Objective/Hypothesis: Sport climbing involves high demands on the load undergone by the structure of the hand. It is known that the structure of the hand in climbers tends over time to become reinforced and increase in resistance. This resistance increase has a direct impact on the mobility of climbers’ fingers, which is gradually reduced. This loss of mobility especially affects interphalangeal extension. This clinically evident concept has never been scientifically verified. The purpose of this study is to demonstrate that this reduction of mobility is quantifiable and follows a certain pattern. Materials and Methods: Four groups of individuals, both men and women, climbers and nonclimbers, were evaluated. The group of climbers was evaluated in the Climbing World Championship; thus, it consisted of a group of experienced climbers with a high load of daily and weekly sports hours. The control group was a group of people having the same age and sex distribution as that of the study group but who had never done any climbing-related sports activity. The mobility toward extension of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) of the second, third, and fourth fingers was measured in all the participants. Results: In the group of both men and women, a statistically significant difference was obtained in terms of both PIP and DIP extension, with average differences reaching 20°. Conclusions: Stiffness in PIP or DIP extension in climbers is a physiological constraint that cannot be interpreted as a deformity associated with an injury, but part of an adaptation of tissues to the sport.
