Responsiveness of the H reflex to loading and posture in patients following stroke

The effects of body weight on the soleus H-reflex modulation during standing

“…According to Hwang et al, the soleus HM ratio in healthy adults decreased as body weight bearing in the lower limb decreased. This was demonstrated in three different asymmetrical body weight bearing conditions (10%, 50%, and 90%) on two body scales (Hwang et al, 2004). Other researchers have reported no significant relationship between limb unloading conditions and the soleus H-reflex amplitude (Ali and Sabbahi, 2000;Field-Fote et al, 2000;Hwang et al, 2004;Phadke et al, 2006).…”

“…Findings from previous studies that have examined the relationship between the amplitude of the soleus H-reflex and limb loading in a standing position have been controversial (Ali and Sabbahi, 2000;Field-Fote et al, 2000;Hwang et al, 2004;Miyoshi et al, 2003;Nakazawa et al, 2004;Phadke et al, 2006). Miyoshi et al found that the soleus H-reflex amplitude was significantly larger in the hyper-gravity and microgravity conditions compared to normal gravity condition (Miyoshi et al, 2003).…”

“…In order to vary the amount of limb loading, each study measured the soleus H-reflexes in various experimental limb loading situations. These situations included asymmetrical standing on two body scales or force plates using feedback (Hwang et al, 2004), different-gravity conditions including microgravity, normal gravity, and hypergravity (Miyoshi et al, 2003), different joint loading on a waterproof force platform in the water tank (Nakazawa et al, 2004), or suspension system composed of an overhead I-beam and support harness (Field-Fote et al, 2000;Phadke et al, 2006). Although we chose a suspension system that corresponded to the methods described by Phadke et al (2006), they could not find statistical significance across BWL conditions nevertheless there was a similar tendency to our results.…”

“…Based on this hypothesis, the H-reflex has been used in several studies as a tool to examine the neurological effectiveness of interventions for stroke (Bakheit et al, 2003;Knikou et al, 2009;Lo et al, 2009;Stewart et al, 2004;Trimble et al, 1998Trimble et al, , 2001, spinal cord injury (Phadke et al, 2007), and cerebral palsy (Hodapp et al, 2009). In recent years, several researchers have tried to evaluate whether the amplitudes of the soleus H-reflex are affected by changes of limb loading in standing using various experimental procedures, the findings of these experiments were also varied (Ali and Sabbahi, 2000;Field-Fote et al, 2000;Hwang et al, 2004;Miyoshi et al, 2003;Nakazawa et al, 2004;Phadke et al, 2006). Therefore, the present study was conducted in order to examine how the soleus H-reflex is affected by gradual changes in the amount of limb loading by a body weight support system during static standing.…”

Modulation of soleus H reflex due to stance pattern and haptic stabilization of posture

“…Stimulus consistency was reassured by the insignificant difference in the mean amplitude of the M trials and maximal M response across different experimental conditions (Table 2), and H reflex amplitude was normalized to M max for proper comparison. This economical approach has been widely accepted to detect activity-dependent changes in axonal excitability such as during quiet stance (Goulart et al, 2000;Hwang et al, 2004;Sibley et al, 2007), steeping (Brooke et al, 1995), pedaling (Staines et al, 1997), or locomotion (Petersen et al, 1999;Simonsen and DyhrePoulsen, 1999), though the M-wave/H-wave (H-M) recruitment curve is not established. In fact, it would not have been practical to acquire the curve in this study to reveal all modifications of H reflex excitability controlling perfectly over the effect of reflex size, on account of timeconsuming measurements of both postural sway and H-M recruitment, which could have caused a fatigue effect.…”