ArticlePDF AvailableLiterature Review

Abstract

Diet composition can affect systemic pH and acid-base regulation, which may in turn influence exercise performance. An acidic environment in the muscle impairs performance and contributes to fatigue; therefore, current trends in sports nutrition place importance on maximizing the alkalinity of the body with ergogenic aids and dietary strategies. This review examines the evidence on the effects of dietary manipulations on acid load and exercise performance. Ten studies that investigated the effect of high versus low dietary acid loads on athletic performance generally identified that low dietary acid loads increased plasma pH, but did not consistently improve exercise performance at maximal or submaximal exercise intensities. In addition, the few studies conducted have several limitations including lack of female subjects and use of exercise tests exclusive to cycling or treadmill running. Although the research does not strongly support a performance benefit from low dietary acid loads, a more alkaline dietary pattern may be beneficial for overall health, as dietary induced acidosis has been associated with greater risk of cardiovascular disease and bone disease. The review includes dietary recommendations for athletes to reduce dietary acid load while still meeting sports nutrition recommendations.
213
ORIGINAL RESEARCH
International Journal of Sport Nutrition and Exercise Metabolism, 2017, 27, 213 -219
https://doi.org/10.1123/ijsnem.2016-0186
© 2017 Human Kinetics, Inc.
The authors are with the Dept. of Nutrition and Foods, School
of Family and Consumer Sciences, Texas State University,
San Marcos, TX. Address author correspondence to Krystle E.
Zuniga at k_z17@txstate.edu.
Influence of Dietary Acid Load on Exercise Performance
Catherine Applegate, Mackenzie Mueller, and Krystle E. Zuniga
Diet composition can affect systemic pH and acid-base regulation, which may in turn inuence exercise
performance. An acidic environment in the muscle impairs performance and contributes to fatigue; therefore,
current trends in sports nutrition place importance on maximizing the alkalinity of the body with ergogenic
aids and dietary strategies. This review examines the evidence on the effects of dietary manipulations on
acid load and exercise performance. Ten studies that investigated the effect of high versus low dietary acid
loads on athletic performance generally identied that low dietary acid loads increased plasma pH, but did
not consistently improve exercise performance at maximal or submaximal exercise intensities. In addition,
the few studies conducted have several limitations including lack of female subjects and use of exercise tests
exclusive to cycling or treadmill running. Although the research does not strongly support a performance
benet from low dietary acid loads, a more alkaline dietary pattern may be benecial for overall health, as
dietary induced acidosis has been associated with greater risk of cardiovascular disease and bone disease. The
review includes dietary recommendations for athletes to reduce dietary acid load while still meeting sports
nutrition recommendations.
Keywords: alkaline diet, renal acid load, acid-base balance, aerobic performance, anaerobic performance
High dietary acid loads can contribute to a chronic
low-grade acidosis that has been associated with a greater
risk for cardiovascular, kidney, and bone disease (Cordain
et al., 2005). Diet composition can be modied to reduce
acid loads and improve acid-base balance (Hietavala et
al., 2012), and new diets and supplements to combat aci-
dosis have emerged (Cordain et al., 2005, Adeva & Souto,
2011). Alkaline diets have gained popularity and are mar-
keted in books, diets, and products such as alkaline water
and ergogenic aids (Fenton & Huang, 2015). Changes in
acid-base balance contribute to the onset of fatigue; thus,
athletes may be interested in utilizing dietary strategies
or ergogenic aids to enhance the buffering capacity of the
muscle for performance benets. Early sports nutrition
research identied a relationship between low carbohy-
drate diets and acute acidosis that resulted in reduced high
intensity exercise and endurance performance (Greenhaff
et al., 1987, 1988a, 1996; Ball, Greenhaff et al., 1996).
Current investigations question how alkaline diets low in
protein and fat and high in carbohydrate, could improve
performance and reduce acidosis before, during, and after
exercise. This review will examine the evidence on the
impact of dietary modications on acid-base balance and
subsequent exercise performance.
Physiological Systems Regulating
Acid-Base Balance
Maintenance of a stable intracellular and extracellular
pH in the body is essential for normal physiological
function (Goel & Calvert, 2012) and involves complex
biological processes. As thoroughly reviewed by Goel
and Calvert (2012), the systems that regulate acid-base
balance include extracellular and intracellular buffers, the
respiratory system, and the renal system. The changes of
the acid-base balance by cellular metabolism is highly
inuenced by dietary composition, as the metabolism of
lipids, carbohydrates, and proteins all impact pH in the
body and generate approximately 2–3 mEq/kg/day of H+
ions (Goel & Calvert, 2012).
Extracellular buffering relies on the use of bicarbon-
ate (HCO3-) in the extracellular uid, which can bind to
H+ ions to release carbon dioxide (CO2) and water (H2O)
(Yucha, 2004). The intracellular buffer system is domi-
nated by a nonbicarbonate system which utilizes proteins
and organic phosphates for acid-base regulation (Goel &
Calvert, 2012). Buffering systems are only short-term
solutions for alkalaemia or acidaemia; thus, compensa-
tory mechanisms exist to regulate extracellular pH such as
the respiratory and renal systems. The respiratory system
can increase respiration to expel weakly acidic CO2 when
extracellular H+ ion concentration is sensed (Goel &
Calvert, 2012). Conversely, a decrease in H+ ion con-
centration stimulates chemoreceptors in the brain to slow
respiration and retain CO2 (Clancy & Mcvicar, 2007).
The response of the respiratory system is relatively quick,
214 Applegate et al.
IJSNEM Vol. 27, No. 3, 2017
changing pH concentrations within minutes to hours. The
renal system is much more complex and slow, changing
hydrogen ion concentrations within hours or days (Clancy
& Mcvicar, 2007). During the renal response, excess H+
ions and ammonium (NH4+) are excreted in the urine.
Ammonia (NH3), produced in renal tubule cells, diffuses
into the intraluminal space to combine with H+ ions and
facilitate their irreversible excretion during periods of
acidosis. In addition, potassium ions (K+), calcium ions
(Ca2+), and urinary phosphate (H2PO4) are excreted in
the urine during acute and chronic acidosis (Adeva &
Souto, 2011; Poupin et al., 2012). Plasma bicarbonate is
preserved for its function as a buffer and is reabsorbed
by the renal system and released back into plasma. Cel-
lular metabolism is responsible for the constant ux in
the acid-base balance, which is then corrected through
one or more of these compensatory processes.
Influence of Diet on Acid-Base
Balance
During normal physiological conditions, the net endog-
enous acid production is primarily modied by diet
(Poupin et al., 2012). Dietary choices provide acidic or
alkaline substrates for the body to respond to or use as
buffering agents. The major source of H+ ion production
is the reversible hydrolysis of ATP and the production of
carbonic acid (H2CO3) that occurs during the metabo-
lism of lipids, carbohydrates, and proteins (Poupin et
al., 2012). The catabolic and anabolic reactions during
macronutrient metabolism generate and consume equal
amounts of H+ ions to maintain acid-base homeostasis.
Not only do macronutrients inuence the acid-base bal-
ance, but the dietary consumption of organic and inor-
ganic acids can also mediate changes. The consumption
of organic acids ingested in the form of salts such as
citrate, malate, and lactate lead to the production of
bicarbonate (Poupin et al., 2012). The potassium salts
of the organic acid anions such as citrate and malate are
present in fruits and vegetables (Adeva & Souto, 2011).
Other nonmetabolisable organic acids such as uric, oxalic,
tartrate, and hippuric acids are directly excreted in the
urine without producing bicarbonate and result in H+
retention (Poupin et al., 2012).
A direct relationship exists between the composi-
tion of the diet and urinary pH (Aerenhouts et al., 2011).
The Western diet, which is low in fruits and vegetables
and high in animal products and sodium chloride, is
considered to be an acidic diet (Adeva & Souto, 2011).
Animal proteins and cereal grains are abundant in sulfur-
containing amino acids such as methionine, homocysteine
and cysteine, and oxidation of these amino acids gener-
ates sulfate, a nonmetabolisable anion that is a major
contributor to daily acid production (Adeva & Souto,
2011). Proteins are generally considered to be buffers
due to their negative charge and H+ ion-consuming amine
and carboxylic acid groups that can bind to excess H+
ions and release H+ ions (Poupin et al., 2012). It has been
suggested that the Western diet induces a chronic state of
metabolic acidosis, which increases the renal glomerular
ltration rate to excrete acids in the urine (Adeva & Souto,
2011). Compared with individuals with a plant-based
diet, the Western diet results in more acidic urine and an
increased rate of kidney hypertrophy (Adeva & Souto,
2011). In a more balanced diet, additional alkali loads,
such as those consumed from foods containing sodium
citrate, can increase the alkali reserve in the plasma to
raise urinary pH and compensate for the protein-related
increase in acid production (Remer, 2001).
