Micronutrient functions are needed for aerobic exercise. Therefore, aerobic performance should be helped by optimal intake of these nutrients including trace minerals. For instance, iron, even apart from its role in hemoglobin, affects aerobic energy metabolic pathways through functions in enzymes and cytochromes . Another trace mineral, copper, is part of cytochrome c oxidase, the terminal enzyme in aerobic energy metabolism . Other copper enzymes work against oxidative stress , which contributes to exercise-induced fatigue . A third trace mineral, zinc, could affect aerobic exercise performance in a variety of ways: indirect antioxidant actions [3–5], a cofactor role in carbonic anhydrase that eliminates carbon dioxide [6, 7], a cofactor role in lactate dehydrogenase , and an activator of enzymes in energy metabolism .
For active young adult women, intake of these 3 minerals may often fall below optimal amounts. For iron, it well documented that exercising women often get a degree of deficiency . Severe deficiency causes anemia, but even milder deficits could affect energy metabolism . For copper, in young adult women, supplemental copper has improved copper function . For zinc, in one USA diet survey, for about 40% of the women, intake fell below the RDA . Moreover, the zinc RDAs may not even be set high enough [12, 13]. Multiple studies [1, 12–15] find low intake of zinc in active people. This low intake especially applies to participants in sports that need weight control, people who avoid animal products, and people eating high carbohydrate, low fat and protein diets. Furthermore, exercise training may raise copper and zinc requirements [14, 16, 17]. This situation may not be fixed easily by all multi-vitamin-mineral supplements since many use zinc and copper oxide, which are not the best absorbed forms .
On a related note, increased zinc or copper intake might benefit exercise performance even in non-deficient situations. In a controlled feeding study, eating above the copper RDA improves cycling performance and muscle cytochrome c oxidase versus RDA intake . For zinc, in a rat study , plasma lactate level after swimming is highest in a low zinc diet group, medium in a zinc adequate group, and lowest in a zinc supplemented group. In similar work, moderately high zinc intake can raise lung levels of glutathione, an antioxidant, in swim trained rats .
Besides essential minerals, conditionally essential nutrients (CENs) also hold relevance to exercise. These molecules are both made by the body and eaten . Traditionally, intake has been studied mostly for people with health problems i.e. . However, in healthy rats or mice [21, 22], supplementation with the CEN carnitine delays exercise-induced fatigue. In humans, supplementing this same agent can influence muscle recovery, which can enhance training effects on exercise performance . Carnitine can theoretically affect exercise performance and recovery via a role in fat oxidation for energy  and possibly via an anti-ischemic effect . Another CEN, phosphatidylserine, could affect exercise performance by neuroendocrine effects, enzyme cofactor functions, and anti-inflammatory actions [26, 27]. Supplementation with this CEN influences perceived fatigue during exercise . In addition, phosphatidylserine supplementation can extend time to exhaustion in a long biking session in active males . The effects on other types of exercise measures in other types of exercisers await further research.
A new study tested the following hypothesis: increased intake of three trace minerals in well absorbed forms, plus two CENs, will improve aerobic exercise performance in recreationally trained, young adult women. The primary outcome was 3 mile runtime; secondary outcomes were distance covered in 25 min stationary biking and step number in a 90 s step test, both done shortly after the run. Positive results would show that increased trace mineral intake and/or CENs can improve aerobic exercise performance in aerobically active women. Later studies can further define the minimal combination of the 5 nutrients needed to produce the effects.