Soleus- and Gastrocnemii-Evoked V-Wave Responses Increase After Neuromuscular Electrical Stimulation Training

Abstract

The aim of the study was to use combined longitudinal measurements of soleus (SOL) and gastrocnemii evoked V-wave and H-reflex responses to determine the site of adaptations within the central nervous system induced by 5 wk of neuromuscular electrical stimulation (NMES) training of the plantar flexor muscles. Nineteen healthy males subjects were divided into a neuromuscular electrostimulated group (n = 12) and a control group (n = 7). The training program consisted of 15 sessions of isometric NMES over a 5-wk period. All subjects were tested before and after the 5-wk period. SOL, lateral gastrocnemius (LG), and medial gastrocnemius (MG) maximal H-reflex and M-wave potentials were evoked at rest (i.e., H(max) and M(max), respectively) and during maximal voluntary contraction (MVC) (i.e., H(sup) and M(sup), respectively). During MVC, a supramaximal stimulus was delivered that allowed us to record the V-wave peak-to-peak amplitudes from all three muscles. The SOL, LG, and MG electromyographic (EMG) activity as well as muscle activation (twitch interpolation technique) were also quantified during MVC. After training, plantar flexor MVC increased significantly by 22% (P < 0.001). Torque gains were accompanied by an increase in muscle activation (+11%, P < 0.05), SOL, LG, and MG normalized EMG activity (+51, +54, and +60%, respectively, P < 0.05) and V/M(sup) ratios (+81, +76, and +97%, respectively, P < 0.05). H(max)/M(max) and H(sup)/M(sup) ratios for all three muscles were unchanged after training. In conclusion, the increase in voluntary torque after 5 wk of NMES training could be ascribed to an increased volitional drive from the supraspinal centers and/or adaptations occurring at the spinal level.

Chronic low-frequency rTMS of primary motor cortex diminishes exercise training-induced gains in maximal voluntary force in humans

“…However, resistance training of the tibialis anterior was associated with a 32% increase in MEP amplitude produced by TMS during low-level contractions without changes in M-wave amplitude, indicating a role for spinal, corticospinal neurons, possibly M1 (25). In addition, several other studies showed that adaptations to acute and chronic voluntary and electrical stimulation-evoked muscle contractions, without a skill component, increased volitional drive from supraspinal centers (4, 13, 15, 24, 31, 32) without concomitant changes in H reflex, measured at rest or during mild voluntary contraction (1,10,13,15,23,24,35,38,50,55). However, the interpretation of these studies must be viewed carefully because they do not provide direct evidence for M1's involvement in strength gains and some studies did find increases in H reflex after resistance training (1,4,15,32).…”

“…We did not test for any spinal effects. Considering the inconsistent results from TMS (9,25,30) and peripheral nerve stimulation studies (1,4,13,15,23,24,32,35,38), a role for segmental effects cannot be dismissed. We intentionally designed the study to consist of only 10 sessions so that the nature of adaptation would primarily be neuronal (9); it is still possible that a portion of the strength gains was due to muscle hypertrophy.…”

Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation

“…Increase the stimulation intensity to obtain maximal soleus M-wave amplitude (M max ; usual range: 40-100 mA). Usually, set the increment in stimulation intensity at 2-4 mA, with an interval of 8-10 sec between two stimuli 12,35 . The desired intensity is reached when M max is obtained, and no H-reflex response can be observed.…”

Uso da eletroestimulação na clínica fonoaudiológica: uma revisão integrativa da literatura

“…spasticity, where muscle paralysis such as facial paralysis, etc. 3,4 . The Physiotherapy finds in the electrostimulation a powerful resource to assist the process of rehabilitation of several distúrbios 5 .…”