Back skin deformation during anaerobic exercises for ergonomics design application
Authors: Huang Tsai-chun , Li Bingxue 
Published: June 2024

The purpose of this study is to propose a muscular-based superficial skin deformation method to visualise the deformation of human back during resistance training, thus, to provide a reference for the back design of gym wear and wearable devices.  Among the muscle groups, the back has numerous muscles and is a very difficult area to train, therefore, there is an urgent need for the study of the skin deformation of the back during anaerobic training.  Several studies have been conducted on skin deformation during aerobic exercise, such as rowing and cycling using the division of anthropometric measurements, however, back muscle contractions in anaerobic exercise in which the skin deformation was caused by muscle movements need more exploration. In this study, eight regular trained males were instructed to perform three back training exercises: seated pulldown, seated row and standing pulldown. Their backs were marked points of 3 cm interval according to the surface division of the two major muscles: the trapezius and the latissimus dorsi.  The statistics skin measurements of starting point and completion of the exercises were taken by 3D scanner Artec Eva. The mean, maximum values and standard deviation of the data were compared and analyzed according to muscle morphology and fibre bundle orientation.  The results showed that the maximum deformation of trapezius, was 24.23% and 11.97%, 9.31% and 8.94%, 1.51% and 9.78%, for starting and completion in the horizontal, longitudinal and diagonal direction, respectively. For the latissimus dorsi, the greatest deformation manifested as 7.23% and 5.36 %, 14.59% and 8.52%,17.60% and 9.70% for starting and completion along the longitudinal and diagonal directions, respectively. These muscle-based deformation can be implemented in the design of prototypes in the corresponding regions to improve the dynamic fit during exercise.Both muscles showed different degrees of segmental deformation on the triangular shaped sides. The horizontal and longitudinal directions of the trapezius muscle show a state of compression in the whole segment during movement, but with the degree of compression ranging from 1.99% to 14.29% for each sub-segment. The oblique side of the trapezius showed a concentration of deformation in the lower half of the muscle, with a range of 10.83%-38.49%, while the latissimus dorsi shows a more uneven deformation dominated by the oblique upper third extrusion deformation. For the dramatic variable sub-regions, additional structures or strengthen materials should be taken into account to support the muscle, providing bracing forces for better muscle perception and avoid injuries.In this research, skin deformation characteristics during back anaerobic training were proposed and regional analysis based on muscle morphology and kinesiology are performed. These zoning values can be used as a reference for intelligent monitoring, so that the design of sensing accessories can be better matched. The visual mapping of results offered guidance for the cutting lines of tight fitness apparel prototype and the back structural design of sportswear, applying the deformation characteristics of anaerobic exercise to improve the dynamic comfort.