Josie Riggs ran track at Southern Utah University, specializing in the mile and the 5K. That’s when she first discovered that something wasn’t quite right.

She started feeling lightheaded and dizzy, especially when standing up after tying her shoes. She thought this was weird, but brushed it off. Then she began experiencing an extreme fatigue she couldn’t ignore. She finished last in all of her races.

“I would push as hard as I possibly could, but my body simply couldn’t hit the paces I’d previously been able to hit without a problem,” Riggs says.

After a few months of this deep fatigue, she went to the doctor and got a blood test, which confirmed that her symptoms were the result of low iron levels.

Rigg’s story is not rare. In fact, she’s part of the 35 percent of women under 50 in the U.S. who are iron deficient.

Blood work can help solve the puzzle of why you feel crummy, and what to do about it: Iron deficiency is when the body lacks enough iron to create healthy, red blood cells. Without iron, the body can’t produce hemoglobin, a component in cells that transports oxygen throughout the body. When you run, your muscles require oxygen, and if your body can’t keep up with the demand, you may experience symptoms like fatigue, decreased endurance, and impaired performance.

Even if your blood work comes back within the “normal” range, your iron may be below optimal levels for peak performance.

“Iron deficiency is the first step on a spectrum. People can be iron deficient without being anemic, and the goal is to find those people early on, because it’s a lot easier to deal with at the onset,” says Dr. Ted Farrar, who has 28 years of experience in family medicine. He’s also the Sports Medicine Fellowship Director at The University of South Florida and an Ironman triathlete and runner.

Farrar confirms that within the general population of adolescent women, 17 percent are iron deficient and 6 percent have iron deficiency anemia. For those over 21, the percentages are 12 percent and 4 percent, respectively. But for female athletes, nearly one third have some level of iron deficiency.

“With athletes, it’s 15 percent to35 percent, which is a crazy range, so we start asking, ‘why does this happen?’ One reason is because of higher iron turnover and greater iron needs,” he says.

Who’s At Risk

It’s important to note that, even though women are more likely to be iron deficient, men can be, too. Studies show that 11 percent of male endurance athletes are iron deficient.

Iron deficiency is common among endurance athletes for a few reasons. Endurance training stimulates the creation of red blood cells, and iron is crucial to the production of hemoglobin, the protein in red blood cells that carries oxygen throughout the body. If the increased demand for iron isn’t met, the body can become iron deficient, leading to symptoms such as chronic fatigue, decreased endurance, and weakness.

Another reason why endurance athletes are more likely to be iron deficient is because runners have higher iron requirements than the average person due to a condition called foot strike hemolysis. “The repetitive pounding of the foot against the ground causes microvascular trauma that destroys red blood cells,” Dr. Farrar says. “So if you’re running 20 to30 miles a week, you would have a lot more iron turnover than a swimmer or cyclist.”

Studies show that exercise-induced iron deficiency anemia is found mostly in athletes with heavy training loads, like middle to long distance runners.

Women are disproportionately affected by iron deficiency due to blood loss from menstruation. Among reproductive aged women in the US, 20 percent have iron deficiency and 38-39 percent have iron deficiency anemia.

Also, women are more likely to have a diet low in iron, as there are more women than men who are vegan or vegetarian. Dietary iron comes from two sources: heme and non-heme. Heme includes animal sources like beef, eggs, oysters, tuna, salmon, and liver. Non-heme includes non-animal sources like nuts and seeds, beans and legumes, dark leafy vegetables, broccoli, peas, and dried fruit. Iron from heme sources has a 30 percent absorption rate, while non-heme sources are only 10 percent. Therefore, if you eat a vegan or vegetarian diet, it’s important to track your dietary iron intake.

Restrictive eating also can increase your risk of becoming iron deficient. One study found that 39 percent of those with anorexia nervosa are diagnosed with anemia. Depriving yourself of food can lead to being deficient in all kinds of nutrients—not just iron.

In addition, conditions like Crohn’s disease, Celiac disease, stomach ulcers, fibroids, and pregnancy can increase your risk for iron deficiency.

 Reading the Signs

One reason iron deficiency in female athletes may be overlooked is because the symptoms are wide-ranging and similar to other conditions. Chronic fatigue, weakness, headaches, and dizziness are symptoms of iron deficiency, but they can also be related to overtraining and/or undereating.

Sometimes, like in the case of Riggs, the onset of symptoms is so insidious that you normalize them. You may not realize you feel different, or may attribute the feelings to life stress or simply being in your head.

“Oftentimes, an athlete isn’t even in a doctor’s office until after many of the symptoms show up,” Farrar says.

Other symptoms include shortness of breath, trouble concentrating, restless legs, and brittle hair, skin, and nails, as well as a condition called pica, or cravings for non-food substances like ice, dirt, and paper.

