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Updated: Jan 10, 2026
Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
Published on: September 13, 2015
Part I: Effects of Asynchronous vs Conventional Synchronous Neuromuscular Electrical Stimulation on Maximal Evoked
Jonathan Cavalcante1, Victor Ribeiro1, Rita Marqueti2
1University of Brasília, Laboratory of Muscle and Tendon Plasticity, Graduate Program of Rehabilitation Sciences, Distrito Federal, Brazil; University of Brasília, Graduate Program of Physical Education, Distrito Federal, Brazil.
Objective:
To compare the effects of asynchronous versus conventional synchronous neuromuscular electrical stimulation (NMES) on evoked torque, fatigability, discomfort, and training-induced strength gains.
Data Sources:
A systematic search was conducted in 6 electronic databases (PubMed, EMBASE, PEDro, LILACS, SciELO, and Web of Science) for studies published up to April 2025. Guided by a Population, Intervention, Comparator, Outcome, Time Frame framework, we combined terms for the population (humans), intervention (electrical stimulation), comparator (synchronous, asynchronous, spatially distributed sequential, conventional), and outcomes (torque, muscle strength, fatigue, discomfort, evoked contraction).
Study Selection:
We included cross-sectional, repeated measures, or randomized controlled trials of adult or elderly participants (healthy or clinical) receiving electrically induced isometric or dynamic contractions without voluntary effort. Comparisons involved synchronous vs asynchronous current delivery. Outcomes were maximal evoked torque, fatigability, perceived discomfort, and strength adaptations. A total of 22 studies were included from 11,044 records.
Data Extraction:
Two independent reviewers extracted participant demographics, stimulation parameters, electrode configurations, and outcomes. Study quality was assessed with the PEDro scale and evidence quality via GRADE.
Data Synthesis:
Meta-analysis showed that asynchronous NMES produced greater isometric evoked torque than synchronous NMES (P<.01; SMD 95% CI, 0.245-0.957), especially when using larger electrodes (P=.042, β=0.0023). No difference was found in dynamic evoked torque (P=.95; 95% CI, -1.44 to 1.35). Fatigability was significantly lower with asynchronous NMES for both isometric (P<.01; SMD 95% CI, 0.49-1.21) and dynamic contractions (P<.01; SMD 95% CI, 0.61-2.76). Discomfort and strength data were insufficient for firm conclusions.
Conclusions:
Asynchronous NMES effectively reduces muscle fatigability compared with synchronous stimulation. These findings may help clinicians and researchers in optimizing NMES protocols and support the development of asynchronous NMES solutions for clinical use.
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