Potential Renal Acid Load (PRAL)
PRAL is an estimate of the acidic potential of foods
expressed in mEq of H+ ions per 100 g of a particular
food (Aerenhouts et al., 2011). A positive PRAL food
(PRAL > 0) increases the renal acid load by producing
H+ ions. Conversely, a negative PRAL food (PRAL
< 0) is considered to decrease the renal acid load and
thus increase the buffering capacity of the body. Fruits
and vegetables have a negative PRAL while grains and
animal products rich in protein, phosphorous, potassium,
calcium, and magnesium such as eggs, meat, and cheese
have a positive PRAL (Aerenhouts et al., 2011). The diet-
dependent net acid production can be calculated as the
sum of organic acids produced from basal metabolism
and the PRAL of all consumed food items (Aerenhouts et
al., 2011). It has been suggested that long-term net acid
excretion should not exceed 100–120 mEq/day because
it can result in long-term increased renal acid load and a
lower availability of plasma bicarbonate (Aerenhouts et
al., 2011). To compensate for this long-term metabolic
acidosis, some studies have suggested that the bone may
release large quantities of alkalinizing minerals, such as
calcium, to buffer the increased acid load (Aerenhouts
et al., 2011). Indeed, higher rates of urinary calcium
excretion have been identied in omnivores compared
with vegetarians, which is likely a result of higher protein
intake that increased renal acids (Ball & Maughan, 1997).
In the European Prospective Investigation into Cancer and
Nutrition (EPIC)-Norfolk Population study, increased
vegetable and fruit and decreased meat consumption
was positively associated with alkaline urine pH and an
alkaline PRAL diet. (Welch et al., 2008).
Athletes need to consume larger amounts of car-
bohydrates and protein to compensate for the increased
metabolic breakdown of these macronutrients during
training periods, and are thus at risk for consuming
perpetually positive PRAL diets. To achieve the recom-
mended 5–10 g carbohydrates/kg body weight and 1–2
g protein/kg body weight (Thomas et al., 2016), athletes
may consume diets rich in grains such as bread, pasta,
and rice, and animal proteins which are positive PRAL
foods. Aerenhouts et al. (2011) calculated the acid load of
adolescent sprinters’ usual diets. Sixty adolescents aged
12–18 years old were followed for 3 years, during which,
7-day dietary intakes were recorded every 6 months and
used to estimate the net endogenous acid production. All
Downloaded by Alkek Lbry Serials Acq on 06/22/17, Volume 27, Article Number 3
Dietary Acid Load and Exercise Performance 215
IJSNEM Vol. 27, No. 3, 2017
individuals consumed consistently positive PRAL diets
throughout the duration of the study. Those with lower
PRAL diets reported consuming more fruits and fruit
juices than those with higher PRAL diets. Adherence to
sports nutrition recommendations may result in a positive
PRAL diet; however, lowering the PRAL of diets can be
achieved through increasing consumption of fruits and
vegetables, rather than limiting the consumption of pro-
tein from moderate PRAL sources like legumes and beans
or high PRAL sources such as meat, poultry, and sh.
Influence of Exercise on the Acid-
Base Balance
While diet composition continuously inuences the acid-
base balance of the body through changes incurred by
the metabolism of individual dietary components, other
physiological factors such as exercise can acutely affect
pH levels. Exercising muscles can generate lactate and
H+ ions that contribute to minor or moderate states of
muscle acidosis in the short-term, until compensatory
mechanisms respond to the decrease in pH to neutralize
the excess acid (Cairns, 2006; Lindinger et al., 1985).
During prolonged submaximal exercise, muscle pH
is minimally affected, whereas the largest pH change
can be observed during maximal continuous exercise
of 1–10 min in duration (Cairns, 2006). Muscle pH is
subsequently restored to its resting level after 10 min of
recovery (Bangsbo et al., 1993). During low-intensity
exercise, muscles are adequately supplied with oxygen
to enable aerobic respiration. Small amounts of lactate
are produced anaerobically through substrate level
phosphorylation; however, the levels remain low as the
lactate is continually produced and removed from the
blood by aerobic tissues (Blair et al., 1996). As exer-
cise intensity increases, the rate of ATP produced by
nonaerobic systems generates H+ ions, promoting an
acidic environment. This acidosis results in a decrease in
muscle contractile force and potentially amplies muscle
fatigue during additional exercise events (Cairns, 2006).
As previously reviewed (Cairns, 2006; Green, 1997),
other factors such as the increase in ADP and AMP, the
accumulation of inorganic phosphate, changes in calcium
cycling, and imbalances of the sodium/potassium pump
contribute to fatigue during high intensity exercise. Intra-
cellular and extracellular changes in pH affect the buffer-
ing capacity of the muscle and contribute to the onset of
fatigue, thus strategies to enhance the buffering capacity
of the muscle such as ergogenic aids, training, or dietary
conditions are promoted to enhance performance and
delay the onset of fatigue (Sahlin, 2014). Sodium citrate
and sodium bicarbonate are well-studied ergogenic aids
that enhance performance during both anaerobic activity
and prolonged exercise (McNaughton et al., 2008; Peart
et al., 2012; Sahlin, 2014). These results are attributed to
the alkalinizing effect of these supplements, increasing
lactate efux and neutralizing lactic acidosis (Schubert
& Astorino, 2013).
Influence of Diet on Acid Load and
Performance During Exercise
Diet type and exercise strongly inuence the acid-base
homeostasis of the body by their own mechanisms;
however, they may also interact, inuencing exercise
performance. It has been hypothesized that creating a
more alkaline systemic environment through reducing
dietary acid load can enhance the clearance of protons and
inhibitory molecules that affect working muscles during
exercise-induced acidosis, thus, improving aerobic and
anaerobic exercise performance.
Greenhaff, Gleeson, and Maughan (1988a) proposed
that diets low in carbohydrate and high in fat and protein
would lead to a resting state of metabolic acidosis. Since
enzyme activity is highly dependent on intracellular pH
values, Greenhaff and colleagues suggested that meta-
bolic acidosis would reduce muscle buffering capacity
and decrease the rate of muscle glycolysis and H+ ion
efux during high intensity exercise. To test the effect of
diet on muscle pH and glycolytic activity, Greenhaff and
colleagues completed a randomized, cross-over design,
in which six healthy young men consumed a diet high
in carbohydrates (73% of energy), low in fat, and low in
protein (low acid load), a diet low in carbohydrate (3% of
energy), high in fat, and high in protein (high acid load),
or a normal carbohydrate (47% of energy), low in fat, and
high in protein diet for 4 days. In a high-intensity cycling
test at 100% VO2max for 3 min, the low carbohydrate,
high protein diet resulted in a lower plasma pH, partial
pressure of CO2, and bicarbonate levels before exercise
compared with both the normal and high carbohydrate
diet. However, there were no differences in postexercise
measures of plasma pH or blood base excess between
dietary treatments. Similar results were found in another
investigation by Greenhaff, Gleeson, and Maughan
(1988b) in which ve subjects cycled for three minutes
at 100% VO2max on either a low carbohydrate or high
carbohydrate diet. Preexercise measures showed a lower
plasma pH, partial pressure of CO2, plasma bicarbonate,
and blood base excess from the low carbohydrate diet.
Muscle biopsies indicated that the low carbohydrate diet
(high acid load) resulted in a pH decline during exercise
that was 104% greater than the high carbohydrate diet.
Intramuscular lactate concentrations were not different
between treatments, and similarities between postexercise
measures among the treatments suggest that lactate efux
was not the cause of fatigue. Greenhaff, Gleeson, and
Maughan (1987) found that subjects consuming a low
protein and high carbohydrate diet for 4 days presented
with increased plasma pH values and a greater time to
exhaustion in a cycling test compared with individuals on
a high protein and low carbohydrate diet. Together these
early studies by Greenhaff et al. (1987, 1988a, 1988b)
suggest that variation in the levels of dietary carbohydrate
and protein changes the acid-base status of plasma and
skeletal muscle, before and during exercise, perhaps
affecting performance. Thus, it was hypothesized that
a high carbohydrate diet would improve performance
Downloaded by Alkek Lbry Serials Acq on 06/22/17, Volume 27, Article Number 3
216 Applegate et al.
IJSNEM Vol. 27, No. 3, 2017
similar to sodium citrate supplementation (Ball &
Maughan, 1997). However, Ball and Maughan (1997)
showed that in six untrained, young men, sodium citrate
in combination with an alkalinizing high carbohydrate
diet did not improve cycling performance (as measured
by TTE) when compared with placebo + high carbo-
hydrate diet or placebo + low carbohydrate diet. While
both Greenhaff et al. (1988a) and Ball and Maughan
(1997) demonstrated that high carbohydrate diets do
create a more alkaline environment before exercise when
compared with high protein and low carbohydrate diets,
this difference alone did not result in improvements in
cycling performance in small groups of active men. Con-
versely, a study involving both men and women indicated
improvements in performance by a reduced dietary acid
load. Rios Enriquez et al. (2010) instructed 13 active men
and women to consume either a positive PRAL (acidic
diet) or negative PRAL diet (alkaline diet) for 2.5 days
with a crossover after a 7-day washout. The alkaline diet
resulted in an 83% higher urinary pH than the acidic diet,
and TTE on a cycling test was longer in 58% of subjects
consuming the alkaline diet. The PRAL of the diet may
aid in creating a less acidic environment during exercise,
but the evidence does not suggest a consistent benet in
exercise performance as measured by TTE.
