Past research suggests that eating an abundance of fresh fruits and vegetables, high in antioxidants, can improve lung function. Unfortunately, many sports require athletes to limit their diet (and restrict calories from fruits and high carb veggies) in an effort to meet weight class cut offs or maintain light and lean physiques.
In the fitness supplement world, antioxidant supplements are generally associated with decreased exercise-induced muscle damage, faster recovery, and decreased sick time. However, research published in the European Journal of Applied Physiology shows us that taking a blend of antioxidant vitamins (vitamin C, E, and beta-carotene) and minerals (zinc, selenium, copper, and manganese) can significantly improve lung function and decrease shortness of breath and perceived exertion during exhaustive treadmill exercise. This is especially relevant for athletes competing in tournament sports (like wrestling, MMA, and boxing) and where performances last for several minutes and include repeated efforts or bouts.
ACTION POINT: If your diet consists of less than 5 servings of fruit and vegetables per day, then you can boost your lung function and decrease perceived exertion by taking an antioxidant supplement. The best way to get all the antioxidant support you need is to take a multi-vitamin and mineral supplement designed for athletes. Make sure it contains the following minimum doses of vitamins and minerals: C (500 mg), E (400 IU), beta-carotene (15,000 IU), zinc (7.5 mg), selenium (50 mg), copper (1 mg), and manganese (2.5 mg).
Reference: Chenoweth LM, Smith JR, Ferguson CS, Downey AE, Harms CA. The effects of antioxidant vitamin supplementation on expiratory flow rates at rest and during exercise. Eur J Appl Physiol. 2015 Oct;115(10):2049-58.