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MUSCLES: M. Jeffery Mador, Erkan Bozkanat, and Thomas J. Kufel Quadriceps Fatigue After Cycle Exercise in Patients With COPD Compared With Healthy Control Subjects Chest 2003; 123: 1104-1111 [Abstract] [Full text] [PDF]

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Exercise Induced Fatigue in COPD

Ketan K Dhatariya   (13 April 2003)

Exercise Induced Fatigue in COPD 13 April 2003
Ketan K Dhatariya, Research Fellow in Endocrinology Mayo Clinic, Rochester, Minnesota, 55905 Send letter to journal: Re: Exercise Induced Fatigue in COPD dhatariya.ketan{at}mayo.edu Ketan K Dhatariya	Sir, In reply to the article by Mador et al (1) there are a number of possibilities for their results that have to be explored. The authors did not take into account the changes in skeletal muscle that occur in COPD, and how these changes may account for the fatigue seen. These changes include alteration lower limb skeletal muscle wasting. There are also changes in fibre type and fibre size such that there is easier muscle fatigability (2). Further there is also decreased activity in the enzymes involved in ATP production from oxidative phosphorylation (2). In addition, while the authors mention some of the medications the subjects were using, they make no mention of the use of other drugs that may alter skeletal muscle function commonly prescribed in this age group. These drugs may either enhance functional capacity, such as angiotensin converting (3;4) or may be detrimental, such as alpha or beta blocker, or calcium channel blockers which are known to cause fatigue and lethargy (5). Yours sincerely Dr Ketan Dhatariya Reference List (1) Mador MJ, Bozkanat E, Kufel TJ. Quadriceps Fatigue After Cycle Exercise in Patients With COPD Compared With Healthy Control Subjects. Chest 2003; 23:1104. 2) Gosker HR, Engelen MP, van Mameren H et al. Muscle fiber type IIX atrophy is involved in the loss of fat-free mass in chronic obstructive pulmonary disease. Am J Clin Nutr 2002; 76:113-119. (3) Onder G, Penninx BW, Balkrishnan R et al. Relation between use of angiotensin-converting enzyme inhibitors and muscle strength and physical function in older women: an observational study. Lancet 2002; 359:926-930. (4) Schaufelberger M, Andersson G, Eriksson BO et al. Skeletal muscle changes in patients with chronic heart failure before and after treatment with enalapril. Eur Heart J 1996; 17:1678-1685. (5) British National Formulary Number 44. Royal Pharmaceutical Society of Great Britian. September 2002.