To determine if diet related acidosis contributes to the
onset of fatigue during high intensity exercise, Ball et al.
(1996) conducted a study in which subjects consumed a
normal or low carbohydrate dietary regimen in addition to
supplementation with alkalizing agents: sodium bicarbon-
ate or sodium citrate. The low carbohydrate diet resulted
in metabolic acidosis before exercise, but the addition of
sodium bicarbonate acutely returned blood pH, HCO3,
and base excess to match values obtained from the normal
diet supplemented with sodium citrate. Subjects cycled
to voluntary exhaustion at 95% VO2max, and endur-
ance time was lower after the low carbohydrate diet,
irrespective of sodium bicarbonate supplementation. The
ingestion of sodium bicarbonate during low carbohydrate
dietary regimens was effective in reversing acidosis but
not at correcting the reduced performance, highlighting
that factors other than acidosis inuence fatigue (Ball et
al., 1996). A study involving nine recreationally active
young men found no acid-base status alterations or per-
formance enhancements from consuming a low protein
vegetarian diet (Hietavala et al., 2012). Participants
consumed their normal diet for 4 days before completing
submaximal and maximal aerobic cycling timed trials.
After a 10–16 day washout period, the subjects crossed
over to a low protein vegetarian (LPV) diet for 4 days
before completing the same exercise tests. The LPV
diet consisted mainly of fruits and vegetables to keep
the PRAL value of every food consumed below zero,
and subjects were not allowed to consume meat, cheese,
eggs, or bread. Measurements collected at rest and during
exercise indicated similar venous pH, total concentration
of weak acids and partial pressure of CO2 and HCO3
between both diets. Strong ion difference, a measure of
acid-base disturbances, increased 3.1% during the LPV
diet, reecting a trend toward alkalosis. Although VO2
was signicantly higher in the LPV diet group during
submaximal aerobic cycling, no differences were noted
in TTE or VO2max during the VO2max testing indicating
the alkaline diet did not improve submaximal or maximal
aerobic performance.
Due to age related declines in kidney function,
increased age is related to impaired ability to maintain
acid-base equilibrium (Pizzorno et al., 2010). To examine
the acid-base response and performance effects of diet
among three age groups, Hietavala et al. (2015) tested
recreationally active adolescents (ages 12–15 years),
young adults (ages 25–35 years), and elderly adults (ages
60–75 years) at rest and during exercise. Participants
were randomized to consume a normal protein diet
with high fruits and vegetables (HV) for 7 days, with a
crossover to a 7-day high protein diet with no fruits and
vegetables (HP) after a 2–4 week washout period. Lower
amounts of protein, higher amounts of carbohydrates,
and less calories were consumed in the HV diet than the
HP diet. The HV diet pattern exhibited negative PRAL
values (-47.1, -68.1, -61.8 mEq/day in the adolescent,
young adult, and elderly adults, respectively), and the
HP group consumed diets with positive PRAL values
(22.8, 53.3, 53.5 mEq/day in the adolescent, young adult,
and elderly adults, respectively). At the end of each diet
period, participants underwent three, 10-min cycling trials
at 35, 55, and 75% of their VO2max. Young adults and
elderly adults both exhibited higher plasma and urinary
pH values at rest and during exercise while consuming
the HV diet when compared with consumption of the HP
diet. There were no differences in plasma or urinary pH
values among adolescents at rest or during high intensity
cycling regardless of diet type, suggesting age is a predic-
tor of the ability of buffering systems to compensate for
dietary acid load changes.
To determine whether a true VO2max has been
achieved, a respiratory exchange ratio (RER) of ³1.10 is
often required. The RER is inuenced by the CO2 pro-
duced during respiratory compensatory buffering. Caciano
and colleagues (2015) investigated the effects of a short-
term (4–9 days) low-PRAL or high-PRAL diet on the RER
during maximal and submaximal exercise. Ten participants
completed a crossover trial in which they consumed a low-
PRAL (<1.5 mEQ/d) or high-PRAL diet (>15 mEQ/d), and
completed a graded treadmill exercise test to exhaustion
and a high-intensity running TTE treadmill test after each
dietary intervention. Carbohydrate intakes during the low-
PRAL and high-PRAL diets met minimum sport nutrition
recommendations (5 g/kg/day) (Rodriguez et al., 2009),
and consideration was taken during the dietary phases to
ensure that total energy, carbohydrate, and fat intake did
not differ between the trials. Protein content of the inter-
vention diets were signicantly different, with low-PRAL
diets containing less protein (~60 g/day) than high-PRAL
diets (~110 g/day). The maximal RER achieved at 100%
VO2max was greater after adherence to the high-PRAL
diet compared with the low-PRAL trial (1.20 ± 0.05,
1.10 ± 0.02). TTE was 21% greater in the low-PRAL
Downloaded by Alkek Lbry Serials Acq on 06/22/17, Volume 27, Article Number 3
Dietary Acid Load and Exercise Performance 217
IJSNEM Vol. 27, No. 3, 2017
trial compared with the high-PRAL trial during the high-
intensity treadmill running. Niekamp et al. (2013) had
similar ndings from evaluating the relationship between
a habitually alkaline diet and RER during VO2max testing.
Seven-day food diaries of 57 sedentary men and women
(ages 47–63 years) were collected to determine habitual
intake, and diets were scored as low-PRAL (-10.8 mEq/
day on average), mid-PRAL (8.2 mEq/day on average), or
high-PRAL (27.1 mEq/day on average). Low-PRAL diets
correlated with a lower intake of protein and phosphorous
in the diet. Individuals consuming lower PRAL diets dem-
onstrated a higher RER (≥ 1.10) when tested to VO2max
on a treadmill than those consuming mid or higher PRAL
diets. It is interesting to note that these differences were
only seen at maximal RER, and that at submaximal exer-
cise, RER values were not associated with the PRAL of
the diet. Therefore, habitual dietary intake, either acidic
or alkaline, may affect variability in maximal RER, with
higher values attained during maximal exercise after low
acid loads. However, it is important to note that Niekamp
et al. did not report the macronutrient content of the differ-
ent diets. The relative substrate utilization of carbohydrate
and fat during exercise is dependent on several factors
including diet composition (Jeukendrup, 2003). Thus, it is
unknown if higher RER in the low-PRAL diet was due to
a lower dietary acid load or a higher rate of carbohydrate
oxidation due to greater availability of carbohydrates.
Future studies should examine the specic mechanisms
for the relationship between alkaline diets, VO2max, and
RER by measuring multiple metabolic parameters and
substrate utilization.
Conclusion
Theoretically, the maintenance of high alkalinity in the
extracellular uid should enable a faster H+ ion removal
from the muscle cell, delaying the muscle fatigue due
to a lower muscle pH. Although alkalinizing ergogenic
aids such as sodium bicarbonate and sodium citrate have
shown to enhance buffering capacity and improve per-
formance, alkalinizing diets do not demonstrate the same
effect. Ingesting large amounts of sodium bicarbonate and
sodium citrate can result in large increases in pH, whereas
alkalinizing diets only serve to maintain a slightly more
alkaline environment. Side effects of sodium bicarbonate
such as gastrointestinal distress, low tolerability, and high
sodium content promote the use of alternative dietary
strategies to buffer excess H+ ions; however, the alkaline
environment achieved from the consumption of low or
negative PRAL diets is not sufcient to signicantly
enhance the neutralization or clearance of acids from the
muscle during exercise to improve performance (Caciano
et al., 2015). However, the current research has several
limitations which should be considered. The majority of
studies used short-term dietary interventions with young,
male subjects, and primarily assessed performance using
cycling tests to exhaustion. In addition, there was no
consistency in the level of dietary acid or alkaline load
tested among different studies. Future research should
include more diverse samples, longer dietary intervention
protocols, and examine different exercise intensities and
measures of performance.
Although the present review does not clearly estab-
lish and exercise performance benet of reduced dietary
acid load, current investigations support benefits of
reduced dietary acid loads to prevent disease and improve
health (Fenton & Huang, 2015). Reducing diet-dependent
acid loads in young and otherwise healthy athletes can
reduce cardio-metabolic risk factors (Murakami et al.,
2008) and risk of developing hepatic steatosis (Krupp et
al., 2012). Alkaline diets also promote bone health and
can reduce uric acid kidney stone formation (Sellmeyer
et al., 2001; Breslau et al., 1988; Niekamp et al., 2013).
