The significance of the skeletal muscular oxidative capacity during whole body exercise

Abstract

The present thesis consists of four studies with the main objective to examine the significance of the skeletal muscular metabolic capacity during whole body exercise. Exercise capacity was studied in chronic obstructive lung disease (COPD) patients and a control group in study I, and in endurance‐trained subjects and normal physical active subjects in study II. In both studies, muscular metabolic capacity was quantified during exercise with a small muscle mass (1.7‐2.8 kg) to avoid the issue of muscular oxygen uptake being limited by oxygen supply. Thereafter, we tested how much the muscular metabolic capacity could be exploited during whole body exercise (bicycling). Exploitation less than 100% indicated a muscular metabolic reserve probably due to oxygen supply limitations. The muscular metabolic capacity ranged from 264 to 570 ml.kg‐1.min‐1 for the four groups. However, there was less variation in the relative exploitation of the muscular metabolic capacity during whole body exercise for the healthy groups (31%‐37%), while this percentage was smaller (17%) for the COPD patients. Based on these results, we concluded that the exploitation of the muscular metabolic capacity was relatively equal for the healthy groups despite large differences in age and maximal oxygen uptake (VO2max). The COPD patients were least capable of exploiting the muscular metabolic capacity during bicycling and consequently, they had a relatively higher muscular metabolic reserve during whole body exercise compared with healthy subjects.

Paper I: Rud B, Christensen CC, Ryg M, Edvardsen A, Skumlien S, & Hallen J (2008). Higher skeletal muscular metabolic reserve capacity in COPD patients than healthy subjects. Scand J Med Sci Sports.

Paper II: Tatt ut av filen i Brage p.g.a. copyright-restriksjoner. / Not in the file in Brage because of copyright issues.

Paper III: B. Rud, Ø. Foss, P. Krustrup, N.H. Secher and J. Hallén. One‐legged endurance training: leg blood flow and oxygen extraction during cycling exercise (Paper in revision).

Paper IV: B. Rud, N. H. Secher, J. Nilsson, G. Smith, and J. Hallén. Metabolic balance between the arms and the legs during simulated skiing (Paper in preparation).