Idiosyncratic control of the center of mass in expert climbers.

Here, we studied posture and movement coordination adopted by expert climbers. The investigation of such expertise might be of particular interest to gain understanding about the mechanisms underlying the biomechanical control of vertical quadrupedal locomotion. A novel custom setup was developed to analyze the motion of the center-of-mass (COM) and complementary information about the dynamic distribution of vertical reaction forces under the feet during climbing in nine elite climbers (EC) and nine control subjects. Two adaptive features were found in EC. First, unexpectedly they tended to maintain larger COM distances from the wall relative to controls, during both the static and dynamic phases of vertical motion (by ∼5 cm in both cases). Second, while the control subjects tended to restrain the lateral motion of the COM, all EC demonstrated systematic COM oscillations (∼1.3 times larger) associated with a significant alternating dynamic redistribution of the body weight between the limbs during the double support phase. The latter phenomenon likely reflects an adopted basic climbing strategy in experts. Furthermore, a convergence of the optimal solution towards a more diagonal climbing strategy in EC may shed light on the origin of the diagonal gait in primates and early hominids habituated to quadrupedal vertical locomotion.