Athletes may be more likely to consume positive PRAL
starches due to increased energy and carbohydrate
requirements, but the incorporation of fruits, vegetables,
and negative PRAL proteins in the diet may reduce the
risk of metabolic acidosis before, during, and after exer-
cise. A diet abundant in negative PRAL carbohydrates
that is low fat and low protein permits an alkaline state
and has the potential to increase muscle pH (Hietavala
et al., 2012; Greenhaff, Gleeson, & Maughan, 1988b).
It is important for athletes to adhere to sports nutrition
guidelines to maintain health and maximize performance
potential. Proper nutritional guidance should promote
adequate carbohydrate intakes (minimum 5 g/kg/day) to
maintain glycogen stores, even among athletes adhering
to low-PRAL diets (Caciano et al., 2015). This guidance
can also empower athletes to choose high nutritional qual-
ity carbohydrate sources such as fruits and vegetables to
meet nutritional needs, provide vitamins and minerals,
and maintain a more alkaline environment. Studies that
used dietary treatments with only modest differences
in protein content between acidic and alkaline diets did
not identify differences in exercise performance (Ball &
Maughan, 1997). Optimizing an athlete’s intake of fruits
and vegetables can also help to offset protein-induced
acidosis, which may occur from increased protein needs
(Adeva & Souto, 2011). In summary, it is practical to
recommend that athletes of all ages focus on consuming
ample amounts of fruits and vegetables to promote alka-
linity, attenuate protein-induced acidosis, and maintain
long-term health.
Novelty Statement
Research suggests that dietary acid load has little to no
inuence on submaximal exercise, and minor inuence
on exercise that requires maximal effort. Dietary modi-
cations such as increasing fruit and vegetable intake to
reduce the dietary acid load is relevant for athletes of all
ages to maintain long-term health and possibly impact
exercise performance at maximal intensities.
Practical Application
Nutritional guidance on consuming energy dense low-
PRAL foods like potatoes, dried fruits, and plant sources
Downloaded by Alkek Lbry Serials Acq on 06/22/17, Volume 27, Article Number 3
218 Applegate et al.
IJSNEM Vol. 27, No. 3, 2017
of fat in addition to nutrient rich fruits and vegetables
will promote energy intake and the alkaline status of the
individual, which has health benets beyond exercise
performance (Caciano et al., 2015). To improve per-
formance and prevent acid accumulation in muscle and
plasma, athletes should focus on training to attenuate
performance-inhibiting drops in pH during high-intensity
and long duration exercise.
Authorship
CA designed the review; literature review was conducted and
interpreted by CA, MM; data interpretation and manuscript
preparation were undertaken by CA, MM, and KZ. All authors
approved the nal version of the paper. The authors have no
conicts of interest to declare.
References
Abe, H. (2000). Role of histidine-related compounds as intracel-
lular proton buffering constituents in vertebrate muscle.
Biochemistry (Moscow), 65(7), 757–765. PubMed
Adeva, M.M., & Souto, G. (2011). Diet-induced metabolic
acidosis. Clinical Nutrition (Edinburgh, Lothian), 30(4),
416–421. PubMed doi:10.1016/j.clnu.2011.03.008
Aerenhouts, D., Deriemaeker, P., Hebbelinck, M., & Clarys, P.
(2011). Dietary acid-base balance in adolescent sprint ath-
letes: A follow-up study. Nutrients, 3, 200–211. PubMed
doi:10.3390/nu3020200
Ball, D., Greenhaff, P.L., & Maughan, R.J. (1996). The acute
reversal of a diet-induced metabolic acidosis does not
restore endurance capacity during high-intensity exer-
cise in man. European Journal of Applied Physiology
and Occupational Physiology, 73, 105–112. PubMed
doi:10.1007/BF00262817
Ball, D., & Maughan, R.J. (1997). The effect of sodium citrate
ingestion on the metabolic response to intense exer-
cise following diet manipulation in man. Experimental
Physiology, 82, 1041–1056. PubMed doi:10.1113/exp-
physiol.1997.sp004079
Bangsbo, J., Johansen, L., Graham, T., & Saltin, B. (1993). Lac-
tate and H+ efuxes from human skeletal muscles during
intense, dynamic exercise. The Journal of Physiology, 462,
115–133. PubMed doi:10.1113/jphysiol.1993.sp019546
Blair, S., Franks, A., Shelton, D., Livengood, J., Hull, F., &
Breedlove, B. (1996). Physical activity and health: a report
of the Surgeon General. Atlanta, Ga.: U.S. Department of
Health and Human Services, Centers for Disease Control
and Prevention, National Center for Chronic Disease
Prevention and Health.
Breslau, N.A., Brinkley, L., Hill, K.D., & Pak, C.Y. (1988).
Relationship of animal protein-rich diet to kidney stone
formation and calcium metabolism. The Journal of Clinical
Endocrinology and Metabolism, 66(1), 140–146. PubMed
doi:10.1210/jcem-66-1-140
Caciano, S.L., Inman, C.L., Gockel-Blessing, E.E., & Weiss,
E.P. (2015). Effects of dietary acid load on exercise
metabolism and anaerobic exercise performance. Journal
of Sports, Science, and Medicine, 14(2), 364–371. PubMed
Cairns, S.P. (2006). Lactic acid and exercise performance: Culprit
or friend? Sports Medicine (Auckland, N.Z.), 36(4), 279–
291. PubMed doi:10.2165/00007256-200636040-00001
Clancy, J., & Mcvicar, A. (2007). Short-term regulation of
acid-base homeostasis of body uids. British Journal of
Nursing (Mark Allen Publishing), 16(16), 1016–1021.
PubMed doi:10.12968/bjon.2007.16.16.27082
Cordain, L., Eaton, S.B., Sebastian, A., Mann, N., Lindeberg,
S., Watkins, B.A., . . . Brand-Miller, J. (2005). Origins and
evolution of the Western diet:health implications for the
21st century. The American Journal of Clinical Nutrition,
81, 341–354. PubMed
Fenton, T.R., & Huang, T. (2015). Systematic review of the
association between dietary acid load, alkaline water and
cancer. BMJ Open, 6, e010438. PubMed doi:10.1136/
bmjopen-2015-010438
Goel, N., & Calvert, J. (2012). Understanding blood gases/acid-
base balance. Paediatrics & Child Health, 22(4), 142–148.
doi:10.1016/j.paed.2011.09.005
Green, H.J. (1997). Mechanisms of muscle fatigue in intense
exercise. Journal of Sports Sciences, 15(3), 247–256.
PubMed doi:10.1080/026404197367254
Greenhaff, P., Gleeson, M., & Maughan, R. (1987). The effects
of dietary manipulation on blood acid-base status and the
performance of high intensity exercise. European Journal
of Applied Physiology and Occupational Physiology,
56(3), 331–337. PubMed doi:10.1007/BF00690901
Greenhaff, P.L., Gleeson, M., & Maughan, R.J. (1988a).
Diet-induced metabolic acidosis and the performance
of high intensity exercise in man. European Journal of
Applied Physiology, 57, 583–590. PubMed doi:10.1007/
BF00418466
Greenhaff, P.L., Gleeson, M., & Maughan, R.J. (1988b). The
effects of diet on muscle pH and metabolism during high
intensity exercise. European Journal of Applied Physiol-
ogy and Occupational Physiology, 57, 531–539. PubMed
doi:10.1007/BF00418458
Hietavala, E-M., Puurtinen, R., Kainulainen, H., & Mero, A.A.
(2012). Low-protein vegetarian diet does not have a short-
term effect on blood acid-base status but raises oxygen
consumption during submaximal cycling. Journal of the
International Society of Sports Nutrition, 9, 50. PubMed
doi:10.1186/1550-2783-9-50
Hietavala, E-M., Stout, J.R., Hulmi, J.J., Suominen, H., Pit-
känen, H., Puurtinen, R., . . . Mero, A.A. (2015). Effect
of diet composition on acid–base balance in adolescents,
young adults and elderly at rest and during exercise. Euro-
pean Journal of Clinical Nutrition, 69, 399–404. PubMed
doi:10.1038/ejcn.2014.245
Jeukendrup, A.E. (2003). Modulation of carbohydrate and
fat utilization by diet, exercise and environment. Bio-
chemical Society Transactions, 31, 1270–1273. PubMed
doi:10.1042/bst0311270
Krupp, D., Johner, S.A., Kalhoff, H., Buyken, A.E., & Remer,
T. (2012). Long-term dietary potential renal acid load
during adolescence is prospectively associated with indices
of nonalcoholic fatty liver disease in young women. The
Journal of Nutrition, 142, 313–319. PubMed doi:10.3945/
jn.111.150540
Downloaded by Alkek Lbry Serials Acq on 06/22/17, Volume 27, Article Number 3
Dietary Acid Load and Exercise Performance 219
IJSNEM Vol. 27, No. 3, 2017
Lindinger, M.I., McKelvie, R.S., & Heigenhauser, G.J. (1985).
