Maximal resultant four fingertip force and fatigue of the extrinsic muscles of the hand in different sport climbing finger grips.

This study investigates the effect of simulated sport climbing finger grips on the resultant four fingertip force and the rate of fatigue of finger flexor muscles. Six elite sport climbers sat on a chair with the right forearm placed in a handgrip dynamometer modified so that only the fingertips applied direct force. They were asked to perform three maximal voluntary contractions (MVC). After ten minutes, they had to reach 80 % of the peak MVC intermittently with a 5 s contraction followed by 5 s of rest for 20 repetitions. Two common sport climbing finger grips were tested: the "slope" grip and the "crimp" grip. In the "crimp" grip, the distal interphalangeal joint (DIP) is hyper-extended and the proximal interphalangeal joint (PIP) is flexed from 90 degrees to 100 degrees . In the "slope" grip, DIP is flexed from 50 degrees to 70 degrees and PIP is flexed just slightly. The surface EMG of the hand extrinsic flexors and the maximal resultant four fingertip force were recorded. Results show that the maximal resultant four-fingertip force does not depend on the type of finger grips (on average 420 N, p > 0.05). EMG median frequency of finger flexor muscles and resultant four fingertip force rate decrease are similar between both sport climbing finger grips (p > 0.05). This shows that the fatigue rate is not dependent upon the sport climbing finger grips. In conclusion, the results suggest that the use of the "crimp" or the "slope" grip does not provide any benefit with respect to muscular fatigue in sport climbing.