To what purpose serves the application of artificial and superfluous substances, like chalk, to the hands of athletes, as illustrated in the portrait provided?
This especially given the fact that researchers have proven that chalk actually REDUCES the coefficient of friction, making things much much more slippery. (Carre et al, 2012).

Carre, M. J., Tomlinson, S. E., Collins, J. W., & Lewis, R. (2012). An assessment of the performance of grip enhancing agents used in sports applications. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 226(7), 616-625.