Background: Reactive oxygen species (ROS) are small, unstable, highly reactive molecules that can oxidize proteins, lipids, and DNA. It has been shown that ROS levels increase with aging, leading to loss of muscle mass and heart damage as well as muscle diseases such as muscular dystrophy. However, proper exercise and antioxidant consumption like pumpkin seed (PS) can have protective effects against oxidative stress. Objectives: This study aimed to investigate the antioxidant effects of resistance training (RT) and PS extract consumption in the rat’s heart tissue exposed to H2O2-induced oxidative damage. Methods: Forty-two male Wistar rats were selected and divided into seven groups of six subjects, including (1) control (C); (2) treatment control (TC); (3) RT; (4) 1 g/kg PS (1PS); (5) 2 g/kg PS (2PS); (6) RT + 1PS; and (7) RT + 2PS. The groups 2 to 7 received 1 mg/kg of H2O2 peritoneally for eight weeks; groups 4, 5, 6, and 7 received ethanolic extract of PS at given doses by gavage; the groups 3, 6, and 7 performed RT (the initial weight selected was 50% of the rats’ body weight, which gradually increased by the end of the eight-week period and increased by 100% in the final week) three days per week. Forty-eight hours after the last RT and PS administration the rats were sacrificed, and adenosine triphosphate (ATP), glutathione (GSH), malondialdehyde (MDA), and pro-oxidant-antioxidant balance (PAB) levels were measured in the heart tissue. Results: H2O2-induced oxidative damage significantly reduced ATP and GSH as well as increased MDA and PAB levels (P = 0.001); RT significantly increased GSH and decreased MDA and PAB levels (P = 0.001); 1PS and 2PS significantly increased GSH and decreased PAB levels (P = 0.001); RT + 1PS and RT + 2PS significantly increased ATP and GSH as well as decreased PAB levels (P = 0.001) also RT + 2PS had more effect on ATP increase and MDA decrease and PAB compared with RT, 1PS, 2PS, and RT + 1PS (P = 0.001). Conclusions: It seems that RT simultaneously with PS administration compared with RT and PS alone have more protective effects in the heart tissue of rats exposed to H2O2-induced oxidative damage; also, effects of PS consumption are dose-dependent.