Muscle training with repetitive magnetic stimulation of the quadriceps in severe COPD patients☆

Summary 

Background

Previous studies have used electrical neuromuscular stimulation as a physical training method in patients with severe COPD. We introduce the use of the more tolerable magnetic stimulation for the same purpose, investigating the effectiveness of an eight-week protocol.

Methods

Eighteen patients with severe COPD were randomly assigned to a magnetic stimulation training protocol, n=10, FEV₁=30% (SD: 7) or to parallel clinical monitoring, control group, n=8, FEV₁=35% (SD: 8). During eight weeks, patients were stimulated for 15min on each quadriceps femoris, three times per week. Quadriceps muscle strength and endurance measurements, quality-of-life questionnaires (SF36, SGRQ) and a six-minute walking test were all carried out before and after the training period in the stimulated and control subjects.

Results

All patients completed the training with increasing intensity of stimulation, displaying a significant improvement in voluntary quadriceps strength (17.5% of the baseline value) and exercise capacity, with a mean increase of 23m in the six-minute walking test. The questionnaire scores showed greater increases in quality-of-life scores in the trained subjects compared to the controls, particularly in the physical function areas: mean increments in SF36 in “physical function”: +26, “role limitations due to physical problems”: +40 and “vitality”: +17.5, while +13, −4 and +1, respectively in controls. Saint George's “Activity” score improved by 19.6 points, for 11.5 in controls.

Conclusions

In COPD patients who are limited due to dyspnoea, magnetic neuromuscular stimulation of the quadriceps constitutes a feasible training method for the lower limbs, with positive effects on the muscle function, effort capacity and perception areas.

Keywords: Magnetic stimulation, Chronic obstructive pulmonary disease, Muscle strength, Muscle dysfunction, Pulmonary rehabilitation