Modulation of the Hoffmann reflex in soleus and medial gastrocnemius during stair ascent and descent in young and older adults

Publication date: Available online 16 November 2018

Source: Gait & Posture

Author(s): Johanna Johannsson, Jacques Duchateau, Stéphane Baudry

Abstract

Background

The Hoffmann (H) reflex can provide relevant information on spinal control of leg muscles during locomotor tasks in young and older adults.

Research question

Is the H reflex in the leg muscles differently modulated during stair gait in young and older adults?

Method

The H reflex in soleus (SOL) and medial gastrocnemius (MG) (normalized to the maximal M-wave amplitude obtained during upright standing; M_max) was recorded in 19 young and 18 older adults during upright standing, and stair ascent and descent of a 3-step staircase.

Results

H-reflex amplitude during upright standing was greater in young than older adults for SOL (48% vs. 26% M_max; p = 0.001) and MG (23% vs. 14% M_max; p = 0.02). When data were averaged across groups during stair ascent, H-reflex amplitude in SOL increased from 15% M_max at the beginning of the stance phase to 29% M_max at mid-stance, then decreased to be 4% M_max in the swing phase. During stair descent, H-reflex amplitude was maximal (20% M_max) at the beginning of the stance phase, decreased to 5% M_max at the end of stance, and increased to 11% M_max in the swing phase. Similar adjustments were observed for the H reflex in MG for both ascent and descent. H-reflex modulation during gait cycle (relative to upright standing) is less pronounced in older adults (p < 0.05). However, no difference was observed between subgroups of young and older adults matched for H-reflex amplitude in upright standing. In both groups, H-reflex modulation was not associated with changes in background electromyographic activity.

Significance

This study indicates that the H reflex is modulated within the stair gait cycle during ascent and descent. Although its magnitude was slightly reduced, the overall modulation of the H reflex is not affected in healthy older adults.

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