<< Go Back


Why do my ankles swell during menstruation as well as when I fly?

Saul Yudelowitz BSc (Hons)

Many people have flown and experienced their ankles swelling. This is a sign that the mineralocorticosteriods secretion is out of balance. As the name suggests these are steroids that control salt, maintaining a balance between sodium and potassium, the two most abundant salts in the body. Aldosterone is the most important of this group. Aldosterone can be secreted due to 6 basic functional requirements. One of them is by the stretch receptors located in the atria of the heart. If decreased blood pressure is detected, the adrenal gland is stimulated by these stretch receptors to release aldosterone, which increases sodium reabsorption from the urine, sweat, and the gut. This causes increased osmolarity in the extracellular fluid, which will eventually return blood pressure toward normal.

A basic understanding of human biochemistry will show how this works. In the human body in inner surface of the arteries is lined with calcium (Cl-) while the centre has a higher sodium (Na+) concentration. The Na+ has an ionic charge, which repel and thus impede coagulation or what is more commonly known as thinking of the blood. If you don’t agree with this principle of human biochemistry just pop into your local hospital and see what they use to coagulate blood, calcium and what is used to stop blood from coagulation, sodium (Na+)

When blood moves from the Na+ rich environment to the periphery of the vessel it reach the calcium rich environment, this is the start of coagulation. If the vessel is damaged and blood makes contact with air the coagulation process is increased. This is normal physiology and this clotting is what stops us loosing blood. The difference between the blood flow at the surface inside the vessel and in the centre of the vessel is easily explained by fluid mechanics. The calcium and sodium are there to allow normal physiology to occur.

So where can you get sodium? Well the answer to this is everywhere; we should ask where we could acquire unrefined, quality sodium? If you gobble down table salt you will most defiantly create an undesirable effect in the body. Yes cheap refined food products are cheap because of their poor quality and this is why they are produced in such quantity. Saffron Pink Himalayan salt is one source of good Na+Cl- .

I will share a patient history with you to better explain how this works. The patient is an Olympic athlete who competes at long distance events from 10 000m to half marathon distance. While undergoing training in Hong Kong’s summer in an environment of around 28-30 degree Celsius and 75-85% humidity, he began regurgitation after drinking water after his run. At this point in his training he was under performing 2 weeks prior, complaining of aching muscles in his legs and ankle swelling during flight. When this athlete came to see me I placed him on a water and sodium chloride (Na+Cl-) mix relative to his muscle mass. With in 2 days he was back training at the intensity that he was accustomed to with no ankle swelling from flying.

During menstruation there is an increased demand for Na+ so as to allow a normal blood flow during this time. Just as the athlete lost a great deal of sweat, which contains Na+ drinking water will only dilute is minerals even more. It has been proved that drinking water during an endurance event only makes you run slower. Research by James M Winger et al (2010) which was published in the British journal of Sports Medicine1 concluded that: Runners at highest risk of Exercise-associated hyponatraemia exhibit behavior that is shaped by their beliefs about the benefits and risks of hydration. These beliefs are frequently based on misconceptions about basic exercise physiology.

Most passenger jets fly between around 31000 and 37000 feet depending on their weight and the distance being flown, however the smaller business jets typically operate up to 45000 feet and in the case of Concorde it went as high as 51000. At this altitude you can see the curvature of the earth. This has a significant affect on human physiology. It results in more blood traveling to the calcium rich environment and an increase in coagulation coupled with a slowing of blood flow. This presents as swollen ankles. More Na+ is required during this period. Do note that using Na+Cl- should be based on your muscle mass and hydration state, as well as other visceral functions. Just adding Na+Cl- to your water will not resolve the problem. If you undertake this be sure to get advice from a qualified person and do not do this on your own.


1: James M Winger, Jonathan P Dugas and Lara R Dugas. Beliefs about hydration and physiology drive drinking behaviours in runners. Br J Sports Med 2011;45:646–649. doi:10.1136/646 bjsm.2010.075275

<< Go Back