K+ and Lac- distribution in humans during and after high-
intensity exercise: Role in muscle fatigue attenuation?
Journal of Applied Physiology, 78(3), 765–777. PubMed
Manzel, A., Muller, D.N., Haer, D.A., Erdman, S.E., Linker,
R.A., & Kleinewietfeld, M. (2014). Role of “Western diet”
in inammatory autoimmune disease. Current Allergy
and Asthma Reports, 14(1), 404. PubMed doi:10.1007/
s11882-013-0404-6
McNaughton, I.R., Siegler, J., & Midgley, A. (2008). Ergo-
genic effects of sodium bicarbonate. Current Sports
Medicine Reports, 7(4), 230–236. PubMed doi:10.1249/
JSR.0b013e31817ef530
Murakami, K., Sasaki, S., Takahashi, Y., & Uenishi, K.
(2008). Association between dietary acid-base load and
cardiometabolic risk factors in young Japanese women.
British Journal of Nutrition, 100(3), 642–651. PubMed
doi:10.1017/S0007114508901288
Niekamp, K., Zavorsky, G.S., Fontana, L., McDaniel, J.L., Vil-
lareal, D.T., & Weiss, E.P. (2013). Systemic acid load from
the diet affects maximal exercise respiratory exchange
ratio. Medicine and Science in Sports and Exercise, 44(4),
709–715. PubMed doi:10.1249/MSS.0b013e3182366f6c
Peart, D.J., Siegler, J.C., & Vince, R.V. (2012). Practical recom-
mendations for coaches and athletes:A meta-analysis of
sodium bicarbonate use for athletic performance. Journal
of Strength and Conditioning Research, 26(7), 1975–1983.
PubMed doi:10.1519/JSC.0b013e3182576f3d
Pizzorno, J., Frassetto, L.A., & Katzinger, J. (2010). Diet-
induced acidosis: is it real and clinically relevant? British
Journal of Nutrition, 103, 1185–1194. PubMed
Poupin, N., Calvez, J., Lassale, C., Chesneau, C., & Tomé, D.
(2012). Impact of the diet on net endogenous acid pro-
duction and acid-base balance. Clinical Nutrition (Edin-
burgh, Lothian), 31, 313–321. PubMed doi:10.1016/j.
clnu.2012.01.006
Remer, T. (2001). Inuence of nutrition on acid-base balance
- Metabolic aspects. European Journal of Nutrition, 40,
214–220. PubMed doi:10.1007/s394-001-8348-1
Ríos Enríquez, O., Guerra-Hernández, E., & Feriche Fernández-
Castanys, B. (2010). Efectos de la alcalosis metabólica
inducida por la dieta en el rendimiento anaeróbico de alta
intensidad. Nutricion Hospitalaria, 25(5), 768–773. PubMed
Rodriguez, N.R., DiMarco, N.M., & Langley, S. (2009). Posi-
tion of the American Dietetic Association, Dietitians
of Canada, and the American College of Sports Medi-
cine: Nutrition and athletic performance. Journal of the
American Dietetic Association, 109(3), 509–527. PubMed
doi:10.1016/j.jada.2009.01.005
Sahlin, K. (2014). Muscle energetics during explosive activities
and potential effects of nutrition and training. Sports Medi-
cine (Auckland, N.Z.), 44(Suppl. 2), 167–173. PubMed
doi:10.1007/s40279-014-0256-9
Schubert, M.M., & Astorino, T.A. (2013). A systematic
review of the efcacy of ergogenic adis for improving
running performance. Journal of Strength and Condition-
ing Research, 27(6), 1699–1707. PubMed doi:10.1519/
JSC.0b013e31826cad24
Sellmeyer, D.E., Stone, K.L., Sebastian, A., & Cummings, S.R.
(2001). A high ratio of dietary animal to vegetable protein
increases the rate of bone loss and the risk of fracture in
postmenopausal women. The American Journal of Clinical
Nutrition, 73, 118–122. PubMed
Thomas, D.T., Erdman, K.A., & Burke, L.M. (2016). From
the academy: Position of the Academy of Nutrition and
Dietetics, Dietitians of Canada, and the American College
of Sports Medicine: Nutrition and athletic performance.
Journal of the Academy of Nutrition and Dietetics, 11,
6501–6528. PubMed
Welch, A.A., Mulligan, A., Bingham, S.A., & Khaw, K.
(2008). Urine pH is an indicator of dietary acid-base
load, fruit and vegetables, and meat intakes: results from
the European Prospective Investigation into Cancer and
Nutrition (EPIC)-Norfolk population study. British Jour-
nal of Nutrition, 99, 1335–1343. PubMed doi:10.1017/
S0007114507862350
Yucha, C. (2004). Renal regulation of acid-base balance.
Nephrology Nursing Journal, 31(2), 201–206. PubMed
Downloaded by Alkek Lbry Serials Acq on 06/22/17, Volume 27, Article Number 3
... However, they can also interact, affecting exercise performance. It has been hypothesized that creating a more alkaline systemic environment by reducing dietary acid load may increase the clearance of protons and inhibitory molecules affecting working muscles during exercise-induced acidosis, thereby improving aerobic and anaerobic exercise performance (13). ...
... Diet type and exercise strongly influence the body's acid-base balance through their own mechanisms, and they can also interact that affect exercise performance. It has been hypothesized that creating a more alkaline systemic environment by reducing dietary acid load may increase the clearance of protons and inhibitory molecules affecting working muscles during exerciseinduced acidosis, thereby improving aerobic and anaerobic exercise performance (13). There are also several studies examining the positive effects of supplementation with ergogenic aids such as alkaline foods with high pH, sodium bicarbonate (NaHC0 3 ), or dietary nitrate for alleviating exercise performance (20, [32][33][34][35][36]. ...
... Caciano et al. (9) found that the exhaustion times on short-term high-intensity treadmills in athletes with negative PRAL values were 21% higher than in athletes with positive PRAL values, and this is an indicator of increased anaerobic exercise performance. Despite this conclusion, Applegate et al. (13) concluded in a recent review that alkalizing diets do not have the same effects on buffering capacity and athletic performance as alkalizing agents such as NaHC0 3 . Limmer et al. (42) examined the effect of low-PRAL and high-PRAL diets on anaerobic performance in an acute experimental study conducted on 15 healthy, non-specifically trained adult volunteers, and they reported that the low-PRAL diet did not show any improvement in anaerobic performance. ...
Article
Full-text available
Background Diet composition can affect systemic pH and acid–base regulation, which may in turn influence exercise performance. Purpose It was aimed to determine the effects of the alkaline diet and 8 weeks of aerobic exercises on body composition, aerobic performance, and blood lipid profiles in sedentary women. Methods Thirty-two sedentary women participated in the study voluntarily. The research was designed with a true-experimental design and the participants were divided into four different groups as the control group, aerobic exercise group, alkaline diet group, and alkaline diet + aerobic exercise group. The body compositions, aerobic exercise performances, and lipid profiles of sedentary women were measured as pre-test and post-test. In the analysis of the obtained data, One-Way ANOVA with Bonferroni post hoc test was used. Results It was observed that the alkaline diet consumed with 8 weeks of aerobic exercises caused a 5.17% decrease in BMI and an increase of 42.07 and 37.62% in VO2max and aerobic test durations, respectively (p < 0.05). In addition, when lipid profiles were examined, it was determined that there was no statistically significant difference in HDL-C levels (p > 0.05). Despite that, there were statistically significant differences in TG and LDL-C levels (p < 0.05). According to this result, it was determined that there was a decrease in TG and LDL-C levels by 37.61 and 20.24%, respectively. Conclusion An alkaline diet consumed with 8 weeks of aerobic exercises in sedentary women has positive effects on improving body composition, aerobic exercise performances, and TG and LDL-C levels.
... Therefore, the Mediterranean diet is suitable to be adjusted as alkaline [20]. Previous studies reported that alkaline diets and the Mediterranean diet have beneficial properties for physical performance [21,22]. This research was designed assuming that an alkaline diet prepared according to Mediterranean diet principles will have a greater impact on athlete performance and lactate levels. ...
