Underwater Gait Analysis: A Markerless Approach

A fundamental need for modern biomechanical and clinical application is the ability to accurately capture normal and pathologic human movement. In this contest, nowadays, the aquatic environment is gaining an even important role within the rehabilitation world, thanks to water physical properties. Walking is one of the most common motor tasks in water-based exercise programs and it may be considered a major underwater rehabilitative tool. However state of the art marker based gait analysis cannot be performed in water environment, where the attachment of skin surface markers is not easy. A markerless approach, based only on synchronized video sequences, has been proposed as a potential solution for underwater (UW) applications. In the present work, an automatic markerless motion capture system has been investigated and its accuracy in UW three-dimensional (3D) lower limbs joint kinematics reconstruction has been tested. The results demonstrate the feasibility of calculating meaningful joint kinematics from subjects walking underwater without any markers attached to the limb. Thus, a markerless approach seems to offer the promise of expanding the applicability of human motion capture in an aquatic environment.