29 November, 2012 | Written by Recuperat-ion Recuperat-ion
We knew the importance of sodium
and potassium in the water balance and muscle function, in other words the muscles
ability to contract during exercise. We know now that they are just as
important in the recuperative function, which is the body ability (and a
fortiori the muscles) to recover from intense and long physical exercise.
Copyright: Nico Beck – Alpe d’Huez Triathlon
Sodium responsible for water balance
Sodium is an electrolyte (Na +),
in other words a mineral salt circulating in the body and playing a specific
role. In the body, the circulation of the electrolyte is not free. Its
existence remains confined only to the extracellular environment, in other
words in the liquid where our cells, including blood plasma are (liquid phase
of blood).
The sodium concentration of the
various liquid compartments in our body influences the water volume retained in
these compartments and therefore the total water volume in our body. Regarding
the plasma, its sodium concentration modulates the volume of water retained in
the blood, and therefore the “pressure” on the membrane walls, known
as blood pressure.
Sodium is essential to maintain
the water distribution in the body (or water balance) and to maintain a stable
level of blood pressure.
Sodium pillar of the muscle function
The sodium presence in the liquid
compartments of the body goes beyond the water movement regulation.
Circumscribed on the surface of the cell membrane, where it ensures the proper
transmission of the nervous influx through a complex mechanism of ion exchange,
sodium allows muscle contraction.
Sodium is essential to ensure the
transmission of the nervous influx to the cell membranes and muscle
contraction, called the muscle function
Maintenance of plasma concentration in sodium and recovery
The sodium concentration outside
the cells is tightly regulated by renal function. Because the sodium outside
the cells tends to migrate inside the cells, a system therefore exists at the
cell membranes to hold permanently the sodium concentration outside the cell:
it is the pump sodium / potassium.
The physical exercise of long
duration, increased by large sweat losses depending on the intensity or
climatic environment is causing significant disruptions, affecting the sodium
distribution in the body. The level of sodium in the extracellular liquid
compartments, and in particular the plasma, tends to decrease, first because of
large sweat losses, and second because of a sodium leak inside the cell, as the
pump sodium / potassium is less effective. This poses a risk of hyponatremia
(low sodium in plasma) and hypotension. This risk is increased by the ingestion
of large amounts of plain water, both during exercise and during recovery.
Generally, the body protects itself against this risk by increasing diuresis
(urine) to maintain a limited plasma concentration in sodium.
The consumption of sodium
enriched drinks (or solid food rich in sodium), both during exercise and during recovery, allows to properly compensate the drop in sodium levels in the body
and essentially in the plasma (serum sodium). The consumption also limits the
excessive diuresis. Regarding the actual recovery, the consumption of large
volumes of water (up to 150% of sweat losses) with high levels of sodium, presents
the most effective recovery strategy. It can quickly restore the water volume in
the plasma and thus promoting a better irrigation of tissues and improving
cardiac function.
Sodium is essential in the recovery
diet, at sufficiently high levels (through enriched sodium drinks or solid food)
to restore water balance and muscle function, including the cardiac one.
Potassium: the sodium’s
Potassium is the sodium’s partner. It is retained in the reverse sodium
environment, meaning on the other side of the cell barrier, inside the cells.
It is also an electrolyte (K +), and its circulation is not free. Its
concentration inside the cell can withstand the sodium pressure at the gates of
the cell membrane and thus the water movements that may accompany it.
Thanks to the action of the sodium / potassium pump on each side of the
cell membrane, potassium is inseparable from sodium to also ensure the nervous
influx transmission and muscle contraction.
For this reason and like sodium, potassium is essential to maintain
water balance, maintain a stable level of blood pressure, and ensure the nervous
and muscle contraction (including the cardiac one)



Restoration of cellular levels
of potassium and recovery
The physical exercise of long duration disturbs the potassium
concentrations inside the cells. But this phenomenon is really accentuated
after exercise, due to urinary loss potentially abundant (for this reason, it
is necessary to establish a strategy in order to limit the loss).
During exercise, the potassium level tends to diminish due to a
potassium leakage outside the cell (at the contrary sweat losses are limited).
Like sodium, this leakage causes a lower efficiency of the sodium / potassium
pump, but also repetitive muscle contraction and glycogen degradation (inside
the cell, potassium is bound to glycogen, an energy reserve which diminish
during exercise). Potassium being in the extracellular fluids is eliminated
through urinary loss, potentially abundant after exercise, without the
possibility of being properly recovered by the kidney, thus favoring the sodium
recovery in order to restore plasma levels. Intake of large amounts of plain
water is one of the circumstances which potentiate the increase in diuresis
post effort, and the associated potassium loss.
On the other hand, the
consumption of sodium enriched drinks (or solid), by reducing diuresis, allows
to avoid primarily the urinary secretion rich in potassium. Moreover, the associated
potassium addition in such drinks helps to return to initial levels of
potassium and to restore the muscle glycogen with which it binds at the level
of the muscle fiber (water and potassium)
Potassium, linked to sodium in
sufficiently high concentrations, is important in the recovery diet (through sodium
enriched drinks or solid food…) to restore water balance, muscle function
including the cardiac one and cellular glycogen.
Information about the author:
David Padare is a dietician nutritionist specialized in preferred
disciplines such as endurance sports and outdoor running, trail running,
cycling, triathlon, swimming….
He accompanies many athletes in their diverse and varied challenges:
ultra trail, trails stages, marathons, 100kms, 24h….
Member of the AFDN (French Association of Dietitian Nutritionist) and
the nivernais network RESEDIA for the management of DIABETES and OBESITY, he
also put his knowledge to the treatment of pathologies such as obesity,
diabetes, heart disease, food allergies…
Find David in magazines such as Running Coach and Cyclo Coach
Cyclosport, Running attitude trail magazine, running 100%feminin,, nutritiondusportif, traileur outdoor…..
Nuteoconsult is the structure founded to bring together expertise from
various backgrounds (diet, coach, mind trainer…) for one purpose: to provide
simple and clear answers to each level of practice.
Recuperat-ion – Hydration and Nutrition Experts

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