1. How do buffering agents work?
During high intensity exercise, the main source of energy is rapid glycolysis,
a process that results in the production of high amount of lactate anions
and hydrogen ions. In turn, the eventual buildup of these ions is thought
to contribute to muscular fatigue by reducing muscle and blood pH levels,
a state called metabolic acidosis. Buildup of hydrogen ions can inhibit glycolysis
by inhibiting the activities of phosphofructokinase and phosphorylase, inhibit
calcium binding to troponin C and its release from the sarcoplasmic reticulum,
and reduce muscle contractile force [1-2]; all of these can result in increased
fatigue and reduced performance.
Given that acidosis is responsible for many of the processes that can contribute
to muscular fatigue, preventing this state may improve performance. This
is the rationale for the use of buffering agents, which can counteract the
exercise-induced decrease in muscular and plasma pH. The two most popular
buffering agents used for this purpose are sodium citrate and sodium bicarbonate
(baking soda), and research has consistently found that oral administration
of these substances in sufficient quantity prevents the exercise-induced
decrease in pH levels. These agents function both by facilitating lactate
efflux and by increasing glycolytic energy production [2-5].
Mechanisms for improved performance other than increased peripheral buffering
capacity have also been postulated. Buffering agents may also influence the
afferent stimulation from contracting muscles, causing a change in the hormonal
and central response to exercise [2]. High sodium intake also leads to increased
plasma volume, which may improve perfousion of skeletal muscle and alter
sensory feedback to the brain [2], but it is unlikely that this is the only
effect, since many studies finding improved performance from buffering agents
use sodium chloride as a positive control.
2. Are buffering agents effective for all types of exercise?
Studies have been done on the use of buffering agents for many types of exercise.
In theory, buffering agents would be primarily useful for short-term, high-intensity,
intermittent exercise where glycolytic energy production is a major limiting
factor. In support of this, the largest effect is generally seen with exercise
bouts lasting one minute up to 4-8 minutes [4-5]. Buffering agents are less
effective for exercise bouts of shorter duration; this may be because such
exercise does not sufficiently challenge intrinsic buffering capacity and/or
because rapid glycolysis is not as important of an energy source during this
type of exercise. Sport specific protocols have found that buffering agents
improve performance in sprinting, interval swimming, rowing, and cycling
[5]. There are trends toward a greater effect in repeated, high intensity
exercise vs. single, exhaustive bouts, in upper body exercise as compared
to lower body exercise, and in less trained individuals, presumably because
they do not have as high of a natural buffering capacity [5]. Even with high-intensity,
intermittent exercise, some studies do not yield positive results [6], but
this may be explained by use of a dose lower than the ideal [3], inadequate
sample size, inadequate study duration (the effect is more pronounced during
later exercise bouts), or differing study design.
More recent research has addressed a possible performance enhancing effect
for endurance exercise. There is evidence that during endurance exercise,
despite reliance on aerobic energy production, anaerobic glycolysis still
plays a significant role, as evidenced by increased lactate concentration
[2]. Some studies on the effects of buffer ingestion on endurance exercise
have found no benefit, but others have yielded promising results. It has
been pointed out that in studies that showed no effect, subjects were not
allowed to alter their running pace, which is not representative of real
world conditions [2]. In one study, trained cyclists performed 30-km time
trials in a crossover design, and the average time was significantly faster
after citrate ingestion (57:36.6 min:s compared to 59:22.3 min:s) [1]. Other
studies have also found improved performance in both intermittent and steady
state prolonged exercise after buffer ingestion [1-2, 7].
3. What is the optimal dosage to use for increased performance?
Of course, not all of the news is positive. The amount of sodium citrate
or bicarbonate required to significantly increase exercise performance is
substantial. The effective dose falls in the range of .2-.6 g/kg of either
substance – for most individuals, this will be 15 grams at the very least.
Doses this high can lead to significant gastrointestinal discomfort.
Studies that have compared doses indicate that the optimal dose for performance
is in the .4-.6 g/kg range. One study found that .6 g/kg of sodium citrate
lead to the optimal changes in blood pH, while another found improved one
minute spring performance in the .3-.5 g/kg range, with the greatest effect
at .5 g/kg [1]. Another study reports that .5 g/kg sodium citrate is the
ideal amount for changing blood pH [2]. For sodium bicarbonate, the lowest
reported effective dose was .2 g/kg in one trial [1]. However, other literature
indicates that .3 g/kg is not as effective as higher doses [3], and most
studies utilize .3-.5 g/kg. It would appear that from a performance standpoint,
.5 g/kg of either substance is optimal, while .3 g/kg, and possibly .2 g/kg,
can still be of benefit. Doses lower than this are unlikely to change pH
enough to significantly improve performance.
