Electrical Stimulation to the Infraspinatus on Hypertrophy and Strength of the Shoulder

Abstract

The purpose of this study was to determine the effects of six weeks of electrical muscle stimulation (EMS) on the strength and muscle mass of the infraspinatus muscle. Twenty non-athletes (age: 24±3.4 years, height: 171.5±5.6 cm, mass: 65.2±8.1 kg) were randomly classified into two groups, an electrical muscle stimulation group (EMS group) and a control group (CON group). The EMS group completed a total of 18 20- min EMS sessions, three times per week over a period of six weeks, while the CON group received no intervention. The muscle thicknesses of both the infraspinatus and the deltoid muscles, the cross-sectional area (CSA) of the whole infraspinatus muscle, and the isometric and isokinetic peak torques of shoulder external rotations were measured before and after intervention. It was found that the muscle thickness of the superior infraspinatus (Pre 0.92±0.19 cm, Post 0.99±0.16 cm, p=0.02) and the CSA (Pre 10.99±1.32 cm, Post 11.99±1.02 cm, p=0.03) significantly increased in the EMS group. This study demonstrated that EMS of the infraspinatus muscle over a period of six weeks resulted in hypertrophy of the infraspinatus muscle.

Effect of Neuromuscular Electrical Stimulation on Masseter Muscle Thickness and Maximal Bite Force among Healthy Community-Dwelling Persons Aged 65 Years and Older: A Randomized, Double Blind, Placebo-Controlled Study

“…In previous studies, NMES has been applied to various skeletal muscles of the upper or lower limb [37][38][39]. NMES has been shown to induce thickening of skeletal muscles, including shoulder muscles [24], quadriceps [40], mid-thigh, and calf muscles [41], which is consistent with the results of the present study.…”

“…NMES causes evoked contractions of muscles through electrical stimulation, and therefore can be expected to improve motor function, as well as myophysiological changes (e.g., muscle thickening and strength) [19][20][21]. NMES has been applied to limb skeletal muscles, as well as swallow-related muscles (e.g., orbicularis oris and suprahyoid muscle), resulting in increased muscle thickness and improved motor function in the elderly and in patients with neurological disorders including stroke [22][23][24][25][26]. Recent studies have attempted to apply NMES to the masseter muscle.…”

Neuromuscular Electrical Stimulation–Enhanced Physical Therapist Intervention for Functional Posterior Shoulder Instability (Type B1): A Multicenter Randomized Controlled Trial

“…Both the “muscular” and “neural” effects of NMES can offer a potential explanation for the improved outcome after NMES-enhanced physical therapy. It has been shown that NMES is able to improve force production and muscle volume of the infraspinatus, 26 , 36 which has been identified as hypoactive in a dynamic fine-wire electromyography analysis of atraumatic posterior shoulder instability cases. 8 However, no patients with muscle atrophies visible on magnetic resonance imaging demanding increase in muscle volume were involved in the trial and no shoulder strength differences between groups were detected at baseline or follow-up.…”

Changes in Muscle Thickness after 8 Weeks of Strength Training, Electromyostimulation, and Both Combined in Healthy Young Adults

“…Electromyostimulation (EMS) is a training technology known as a complementary training method, applied both locally [ 3 , 4 , 5 ] or to the whole body [ 6 ], which is becoming increasingly popular in recent years. It was developed to achieve greater activation of a higher number of motor units, through non-voluntary muscle contractions at relatively low force levels, compared with dynamic voluntary contractions, generating adaptations by a synchronous recruitment of muscle fibers and an increased firing rate [ 7 , 8 ].…”