Article
Background/objectives: Mediterranean diet is an environmentally friendly and healthy diet model. The diet offers many vegetables, fruits, nuts, and olive oil to consumers. In addition, it provides moderate amounts of fish and chicken, smaller quantities of dairy products, red meat, and processed meat. The Mediterranean diet has a high anti-inflammatory and antioxidant content, and it causes many physiological changes that can provide a physical performance advantage. This study examined the effects of a 15-day menu, which was planned using foods with a low acid load within the Mediterranean diet rules, on the exercise performance, lactate elimination, anthropometric measurements, and body composition. Subjects/methods: Fifteen professional male athletes between the ages of 13 and 18, who were engaged in ski running, were included in the experimental study. Dietary intervention was applied for 15 days. The athlete performances were evaluated by applying the vertical jump test, hand grip strength, 20 meters shuttle run test, and Borg fatigue scale. After the shuttle run test (every 3 min for 30 min), blood was drawn from the finger, and the lactate elimination time was calculated. Performance and lactate measurements, body analysis, and anthropometric measurements were taken before and after dietary intervention. Results: The vertical jump height and hand grip strength increased after the intervention (P < 0.05). The test duration, total distance, the number of shuttles, and maximum oxygen consumption parameters of the shuttle run test increased (P < 0.05). After the intervention, the athletes' perceived fatigue scores decreased in several stages of the shuttle run test (P < 0.05). The lactate elimination time and athlete's body composition were similar in repeated measurements (P > 0.05). In the last measurements, the upper middle arm circumference decreased while the height of the athletes increased (P < 0.05). Conclusions: These results show that the Mediterranean diet is a safe and feasible dietary approach for aerobic performance and strength increase.
... Another way to improve acid-base balance regulation capacity is through the modification of dietary composition 5 . Several factors determine the acid-base balance of the body, including nutrient content, absorption of nutrients in the intestine, metabolic sulphate formation from sulphurcontaining amino acids, the degree of decomposition of phosphorus at pH 7.4, and the ionic valence of calcium and magnesium 6 . ...
Article
Full-text available
Purpose: Since the dietary acid load (PRAL) may affect the acid-base balance of the body, there is an increasing interest in its role in sports performance. Typical nutritional requirements of different sports, associated with its physiological demands, might be reflected in the acid load of their diet. Thus, the purpose of this study is to compare the dietary acid load between team, endurance, and strength athletes and to determine the associations between PRAL and hydration status. Methods: Fifty-one healthy recreational male athletes (age: 18-39 yrs) from team, endurance, and strength sports participated in the study. A 3-day food diary was recorded and dietary PRAL values (mEq/day) were calculated. Urine pH and specific gravity were measured. One-way ANOVA with Bonferroni post-hoc analysis and Pearson correlation coefficient (r) were used for data analysis. Results: PRAL in endurance athletes (25.34 mEq/day) was lower compared to team and strength athletes (46.12 and 46.47 mEq/day, respectively) (p= 0.023). Percentage of high PRAL diet (≥15 (mEq/day)) was highest in team sports (89.5%), followed by strength (83.3%) and endurance sports (60%). PRAL was not associated with hydration status. Conclusion: Typical nutritional requirements of sport disciplines are reflected in the PRAL, thus PRAL should be considered when preparing nutritional strategies to improve performance.
... Further, PB diets tend to be more alkaline, due to higher intakes of fruits and vegetables. However, dietary manipulations do not significantly effect cellular and tissue pH as it is tightly regulated and any changes pH are minimal and controlled for (Applegate et al. 2017;Robergs et al. 2018) Limited evidence is available characterizing the impact of a PB diet on anaerobic, strength, or power performance; however, if the above-noted considerations are taken into account and supplementation occurs as indicated, there is no reason to suggest that such exercise should be impaired by a PB diet. ...
Article
Full-text available
Individuals may opt to follow a plant-based diet for a variety of reasons, such as religious practices, health benefits or concerns for animal or environmental welfare. Such diets offer a broad spectrum of health benefits including aiding in the prevention and management of chronic diseases. In addition to health benefits, a plant-based diet may provide performance-enhancing effects for various types of exercise due to high carbohydrate levels and the high concentration of antioxidants and phytochemicals found in a plant-based diet. However, some plant-based foods also contain anti-nutrional factors, such as phytate and tannins, which decrease the bioavailability of key nutrients, such as iron, zinc, and protein. Thus, plant-based diets must be carefully planned to ensure adequate intake and absorption of energy and all essential nutrients. The current narrative review summarizes the current state of the research concerning the implications of a plant-based diet for health and exercise performance. It also outlines strategies to enhance the bioavailability of nutrients, sources of hard-to-get nutrients, and sport supplements that could interest plant-based athletes.
... Dietary supplements have received widespread attention from athletes for their potential function in regulating acidbase and redox balance and modifying substrate utilization patterns during exercise; increasing number of reports indicate that astaxanthin is one such supplement (Table 6). Oxidative stress and the acidic environment in the muscle contribute to impaired performance and fatigue (Applegate, Mueller, and Zuniga 2017). In a randomized, double-blind, placebo-controlled trial, long-term supplementation of 12 mg astaxanthin daily significantly decreased the increase in blood lactate and improved aerobic recovery in volunteers after the maximal oxygen uptake test (Fleischmann et al. 2019). ...
Article
Astaxanthin is a carotenoid widely found in marine organisms and microorganisms. With extensive use in nutraceuticals, cosmetics, and animal feed, astaxanthin will have the largest share in the global market for carotenoids in the near future. Owing to its unique molecular features, astaxanthin has excellent antioxidant activity and holds promise for use in biochemical studies. This review focuses on the observed health benefits of dietary astaxanthin, as well as its underlying bioactivity mechanisms. Recent studies have increased our understanding of the role of isomerization and esterification in the structure–function relationship of dietary astaxanthin. Gut microbiota may involve the fate of astaxanthin during digestion and absorption; thus, further knowledge is needed to establish accurate recommendations for dietary intake of both healthy and special populations. Associated with the regulation of redox balance and multiple biological mechanisms, astaxanthin is proposed to affect oxidative stress, inflammation, cell death, and lipid metabolism in humans, thus exerting benefits for skin condition, eye health, cardiovascular system, neurological function, exercise performance, and immune response. Additionally, preclinical trials predict its potential effects such as intestinal flora regulation and anti-diabetic activity. Therefore, astaxanthin is worthy of further investigation for boosting human health, and wide applications in the food industry.
... 26 Athletes often consume larger amounts of carbohydrates and protein to compensate for the increased metabolic breakdown of these macronutrients during training periods and are thus at risk for consuming perpetually positive PRAL diets. 23,27 Diets high in PRAL induce a low-grade metabolic acidosis, which is associated with metabolic alterations such as higher adiposity and blood pressure. 26 Some studies have also indicated that age-and diet-related mild metabolic acidosis may play a role in the development of skeletal muscle mass loss 22,28,29 as well as a decrease in bone mineralization and an increase in bone fractures. ...
Article
We evaluated the associations of micronutrient adequacy (measured by the mean adequacy ratio of intakes to nutrient recommendations) and dietary acid load with body composition in 218 football (soccer) players and referees in Iran to provide insights that might help to optimize nutrition and overall performance. Despite the alkaline nature of their diets, there was no association between dietary acid load indices and body composition, and the mean adequacy ratio was positively associated only with percentage body fat (β = .17, P = .01). Further studies with larger sample sizes and longer durations are recommended.
... Bu nedenle sporcuların diyet PRAL değeri pozitif olma eğilimindedir. 10 Diyet PRAL değerinin pozitif olması, yüksek yoğunluklu egzersiz sırasında asidoz gelişimini artırıp, bikarbonat kullanılabilirliğini azaltarak spor performansını olumsuz etkileyebilir. 7 PRAL değerinin negatif olmasının ise alkalozu artırıp, bikarbonat kullanılabilirliğini artırdığı ve spor performansını olumlu etkileyebileceği öne sürülmektedir. ...
