The dorsal anterior cingulate cortex (dACC) has been studied extensively using effort-based decision-making (EBDM) paradigms and has been shown to track effort costs. However, it remains unclear whether the dACC encodes objective measures of effort, such as energy expenditure, or subjective perceptions of effort. Further, prior EBDM research in humans has focused on artificial, seated tasks like gripping hand dynamometers, which 1) do not accurately reflect real-world effort demands and 2) are limited by fMRI's temporal resolution, making it difficult to link neural activity to behavior. To address these gaps, we designed an incline-walking task with mobile electroencephalography (EEG) to investigate how the human dACC encodes both objective (energy expenditure) and subjective (perceived exertion) effort measures. We recorded brain activity, metabolic cost, and self-reported ratings of exertion as healthy participants walked at multiple discrete inclines. Scalp activation patterns varied with incline along the frontal midline, which we localized to cortical sources in the dACC and ventromedial prefrontal cortex (vmPFC). Under high-incline conditions, we observed increased theta (4-8 Hz) and decreased beta (12-30 Hz) oscillations in the dACC during metabolic steady state (constant rate of energy expenditure). However, by comparing cortical activity with both effort measures, we found that dACC beta bandpower was negatively correlated with objective effort, whereas vmPFC theta bandpower was positively correlated with subjective effort. Our study is the first to provide evidence that dACC oscillations contain representations of energy expenditure in humans, building upon previous findings that individual dACC neurons encode treadmill incline in rodent models. We hypothesize that the suppression of dACC beta oscillations may reflect increasing motor demands, aligning with the beta status-quo hypothesis. These signals may then be projected to the vmPFC, where theta oscillations potentially integrate effort costs with internal states such as fatigue, affect, and motivation.