Neuromuscular electrical Stimulation (NMES) can minimize muscle atrophy and complicationsrelated to muscle disuse and help improve neuromuscular performance. Medium andlow-frequency currents have been assessed regarding the generation of evoked torque,sensory discomfort, muscle fatigue, and peripheral oxygen extraction. In addition,metabolic stress is also linked to muscle strength gain, an important aspect to beevaluated in addition to NMES physical parameters. Thus, the aim of this study is tocompare the effects of different NMES protocols applied to the triceps surae muscle forevoked torque, muscle fatigue, sensory discomfort, and peripheral oxygen extraction inhealthy individuals. This is a crossover, experimental, randomized, double-blind trialcomposed of apparently healthy participants. All NMES protocols will be tested on thesame individual with randomization of the sequence of intervention protocols. There willbe a total of 5 encounters with seven days between them. Session 1 will evaluate theanthropometric measures, the maximum intensity for each intervention protocol, and thesequence of intervention protocols for each individual will be randomized. Sessions 2, 3,4, and 5 will be composed equally with the assessment of the maximum voluntary and evokedjoint torque of the triceps surae muscle through the isokinetic dynamometer, evaluationof muscle fatigue through the H-reflex, M-wave, fatigue index, time-torque-integral, andrecruitment curve, evaluation of peripheral oxygen extraction through NIRS (Near InfraredSpectroscopy), electromyographic signals to assessed the RMS (root mean square) and themedian frequency, evaluation of the level of sensory discomfort through the Visual AnalogPain Scale and finally by the NMES protocol. The EENM protocols will be as follows: CR10%(Russian Current at 2500 Hz, modulated in 50 Hz bursts, 200 µs and 10% duty cycle - 2 msof 18 ms bursts and interbusrts), CA10% (Aussie Current with 1000 Hz, modulated in 50 Hzbursts, 500 µs and 10% duty cycle - 2 ms of 18 ms bursts and interbusrts), CP500 (pulsedcurrent with 50 Hz, 500 µs phase) and CP200 (Pulsed current with 50 Hz, 200 µs phase).all protocols will be performed on the triceps surae muscle.
This is a crossover, experimental, randomized, double-blind trial composed of apparently
healthy participants. The objective is to compare the effects of different NMES protocols
applied to the triceps surae muscle for evoked torque, muscle fatigue, sensory
discomfort, and peripheral oxygen extraction. The effects of the types of neuromuscular
electrical stimulation (NMES) protocols on the aforementioned outcomes will be evaluated
in the same participant by randomizing the sequences of interventions for each visit in
the laboratory. The study is considered double-blind, as individuals will not know the
sequence of the protocols applied. The evaluator will also not know which protocol will
be used at the time of the intervention. It will consist of a total of 5 sessions with
seven days between them. In the first session, anthropometry, the maximum intensity level
for each electrical stimulation protocol as well as the protocol sequence for each
individual will be evaluated. From the second to the fifth session, the following will be
considered: voluntary and evoked maximum joint torque of the triceps surae muscle, muscle
fatigue through the evaluation of the H-reflex, M-wave, fatigue index,
torque-time-integral and recruitment curve, peripheral oxygen extraction,
electromyographic signals through RMS (root mean square) and median frequency, and level
of sensory discomfort with the Visual Analog Scale (VAS). From the second to the fifth
session will be composed by the following evaluation sequence: warm-up with six
submaximal contractions with 6 seconds of duration and 10 seconds of rest between them;
then the assessment of muscle fatigue; then two maximal isometric contractions, then two
maximal evoked contractions; fatigue protocol at 20% of the maximum isometric contraction
(this fatigue protocol will use the NMES sequence randomized in the first session; after
the fatigue protocol, two maximum evoked contractions will be performed again; then two
maximal isometric contractions and at the end, the muscle fatigue evaluation will be
performed again. The NMES protocols will be CR10% (Russian Current at 2500 Hz, modulated
in 50 Hz bursts, 200 µs and 10% duty cycle - 2 ms of 18 ms bursts and interbusrts), CA10%
(Aussie Current with 1000 Hz, modulated in 50 Hz bursts, 500 µs and 10% duty cycle - 2 ms
of 18 ms bursts and interbusrts), CP500 (pulsed current with 50 Hz, 500 µs phase) and
CP200 (Pulsed current with 50 Hz, 200 µs phase). All protocols will be performed on the
triceps surae muscle.
Other: Russian current 10%
Russian current with 2500 Hz, modulated in bursts of 50 Hz, 200 µs and 10% duty cycle - 2
ms bursts and 18 ms interbusrts
Other Name: Russian current with 2500 Hz, modulated in bursts of 50 Hz, 200 µs and 10% duty cycle - 2 ms bursts and 18 ms interbusrts
Other: Aussie current 10%
Aussie current with 1000 Hz, modulated in bursts of 50 Hz, 500 µs and 10% duty cycle - 2
ms bursts and 18 ms interbusrts
Other: Pulsed current 500 µs phase
Pulsed current, modulated in 50 Hz, 500 µs
Other: Pulsed current 200 µs phase
Pulsed current, modulated in 50 Hz, 200 µs
Inclusion Criteria:
- Female and male, aged between 18-40 years;
- Be classified as physically active according to the International Physical Activity
Questionnaire (IPAQ);
- The practice of just recreational physical activity;
- Achieve a minimum torque of 20% of the MVIC during the NMES;
- Be at least three months without strength training;
Exclusion Criteria:
- Present musculoskeletal dysfunction that may interfere with the tests, present
intolerance to NMES in the triceps surae muscle;
- Use analgesics, antidepressants, tranquilizers, or other centrally acting agents;
- Present cardiovascular or peripheral vascular problems, chronic diseases,
neurological or muscle disorders that may impair the complete execution of the study
design by the volunteer;
Faculty of Ceilandia UnB
Brasília, DF, Brazil
Investigator: JOAO LUIZ Q DURIGAN, PhD
Contact: 55613107-8418
joaodurigan@gmail.com
João LQ Durigan, PhD
61 3107-8450 - +55
joaodurigan@gmail.com
Luis AO Soares, Graduate
61 3107-8450 - +55
luisandreoliveirasoares@gmail.com
João LQ Durigan, PhD, Principal Investigator
University of Brasilia