Relationships between self-reported ankle function and modulation of Hoffmann reflex in patients with chronic ankle instability

Objective: To examine relationships between self-reported ankle function and Hoffmann (H) reflex modulation during changes in body positions in patients with chronic ankle instability (CAI). Design: Observational. Setting: Laboratory. Participants: Thirty-one young adults with CAI (19 males, 12 females) participated. Main outcome measures: There were two subscales of Foot and Ankle Ability Measure (FAAM) to quantify self-reported ankle function during activities of daily living (ADL) and sports activities. Maximum H-reflexes (H-max) and motor waves (M-max) from soleus and fibularis longus were recorded while participants lied prone and stood in bipedal and unipedal stances. For each muscle, percent change scores in H_max:M_max ratios were calculated between each pair of positions: prone-to-bipedal, bipedal-to-unipedal, and prone-to-unipedal, and used as a measure of H-reflex modulation. Pearson correlation coefficients were calculated between FAAM and H-reflex modulation measures. Results: There were significant correlations between: (1) FAAM-ADL and soleus prone-to-unipedal modulation (r = 0.384, p = 0.04), (2) FAAM-Sport and soleus prone-to-unipedal modulation (r = 0.505, p = 0.005), (3) FAAM-Sport and fibular bipedal-to-unipedal modulation (r = 0.377, p = 0.05), and (4) FAAM-Sport and fibular prone-to-unipedal modulation (r = 0.396, p = 0.04). Conclusions: CAI patients presented moderate, positive relationships between self-reported ankle function and H-reflex modulation during changes in body positions.