If you sometimes struggle to catch your breath after exercise, you’re not alone. About 10% of the general population and 90% of asthmatics have trouble breathing and symptoms like cough or sore throat after vigorous physical activity. It can even happen to competitive athletes, especially those who do endurance sports like running or those who compete in winter sports.
These breathing troubles are often caused by contraction of the airways that deliver air from your mouth to your lungs. As these tunnels narrow, it takes more effort to get air down into the lungs, which leads to a feeling of breathlessness. It’s thought this happens because these normally moist airways lose water with the increase in breathing that comes along with exercise. This loss of water triggers inflammation that leads to muscle contraction around the airway.
Some research has also indicated that oxidative stress may be partially responsible for this airway constriction. When you exercise, your body burns through energy and creates compounds called oxygen free radicals as a byproduct. Those free radicals can damage many of the proteins and other compounds in a cell and trigger unintended reactions. It’s these compounds that antioxidants, like vitamin C, fight. In doing so, they stave off damage to the cell.
In this case, a group of researchers investigated whether vitamin C might help to prevent breathing trouble after exercise by blocking some of the oxidative damage produced by exercise. They picked vitamin C because previous research has shown that it can reduce oxidative damage and free radicals after exercise. It’s also found in high concentrations in the lungs, indicating that it’s important to lung function.
The researchers performed a review of the current research to get a sense of whether they pointed toward a consensus on if vitamin C really helped those who had breathing trouble after exercise. In total, they found nine studies that approached the question from slightly different angles. Three studies found that giving vitamin C before exercise helped to improve lung function above the decline those in the studies normally experienced after exercise.
Another five studies found that giving vitamin C made the reactions less likely overall in the group they tested, but they didn’t measure lung function the way the other three studies did to see if the airways might still be contracting. The last study looked at using vitamin C in swimmers. It found that breathing troubles got better more quickly when vitamin C had been given.
The research reviewed didn’t reveal how or why this happens, but indicates that vitamin C likely does influence lung function after heavy exercise. Vitamin C is cheap, readily available at most pharmacies over the counter, and is generally nontoxic even at higher doses. As a result, the researchers recommend that active individuals who regularly have breathing issues after exercise try taking a vitamin C supplement before exercise to see if it helps with their symptoms.
The team points out that this use isn’t well established and that the optimal dosing hasn’t been precisely worked out. They also point out that vitamin C doesn’t prevent all symptoms in all people. Asthmatics should continue to carry their inhalers with them at all times whenever they exercise in the event of an attack.