You’re fine, and then you’re fighting for your life.
It happens that quickly. In 2007, Pittsburgh Steelers safety Ryan Clark nearly died during a game in Denver. Known as the “Mile High City,” this Colorado capital presented a unique risk to Clark, but little did the successful NFL player realize, as he pressed on at Invesco Field, how high that risk was…
At the time, Ryan was a carrier of the sickle cell trait (SCT), and although he was aware of the condition, as he later recalls, he “didn’t know the severity.”
Soon he would. As the game wore on, he experienced intense pain, resulting in organ damage that would soon require the removal of his spleen and gallbladder. His season would end, his weight would plummet, and Clark would be left sick in a hospital, battling to reclaim his life.
“I had never been through anything like that,” he would later recall.
Today, of course, that harrowing day has passed, but the lesson learned – the health reality realized – will live with current ESPN analyst and Super Bowl Champion, Clark, for the rest of his life. His initiatives, partnerships, and research support continue to form a guiding light in his life, something he vows to cast as long as he can.
The story, Clark recognizes, is far bigger than him. Given that Black adults disproportionately face a higher prevalence of the sickle cell trait and disease, understanding this condition is particularly imperative to the community.
If you or someone you know is at risk, you may not even know it. So with that said, let’s cover everything you need to know.
RELATED: 5 Signs That You Should Get Tested For The Sickle Cell Trait
The Dangerous Triggers of Sickle Cell Trait & Disease
Sickle cell trait (SCT) and sickle cell disease (SCD) are not the same.
Sickle cell trait occurs when an individual inherits one copy of the sickle hemoglobin gene (HbAS), but the disease features two copies (HbSS) inherited, with most or almost all of the person’s hemoglobin being abnormal and sickling.
For the most part, people with SCT live without symptoms. However, when extreme conditions strike, such as exercising at high altitude, which affected Ryan Clark, it can become dangerous.
Why does this happen?
The science is nuanced, but essentially, in SCT, red blood cells can deform (“sickle”) under stress. As a result, oxygen delivery is reduced, leading to blockages. If this happens, something called a “pain crisis” can occur, but it needs various conditions to be present if it’s going to happen to people with the trait.
However, before you understand what precedes a pain crisis, it’s important to understand the symptoms of one, in case you’re caught off guard and don’t know what’s happening.
When a pain crisis or ‘sickle cell crisis’ occurs, it occurs suddenly. Typically marked by severe pain resulting from blocked blood flow, this health emergency is characterized by the following:
- An intense, throbbing, or stabbing pain (in the bones, chest, back, or joints)
- Sudden fatigue
- Fever
- Shortness of breath
- Dizziness
- Swelling in the hands and feet
Although the most common type of crisis happens due to reduced blood flow, crises can also occur because of issues with bone marrow, changes in red blood cell protein levels, and the ‘sticking’ of cells in your spleen.
These crises are more common in people with the disease, not the trait, but under extreme circumstances, they can happen in both.
Usually, four main conditions during intense exercise must be present for it to happen in people with SCT. They are: severe hypoxemia (low oxygen), metabolic acidosis, muscle hyperthermia, and red blood cell dehydration.
Extreme exertion is the primary trigger, and during high-intensity activities like sprinting, conditioning drills, or sudden increases in training volume, the right conditions for a sickle cell crisis may occur.
Exertional collapse is likewise associated with the sickle cell trait, supported by military and athletic data that show rising risks when pushing beyond limits.
But let’s go back to Ryan Clark’s case in particular, as it exemplifies critical conditions necessary for a crisis, even in people who don’t have the full-blown disease. At higher elevations like Denver (over 5,000 feet), lower oxygen pressure increases sickling risk. Clark’s splenic infarction indicates this, with the abnormal cells clogging blood flow to the spleen.
However, what’s interesting about Clark’s case is that, as elevated as Denver is, the city still falls below the threshold of some guidelines for special altitude precautions. In other words, while Denver sits at ~5,280 ft, some guidelines set their thresholds at 8,200 ft, nearly 3,000 ft higher.
Given Clark’s crisis at the lower altitude, this just goes to show the significant variability in individual risks.
Caution, even at lower altitudes, is critical.
