Cardiorespiratory responses of individuals with cervical and thoracic spinal cord injury (SCI) during upper and lower extremity exercise

Nine individuals with spinal cord injury (SCI) participated in a three phase exercise training and testing program. Three of these individuals had a spinal cord level of injury between C4 and C6 (Group 2) and six were between T6 and T12 (Group 1). All three individuals in Group 2 and only two individuals in Group 1 (T6--T7) completed the protocol. The exercise program consisted of 12 sessions of upper extremity armcrank ergometry, 12 sessions of electrically induced lower extremity ergometry and 12 sessions of upper extremity armcrank ergometry with electrically induced lower extremity ergometry. A cardiorespiratory fitness assessment analyzed the cardiorespiratory capability of the participants before and after each phase of exercise training. Mean peak oxygen consumption (VO2) and exercise run times were calculated for each group of participants. Independent samples t-tests were used to determine whether there was a significant difference between the means. The results of this study indicated that there may have been a difference between the two groups. The small sample size must be considered when statistically significant differences were not detected. Furthermore, the thoracic injuries at T6 and T7 may have had autonomic nervous system interruption. Therefore, statistically significant differences between the means may not have occurred because the two groups were more similar than dissimilar. Paired t-tests were used to determine whether within a group there was a significant difference between the means at different phases of the program. Data suggested that there may have been a training effect in both groups following arm exercise training but a greater response in individuals with quadriplegia, as indicated by peak VO2. An increase in exercise capacity for individuals with paraplegia may have been harder to achieve given their baseline upper extremity strength. Peak VO2 and run time data indicated that the last phase of exercise training offered no additional cardiorespiratory training effect in individuals with paraplegia. Furthermore, the data suggested that arm exercise may have resulted in a central training effect, whereas, leg exercise resulted in a peripheral training effect.