Percutaneous Electrical Stimulation in Strength Training: An Update

Abstract

Numerous studies have used percutaneous electrical stimulation (PES) in the context of training programs to develop strength and physical performance in healthy populations (sedentary or trained). Significant increases in muscle and fiber cross-sectional area, isokinetic peak torque, maximal isometric and dynamic strength, and motor performance skills have been found after PES training. These strength gains are explained on the basis of the characteristics of PES motor units (MUs) recruitment: (a) a continuous and exhausting contractile activity in the same pool of MUs during the entire exercise period, (b) a supramaximal temporal recruitment imposed by the high frequency chosen (up to 40 Hz), and (c) a synchronous recruitment of neighboring fibers. The PES training method is complementary to voluntary training, mainly because the application of PES causes an unconventional spatial recruitment of MUs that, depending on the muscular topography, may entail the preferential recruitment of the fast-twitch MUs. In addition, the method does not specifically develop elasticity in skeletal muscle, and it must be accompanied by a technical workout.

The Application of Neuromuscular Electrical Stimulation Training in Various Non‐neurologic Patient Populations: A Narrative Review

“…The force achieved by NMES increases in a sigmoidal manner with increasing stimulation frequency up to approximately 70‐80 Hz [21,22], depending on the fiber type composition of the stimulated muscle [23]. With NMES, to achieve optimal force development greater stimulation frequencies are needed than the physiological firing frequency of the nerves because of the synchronous motor unit firing pattern [24]. In contrast to volitional contractions, motor unit recruitment pattern by NMES is nonselective, spatially fixed and temporally synchronous [25].…”

Unloaded Shortening Velocity of Voluntarily and Electrically Activated Human Dorsiflexor Muscles In Vivo

“…The preferential or selective activation of large motor units innervating fast-twitch fibers is the traditional interpretation [14], [16], whereas the nonselective or random recruitment of motor units is a recently proposed concept [17]–[19]. The similarity in V 0 of submaximally and supramaximally stimulated dorsiflexor muscles seems consistent with both possibilities, implying not only supramaximal but also submaximal stimulation can activate the fastest motor units even when the contraction intensity is low.…”

“…Although a great deal of research has focused on the difference in motor unit recruitment between voluntary and electrically-elicited contractions, the precise recruitment order of motor units during percutaneous electrical stimulation of human muscle remains unresolved (for reviews, see [16], [17], [19]). The preferential or selective activation of large motor units innervating fast-twitch fibers is the traditional interpretation [14], [16], whereas the nonselective or random recruitment of motor units is a recently proposed concept [17]–[19].…”

“…The recruitment order of motor units during electrical stimulation is considered quite different from the natural pattern, which is traditionally interpreted as reversed recruitment order (i.e. from fast to slow type) due mainly to the low input-impedance of fast motor units with thick axons [14]–[16]. However, several researchers have argued that motor unit recruitment during percutaneous electrical stimulation is nonselective, i.e.…”

Physical treatment of the equine athlete

“…51 The same motor units are repeatedly activated by the same amount of electrical current, and it is generally believed that NMES first recruits type II muscle fibers and then type I fibers, which is the reverse of the muscle recruitment pattern in a voluntary contraction. 52,53 However, there are discussions if the recruitment order mainly depends on the amount of electric current at the site of the motor nerve. 54 The contraction leads to an increase in blood circulation 55 , which might increase the rate of healing.…”