NFL star Jalen Hurts is 28 and at peak fitness… but deadly blood clots can strike anyone at any time, say doctors. They warn you must never ignore the subtle signs

At 28, Jalen Hurts is one of the fittest men in America.

The Philadelphia Eagles quarterback is renowned for his extraordinary strength, trains rigorously and is in the prime of his athletic career.

Yet this week, the Super Bowl MVP was diagnosed with a potentially fatal condition more commonly associated with the elderly, the obese and those who lead sedentary lives: blood clots that had traveled from his leg to his lungs.

The diagnosis has ended his NFL season and sparked controversy over his medical care, after it emerged that he had been cleared to play despite doctors having already discovered a less serious clot in his calf.

The NFL Players Association has called for an investigation, although the league insists his treatment was appropriate.

Hurts is reportedly stable and expected to make a full recovery.

But his ordeal has highlighted an alarming medical reality: Blood clots don’t just affect overweight or unhealthy people. They can strike seemingly healthy young adults, too – sometimes with little or no warning.

And the consequences can be devastating.

According to the Centers for Disease Control and Prevention, as many as 900,000 Americans develop deep vein thrombosis (DVT) or pulmonary embolism every year, and an estimated 60,000 to 100,000 die.

In around a quarter of cases of pulmonary embolism, sudden death is the first sign that anything is wrong.

Doctors told the Daily Mail that the danger lies partly in how easily the early symptoms can be mistaken for something harmless – from a pulled muscle to ordinary breathlessness.

They also warn that certain everyday circumstances, including long journeys spent sitting still, can increase the risk, particularly in people who are already susceptible.

Speaking to the Daily Mail, Dr William Shutze, a vascular surgeon and vice president of the Society for Vascular Surgery, said: ‘We have too many people dying every year from blood clots.

‘It doesn’t have to happen.’

So how can a potentially fatal blood clot develop in someone as fit as Hurts – and what are the warning signs everyone should know?

The answer begins with the body’s natural response to injury.

Normally, blood clotting is essential for survival. When a blood vessel is damaged, tiny blood cells called platelets gather at the site of the injury, while a protein called fibrin forms a mesh that helps seal the wound and stop bleeding.

But sometimes this process occurs inside a vein when there is no external bleeding to stop.

A clot can form when blood flow slows, the lining of a vessel is damaged or the blood becomes unusually prone to clotting.

Doctors refer to these three factors as Virchow’s triad.

Clots that develop in the deep veins, usually in the legs, are known as DVT.

The greatest danger comes when part of a clot breaks away and travels through the bloodstream to the lungs, where it can lodge in an artery and obstruct blood flow.

This is called a pulmonary embolism.

A large blockage, or multiple clots, can prevent blood from flowing normally through the lungs, placing enormous strain on the right side of the heart. In the most severe cases, blood pressure can collapse, leading to cardiac arrest and death.

‘If something is not done pretty quickly, it will progress and the patient will pass away,’ Shutze warned.

Although the condition is often associated with older age, smoking and obesity, these are far from the only risk factors.

Recent surgery, serious injuries, prolonged bed rest, cancer and certain inherited blood-clotting disorders can all increase the likelihood of developing a clot.

Pregnancy and estrogen-containing medications, including some contraceptive pills and hormone replacement treatments, can also raise the risk.

And there is another, less obvious factor: remaining still for long periods.

During a lengthy flight or car journey, blood can pool in the legs because the calf muscles are not contracting regularly to help pump it back toward the heart.

‘During that period of immobility, the blood flow in your veins, especially in your legs, slows down dramatically, so it gets very sluggish,’ Shutze explained.

‘That sets the stage for the blood to start forming a clot.’

For most healthy people, the absolute risk of developing a clot during travel remains low. But journeys lasting more than four hours can become more concerning when combined with other risk factors, such as a recent injury, surgery or previous DVT.

In Hurts’s case, the sequence of events is particularly striking.

The quarterback suffered a blow to his calf from another player’s cleat during an October 4 game against the Los Angeles Rams.

An ultrasound performed in London on October 10 revealed a superficial vein thrombosis – a clot in a vein close to the skin.

Such clots are generally less dangerous than those in deeper veins, although they can sometimes extend into the deep venous system.

Hurts was cleared to play the following day after medical specialists assessed his condition. He subsequently returned to Philadelphia, where further testing revealed that his condition had progressed.

