The H-reflex as an important indicator in kinesiology

Abstract

Hoffmann's reflex (the H-reflex) is an electrically-induced reflex that is analogous to the mechanically-induced stretch reflex controlled by the spinal cord. The most common measurements performed concerns the electrical response of the soleus muscle to electrical stimulation in the tibial nerve. The response is induced by a discharge occurring in a motoneuron. The latency time of the H-reflex for the soleus muscle amounts to 30-40 ms. An increase in the strength of the stimulus induces a direct response from the muscle, i.e. the M-wave. The latency time of the M-wave amounts to 4-5 ms. A sport training may affect the parameters of the H-reflex. The Hmax/Mmax ratio is the highest among persons engaged in endurance sports and the lowest among those practising speed and strength sports. A decreased amplitude of the H-reflex characterises the level of the central fatigue, while a decrease in the M-wave amplitude is attributed to the peripheral fatigue. Usually, a decrease in Hmax/Mmax ratio is observed post-exercise. Different times of recovery were reported in the literature. No clear quantitative laws have yet been established that govern the course of the reflex as a result of fatigue. The H-reflex still remains within the scope of the interests of kinesiology as a valuable source of information about the reflex functions in the human motor system.

Effect of Acute Heart Rate Variability Biofeedback on H-reflex Modulation: A Pilot Study

“…The following H-reflex indices were measured offline: a) M wave at maximal H-reflex (M wave at Hmax); b) Hmax; c) Mmax; and, d) Hmax/Mmax ratio (maximal Hmax response to normalized Mmax). Hmax estimates motoneuron excitability activated by Іa afferents, elicited from electrical stimulations ( Gajewski and Mazur-Różycka, 2016 ; Knikou, 2008 ). Mmax represents recruitment of motor axons and provides an estimate of the size of motoneural pool response ( Chen et al, 2012 ; Chen et al, 2015 ; Palmieri et al, 2004 ; Pierrot-Deseilligny and Mazevet, 2000 ).…”

“…The Hoffman reflex (H-reflex) is a tool for assessment of monosynaptic reflex in the spinal cord, modulated by input of 1a afferents to the alpha motoneural pool (MN) ( Chen et al, 2012 ; Gajewski and Mazur-Różycka, 2016 ; Knikou, 2008 ; Palmieri et al, 2004 ; Pierrot-Deseilligny and Mazevet, 2000 ). Percutaneos electrical stimulation to the mixed peripheral nerve is applied to evoke H-reflex, targetting the monosynaptic reflex arc and efferent motor response ( Zehr, 2002 ).…”

Acute Effects of Heart Rate Variability Biofeedback on H-reflex and Maximal Voluntary Isometric Strength

“…A commercial . Hmax estimates the number of activated Іa afferents elicited by electrical stimulations [22,23]. Mmax represents the entire activation of descending inputs to motor axons [24,30,31].…”

“…An enhancement in baroreflex with HRV BFB might positively influence activity in the central autonomic network and facilitate improvement in neural excitability [1,[13][14][15][16][17][18][19][20]. Accordingly, neural excitability of the alpha motoneural pool could be revealed by the determination of the Hoffman reflex (H-reflex), a monosynaptic reflex in the spinal cord [21][22][23][24][25]. Thus, the primary purpose of this study was to determine motoneural excitability after HRV BFB utilizing the activity of H-reflex.…”

Reliability of the Soleus H-Reflex in Different Sitting Postures

“…The H-reflex is elicited by sending an electrical stimulus along the large fast-conducting Ia sensory fibers to the alpha motoneurons (α-MNs) in the ventral horn of the spinal cord. The activation of α-MNs in the spinal cord generates an action potential traveling via α-motor axons toward the neuromuscular junction and produces the reflex contraction of the muscle, as well as the twitch response shown in the electromyography (EMG) unit (i.e., the H-reflex) [ 2 ]. The H-reflex onset latency and amplitude are the commonly used parameters in H-reflex studies.…”