The cyclist’s diet: minerals
Let’s tackle a somewhat difficult topic: the mineral salts in cycling.
Starts with a sporting digression then become a dietitian: as soon as the temperatures rose half a degree, my mother placed next to the training bag a beautiful saline energy drink with an unnatural color, so full of sugar and substances that exalted the thirst rather than remove it and that, without you noticing it, supported your weight increase.
The drink we choose must be commensurate with the activity we do:
the energy contribution of the drink can contrast with the reason that pushes me to go to the gym (for example maintenance or improvement of body weight) and the income of mineral salts can exceed the real sweat losses.
The first concept that I would like you learn is this: there are drinks that bring only minerals and others that also bring energy.
On the famous shelf of supplements there would still be thousands of products with different characteristics, but in a nutshell the big difference is this.
We know very well that drinking water before and after pedaling is essential
to prevent dehydration; losing more than 2% of the body weight during a ride results, as well as a significant drop in performance (up to -45%), in a real danger for the cyclist. Of course, common sense will tell us that this becomes meaningful when the rides exceed 1-2 hours of activity, but the concept is universally important. It is different for the substances that we add to the bottle.
Let’s concentrate on mineral salts. They come into play for outputs longer than one hour and in climatic conditions that cause considerable sweating.
There is no way to give precise indications on how many salts it is necessary to integrate during a ride as this depends first of all on how much we perspire and the composition of the sweat: it is extremely variable from one individual to another and in the performance, and also depends on the climate, training, acclimatization and intrinsic conditions of the sportsman.
First of all, we see that the most representative mineral salts in the sweat are sodium and chlorine, to which much more modest amounts are added potassium and magnesium.
The sweat, despite the variability in the concentration, is however hypo tonic with respect to the plasma. In fact, the liquid that is introduced into the sweat gland is initially isotonic compared to the plasma, but then, along the duct sweat before the sweat comes to the surface, sodium and chlorine can be reabsorbed precisely to protect the osmolarity of the plasma as much as possible. The final product is therefore hypo tonic for this reason.
This is why a re hydrating drink must also be preferably hypo tonic.
Sodium in particular is the substance that most of all regulates the body’s water balance: adding it to drinks stimulates the re absorption of liquids and avoids the reduction of plasma volume with increased osmolarity which, otherwise, would negatively affect the cardiovascular system, the performance and thermoregulation. When we sweat a little sodium and chlorine are reabsorbed, when we sweat a lot we lose significant amounts of these electrolytes.
Below we analyze the four most important mineral salts for a cyclist engaged in long rides:
Magnesium is an intracellular mineral, only 1% is found in the extracellular space. It performs various functions related to the metabolism of carbohydrates, proteins and lipids as well as being involved in the functioning of the central nervous system, neuromuscular, cardio circulatory and bone. It is essential for protein synthesis and muscle contraction. Stress conditions, such as demanding and prolonged workouts, can increase magnesium losses with the appearance of asthenia, muscle weakness, cramps and reduced performance (over training syndrome).The intestinal absorption of magnesium is very efficient, unless there are high concentrations of calcium in the intestinal lumen. Excretion is predominantly fecal; the share lost with the sweat is on average poor, comes to 1% of the total magnesium content in the body with sweats of at least 4l.
Potassium (K +)
Potassium is an intracellular ion, the protagonist together with sodium (Na +, extracellular ion) of the regulation of the pressure between the infra and extracellular liquids. The distribution and concentration of the two ions is maintained by the active transport mechanism (sodium-potassium ATP dependent pump) that constantly transfers potassium into the sodium outside the cell, maintaining the necessary difference in electrical potential between the inside and the external of the cell (membrane potential).
Potassium, together with sodium and chlorine, regulates the water balance. The intestinal absorption of potassium can be reduced by the simultaneous intake of alcohol, coffee and sugar. Excretion is predominantly urinary; the share lost with the sweat is on average poor, comes to 1% of the total potassium content in the body with sweats of at least 4l
Sodium (Na +) and Chlorine (Cl-)
As already mentioned, sodium is an extracellular co protagonist ion of the regulation of infra and extracellular fluid pressure. Chlorine, fundamental for acid-base balance, is the main component of gastric juice where it is present as hydrochloric acid. Sodium and chlorine are the main components of sweat. Sodium and chlorine, we know, form the common kitchen salt (1g NaCl = 0.4g Na + 0.6g Cl). Of sodium, our diet is far too rich either as salt added to the preparations or as salt hidden in preserved food.
The Reference Nutrient Value (VNR) indicated by the Minister of Health for salt is a maximum of 6g / day (equal to about 2.4g of sodium): for a cyclist, in relation to the rate of sweating, a higher requirement can be assumed. always and in any case proportional to the entity of the output and related to it. For sweats equal to 1-2 l the losses of sodium and chlorine are negligible; with losses of at least 4l of sweat, sodium losses of about 3655mg and of chlorine equal to 4864mg are estimated, corresponding respectively to 5% and 7% of the body contents of the two minerals. Significant sodium losses result in weakness, dizziness and minor cramps up to nausea, hypo tension, collapse and violent cramps.
A further good reason not to get off the saddle is to have to grant the much feared kitchen salt that is our intimate ally during the most sweaty rides. Good nutrition ensures a daily supply of mineral salts. In the saddle the preparations of the trade surely come to our aid, without ever forgetting that even a well-made housework preparation has its dignity. To reintegrate the salts lost in the saddle, after a long ride we do not underestimate the high availability salt content also present in natural foods.