Quercetin is suggested as a nitric oxide regulator which may in turn influence blood parameters and weight gain. Wistar rats were classified as: quercetin-exercise training, QT; placebo-exercise training, PT; quercetin-sedentary, QS; and placebo sedentary, PS. After 6 weeks of treatment with quercetin and/or exercise, an incremental test was run to measure oxygen consumption. QT had lower levels of NO compared with PS (p = 0.029) and QS (p = 0.002). Red cell distribution width increased in both exercised groups, especially in the QT group (p < 0.001). Pearson correlation analysis showed that nitric oxide levels were associated with weight (r = 0.675) and red distribution width (r = -0814) in the QT group. Quercetin effect on NO production seems to be more powerful when it is supplemented during exercise training. Moreover, RDW relationship with NO production need to be further investigated in regards to health.