## 5 Significant Gaps in the Current Research
### The Lack of a General Method for Identifying Motor-Control Patterns  
It would be a practitioner's desire that, just like physiological, neurological, and biochemical wearables, the biomechanical one could also be universally applied to all motor skills for their learning and training in sports and arts. A general application means that a general method should exist for data interpretation (i.e., identification of motor-control patterns). Unfortunately, we are still far away from the goal. Apart the lack of a general full-body biomechanical model, there is not a general method for data interpretation. All existing studies are specific/isolate ones. So far, only few studies explored the real-time biomechanical feedback related to sport activities [64; 82; 83]. On one side, the feedbacks were force, power, or velocity; not the feedbacks of limbs' coordination, i.e., motor control patterns. On the other side, the evaluation methods were tailed to the activities being examined, i.e., no potential for delimitation.  
Another confounding factor influencing the identification of motor-control patterns is anthropometry. In great part, the personal control'style' derives from an individual development of a  
Figure 1: 15-segment biomechanical modeling of the Grande Jéé (**a**) in Ballet and the Axe Kick (**b**) in Taekwondo [56; 81].  
variety of motor behaviors that are compensatory in nature; accommodating body size and shape as well as physical ability, such as flexibility and agility. This individualization, in turn, poses particular challenges for both research and pedagogy. An astonishing example of motor compensation can be observed in the performance of Canadian violinist [PERSON] [84]. [PERSON] was born without a right hand, no wrist, and only a partial forearm. This means he has only two arm segments with two functional joints in his bowing arm--the arm responsible for much, if not most of the violinistic nuances that are associated with articulation and expression. A \"normal\" violinist would have the use of three large segments in the arm (upper arm, forearm, hand) plus the fingers (with a total of 17 functional joints) for the finest motor adjustments. Astoundingly, [PERSON] has found compensatory motor control mechanisms that allow him to accomplish performance at the highest of professional levels [85]. His accomplishments highlight that there are many motor control means to the same end. For meaningful motor control identification, novel methodology must be developed to examine its many facets simultaneously.  
How Past and Current Developments Influencing New Endeavors--Ideas of Where Research Might Break Through  
In area of human motor skill learning, people are always looking for ways to speed up training, ways to make it more economical, efficient, and effective, ways to minimize injuries. Real-time biomechanical feedback training could be the best way that people are looking for, because the technology would have potentials for: (1) making scientific monitoring from a lab-based environment to in field, (2) simplifying a scientific quantification from using a complicated motion capture system to easily-applied wearables, and (3) transferring the vital biomechanical feedback in a right time for preventing the worst/movement errors happening, while finding individual compensation/optimization [50]. For reaching this goal, further studies should focus on solving the challenges (Section 4.3) and bridging the gaps (Section 5). The research focuses could be summarized, as follows:  
* Developing a wearable-based full-body biomechanical model that is equivalent to the current 3D 15-segment one
* Searching new method for wearable data interpretation, i.e., motor control characterization
* Generalizing the approach to various sports and arts performance.  
The past and current studies of anthropometry, biomechanics, sensing technology, and AI have supplied rich food of thoughts that might be benefit to the future research endeavors.