Ventilator-induced lung injury (VILI) has recently been reinterpreted from a physical and mechanical perspective through the concept of Mechanical Power (MP), defined as the amount of energy transferred by the ventilator to the respiratory system per unit time. Since the seminal work by Gattinoni et al. [1], MP has emerged as a unifying variable that integrates tidal volume, airway pressures, flow and respiratory rate, and has been associated with lung injury and mortality. However, most existing formulations have been developed and validated in adult populations, and their applicability to pediatric patients remains unexplored. In this study, several analytical formulations of inspiratory mechanical power previously proposed in the literature are experimentally validated. These formulations include those by Gattinoni [1] and Giosa [2]. The validation is performed in mechanically ventilated children under volume-controlled ventilation. In addition, the concept of Effective Mechanical Power (MPeff) is introduced. It is defined as the difference between inspiratory and expiratory Mechanical Power. This concept aims to estimate the amount of energy that is effectively dissipated within the lung. Experimental measurements of energy per breath were obtained from real pressure-volume loops recorded directly from the ventilator. The signals were acquired as high-resolution digital data and they were processed using trapezoidal numerical integration. These experimental values were used as a reference to assess the accuracy of the theoretical equations. Our results demonstrate that adult-derived inspiratory MP equations are valid in pediatric patients, with the simplified formulation proposed by Gattinoni showing the most robust agreement. Moreover, the newly derived expressions for MPeff exhibit a strong correlation with experimentally measured values. This work highlights the relevance of analyzing real clinical data to verify commonly accepted formulations in underexplored populations. Quantifying clinically measurable parameters such as effective MP may provide a more physiologically meaningful metric for characterizing ventilatory settings potentially associated with lung injury than inspiratory Mechanical Power alone.