Effects of an Acute Sensorimotor and Neurological Training Intervention on Knee Flexor Performance in Females

Abstract

Sensorimotor failure of the dynamic stabilizers is implicated in anterior cruciate ligament (ACL) injury of the knee. The dose of training required to elicit a biologically meaningful improvement in sensorimotor performance (SMP) is unknown. Novel dynamic SMP assessment tasks have not been previously used to assess the effects of training. PURPOSE: To assess the effects of an intensive functional training intervention on dynamic SMP and neuromuscular performance (NMP) of the knee flexors in females. METHODS: Twelve females (22 ±1.8 yrs) were randomly assigned to a control (CON) [n=5] or experimental (EXP) [n=7] group. The EXP group trained their non-preferred limb (NPL) using six exercises for six sessions a week over two weeks. SMP (constant error (CE) arising from a 'slow' and 'fast' force reproduction task of 50% peak force (PF)) and NMP (PF) were assessed pre and post intervention using a single leg intervention (NPL) contra-lateral control model. The NPL was also assessed pre and post intervention following a single bout of induced fatigue (EXP/CON). Time by limb by group comparisons were made using separate three-way mixed model ANOVA's for PF and CE (expressed as a % of the target force). Three-way mixed model ANOVAs, with repeated measures on time and occasion with group as a between subjects factor were used to evaluate the effects of the intervention on PF and CE during fatigue (NPL only). RESULTS: No significant changes were seen for PF or CE in the CON group across time (p>0.05). In the EXP group, PF was not significantly altered in the NPL from pre to post intervention at rest (196.6 ±43.0 vs. 224.4 ± 74.1 N, p>0.05) or following fatigue (185.9± 39.0 vs. 201.2 ± 67.8 N, p>0.05). CE was not significantly altered in the NPL (EXP group) from pre to post intervention at rest for the slow task (-4.1± 23.6 vs. 2.0 ± 22.2, p>0.05) or the fast task (-9.4 ± 19.1 vs. -5.8 ± 14.2, p>0.05) and was not significantly altered in the NPL from pre to post intervention during fatigue for the slow task (2.0 ± 22.2 vs. 13.3 ± 21.3, p>0.05) or the fast task (-5.8 ± 14.2 vs. -13± 18.5, p>0.05). CONCLUSIONS: No significant alteration to SMP or NMP of the knee flexors was seen at rest or during fatigue following a two-week intensive training intervention in the NPL of females. A greater dose of training may be needed to enhance dynamic stabilization of the knee flexors.