Which factor might restrict the use of thermoplastic in sports?

The hardness of the material is a significant factor that can restrict the use of thermoplastic in sports. Thermoplastic materials, while often adaptable and moldable, can vary in their hardness. If the material is too hard, it may create discomfort or restrict movement for the athlete, which could be detrimental in a sport where flexibility and agility are essential. This is particularly important in sports where protective gear or custom molds are required, as inadequate flexibility or excessive rigidity could lead to ineffective support or increase the risk of injury.

The hardness also affects how well the thermoplastic can absorb impact or distribute stress during play. A balance between protective qualities and comfort is vital, and overly hard materials may fail to meet those requirements, leading to limited use in certain applications.