# Special Issue \"Biomechanics and Human Motion Analysis\"
###### Abstract  
In March 2021, we invited submissions to the MDPI Special Issue \"Biomechanics and Human Motion Analysis\", in the form of original research papers, methodological advances, mini reviews or perspective articles. The topic was solicited through the scientific experience of these three Guest Editors, with each of them having made considerable contributions to the areas of Human Motion Analysis (HMA) and Biomechanics. The latter discipline generally refers to the application of mechanical terms, concepts and knowledge to biological systems, traditionally the human body and its major organs and systems. This is performed with many different instruments and tools, including in silico modelling, and in vitro and in vivo experimental measurements. These instruments and techniques are also traditionally used for the purposes of HMA. Strengthening the connections between these two research specialities will enable greater insights into human motion [1, 2]. Due to its ability to gather, analyse and interpret, and hence somehow capture, the complexity of the overall dynamics of human motion [3, 4], HMA and its tools have attracted the interest of many clinicians in recent decades [5, 6, 7, 8, 9, 10], and also the attention of many scientists from a wide range of other disciplines [4], as well as application domains as diverse as elite sport, art, law, the military and entertainment. The measurements used in HMA are usually non-invasive and can now be very accurate and repeatable, very comprehensive, and with limited encurnbrance for the subject being analysed. The apparatus of a fully instrumented motion analysis laboratory [3, 6], for example, can include a stereophotogrammetric system to track in reflective markers which would have previously been stuck on the skin in 3D space by using a set of digital cameras, force plates on the ground to measure the ground-reaction force, EMG surface electrodes to capture myoelectric signals from the muscles and instrumented platforms in the floor or in insoles to map the plantar pressure distribution. In addition, as a result of recent technological advancements, in modern laboratories the major kinematics and kinetics variables of a large number of joints and in all anatomical areas of the human body can be calculated in 3D, and this is possible even in real-time during the execution of those locomotion exercises that are typical of daily living. Due to these attractive features, HMA techniques have been largely exploited worldwide to assess medical conditions, e.g., the effects of neurological or orthopaedic pathologies and those of trauma and amputations, and to assess the efficacy of pharmacological, orthotic and surgical treatments. This area of application is clearly the largest and best known, in the way that the phrase HMA is usually only associated with the more traditional concept of \"clinical gait analysis\", where established procedures are used to assess patients before and after interventions. These routine procedures, however, still frequently use minimal marker-sets, primitive experimental protocols and complex graphical reports [8, 11]. In the last two decades HMA has been expanded to include videofluavoscopy [12], in which algorithms for 2D-to-3D spatial matching take planar medical images of human joint motion in three anatomical planes, and wearable inertial sensing technology, which integratesvarious sensors into so-called Inertial Measurement Units [13; 14]. In this latter context, this technology, which is also the standard technology embedded into common smart phones, is used to track elementary human motion. In the present Special Issue, all of these technologies have been explored to develop a full and valuable picture of their advantages and drawbacks.