It is not known precisely which factors contributed to his DVT and pulmonary emboli, or whether his transatlantic travel played a role.

But the case illustrates why doctors take blood clots seriously even when a patient appears otherwise fit and well.

Indeed, one of the most frightening aspects of DVT is that it may initially cause very little discomfort.

Most clots develop in the deep veins of the legs, where they may not be visible or produce obvious symptoms.

‘When that blood clot is first forming, it may be very subtle until it gets to be extensive enough that a person is going to notice that they’re having some pain in that area or swelling in the lower part of the leg,’ Shutze said.

The classic warning signs are swelling in one leg, pain or tenderness – particularly in the calf – and skin that feels unusually warm or appears red or discolored.

But not everyone experiences all these symptoms.

A dull ache in the calf, for example, can easily be dismissed as muscle soreness after exercise, while mild swelling might be blamed on spending too long standing or sitting.

Crucially, some people with DVT have no noticeable symptoms at all.

‘And amazingly, you can have blood clots that are silent until they move and become an embolism,’ Shutze said.

‘It’s pretty frightening. That’s what makes these clots in the legs so dangerous – they can be silent, and then the first symptom is when it moves to the lung.’

Once a clot reaches the lungs, the symptoms can be dramatically different.

Sudden, unexplained shortness of breath is one of the most important warning signs, particularly when it occurs at rest or during activities that would not normally cause difficulty.

Patients may also develop sharp chest pain, often made worse by taking a deep breath or coughing, along with a racing heartbeat.

Other possible symptoms include coughing up blood, feeling faint or collapsing.

These symptoms require emergency medical attention, even in someone who is young, physically active and has no known medical problems.

Dr George Bolotin, medical director at the Astra Vein Treatment Center in New York City, warned that clots can reach the lungs without causing obvious symptoms.

‘Even when you’re asymptomatic, you could already have a small aspect of a blood clot move to the lungs. You can be completely asymptomatic,’ he said.

This is why doctors stress the importance of investigating unexplained swelling or pain in one leg rather than waiting for more serious symptoms to appear.

A suspected DVT is usually investigated with an ultrasound scan, which can identify clots in the deep veins.

If doctors suspect a pulmonary embolism, they may use a specialized CT scan to examine the blood vessels in the lungs.

Blood tests, including a test called D-dimer, can also help doctors rule out a clot in patients whose overall risk is considered low.

The good news is that blood clots are treatable, particularly when detected early.

Most patients with DVT or pulmonary embolism are prescribed anticoagulants, commonly known as blood thinners.

These drugs do not directly dissolve an existing clot. Instead, they prevent it from growing and reduce the likelihood of new clots forming, allowing the body to gradually break down the blockage.

Commonly prescribed treatments include apixaban, sold under the brand name Eliquis, and rivaroxaban, marketed as Xarelto.

Treatment generally lasts at least three months, although some patients require medication for considerably longer, depending on what caused the clot and their risk of developing another.

For Hurts, the treatment means he cannot safely participate in contact football while taking anticoagulants because of the risk of serious bleeding following an injury.

Doctors expect him to recover, but the episode is a reminder that even exceptional physical fitness cannot eliminate the risk of a blood clot.

So what can ordinary Americans do to protect themselves?

Bolotin says one of the simplest precautions is to avoid remaining motionless for extended periods, particularly during long journeys.

Walking around regularly and flexing the ankles and calf muscles can help keep blood moving through the legs.

‘Sit and then go on your tippy toes for about five to 10 minutes, or take a little walk around the plane every hour or so,’ he advised.

Regular exercise and maintaining a healthy weight can also help reduce the risk over time.

For people at increased risk, properly fitted graduated compression stockings may be recommended during long journeys, although they are not necessary for everyone.

Staying adequately hydrated is sensible, too, particularly during travel, but there is limited evidence that drinking extra water alone prevents DVT.

People who have recently undergone surgery, suffered a significant injury or previously experienced a clot should speak to their doctor about whether they need additional precautions.

Above all, the experts say the most important protection is recognizing when something may be wrong.

New swelling or unexplained pain in one leg should never simply be ignored, particularly after a long journey or period of immobility.

And sudden breathlessness, chest pain or fainting should be treated as a medical emergency.

‘Go get it checked out right away,’ Shutze said.

‘We would much rather have somebody come in concerned about a blood clot, do an ultrasound, find out they don’t have one, and reassure them than have them delay getting it checked out, delay getting it treated and have this turn into something much worse.’