Our objective was to compare the effect of a 4-week homebased low and middle intensity and frequency training program in patients with moderate to severe chronic obstructive pulmonary disease. From 124 patients hospitalized with chronic obstructive lung disease (COPD) in an 18-month period 65 fulfilled the inclusion criteria and were invited to participate. Only 31 (48%) accepted and among these only 20 patients (31% of invited) completed the 4-week study period. The walking time in seconds in a standardized treadmill walking test was unchanged after 4 weeks of low intensity training 60 minutes per week for two weekly training sessions. In contrast, the walking time in seconds increased 55% (p < 0.001) from 321 seconds to 499 seconds in 9 patients who completed 4 weeks of middle intensity training which comprised 2 1/2 hours of training per week for 5 weekly training sessions. There was no change in lung function over the 4 weeks but the combined score for physical quality of life (physical component summary) measured by SF-36 increased (p < 0.05) with both low intensity and middle intensity physical training. In conclusion, homebased physical training, which aims at improvements in patient performance and quality of life as part of pulmonary rehabilitation programs, is only accepted by about one-third of unselected patients with moderate to severe COPD. The minimum training time necessary to improve physical performance is 2-3 hours per week of middle intensity training.