Fine adaptive precision grip control without maximum pinch strength changes after upper limb neurodynamic mobilization

Abstract

Before and immediately after passive upper limb neurodynamic mobilizations targeting the median nerve, grip (GF) and load (LF) forces applied by the thumb, index and major fingers (three-jaw chuck pinch) were collected using a manipulandum during three different grip precision tasks: grip-lift-hold-replace (GLHR), vertical oscillations (OSC), and vertical oscillations with up and down collisions (OSC/COLL/u, OSC/COLL/d). Several parameters were collected or computed from GF and LF. Maximum pinch strength and fingertips pressure sensation threshold were also examined. After the mobilizations, LF max changes from 3.2 ± 0.4 to 3.4 ± 0.4 N (p = 0.014), dGF from 89.0 ± 66.6 to 102.2 ± 59.6 Ns-1 (p = 0.009), and dLF from 43.6 ± 17.0 to 56.0 ± 17.9 Ns-1 (p< 0.001) during GLHR. LF SD changes from 0.9 ± 0.3 to 1.0 ± 0.2 N (p = 0.004) during OSC. LF peak changes from 17.4 ± 8.3 to 15.1 ± 7.5 N (p< 0.001), GF from 12.4 ± 6.7 to 11.3 ± 6.8 N (p = 0.033), and LF from 2.9 ± 0.4 to 3.00 ± 0.4 N (p = 0.018) during OSC/COLL/u. GF peak changes from 13.5 ± 7.4 to 12.3 ± 7.7 N (p = 0.030) and LF from 14.5 ± 6.0 to 13.6 ± 5.5 N (p = 0.018) during OSC/COLL/d. Sensation thresholds at index and thumb were reduced (p = 0.001, p = 0.008). Precision grip adaptations observed after the mobilizations could be partly explained by changes in cutaneous median-nerve pressure afferents from the thumb and index fingertips.