If you’re experiencing any of these symptoms, it may be time to order a blood test. There is only upside to getting a complete blood count (CBC), which measures red blood cells, white blood cells, hemoglobin, hematocrit, and platelets. And make sure to ask for an additional ferritin test. In fact, many sports medicine professionals recommend getting this type of blood work once a year.

“One thing female endurance athletes can do is ask their family doctor or Ob/Gyn to run a CBC with ferritin once a year,” Farrar says. “Especially if they’ve ever had iron deficiency or have any risk factors like fibroids, heavy periods, or if they’re a vegetarian.”

Diagnosing Iron Deficiency 

To test for iron deficiency, your doctor will order a CBC test, which will include values for hemoglobin and hematocrit. They may also test ferritin, iron binding capacity, and total iron.

Standard ferritin range:

– 30-200 ng/dL for women

– 30-300 ng/dL for men

Standard hemoglobin range:

– 12-15 g/dL for women

– 13-16.5 g/dL for men

*Ranges may vary by laboratory and method of measurement  

“A ferritin level under 15 ng/dL is definitely a problem,” Farrar says. “For those ladies, we’d also look at hemoglobin to see if they’re anemic.”

Iron deficiency is when the body lacks enough iron to meet demand, whether that’s due to low dietary intake, poor absorption, blood loss, or increased iron needs. Whereas iron deficiency anemia is a condition characterized by a deficiency of red blood cells or hemoglobin, which leads to decreased oxygen-carrying capacity. Iron deficiency is one of the most common causes of anemia, but there are others, such as chronic disease and genetic disorders.

Ferritin is a protein that stores iron, so a low value can indicate iron deficiency. However, low ferritin isn’t enough information to diagnose low iron; you also need to know why. That’s why your doctor might look at other values, like iron binding capacity, which is your body’s ability to take in more iron.

While these are the standard ranges, an endurance athlete, who is losing iron more quickly than they can replenish, shouldn’t be at the lower range of ferritin or hemoglobin. While those numbers may be considered “normal” for a non-athlete, it’s important to consider how you feel and how much activity you do. If your symptoms mimic iron deficiency, your ferritin or hemoglobin levels are on the lower side of the standard ranges, and your doctor won’t take your endurance training into account, it may be time to seek out a sports medicine specialist.

Taking an iron supplement will help if you’re not getting enough iron in your diet, but it won’t help if your body isn’t absorbing iron for some reason, such as a gastrointestinal issue. That’s why it’s important to get a blood test before starting an iron supplement.

“The dirty little secret of supplementing with iron is that you have to be careful of iron overload,” Farrar says. “Bad performance is one thing, but liver damage is another.”

How to Increase Your Iron Levels

The recommended, daily, dietary allowance for iron, in adults 19 to 50 years of age, is 8 mg for men and 18 mg for women. However, the U.S. military recommends 22 mg for female recruits, and Farrar says that’s a good recommendation for female athletes as well. Studies have shown that endurance athletes may need up to 70 percent more dietary iron than the daily recommended dosage.

For those who don’t get enough iron in their diet, taking an iron supplement may help. Ferrous fumarate and ferrous sulfate are two options that are generally easy on the stomach. Farrar says the best protocol for maximum absorption is to take an iron pill once every other day.

“Take your iron pill in the morning on an empty stomach with a glass of orange juice,” Farrar suggests. “Don’t drink tea, coffee, or milk together, or one hour before or after, taking iron. Also, avoid taking antacids with iron.”

Sometimes, a person’s iron levels are too low for supplementation to help. In this case, an intravenous iron infusion might be necessary. “Know that it takes about eight weeks for iron deficiency anemia to improve,” Farrar says.

For Riggs, it took a liquid iron supplement and an entire track season before she started feeling like herself again. Now, as a registered nurse and mom to two young boys, she wants to spread awareness about this deficiency commonly found among female endurance athletes so that runners can get back to performing at their best. “We need to be vigilant in watching for signs and symptoms,” she says. Riggs recently completed the Eugene Marathon, finishing in two hours, forty-nine minutes, and fifty-eight seconds as the 6th overall woman.

When Bec Wilcock moved from Australia to Los Angeles in 2018, she realized there were no women’s running or training groups in the area. So, a year later, she founded one of her own. HER Sports now brings together women of all ages and levels, from newbies to Boston Qualifiers and Ironman triathletes.

Wilcock, 36, is always looking to  challenge herself and her training group. So when she learned about the 75-mile Hollywood to Sea relay that traverses the region she and her team had been running every week for years, she figured it could be an ideal way to celebrate the group’s fifth anniversary.

No women’s-only teams competed in the inaugural Hollywood to Sea last spring. Wilcock saw the second edition on May 4 as a prime opportunity to set a new precedent.

