Effect of simulated rock climbing finger postures on force sharing among the fingers.

OBJECTIVE

To study the forces applied by each finger in different joint postures simulating rock climbing gripping postures.

DESIGN

Subjects in sitting posture applied fingertip forces perpendicular to horizontal force sensors in three different finger postures.

BACKGROUND

Data provided by the literature indicate that middle and ring finger are commonly injured. However, no quantitative assessment of the forces applied by each finger related to the joint postures has been made.

METHODS

Six elite rock climbers performed finger flexion in a single-finger task and a four-finger task. The tests were conducted in an extended posture, a curved posture (the joints belonging to the finger were flexed) and an intermediate posture (the joints were flexed, except the distal one which was fully extended). Each fingertip force was expressed in absolute value and in percentage of the maximal force capacity of the finger.

RESULTS

The greater force was applied by the middle finger (20.8 N), whatever the posture. The relative involvement amounted to 105% for the ring finger in the curved posture.

CONCLUSIONS

The great force applied by the middle finger and the great relative involvement of the ring finger in the curved posture seem to be the main factors of injuries of these fingers.

RELEVANCE

The analysis of force sharing among the fingers during different joint postures mimicking rock climbing is essential to a better understanding of finger injuries.