The aerobic power during maximal exercise was studied in 58 males with traumatic spinal cord lesions from C4 to L4 (25 well-trained "world-class athletes" and 33 untrained). For comparison we tested five well arm-trained and five arm-untrained able-bodied subjects. During maximal wheelchair exercise the aerobic power (VO2 peak), pulmonary ventilation and blood lactate concentration was higher in subjects with lower levels of spinal cord injury. At each injury level above C6-C7, nearly all trained subjects reached higher VO2 peaks than untrained subjects with the corresponding level of lesion. The mean values for trained paraplegic persons were 2.16 +/- 0.38 l x min-1, corresponding to 33.6 +/- 6.7 ml x kg-1 x min-1. The peak heart rate was lower in the quadriplegic than in the paraplegic group with no or only small difference between trained and untrained subjects at the same level of spinal cord injury. Spinal cord lesions with pareses reduce the total active skeletal muscle mass. This can cause physical inactivity, medical complications and social isolation. As a consequence, cardiovascular disorders as cause of death is higher in this group compared to the general population. Therefore, one aim of rehabilitation is to increase the individual's performance in daily life activities. It has been shown that the normal daily life activities of quadri- and paraplegic individuals with no additional physical training are not intense enough to maintain a satisfactory level of physical fitness.(ABSTRACT TRUNCATED AT 250 WORDS)