“As a coach, I like to challenge my runners, and I loved the fact that we could be the first female team to finish this race and that if I stacked the team correctly, we could take the record as well,” says Wilcock, who is also a mother of two young sons.

Wilcock succeeded in executing that goal. One of HER Sports’s teams—made up of herself, Anya Kosova, Brady Chaney, and Crystal Cooper—won the event in 12 hours and 19 minutes, beating the overall course record from the previous year by more than three hours.

In total, Wilcock recruited 11 of her athletes to make up three of the four teams that participated.  They trained on the course to not only build their confidence when it came to navigating technical trails, but also to familiarize themselves with the course for race day. It was a strategy that proved successful, as the three teams she coached, all composed entirely of women, were the only ones that finished this year’s relay. (The fourth and final team competing in the event was disqualified.)

But the results don’t tell the whole story. Wilcock knew convincing a dozen or so of her athletes to take on this challenging relay would be a tall order. In total, the race covers 75 miles from Hollywood to Malibu, complete with 14,000 feet of elevation gain and loss across the course.

Runners start at the Los Angeles River before running through Griffith Park, under the Hollywood sign, and through the Santa Monica Mountains all the way to Malibu and the Pacific Ocean. With 12 legs split among four runners on each team, individual athletes would be tasked with completing around 20 cumulative miles over the course of three legs that day.

“We’ve sometimes done [trail segments] as a community, but many of them had never done a trail race before,” Wilcock says. “There were others who had never run 20 miles in a day before, so they were very intimidated by it.”

Hollywood to the Sea founder and race director Fred Buescher was inspired to create the event in 2023 after reading about the 100-year history of Mulholland Drive, which was one of the first Los Angeles roadways created to get people out of the city and into the mountains and beaches. He had participated in 200-mile relays before, including one in southern California which had a course that was largely in suburban neighborhoods rather than the semi-wild routes through the nearby Santa Monica Mountains.

“I just thought, ‘Wow, LA has so much to offer, wouldn’t it be great to showcase the beaches in the mountains?,’” he says. “From there, I did a lot of research and saw there are trails alongside that we could run on and when there aren’t, we can run on the road. Six years later, I had the course for Hollywood to the Sea.”

According to Buescher, the relay’s challenging course includes several 1,500- to 2,000-foot climbs and descents through the mountains with roads cutting through the valleys for the exchange points. While this results in a lot of ascent and descent for every runner, it makes for a memorable experience out on the course and between the exchanges, he says.

But a big reason Wilcock was so set on convincing her athletes to step outside of their comfort zone and compete in the relay was to get more women into trail and ultrarunning, where they are underrepresented. This sentiment was echoed by Buescher: although he eventually hopes to grow the small, unsanctioned event to allow individual runners to complete the entire 75 miles, he purposely started with the relay to provide a more accessible and introductory event for runners making their first foray onto the trails, and perhaps eventually, ultrarunning.

“As far as I’m concerned, it’s great that women want to take this challenge on and that they see themselves running on these trails and this terrain,” Buescher says. “That’s what I love about relay running; I just think the camaraderie of commiserating in the car together and building those friendships while completing a very challenging course is what hooks a lot of people.”

Buescher intentionally started the event out small, allowing a maximum of six teams to register each year in an effort to grow the event in a manageable way that allows him to improve the  experience for participants.

“I’m really excited for what’s to come for females in ultra and trail running and just running in general because we are showing up and we’re believing in ourselves more and more,” Wilcock says. “We need to get more and better opportunities for females to do kick-ass things, and for them to be seen.”

This winning team, which wasn’t shy in sharing how challenging the event was, was made up of seasoned runners. Kosova recently completed The Speed Project—a 290-mile underground event from Santa Monica Pier to Las Vegas—as an individual in just under 91 hours on March 29 through April 1, followed by the Zion 100K in Utah on April 13. Wilcock has also completed various ultramarathons over the years, and both Chaney and Cooper have completed marathons and half-Ironman events.

“Race day went by so quickly, but I am so glad we had time to bond with the girls from my team and other teams during our preparation,” Kosova says. “I’m sometimes lazy about running trails by myself, so training with the girls before the race was a good push for me to run in more beautiful areas around our mountains.”

“The unpredictable terrain was the most challenging part of the race day, since I’m used to flat road running, which allows you to exclusively focus on speed with little to no distraction. Trail running requires agility, quick decision-making, and balance, all of which I’m still refining,” Chaney says. “Being the first all-female team to complete this race symbolizes the collective power of women supporting and uplifting each other, and for me, it’s a really proud moment of sisterhood and achievement for all the HER Sports teams who participated.”

Even though the event will continue to be small-scale in terms of number of teams for the immediate future, Buescher still hopes to spread the word to spark interest in the 2025 event, which will open registration this fall.