The addition of electrical stimulation to progressive resistance training does not enhance the wrist strength of people with tetraplegia: a randomized controlled trial.

OBJECTIVE

To determine whether the addition of electrical stimulation to progressive resistance training increases the voluntary strength of the wrist muscles in people with tetraplegia.

DESIGN

Assessor-blind within-subject randomised controlled trial.

SETTING

Two Australian spinal cord injury units and the community.

PARTICIPANTS

Sixty-four wrists of 32 people with tetraplegia and bilateral weakness of the wrist extensor or flexor muscles (grade 2 - 4 Medical Research Council grades).

INTERVENTIONS

Participants' wrists were randomly allocated to one of two conditions. Wrist muscles of the experimental arm received electrical stimulation superimposed on progressive resistance training. The wrist muscles of the contralateral arm received sham electrical stimulation superimposed on progressive resistance training. Both arms received 6 sets of 10 contractions three times a week for eight weeks such that the only difference between arms was the application of electrical stimulation.

MAIN MEASURES

The primary outcome was maximal voluntary isometric strength. Secondary outcomes were a fatigue resistance ratio representing voluntary and electrically-stimulated endurance. Measurements were taken at the start and end of the eight-week treatment period.

RESULTS

The mean treatment effect (95% Confidence Interval) of electrical stimulation for voluntary strength was 0.04 Nm (95% CI, -0.5 to 0.6; p =0.89). The mean treatment effect (95% CI) for fatigue ratio representing voluntary endurance and electrically-stimulated endurance was -0.01 (95% CI, -0.1 to 0.1; p =0.78) and -0.07 (95% CI, -0.3 to 0.1; p =0.47), respectively.

CONCLUSIONS

Voluntary strength of the wrist is not enhanced by the addition of electrical stimulation to progressive resistance training programs in people with tetraplegia.