Effect of endurance versus resistance training on quadriceps muscle dysfunction in COPD: a pilot study.
BACKGROUND
Exercise is an important countermeasure to limb muscle dysfunction in COPD. The two major training modalities in COPD rehabilitation, endurance training (ET) and resistance training (RT), may both be efficient in improving muscle strength, exercise capacity, and health-related quality of life, but the effects on quadriceps muscle characteristics have not been thoroughly described.


METHODS
Thirty COPD patients (forced expiratory volume in 1 second: 56% of predicted, standard deviation [SD] 14) were randomized to 8 weeks of ET or RT. Vastus lateralis muscle biopsies were obtained before and after the training intervention to assess muscle morphology and metabolic and angiogenic factors. Symptom burden, exercise capacity (6-minute walking and cycle ergometer tests), and vascular function were also assessed.


RESULTS
Both training modalities improved symptom burden and exercise capacity with no difference between the two groups. The mean (SD) proportion of glycolytic type IIa muscle fibers was reduced after ET (from 48% [SD 11] to 42% [SD 10],P<0.05), whereas there was no significant change in muscle fiber distribution with RT. There was no effect of either training modality on muscle capillarization, angiogenic factors, or vascular function. After ET the muscle protein content of phosphofructokinase was reduced (P<0.05) and the citrate synthase content tended increase (P=0.08) but no change was observed after RT.


CONCLUSIONS
Although both ET and RT improve symptoms and exercise capacity, ET induces a more oxidative quadriceps muscle phenotype, counteracting muscle dysfunction in COPD.
The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Denmark.
Ulrik Winning
UW
Iepsen
The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Denmark.
Gregers Druedal Wibe
GD
Munch
The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Denmark.
Mette
M
Rugbjerg
The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Denmark.
Anders Rasmussen
AR
Rinnov
The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Denmark.
Morten
M
Zacho
The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Denmark; Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense.
Stefan Peter
SP
Mortensen
Department of Anesthesiology, University of Copenhagen, Rigshospitalet, Copenhagen.
Niels H
NH
Secher
Department of Respiratory Medicine, University Hospital Hvidovre, Hvidovre.
Thomas
T
Ringbaek
The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Denmark.
Bente Klarlund
BK
Pedersen
Department of Nutrition, Exercise and Sports, University of Copenhagen.
Ylva
Y
Hellsten
The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Denmark; Department of Respiratory Medicine, University Hospital Hvidovre, Hvidovre; Department of Public Health, Section of Social Medicine, University of Copenhagen, Copenhagen, Denmark.
Peter
P
Lange
The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Denmark; Department of Respiratory Medicine, University Hospital Hvidovre, Hvidovre.
Pia
P
Thaning
D000368:Aged; D002196:Capillaries / Q000503:physiopathology; D003718:Denmark; D004734:Energy Metabolism; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018919:Neovascularization, Physiologic; D010084:Oxidation-Reduction; D010641:Phenotype; D010807:Physical Endurance; D010865:Pilot Projects; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D052097:Quadriceps Muscle / Q000098:blood supply / Q000378:metabolism / Q000503:physiopathology*; D020127:Recovery of Function; D012039:Regional Blood Flow; D055070:Resistance Training; D013997:Time Factors; D016896:Treatment Outcome; D014797:Vital Capacity; D000070857:Walk Test
muscle fibers; phosphofructokinase-1; randomized controlled trial; rehabilitation; vasodilation