Again, studies of military personnel – in this case, at simulated altitudes – link significantly more sickling at 4000m altitude versus lower levels. For individuals who risk suffering splenic infarction as Clark did, it’s important to know the symptoms. Typically, there is a sudden left-sided pain accompanied by nausea and vomiting.
Combined with heat, illness, and/or asthma, these elevations can create a perfect storm, even in otherwise healthy carriers. Although most people with SCT participate safely, rare complications, even potentially life-threatening events, do occur.
In one seminal study of 47,944 Black U.S. Army soldiers, those with the sickle cell trait had a 54% higher adjusted risk of exertional rhabdomyolysis compared to those soldiers without the trait. While there was no increased risk of death, exertional rhabdomyolysis is a serious, potentially life-threatening condition, characterized by the rapid breakdown of skeletal muscle and its subsequent release of contents into the bloodstream.
Similarly, the American Society of Hematology (ASH) has found no evidence to support sudden death in people with SCT, when exertional rhabdomyolysis or heat injury are absent. When these variables are controlled, it appears the race-adjusted risk of death is no different in individuals with SCT than in individuals without SCT.
Clearly, controlling for these two conditions – in all people, with or without SCT – is of paramount importance.
Thus, it’s critical (even life-saving) that individuals learn to control their environments as best as possible, and should symptoms appear, address them immediately and effectively.
What to Look For & What to Do
Knowing the signs early can save lives.
When it comes to exertional sickling, it often presents differently from typical cramps.
Here are the most common signs:
- Extreme muscle pain, swelling, or weakness without visible cramping (often in the legs or lower back)
- Difficulty breathing that is disproportionate to one’s effort
- Muscle tenderness and/or swelling
Of course, one problem here is the natural tendency in athletes to ‘tough it out.’ When athletes discount these early signs as just intense exercise, they may push through, facing outcomes like collapse or rhabdomyolysis, where damaged skeletal muscle breaks down rapidly, severely hurting the kidneys through the release of proteins and electrolytes.
Parents and coaches should be especially wary. Coaches of youth athletes should watch for these symptoms during drills, especially in hot weather or unfamiliar environments. Other red flags may include dark urine, extreme fatigue, and ‘out-of-nowhere’ pain that is severe and even debilitating.
This is where education plays its role. Coaches and families must treat these as medical emergencies, even if they haven’t reached their ultimate severity. When these conditions occur in individuals with the sickle cell trait, it’s important to stop and evaluate the person involved.
Thankfully, there are some simple steps people can take to lower the likelihood of these issues. First comes hydration. Athletes should hydrate before, during, and after activity, even using weight charts to track fluid losses. The rule of thumb is to stay within 1-2% of body weight, especially in hot environments.
It’s also important to gradually adapt. Athletes shouldn’t just rush into high-intensity intervals they can’t handle or have no experience completing. Instead, build intensity over 7-14 days for heat, altitude, or new training types. Obviously, if there are additional environmental stressors, modifications should be made to the workout routine. It may be shortened, intensity may be dialed down, rest may be increased, and so on.
These are guidelines that are smart for all athletes, not just individuals with SCT, especially when it comes to excessive heat.
That said, for individuals who do have SCT, there should be no negotiations on these guidelines. After all, although they may be called guidelines, what they really are are hard lines.
No training when sick. No ‘mind over matter’ when an athlete is dehydrated. No ‘tough it out’ when other symptoms pop up. In some cases, supplemental oxygen availability at high altitudes can help, but if commonsense precautions aren’t taken, these additional efforts may be too late.
This is why screening is so important, too. Currently, the NCAA requires Division I, II, and III athletes to provide results from official sickle cell solubility tests or to undergo testing during pre-participation exams.
For youth sports, it’s a bit different. There are no universal testing mandates, but voluntary screening or a family history review is highly recommended. Newborn screening (common in the U.S.) can also provide early data, and families should share those results with coaches and physicians before engaging in any sports.
Being proactive can literally save a life. Although individuals with SCT, like Ryan Clark, are not commonly at risk of sudden, severe health events, they can certainly occur. Fortunately, by applying the best practices outlined in this article, from risk awareness to physician-supervised pre-participation physicals, outcomes can and do improve.
Let us not forget: Clark returned to play after that fateful day in 2007 and has since built a post-career legacy. Bottom line: you can protect your health while pursuing your dreams. Just make sure you know your status, train intelligently, and advocate for greater awareness.
Lives depend on it—starting with your own.