Vitamin D: What Low Levels Do to Your Training

The sunny-country paradox

It sounds like a contradiction, and the data makes it real. A five-year study of more than 22,000 people in Saudi Arabia found that around 67% had vitamin D below the sufficiency mark, with deficiency clearly more common in women than men, a pattern worth knowing if you train in a ladies-only gym. Reviews across the region describe the same thing: high sun, low vitamin D.

The reason is that sunshine only helps if it reaches your skin. Life in the Gulf is largely indoors and air-conditioned, the summer heat pushes everyone inside during the strongest daylight, everyday clothing covers the skin that would otherwise make vitamin D, and sunscreen blocks the same wavelengths. Add a diet that is not naturally rich in vitamin D and the sun outside your window never becomes vitamin D inside your body.

What low vitamin D does to a body that trains

Vitamin D's main job, according to the NHS, is to regulate calcium and phosphate, the minerals that keep bones, teeth and muscles healthy. When it stays low for long enough, adults can develop osteomalacia, a softening of the bones that shows up as bone pain and tenderness; in children the equivalent is rickets. For anyone lifting, running or playing sport, weak bones and aching muscles are the opposite of a foundation.

Muscle is part of the story too. Because vitamin D helps keep muscles working normally, being low is often felt as heavy legs, weakness or a fatigue that no amount of motivation fixes. Some people also report low mood when deficient, though the evidence on mood is less settled than the bone and muscle science. What is clear is that running low does you no favours in the gym, and topping up to a normal level is about removing a handicap, not gaining a superpower.

How vitamin D is actually tested

You cannot feel your exact level, and you certainly cannot read it off how sunny it is outside. The only way to know is a simple blood test that measures 25-hydroxyvitamin D, the form doctors use to judge your status. It is a routine test, widely available in Saudi clinics, and it is the honest starting point before anyone reaches for a supplement. Guessing is how people end up either ignoring a real deficiency or overcorrecting one that was never there.

Where vitamin D comes from

There are three taps, and most people in the Gulf under-use all of them:

• Sunlight. Short, regular exposure of bare skin, arms and face, outside the harshest midday hours, is the body's natural source. In practice, Gulf life makes this hard to rely on year round.
• Food. Oily fish such as salmon, sardines and mackerel are the richest natural source, with smaller amounts in egg yolks, red meat and liver. Some spreads and cereals are fortified.
• Supplements. Because sun and food often fall short here, a daily supplement is a practical route for many people, which is exactly why the next section matters.

Where the gym question becomes a doctor's

This is the line that matters most. General guidance from the NHS is that adults who need a supplement take around 10 micrograms (400 IU) a day, and that most people should not exceed 100 micrograms (4,000 IU) a day, because too much vitamin D pulls calcium into the blood and can damage the bones, kidneys and heart over time.

That upper limit is not theoretical in Saudi Arabia. Research on Saudi vitamin D users found that people who dosed themselves on the advice of friends or relatives were the most likely to report toxicity symptoms, and that very high doses, such as 50,000 IU capsules, were being taken without any monitoring. The takeaway is simple: a blood test and a doctor decide your dose, not a training partner or a social media post. Persistent tiredness, bone or muscle pain, or a known deficiency are all reasons to see a professional, not to self-prescribe.

Build the foundation, then train on it

Once your level is sorted with a test and, if you need it, a doctor's guidance, training does the rest of the work. Loading your skeleton is what keeps it strong, so strength sessions like a BodyPump class earn their place once the vitamin side is handled, and a personal trainer can shape it around your week. If you are in the capital, find your nearest GymNation in Riyadh and put the foundation to work.

Sources:
nhs.uk
pmc.ncbi.nlm.nih.gov
frontiersin.org

The opinions shared in the GymNation blog articles are solely those of the respective authors and may not represent the perspectives of GymNation or any member of the GymNation team.