Article
Full-text available
ZET Amaç: Bu çalışma, potansiyel renal asit yükünün [potential renal acid load (PRAL)] taekwondo sporcularında diz ekstansör kasla-rının izokinetik kuvveti ve anaerobik performansa etkisini incelemek amacıyla gerçekleştirildi. Gereç ve Yöntemler: Çalışmaya 27 erkek, 19 kadın olmak üzere toplam 46 taekwondo sporcusu dâhil edildi. Spor-cuların beslenme durumu 7 günlük "Besin Tüketim Kaydı Formu" dol-durularak değerlendirildi. Vücut kompozisyonu, Biyoelektrik İmpedans Ölçümü ile diz ekstansör kaslarının kas kuvveti izokinetik dinamometre ile anaerobik performans Wingate testi ile değerlendirildi. Çalışmaya katılan sporcuların besin tüketim kaydı değerlendirilerek diyet PRAL değerleri hesaplandı ve sporcular diyet PRAL değeri negatif [PRAL (-)] olanlar (n=14) ve diyet PRAL değeri pozitif [PRAL (+)] olanlar (n=32) olarak ayrıldı. İstatistiksel analizlerde anlamlılık düzeyi p<0,05 olarak belirlendi. Bulgular: PRAL değeri (-) ve (+) olan kadın ve erkek sporcular arasında günlük enerji, makro besin öğesi ve lif alım düzey-leri açısından istatistiksel olarak fark olmadığı (p>0,05); kadın sporcu-ların hayvansal protein alım düzeylerinin PRAL (+) grubunda daha fazla olduğu (p<0,05), erkek sporcularda ise fark olmadığı belirlendi (p>0,05). Kadın ve erkek sporcularda PRAL (+) ve (-) olan gruplarda diz ekstansör kaslarının izokinetik kas kuvvetinin benzer olduğu, grup-ların anaerobik performansları arasında fark olmadığı belirlendi (p>0,05). Sonuç: Çalışma sonucunda PRAL değeri negatif ya da pozi-tif olan kadın ve erkek sporcuların diz ekstansör kasının izokinetik kuv-vetinin ve sporcuların anaerobik performansının benzer olduğu belirlendi. Anah tar Ke li me ler: Diyet asit yükü; izokinetik kas kuvveti; anaerobik performans ABS TRACT Objective: This study was carried out to examine the effect of potential renal acid load (PRAL) on the isokinetic strength of knee extensor muscles and anaerobic performance in taekwondo athletes. Material and Methods: A total of 46 taekwondo athletes, 27 males and 19 females, were included in the study. Body composition was evaluated by bioelectrical impedance measurement, muscle strength with isokinetic dynamometer, anaerobic performance was evaluated by Wingate test. Food intake records of athletes were evaluated , their PRAL values were calculated and athletes were separated to groups: those with negative PRAL value [PRAL (-)] (n=14) and those with positive PRAL value [PRAL (+)] (n=32). The statistically significance value was accepted as p<0.05 for data analysis. Results: There is no statistically significant difference between male and female athletes with PRAL value (-) and (+) in terms of daily energy, macronu-trient and fiber intake levels (p>0.05); It was determined that animal protein intake levels of female athletes were higher in the PRAL (+) group (p<0.05), while there was no difference in male athletes (p>0.05). In female and male athletes, in the PRAL (+) and (-) groups, the isoki-netic muscle strength of the knee extensor muscles was similar, and there was no difference between the anaerobic performances of the groups (p>0.05). Conclusion: As a result of the study, it was determined that the isokinetic strength of the knee extensor muscle and the anaerobic performance of the athletes were similar for male and female athletes with a negative or positive PRAL value.
... It is extensively demonstrated that an active life style and a healthy diet are both related with a better physiological response of the organism (expressed in heart rate and blood lactate) [24,25]. Based on these observations, we decided to analyze whether university students who adhere more to a Mediterranean diet demonstrate a better physiological response to exercise, and to compare whether their habits have a significant impact on different anthropometric parameters. ...
Article
Full-text available
Background: The purpose of the study was to determine to what degree the health habits of university students influence their physiological response during a 10-min high-intensity exercise. Methods: We conducted a cross-sectional cohort study with 59 health science students, in which we analyzed their adherence to a Mediterranean and low-fat diet, as well as their activity levels. We correlated these factors with the physiological response (lactic acid and heart rate) and a series of anthropometric parameters in intense physical activity (cardiopulmonary resuscitation (CPR) for 10 min) in three scenarios: extreme cold, extreme heat and a control situation at room temperature. Results: The results of this study demonstrate that in university students, a greater adherence to the Mediterranean diet was associated with a better response to physical exercise, in this case, 10-min CPR, in hostile environments. Conclusions: Following healthy eating guidelines improves physical performance and delays the appearance of fatigue; both are important aspects for a better performance of CPR.
Article
Poor oral hygiene is an important issue, as it can cause pain, adverse effects and psychosocial impacts on morale and quality of life, as well as long-term effects. Also self-reporting data also show an effect on the training and progress of athletes. Athlete's oral health can be threatened by multiple items such as dietary supplements, oral dehydration, immune suppression triggered by exercise, lack of awareness and negative behaviors. Oral diseases can be avoided in theory, however, by simple interventions with clear proofs of efficacy. This paper aims to raise awareness, in addition to future study plans of oral health issues in elite sports, and proposes prevention and health promotion strategies
Article
Full-text available
Introduction A limited number of studies have assessed the accuracy and precision of methods for determining the net endogenous acid production (NEAP) and its components. We aimed to investigate the performance of methods quantifying the diet dependent acid-base load. Methods Data from metabolic balance studies enabled calculations of NEAP according to the biochemical measures (of net acid excretion (NAE), urinary net endogenous acid production (UNEAP) and urinary potential renal acid load (UPRAL)) as well as estimative diet equations (by Frassetto et al., Remer and Manz, Sebastian et al. and Lemann et al.) which were compared amongst themselves in healthy participants fed both acid and base forming diets for 6 days each. Results Seventeen participants (mean ± SD age, 60 ± 8 years; BMI, 23 ± 2 kg/m²) provided 102 24-hr urine samples for analysis (NAE, 39 ± 38 mEq/d (range: -9 to 95 mEq/d)). Bland-Altman analysis comparing UNEAP to NAE showed good accuracy (Bias: -2 mEq/d, 95% CI: -8 to 3) and modest precision (limits of agreement: -32 to 28 mEq/d). Accurate diet equations included PRAL by Sebastian et al. (Bias: -4 mEq/d, 95% CI: -8 to 0) as well as NEAP by Lemann et al. (Bias: 4 mEq/d, 95% CI: -1 to 9) and Remer and Manz (Bias: -1 mEq/d, 95% CI: -6 to 3). Conclusions Researchers are encouraged to collect measures of UPRAL and UNEAP however, investigators drawing conclusions between the diet-dependent acid-base load and human health should consider the limitations within all methods.
Article
Full-text available
Objectives To evaluate the evidence for a causal relationship between dietary acid/alkaline and alkaline water for the aetiology and treatment of cancer. Design A systematic review was conducted on published and grey literature separately for randomised intervention and observational studies with either varying acid–base dietary intakes and/or alkaline water with any cancer outcome or for cancer treatment. Outcome measures Incidence of cancer and outcomes of cancer treatment. Results 8278 citations were identified, and 252 abstracts were reviewed; 1 study met the inclusion criteria and was included in this systematic review. No randomised trials were located. No studies were located that examined dietary acid or alkaline or alkaline water for cancer treatment. The included study was a cohort study with a low risk of bias. This study revealed no association between the diet acid load with bladder cancer (OR=1.15: 95% CI 0.86 to 1.55, p=0.36). No association was found even among long-term smokers (OR=1.72: 95% CI 0.96 to 3.10, p=0.08). Conclusions Despite the promotion of the alkaline diet and alkaline water by the media and salespeople, there is almost no actual research to either support or disprove these ideas. This systematic review of the literature revealed a lack of evidence for or against diet acid load and/or alkaline water for the initiation or treatment of cancer. Promotion of alkaline diet and alkaline water to the public for cancer prevention or treatment is not justified.
Article
Full-text available
Background: Diets rich in animal protein and cereal grains and deficient in vegetables and fruits may cause low-grade metabolic acidosis, which may impact exercise and health. We hypothesized that (1) a normal-protein diet with high amount of vegetables and fruits (HV) induces more alkaline acid-base balance compared with a high-protein diet with no vegetables and fruits (HP) and (2) diet composition has a greater impact on acid-base balance in the elderly (ELD). Subjects/methods: In all, 12-15 (adolescents (ADO)), 25-35 (young adults (YAD)) and 60-75 (ELD)-year-old male and female subjects (n=88) followed a 7-day HV and a 7-day HP in a randomized order and at the end performed incremental cycle ergometer tests. We investigated the effect of diet composition and age on capillary (c-pH) and urine pH (u-pH), strong ion difference (SID), partial pressure of carbon dioxide (pCO2) and total concentration of weak acids (Atot). Linear regression analysis was used to examine the contribution of SID, pCO2 and Atot to c-pH. Results: In YAD and ELD, c-pH (P⩽0.038) and u-pH (P<0.001) were higher at rest after HV compared with HP. During cycling, c-pH was higher (P⩽0.034) after HV compared with HP at submaximal workloads in YAD and at 75% of VO2max (maximal oxygen consumption) in ELD. The contribution of SID, pCO2 and Atot to c-pH varied widely. Gender effects or changes in acid-base balance of ADO were not detected. Conclusions: A high intake of vegetables and fruits increases blood and u-pH in YAD and ELD. ELD compared with younger persons may be more sensitive for the diet-induced acid-base changes.
