Improved work capacity but unchanged peak oxygen uptake during primary rehabilitation in tetraplegic patients

Individuals with cervical spinal cord lesions are characterised by markedly decreased aerobic capacity, accompanied by increased risk of developing cardiovascular disease. The aim of this study was to evaluate the effects of a primary rehabilitation programme that included three sessions of arm cycling per week on the endurance capacity in 10 male tetraplegic subjects (injury level C6-C8; eight ASIA-A and two ASIA-B). Peak oxygen uptake (peak VO2) was measured three times (at T1 approximately 99 +/- 10 days after injury. T2 approximately 2 months after T1, and at T3 approximately 2 months after T2). Ten paraplegic patients admitted to the hospital for primary rehabilitation served as controls. In the tetraplegic patients, mean peak load increased (22 +/- 2, 32 +/- 5, and 32 +/- 7 watt, at T1, T2 and T3 respectively) (P < 0.01), while mean peak VO2 did not change during the study (0.78 +/- 0.07, 0.86 +/- 0.08, and 0.81 +/- 0.06 1 x min-1, at T1, T2 and T3, respectively) (ns). In contrast peak VO2 was significantly higher in the paraplegic control group (1.37 +/- 0.08, 1.64 +/- 0.10 and 1.75 +/- 0.08 1 x min-1, respectively) (P < 0.001), and increased significantly during the study period (P < 0.001). Mean heart rate (HR) and mean stroke volume (SV), measured at corresponding submaximal work loads during the study did not change significantly in the tetraplegic patients. Mean systolic blood pressure (SBP), recorded immediately after peak arm exercise was low at all three tests (93 +/- 8, 89 +/- 6 and 84 +/- 6 mmHg) in the tetraplegic group. However, both muscle strength and 'activities of daily life' index improved significantly during the study period. Our results suggest that functional improvement in tetraplegic patients is not necessarily followed by aerobic metabolic improvement. We conclude that more time should be spent on arm endurance training, or training methods which activate larger muscle groups and/or increases blood pressure.