Effects of Functional Electrical Stimulation on Metaboreflex Activation in Healthy Individuals

Summary

Cardiovascular exercise adjustments are required during in order to redistribute blood flow from non-exercising vascular areas to active muscles. This hemodynamic adjustments, which are partially mediated by mechanosensitive and metabosensitive reflexes, ultimately increase oxygen and nutrient delivery to exercising muscle tissues (Mitchell, 1990). Static handgrip exercise has been shown to induce alterations in the arterial baroreflex function (Kim, 2005) and activation of muscle metaboreflex that increases arterial blood pressure and peripheral vasoconstriction, respectively. Functional electrical stimulation (FES) treatment used in physical therapy in patients who are unable to tolerate conventional exercise showed to be a good alternative for muscle strengthening (Sbruzzi, 2010) and to improve metabolic abnormalities (Karavidas, 2006). However, the effect of FES on metaboreflex activation in healthy individuals has never been investigated. Therefore, this study aims to evaluate the metaboreflex activation induced by FES in upper and low limbs in healthy individuals, and also to compare their results with the effects caused by isometric exercise.

Conditions

• Reduction of Blood Flow

Interventions

OTHER

Functional electric stimulation

The FES will be placed at the flexor muscles of the forearm and knee extensors, for evaluation of upper and lower limbs, respectively. The stimulation frequency will be 20 Hz. The pulse width used will be 0.5 milliseconds and the contraction time will be 60 seconds (TON: 60s) with a 1-second rest interval (TOFF: 1s). The total time of application will be determined for the muscle fatigue that will be evaluated by 10-point Borg scale and by the measurement of lactate accumulation that must not exceed 30 minutes. The intensity will be adjusted individually, taking into account the patient's ability to promote the full flexion of the wrist / knee extension and comfort during contractions. Along with the application of FES a 1 Kg overload will be applied to intensify the fatigue time.

OTHER

Isometric exercise

For the upper limbs the isometric contraction exercise with handgrip will be performed for 5 minutes with 30% of loading, previously measured by maximum voluntary contraction test. For the lower limbs the knee extension exercise will be conducted in a training station. The SBP, DBP, MBP and HR will be recorded through the protocols. Fatigue will be determined every minute by the 10-point Borg scale and by measurement of lactate accumulation before, immediately after the protocol, and 5 minutes during the recovery period.

Sponsors & Collaborators

• Hospital de Clinicas de Porto Alegre

  lead OTHER

Principal Investigators

• Beatriz Dr Schaan, PhD · Hospital de Clinicas de Porto Alegre

• Aline Macedo, Graduate · Federal University of Rio Grande do Sul

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Model

CROSSOVER

Eligibility

Min Age

35 Years

Max Age

70 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2015-03-31

Primary Completion

2015-12-31

Completion

2016-03-31

Countries

• Brazil

Study Locations