Effects of Neuromuscular Electrical Stimulation Parameters on Torque, Fatigue, and Oxygen Extraction
Condition: Fatigue
MeSH terms: Fatigue
Study type: Interventional

Summary: 
      Neuromuscular Electrical Stimulation (NMES) can minimize muscle atrophy, complications
      related to muscle disuse and improved neuromuscular performance. However, it is still unclear
      the influence of specific physical parameters, including carrier frequency, burst duration,
      and duty cycle regarding the greater generation of evoked torque, sensory discomfort, muscle
      fatigue, and peripheral oxygen extraction. Thus, the aim of this study 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 in healthy individuals.
      This is a crossover, experimental, randomized, double-blind trial composed of apparently
      healthy participants. All NMES protocols will be tested on the same individual with
      randomization of the sequence of intervention protocols. There will be a total of 6
      encounters with seven days between them. Session 1 will evaluate the anthropometric measures,
      the maximum intensity for each intervention protocol, and the sequence 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 evoked joint torque of the triceps
      surae muscle through the isokinetic dynamometer, evaluation of muscle fatigue through the
      H-reflex, M-wave, fatigue index, time-torque-integral, and recruitment curve, evaluation of
      peripheral oxygen extraction through NIRS (Near Infrared Spectroscopy), electromyographic
      signals to assessed the RMS (root mean square) and the median frequency, evaluation of the
      level of sensory discomfort through the Visual Analog Pain Scale and finally by the NMES
      protocol. The 6th session will be the replication of the 2nd session of each individual. The
      EENM protocols will be as follows: CR10% (Russian Current with 2500 Hz, modulated in bursts
      of 50 Hz, 200 µs and 10% duty cycle - 2 ms bursts and 18 ms interbusrts), CR20% (Russian
      Current with 2500 Hz, modulated in bursts of 50 Hz, 200 µs and 20% of duty cycle - 4 ms
      bursts and 16 ms interbusrts), CA10% (Aussie current with 1000 Hz, modulated in bursts of 50
      Hz, 500 µs and 10% duty cycle - 2 ms of bursts and 18 ms interbusrts), CA20% (Aussie current
      with 1000 Hz, modulated in bursts of 50 Hz, 500 µs and 20% of duty cycle - 4 ms of bursts and
      16 ms interbusrts) all protocols will be performed on the triceps surae muscle.
    

Detailed description: 
      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 6 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). The last
      session will consist of the same electrical stimulation protocol from the second session of
      assessment. 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 three maximal isometric
      contractions, then three 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, except on the fifth day that the NMES protocol used will be the same as the
      second day); after the fatigue protocol, three maximum evoked contractions will be performed
      again; then three maximal isometric contractions and at the end, the muscle fatigue
      evaluation will be performed again. The NMES protocols will be CR10% (Russian Current with
      2500 Hz, modulated in bursts of 50 Hz, 200 µs and 10% duty cycle - 2 ms bursts and 18 ms
      interbusrts), CR20% (Russian Current with 2500 Hz, modulated in bursts of 50 Hz, 200 µs and
      20% of duty cycle - 4 ms of bursts and interbusrts of 16 ms), CA10% (Aussie current with 1000
      Hz, modulated in bursts of 50 Hz, 500 µs and 10% duty cycle - 2 ms bursts and 18 ms
      interbusrts), CA20% (Aussie current with 1000 Hz, modulated in bursts of 50 Hz, 500 µs and
      20% duty cycle - 4 ms bursts and 16 interbusrts) ms) all protocols will be performed on the
      triceps surae muscle.
    

Intervention name(s): Russian current 10%; Russian current 20%; Aussie current 10%; Aussie current 20%
Intervention type(s): Other; Other; Other; Other
Intervention description(s): Russian current with 2500 Hz, modulated in bursts of 50 Hz, 200 µs and 10% duty cycle - 2 ms bursts and 18 ms interbusrts; Russian current with 2500 Hz, modulated in bursts of 50 Hz, 200 µs and 20% duty cycle - 4 ms bursts and 16 ms interbusrts; Aussie current with 1000 Hz, modulated in bursts of 50 Hz, 500 µs and 10% duty cycle - 2 ms bursts and 18 ms interbusrts; Aussie current with 1000 Hz, modulated in bursts of 50 Hz, 500 µs and 20% duty cycle - 4 ms bursts and 16 ms interbusrts
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Other
Keywords: Healthy Young; Electric Stimulation Therapy; Evoked torque; Sensory discomfort; Peripheral oxygen extraction