Fig. 3. The average of linear approximation equations of the relationship between the flexor traction force and the finger flexion force for each tendon. A strong first-order correlation was observed between the flexor traction force and the finger flexion force recorded by the Jamar Plus+ Digital Hand Dynamometer for each tendon and for all fingers (maximum R2 = 0.999, minimum R2 = 0.964) . The left FDS and FDP of the little finger were too small to be investigated.