Article
Full-text available
The high-energy demand during high-intensity exercise (HIE) necessitates that anaerobic processes cover an extensive part of the adenosine triphosphate (ATP) requirement. Anaerobic energy release results in depletion of phosphocreatine (PCr) and accumulation of lactic acid, which set an upper limit of anaerobic ATP production and thus HIE performance. This report focuses on the effects of training and ergogenic supplements on muscle energetics and HIE performance. Anaerobic capacity (i.e. the amount of ATP that can be produced) is determined by the muscle content of PCr, the buffer capacity and the volume of the contracting muscle mass. HIE training can increase buffer capacity and the contracting muscle mass but has no effect on the concentration of PCr. Dietary supplementation with creatine (Cr), bicarbonate, or beta-alanine has a documented ergogenic effect. Dietary supplementation with Cr increases muscle Cr and PCr and enhances performance, especially during repeated short periods of HIE. The ergogenic effect of Cr is related to an increase in temporal and spatial buffering of ATP and to increased muscle buffer capacity. Bicarbonate loading increases extracellular buffering and can improve performance during HIE by facilitating lactic acid removal from the contracting muscle. Supplementation with beta-alanine increases the content of muscle carnosine, which is an endogenous intracellular buffer. It is clear that performance during HIE can be improved by interventions that increase the capacity of anaerobic ATP production, suggesting that energetic constraints set a limit for performance during HIE.
Article
Full-text available
Abstract Background Acid–base balance refers to the equilibrium between acids and bases in the human body. Nutrition may affect acid–base balance and further physical performance. With the help of PRAL (potential renal acid load), a low-protein vegetarian diet (LPVD) was designed to enhance the production of bases in body. The aim of this study was to investigate if LPVD has an effect on blood acid–base status and performance during submaximal and maximal aerobic cycling. Methods Nine healthy, recreationally active men (age 23.5 ± 3.4 yr) participated in the study and were randomly divided into two groups in a cross-over study design. Group 1 followed LPVD for 4 days and group 2 ate normally (ND) before performing a cycle ergometer test. The test included three 10-min stages at 40, 60 and 80% of VO2max. The fourth stage was performed at 100% of VO2max until exhaustion. After 10–16 days, the groups started a second 4-day diet, and at the end performed the similar ergometer test. Venous blood samples were collected at the beginning and at the end of both diet periods and after every stage cycled. Results Diet caused no significant difference in venous blood pH, strong ion difference (SID), total concentration of weak acids (Atot), partial pressure of CO2 (pCO2) or HCO3- at rest or during cycling between LPVD and ND. In the LPVD group, at rest SID significantly increased over the diet period (38.6 ± 1.8 vs. 39.8 ± 0.9, p=0.009). Diet had no significant effect on exercise time to exhaustion, but VO2 was significantly higher at 40, 60 and 80% of VO2max after LPVD compared to ND (2.03 ± 0.25 vs. 1.82 ± 0.21 l/min, p=0.035; 2.86 ± 0.36 vs. 2.52 ± 0.33 l/min, p
Article
Full-text available
Sodium bicarbonate (NaHCO3) is a buffering agent that is suggested to improve performance by promoting the efflux of hydrogen ions from working cells and tissues. Research surrounding its efficacy as an ergogenic aid is conflicting, making it difficult to draw conclusions as to its effectiveness for training and competition. This study performed a meta-analysis of relevant research articles to allow the development of concise practical recommendations for coaches and athletes. The overall effect size for the influence of NaHCO3 on performance was moderate, and was significantly lower for specifically trained as opposed to recreationally trained participants.
Article
Background: Different sources of dietary protein may have different effects on bone metabolism. Animal foods provide predominantly acid precursors, whereas protein in vegetable foods is accompanied by base precursors not found in animal foods. Imbalance between dietary acid and base precursors leads to a chronic net dietary acid load that may have adverse consequences on bone. Objective: We wanted to test the hypothesis that a high dietary ratio of animal to vegetable foods, quantified by protein content, increases bone loss and the risk of fracture. Design: This was a prospective cohort study with a mean (±SD) of 7.0 ± 1.5 y of follow-up of 1035 community-dwelling white women aged >65 y. Protein intake was measured by using a food-frequency questionnaire and bone mineral density was measured by dual-energy X-ray absorptiometry. Results: Bone mineral density was not significantly associated with the ratio of animal to vegetable protein intake. Women with a high ratio had a higher rate of bone loss at the femoral neck than did those with a low ratio (P = 0.02) and a greater risk of hip fracture (relative risk = 3.7, P = 0.04). These associations were unaffected by adjustment for age, weight, estrogen use, tobacco use, exercise, total calcium intake, and total protein intake. Conclusions: Elderly women with a high dietary ratio of animal to vegetable protein intake have more rapid femoral neck bone loss and a greater risk of hip fracture than do those with a low ratio. This suggests that an increase in vegetable protein intake and a decrease in animal protein intake may decrease bone loss and the risk of hip fracture. This possibility should be confirmed in other prospective studies and tested in a randomized trial.
Article
Dietary acid load, quantified as the potential renal acid load (PRAL) of the diet, affects systemic pH and acid-base regulation. In a previous cross-sectional study, we reported that a low dietary PRAL (i.e. alkaline promoting diet) is associated with higher respiratory exchange ratio (RER) values during maximal exercise. The purpose of the present study was to confirm the previous findings with a short-term dietary intervention study. Additionally, we sought to determine if changes in PRAL affects submaximal exercise RER (as a reflection of substrate utilization) and anaerobic exercise performance. Subjects underwent a graded treadmill exercise test (GXT) to exhaustion and an anaerobic exercise performance test on two occasions, once after following a low-PRAL diet and on a separate occasion, after a high-PRAL diet. The diets were continued as long as needed to achieve an alkaline or acid fasted morning urine pH, respectively, with all being 4-9 days in duration. RER was measured during the GXT with indirect calorimetry. The anaerobic performance test was a running time-to-exhaustion test lasting 1-4 min. Maximal exercise RER was lower in the low-PRAL trial compared to the high-PRAL trial (1.10 +/- 0.02 vs. 1.20 +/- 0.05, p = 0.037). The low-PRAL diet also resulted in a 21% greater time to exhaustion during anaerobic exercise (2.56 +/- 0.36 vs. 2.11 +/- 0.31 sec, p = 0.044) and a strong tendency for lower RER values during submaximal exercise at 70% VO(2)max (0.88 +/- 0.02 vs. 0.96 +/- 0.04, p = 0.060). Contrary to our expectations, a short-term low-PRAL (alkaline promoting) diet resulted in lower RER values during maximal-intensity exercise. However, the low-PRAL diet also increased anaerobic exercise time to exhaustion and appears to have shifted submaximal exercise substrate utilization to favor lipid oxidation and spare carbohydrate, both of which would be considered favorable effects in the context of exercise performance.
Article
Acid–base balance is regulated by intracellular & extracellular buffers and by the renal and respiratory systems. Normal pH is necessary for the optimal function of cellular enzymes and metabolism. Disorders of acid–base balance can interfere with these physiological mechanisms leading to acidosis or alkalosis and can be potentially life threatening. Blood gas analysis is a routine procedure performed in the neonatal unit and combined with non-invasive monitoring, aids in the assessment and management of ventilation and oxygenation and provides an insight into the metabolic status of the patient. The following discussion details the basic terminology and pathophysiology of acid–base balance and the main disorders. It aims to provide a logical and systematic approach to the understanding and interpretation of blood gases in the newborn period. The application of these concepts, together with relevant history and examination, will help the clinician assess the medical condition, make therapeutic decisions and evaluate the effectiveness of any intervention provided.
Article
Running is a common form of activity worldwide and participants range from "weekend warriors" to Olympians. Unfortunately, few studies have examined efficacy of various ergogenic aids in runners, as the majority of the literature consists of cycling-based protocols which do not relate to running performance. The majority of running studies conducted markedly vary in regards to specific distance completed, subject fitness level, and effectiveness of the ergogenic aid examined. The aim of this paper was to systematically examine the literature concerning utility of several ergogenic aids on middle-distance (400-5,000 meters) and long-distance running (10,000 meters-marathon/42.2 km) performance. In addition, this paper highlights the dearth of running-specific studies in the literature, and addresses recommendations for future research to optimize running performance through nutritional intervention. Results revealed 23 studies examining effects of various ergogenic aids on running performance, with a mean PEDro score equal to 7.85 ± 0.70. Of these studies, 71 % (n=15) demonstrated improved running performance with ergogenic aid ingestion when compared to a placebo trial. The most effective ergogenic aids for distances from 400 m to 40 km included sodium bicarbonate (4 studies; 1.5 ± 1.1 % improvement), sodium citrate (6 studies; 0.3 ± 1.7 % improvement), caffeine (CAFF) (7 studies; 1.1 ± 0.4% improvement), and carbohydrate (CHO) (6 studies; 4.1 ± 4.4 % improvement). Therefore, runners may benefit from ingestion of sodium bicarbonate to enhance middle distance performance and caffeine and carbohydrate to enhance performance at multiple distances.