Research has also been done on the optimal timing of ingestion, which falls
in the range of 1-3 hours before exercise [7]. In one study, ingestion of
.5 g/kg sodium citrate lead to an optimal alkalotic state 100-120 minutes
after ingestion [2] – but one must keep in mind that having this period coincide
with the later period of exercise would be ideal, so for a 45 minute training
session, for example, one would want to consume the buffering agent 80-90
minutes before exercise.
The performance standpoint is not the only one that should be taken into
consideration. Reports indicate that gastrointestinal discomfort is quite
common, although it generally occurs in the first hour after ingestion, and
therefore shouldn't coincide with the exercise period [2]. The best way to
reduce this side effect is by lowering the dose. Reports of gastrointestinal
discomfort and stomach cramps are much more common after .6 g/kg sodium citrate
than .4 g/kg (five of eight subjects complaining versus two of eight) [1].
This effect may also be worse with sodium bicarbonate [2]. In three trials
with .5 g/kg sodium citrate, one reports GI discomfort in 3 of 8 subjects
while the other two report no problems [2]. It would appear that .4 g/kg
sodium citrate is a relatively comfortable dose, with .5 g/kg still being
tolerable to many. Since individual reactions can vary, experimentation is
necessary to determine the highest tolerable dose.
A final issue is whether or not chronic ingestion is superior to acute ingestion.
To answer this question, a study was conducted comparing .5 g/kg sodium bicarbonate
acutely or over a period of six days on 90 second maximal cycling performance.
Both groups had improved performance, but performance was still increased
two days after chronic supplementation was discontinued [8]. This indicates
that chronic ingestion of buffering agents may yield a greater and longer
lasting effect. It is also possible that the required dosage needed for a
benefit is lower with chronic ingestion.
4. What type of buffering agent is best?
Many forms of citrates and bicarbonates are available, including sodium,
potassium, calcium, and magnesium. Although the research in athletes has
been carried out with sodium citrate and bicarbonate, the other forms will
presumably have the same effect.
A gram of calcium daily can be taken safely. Some people are comfortable
taking more, while others are not. Some literature recommends that those
on high protein diets take a gram of calcium per 50 g protein to begin with.
Magnesium can then be added in a 2:1 calcium:magnesium ratio, although greater
amounts are acceptable. Too much magnesium has a laxative effect.
Sodium and potassium are two electrolytes commonly recommended during endurance
exercise. There is now substantial evidence that many endurance athletes,
especially those who are less experienced, do not consume enough sodium during
exercise, which can result in hyponatremia (low blood sodium), which has
dangerous or even fatal effects. Hyponatremia is most common in endurance
athletes, military trainees, and hikers. Although the common perception is
that electrolytes should be supplemented during exercise because they are
lost in sweat, the majority of cases of hyponatremia are due to fluid overload.
This is because a large amount of secondary literature urges athletes to
consume too much water during exercise. Most organizations and researches
recommend that water intake be in the range of .5-1 liters hourly during
exercise. Additionally, each liter of water should contain 400-800 mg, more
than in most sports drinks. Thus, supplementation with sodium citrate or
bicarbonate will provide more protection against this condition. [9-12]
In contrast, large amounts of potassium supplements are strongly discouraged
during intense exercise. Exercise causes the release of potassium from muscle
cells, which elevates blood levels of potassium (known as hyperkalemia).
This is rapidly corrected after exercise is completed, but hyperkalemia has
been linked to some cases of sudden death and other incidences of cardiovascular
problems in endurance athletes with cardiovascular conditions. It is doubtful
that this is a significant risk in healthy individuals, but there is no reason
to worsen the situation by consuming a large amount of potassium supplements,
which will significantly elevate blood levels of potassium leading to an
additive effect. Potassium supplements after exercise and during other periods
are acceptable, and in some cases recommended. [12]
In summary, the use of buffering agents has the potential to improve performance
for many types of exercise. The optimal dosage is .5 g/kg of sodium citrate
or sodium bicarbonate; although other buffering agents (such as calcium or
magnesium citrate) presumably work, they have not been tested. This dose
should be worked up to until the maximum tolerable dose is achieved, and
sodium citrate may be more tolerable than sodium bicarbonate. Chronic ingestion
may cause a further increase in exercise performance.
If you have any questions or comments regarding this article, please email
dvdtlsn@bulknutrition.com. email -
dvdtlsn@bulknutrition.comNo part of this article may be reproduced in any form without the permission of David Tolson or Mike McCandless. 
