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PURPOSE: To assess the severity of peripheral neuropathy (PN) on lateral gastrocnemius Hoffman reflex (H-reflex, both H/M ratio and H-index) modulation during walking stance phases (heel-contact, mid-stance, and toe-off). METHODS: Thirty-two participants were recruited in this study. Nine of them were in the Control group (healthy population) with intact plantar sensitivity. Twenty-three of them with doctordiagnosed PN. The participants with PN were further divided into two groups based on their plantar pressure sensitivity: the less affected group (scored 6-9 points), more affected groups (scored 0-5 points). Plantar pressure sensitivity was assessed with 5.07-gauge monofilaments at the hallux, bases of first/fifth metatarsals, mid arch, and heel. H-reflex of lateral gastrocnemius was collected during three stance phases (Heel-contact, Midstance, Toe-off). RESULTS: No group by stance phases interaction detected in H/M ratio (p=0.245). The mean H/M ratio of the three phases was significantly different across all three groups (p=0.049, partial η2=0.200) with no group main effect detected (p=0.407). The H/M ratio of Midstance (11.1±1.8%) was greater than that of Toe-off (9.4±1.7%, p=0.024, d=0.537). No significant difference was observed between H/M of Heel-contact (10.3±1.7%) and Midstance or Toe-off. No significant interaction was detected in H-index either. No phase nor group main effects were detected for H-index. CONCLUSIONS: The deficiency in plantar sensitivity did not affect the gastrocnemius H-reflex, both H/M ratio and H-index, during the walking stance phase. [ABSTRACT FROM AUTHOR]

PURPOSE: To examine the effects of Hoffman-reflex (H-reflex) and foot sole sensitivity on low extremity kinematics in people with peripheral neuropathy (PN). METHODS: People who are more (MST group, N=13) and less (LST group, N=10) sensitive to touch with physician-diagnosed PN were recruited for the experiment. Key outcome variables were H-reflex of the right soleus (SO), medial (MG) and lateral (LG) gastrocnemius muscles during standing, 6-minute walk distance (6MWD), duration of the timed up-and-go test (TUG), range of motion of the right hip, knee and ankle joints in the sagittal plane during walking on the treadmill, and three pairs (hip-knee, hip-ankle, and knee-ankle) of continuous relative phase variabilities (CPRv) used to evaluate lower extremity joint coordination. Statistically, the difference between LST and MST was examined using an independent sample T-test with p-value and effect size (Cohen's d). RESULTS: NO significant differences in H-reflex, both H/M ratio and H-index detected between the two groups. The LST group walk shorter distances in the 6MWD test (380.4±52.7 vs. 463.5±47.6m, p=.001, d=1.64) and slower in the TUG test (9.0±1.5 vs. 7.2±1.1s, p=.003, d=1.38). The range of motion of the right hip, knee, and ankle of LST group were significantly less than that of the MST group (27.1±6.6 vs. 34.6±4.3 deg., p=.006, d=1.35; 43.7±13.8 vs. 58.0±5.7 deg., p=.003, d=1.34; and 17.0±5.2 vs. 23.5±6.3 deg., p=.015, d=1.12). The LST group showed a greater amount of CRPv than the MST group (31.0±10.4 vs. 21.4±6.6, p=.013, d=1.11) with no differences observed in the other two sets of CRPv values. A significant positive linear correlation was observed for the LST group between the range ankle range of motion and the H-index of LG (r=.681, p=.044). CONCLUSION: The deficits of foot sole sensitivity led to the decrease of range of motion and functional gait, and increased hip-ankle coordination variability during walking. The tactile sensation plays a role in regulating the range of motion of the lower extremity. Interestingly, with the increase of the nerve conduction velocity, the range of motion of the lower extremity increases accordingly. Thus, the lower threshold of tactile sensation in conjunction with faster proprioceptive feedback contributes to an increased range of motion and faster walking speed. [ABSTRACT FROM AUTHOR]