Noise-enhanced eversion force sense in ankles with or without functional instability

Abstract

Context: Force sense impairments are associated with functional ankle instability. Stochastic resonance stimulation (SRS) may have implications for correcting these force sense deficits. Objective: To determine if SRS improved force sense. Design: Case-control study. Setting: Research laboratory. Patients or Other Participants: Twelve people with functional ankle instability (age=23 ± 3 years, height=174 ± 8 cm, mass=69 ± 10 kg) and 12 people with stable ankles (age=22 ± 2 years, height = 170 ± 7 cm, mass = 64 ± 10 kg). Intervention(s): The eversion force sense protocol required participants to reproduce a targeted muscle tension (10% of maximum voluntary isometric contraction). This protocol was assessed under SRSon and SRSoff (control) conditions. During SRSon, random subsensory mechanical noise was applied to the lower leg at a customized optimal intensity for each participant. Main Outcome Measure(s): Constant error, absolute error, and variable error measures quantified accuracy, overall performance, and consistency of force reproduction, respectively. Results: With SRS, we observed main effects for force sense absolute error (SRSoff = 1.01 ± 0.67 N, SRSon = 0.69 ± 0.42 N) and variable error (SRSoff = 1.11 ± 0.64 N, SRSon = 0.78 ± 0.56 N) (P