Walking is a complex task that can be viewed as an indicator of human health. One reason it serves this role is because walking depends on finely tuned coordination, requiring healthy neuromuscular systems to use energy-saving mechanisms. One energetically efficient mechanism is captured by the inverted pendulum model, in which the exchange of kinetic energy (KE) and potential energy (PE) helps conserve mechanical energy during gait at normal speeds (>0.5 m/s). However, it is unclear how this pendular mechanism may contribute to energetic efficiency at slow speeds (<0.6 m/s). This thesis investigates the energy exchange between KE and PE across a range of walking speeds, mainly focusing on studying slow speeds. The phase shift between KE and PE were calculated from each of sixteen healthy human participants who walked on an instrumented treadmill at thirteen prescribed speeds. We determined the phase shifts between the KE and PE signals using two methods:​ one method developed and described by Cavagna & Legramandi 2020 which used peak-trough landmarks and a second method using cross correlation. We found that as walking speed decreases, the phase shifts between KE and PE increases within the range of 0.4 to 2.0 m/s before declining at lower speeds. While the phase shifts appear to move closer in phase as speed slowed - more closely resembling pendular behaviour - more external energy is required to maintain gait at slow speeds. Our results suggest that phase shifts appear to decrease at very slow speeds, and the energetic advantage of pendular motion diminishes. Even though this decreased phase shift should imply pendular dynamics resume, we found that more external energy was required to remain in motion at very slow speeds.