I know there are quite a few Forum members with chronic obstructive pulmonary disease (COPD), so I thought this article about an abstract from the American Thoracic Society (ATS) 2010 International Conference would be of interest to them.
cheersNeuromuscular Electrical Stimulation Reduces Muscle Atrophy in Severe COPD
by
Caroline Helwick
May 18, 2010 (New Orleans, Louisiana) — Neuromuscular electrical stimulation (NMES) of the lower limbs reduced muscle atrophy in patients with severe chronic obstructive pulmonary disease (COPD) and improved symptoms of their disease, Canadian investigators reported here at the American Thoracic Society 2010 International Conference.
"NMES improved muscle mass, and this was positively correlated with changes in the levels of proteins involved in the muscle signaling pathway," said Isabelle Vivodtzev, PhD, a postdoctoral student at L'Institut Universitaire de Cardiologie et de Pneumologie de Québec, in Québec City
Muscle wasting is common in patients with severe COPD, and there is no effective treatment other than general physical reconditioning. Up to one third of patients with COPD who undertake exercise training do not show the expected gain in functional status or muscle function, she said.
"We know that electrical stimulation can increase muscle strength and functional capacity. We wondered if we could improve muscle mass with stimulation in COPD patients who are very deconditioned, and by which mechanisms this could happen," she said.
The investigators enrolled 20 patients with severe disease (forced expiratory volume in 1 second <50% expected; 6-minute walking distance <400 m) in a double-blind study in which patients were randomly assigned to NMES or sham treatment. The home-based "training" (6 seconds of contraction, 10 seconds of relaxation) was performed on the lower limbs for 30 minutes, 5 days a week, for 6 weeks. In the sham group, electrical stimulation was applied, but at a very low frequency so that it induced a sensation of tremor without muscle contraction.
Muscle biopsies were performed to look for changes in muscle cellular signaling pathways. This included evaluations of quadriceps and calf muscle cross-sectional areas and protein levels of AKT, atrogin-1, the phosphorylated form of AKT (pAKT), p70S6K, glycogen synthase kinase-3β, eukaryotic translation initiation factor 4E binding protein-1, mRNA expression of atrogin-1, muscle ring finger protein 1, and forkhead box class O.
NMES resulted in increases in quadriceps and calf muscle cross-sectional areas, compared with sham treatment (+6% ± 2% vs –1% ± 1% for quadriceps and +6% ± 2% vs –2% ± 2% for calf; P < .05), Dr. Vivodtzev reported.
Clinically, patients in the NMES group demonstrated gains in muscle force and endurance and walking distance. Improvements were proportional to the intensity of the stimulation.
Muscle Signaling Pathway Also Showed Changes
The improvement in muscle mass after NMES in patients with COPD was associated with a more favorable anabolic/catabolic balance, she added.
"Importantly, we saw significant improvements in muscle mass, as well as a reduction in the catabolism pathway involved in muscle mass regulation," she said at a press briefing.
The atrogin-1 protein level, which is associated with catabolism, was significantly reduced after stimulation (P = .01). The p70S6K protein level, which is involved in synthesis, was maintained in the active intervention group, whereas in the sham group, it was reduced (P = .03).
The changes in quadriceps and calf cross-sectional areas correlated positively with changes in the pAKT/total AKT ratio (P = .02) and in p70S6K (P = .009). Changes in pAKT also correlated with the NMES training intensity (P = .009), she reported.
"The findings are an argument for the use of electrical stimulation in severely deconditioned COPD patients," she told journalists. She recommended the approach in severely affected patients who cannot manage rehabilitation.
"A lot of our patients will first have electrical stimulation to help gain muscle mass, [after which] it is easier for them to exercise."
Richard Casaburi, PhD, MD, from the UCLA School of Medicine in Los Angeles, California, said that electrical stimulation has been shown to improve clinical outcomes in COPD patients, but the question has been: "Is there a scientific basis for this?" He said this study provides the first evidence of an underlying mechanism for these effects.
"The muscle biopsies show that we are actually seeing benefits," he said. "The virtue of this paper is that now we have a scientific basis for this practice."
American Thoracic Society (ATS) 2010 International Conference: Abstract 2104. Presented May 17, 2010.
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