Many veterans, especially those who were deployed in Southwest Asia or Afghanistan, face a lesser-known but serious health risk after they return home: respiratory illness.
While on duty, soldiers in these parts of the world often get exposed to airborne hazards, including sandstorms, diesel fumes, and smoke from open-air burn pits. These same soldiers can later develop deployment-related respiratory disease (DRRD), which includes long-term lung and breathing disorders such as unexplained shortness of breath, chronic sinusitis, asthma, and vocal cord problems.
And DRRD doesn’t just affect the airways: There’s growing evidence that it can also cause changes in the blood vessels closest to the lungs. Some veterans living with DRRD may develop early signs of pulmonary vascular disease (PVD).
A pilot study led by researchers in the University of Colorado Anschutz Department of Medicine suggests intense exercise could be a potent treatment for veterans with DRRD and signs of PVD. After a 12-week high-intensity interval training (HIIT) regimen, the veterans in the study showed not only improved exercise capacity, but also positive changes in markers of PVD. Few other studies to date have looked at the effect of exercise on pulmonary blood vessels, particularly in this patient population.
“We weren’t shocked to see signs of early PVD in these patients, but what was surprising was seeing those signs improve with exercise,” says Lindsay Forbes, MD, an assistant professor of medicine in the Division of Pulmonary Sciences and Critical Care Medicine and senior author of the new study. “We could help modify the course of their disease, and modify it via lifestyle changes rather than just medications that could have side effects.”
Justin Cillay, MD, led the study and is a fellow in the Division of Pulmonary Sciences and Critical Care Medicine. The study was supported by the VA Airborne Hazards and Burn Pits Center of Excellence Pilot Research Project Program. Cillay and Forbes were helped in their efforts by a team of investigators, including the Rocky Mountain Regional VA Medical Center Post-Deployment Cardiopulmonary Evaluation Network site director Silpa Krefft, MD.
Soldiers routinely encounter danger on the job, but modern chemical agents and environmental conditions in different parts of the world can create additional, hidden health hazards.
Part of the problem lies in man-made toxins. Military personnel often work around substances such as gasoline, paint, and chemical weapons. Agent Orange, the toxic herbicide infamously used during the Vietnam War, is now known to cause cancer and other serious long-term health problems. Soldiers may also be stationed in polluted areas, close to airplane landing strips or open pits where plastic and chemical debris is burned.
But nature can also complicate things. Sandstorms are also common in Southwest Asia and Afghanistan. They kick sand, soil, chemical particles, and even pathogens into the air, making it dangerous to breathe for soldiers and civilians alike. People living in these areas have higher-than-normal rates of respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD).
Breathing unhealthy air can cause long-term inflammation in the lungs, and DRRD can develop. The damage can spread beyond the lungs into nearby blood vessels, which can stiffen and develop scarring. These stiffened blood vessels can increase blood pressure in the vessels surrounding the lungs, a condition known as pulmonary hypertension.
The CU Anschutz researchers evaluated clinical signs of these blood vessel changes in their study. They asked a small group of veterans to ride an upright stationary bicycle three times per week, performing HIIT intervals for four minutes at a time so they would reach 90% to 95% of their maximum heart rate.
In the first week, the participants did one HIIT interval per session, gradually increasing to four HIIT intervals per session by the fourth week. They continued at that prescription for the remainder of the 12-week program. The researchers used cardiopulmonary exercise testing (CPET) and transthoracic echocardiography (TTE) to assess the patients before and after the HIIT exercise regimen.
The 11 veterans who completed the exercise program were men aged 37 to 58 with symptoms of DRRD who had served in Southwest Asia or Afghanistan. Many of them had high blood pressure, diabetes, obstructive sleep apnea, and other conditions in addition to their DRRD symptoms.
After 12 weeks of HIIT exercise, the veterans showed signs of improved cardiovascular health and fitness, such as significantly increased VO2 max scores (which measure how much oxygen the body can take in during physical activity). They also showed fewer markers of PVD after finishing the HIIT program.
One marker, called the VE/VCO2 slope, measures how efficiently a person clears carbon dioxide through the breath. Pulmonary blood vessels damaged from PVD force the lungs to work overtime to expel carbon dioxide. The veterans showed a decreased VE/VCO2 slope after the 12-week HIIT program, which suggests their lungs became more efficient.
Study participant Andrew Beckman completes a round of HIIT exercise on a stationary bike. Photo courtesy of Lindsay Forbes.
“Trying to use exercise as a medicine for veterans, and for a disease that isn’t highly publicized or well-known, is really exciting,” says Cillay. “Our positive results were kind of unexpected in a way. HIIT exercise has been successful in showing improvements in cardio and pulmonary function, but we weren’t sure if it would work in this context.”
It’s too soon to say exactly how exercise caused the changes in the veterans’ health over those 12 weeks, or if those findings will be confirmed in larger studies. But it’s possible the HIIT exercise may have actually helped repair damaged cardiovascular tissues — in animal models, HIIT training has been shown to decrease scarring and improve aerobic metabolism in the heart.
Forbes and Cillay intend to continue their research with another, larger study where they test out a similar exercise regimen on a bigger group of veterans. But if the same positive health trends hold true for the larger group, HIIT exercise may indeed be a great medicine for soldiers with long-term respiratory illness who’ve struggled to find relief in other places.
Forbes says participants really enjoyed the exercise program, and she hopes the research team can deliver it to more people in the future.
“There are patients who don’t want another medicine, who don’t want to add to the list of things they have to take every day,” she says. “They’re interested in a different way of improving their health. And hopefully we can offer them that.”