maximal oxygen consumption for performance, body composition, and damage marker (myoglobin) were measured before and after the intervention. Comparing the result of the test in performance of sport, there was no significant difference between groups in VO2 max. Also, vitamin supplements had no significant effect on subcutaneous fat between the groups, however, in the intergroup comparison, were significantly increased in group control (P = 0.03). But, there were no significant differences, change in myoglobin between the groups. There was a significant increase in group A (P = 0.04). Vitamins C and E supplementation had no significant effect on any of the studied parameters.
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A decrease of the blood supply to the muscle can be significant to the development of muscular fatigue, an important factor of incapacity. In this study, the effect of L-arginine taken orally, on the physiologic process of the muscular fatigue in 12 healthy volunteers, was investigated through located exercise controlled by isokinetic dynamometer (Biodex Multi-Joint System 3 dynamometer). A protocol of the isokinetic concentric, continuous and reciprocal test was used for acquisition of the Work Fatigue Indexes and it was accomplished the bilateral evaluation of the knee extension and flexion of the volunteers to an angular speed of 180°/s. The study was divided into two phases of test, Phase 1 being the control. At Phase 2, 3 g of arginine was given orally to each volunteer, daily for 15 days. The reliability and the estimate of the error in our measurements were analyzed, respectively, by Intra-class Correlation Coefficient (ICC) and Percent Standard Error of Measurement (SEM %). Reliable isokinetic measurements were obtained in the knee extension movement (ICC ≥ 0.80). Results demonstrated that for knee extension movement the mean values of Work Fatigue Indexes of Phases 1 and 2 are statistically different (p < 0.05). There was a significant decrease (mean 8.5%) in the Work Fatigue Indexes. Our results indicate an improvement in the muscular resistance capacity to fatigue following the treatment by oral administration of arginine.