Click beetles (Elateridae) are one of many small organisms that use a system of springs and latches to achieve incredible accelerations. This strategy is referred to as latch-mediated, spring-actuated (LaMSA) movement and consists of latching, loading, and release phases. We hypothesized that during the loading phase, the large M4 muscle compresses portions of the beetle and loads the mesonotum, a saddle-shaped structure connecting the two body segments. In this study, we examined three components of the energetics of the loading and release phases of the click beetle Parallelostethus attenuatus (length, ~18 mm), combining data from high-speed x-ray videos with micro-CT scans of the M4 muscle and mesonotum. First, we determined the M4 muscle’s energy input using 3D morphological data of the mesonotum. Then, we calculated the mesonotum’s stored potential energy using Finite Element Analysis. Finally, we compared the energy output from similar unconstrained jumps from this species to the energy input to estimate the energy dissipated. The results of this study support the hypothesis that the M4 muscles are the primary actuator and the mesonotum is the primary spring. The methods developed here also create an energy-based framework relating geometry and kinematics to the resulting dynamics and can be extended to other biological and bio-inspired LaMSA systems.