Reference Fitness Values in the Untrained Spinal Cord Injury Population

Objective: Establish reference values of cardiorespiratory fitness applicable to the general, untrained spinal cord injury (SCI) population.

Design: Data were retroactively obtained from 12 studies (May 2004 to May 2012).

Setting: An institution-affiliated applied physiology research laboratory.

Participants: A total of 153 men and 26 women (age, 18-55y) with chronic SCI (N=179) were included. Participants were not involved in training activities for 1 or more months before testing and were able to complete a progressive resistance exercise test to determine peak oxygen consumption (Vo2peak).

Interventions: Not applicable.

Main Outcome Measure: Percentile ranking (poor<20%; fair; 20%-40%; average, 40%-60%; good, 60%-80%; excellent, 80%-100%) used to establish reference values.

Results: Reference cardiorespiratory fitness values based on functional classification as paraplegic or tetraplegic were established (paraplegic: median, 16.0mL·kg(-1)·min(-1); range, 1.4-35.2mL·kg(-1)·min(-1); tetraplegic: median, 8.8mL·kg(-1)·min(-1); range, 1.5-21.5mL·kg(-1)·min(-1)) for untrained men and women. For the primary outcome measure (Vo2peak), persons with paraplegia had significantly higher values than did persons with tetraplegia (P<.001). Although men had higher values than did women, these differences did not reach significance (P=.256). Regression analysis revealed that motor level of injury was associated with 22.3% of the variability in Vo2peak (P<.001), and an additional 8.7% was associated with body mass index (P<.001). No other measure accounted for additional significant variability.

Conclusions: Established reference fitness values will allow investigators/clinicians to stratify the relative fitness of subjects/patients from the general SCI population. Key determinants are motor level of injury and body habitus, yet most variability in aerobic capacity is not associated with standard measures of SCI status or demographic characteristics.