Bjørgen, S. Hoff, J. Husby, V. Høydal, M. Arnt E. Tjønna, A. Steinshamn, S. Richardson, R. Helgerud, J.
The pulmonary response to exercise has been looked upon as the major factor for the determinants of exercise intolerance in chronic obstructive pulmonary disease (COPD). It has also been suggested a metabolic dysfunction in the skeletal muscles which may con- tribute to limitation in exercise tolerance. However, there is a growing consensus that COPD is a multiorgan system disease resulting in poor exercise performance as maximal ventilation results in dyspnea which limits exercise tolerance andthus reduces metabolic demands on the working skeletal muscles. It has been demonstrated a two to three times greater response for maximal oxygen uptake (VO2max) after high intensity aerobic interval training compared to continuous low intensity training (85– 95% and 70% of maximal heart rate, respectively) in healthy subjects and in patients.
Training using reduced muscle mass has given evidence for an increased blood flow to the working muscles and reduced ventilation because the capacity of the cardiovascular system is not taxed, both in healthy subjects and in COPD patients. Thereby one approach that might allow training at a higher intensity for COPD patients is one leg cycling.
In the present study it is thus hypothesized that aerobic high intensity oneleg interval cycling will maximally challenge the peripheral muscles without gaining a ventilatory limitation, and thereby result in a greater whole body VO2max training response than aerobic high intensity two legs interval cycling.
Nineteen patients trained in 8 weeks and 24 supervised cycling sessions either by one leg training (n = 12) or by two legs training (n = 7) at 4 x 4 min intervals at 85–95% of maximal heart rate. Whole body VO2max and peak work rate increased by 12 and 23% in the one-leg group, and by 6 and 12% in the two-leg group from pre- to post-training, respectively, and were signifcantly greater in the one-leg group.
Conclusion: The present study demonstrates that one leg aerobic high intensity interval cycling is superior to two legs in increasing whole body VO2max, indicating a muscle rather than a cardiovascular limitation to VO2max in these COPD patients. The relative ventilation is reduced duringthe one leg cycling which allows training at a higher muscle-specific intensity compared to whole body exercise resulting in a greater training response.
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