Future robots will need to perform complex and versatile tasks comparable to those of humans. Due to the unavailability of suitable actuators, however, novel intelligent and agile robots are often restricted in their performances and development. The limited output torque range and low energy efficiency of current robotic actuators are the main bottlenecks. We have developed a SPEA with intermittent mechanism that addresses these problems. The SPEA is a novel compliant actuator concept that enables variable recruitment of parallel elastic elements and adaptive load cancellation. This paper describes how a SPEA lowers the motor torque and increases the energy efficiency. Experiments on the first proof of concept set-up endorse the practicability of the SPEA concept and the modeled trend of a lowered motor torque and increased energy efficiency. We expect that features of the biologically inspired SPEA with intermittent mechanism will prove exceedingly useful for robotics applications in the future.