Relationship between physical strain during standardised ADL tasks and physical capacity in men with spinal cord injuries

To describe physical strain during activities of daily living (ADL), 44 men with spinal cord injuries (C4-L5) performed a set of standardised tasks. The physical strain was defined as the highest heart rate response expressed as a percentage of the individual heart rate reserve (%HRR). The physical strain averaged over the subjects who performed all tasks (n = 24) was (mean +/- SD): 20.2 +/- 7.2 %HRR (washing hands), 20.4 +/- 7.3 %HRR (passing a side-hung door), 28.8 +/- 10.8 %HRR (transfer to a toilet), 31.2 +/- 13.1 %HRR (ascending an 8 cm curb). 33.9 +/- 12.0 %HRR (transfer to a shower seat), 35.1 +/- 10.5 %HRR (transfer to bed), 36.4 +/- 13.3 %HRR (preparing lunch), 37.1 +/- 12.0 %HRR (washing up), 38.7 +/- 14.9 %HRR (ascending a ramp), 39.8 +/- 15.6 %HRR (transfer to a shower wheelchair), 41.4 +/- 12.1 %HRR (changing sheets), and 45.9 +/- 10.4 %HRR (entering a car). Physical strain could be notably high, but large variations among subjects were present. During all tasks, subjects with tetraplegia had significantly higher levels of strain than subjects with low (T6-L5) lesions. Physical strain was inversely related to parameters of physical capacity: isometric strength (r: -0.34 to -0.72), sprint power (r: -0.34 to -0.69), peak oxygen uptake (r: -0.41 to -0.81) and maximal power output (r: -0.52 to -0.82). Parameters of physical capacity were better predictors of physical strain than was the lesion level, and explained 37-71% of the variance in strain during ADL. It was also concluded that the method used in this study provides a quantitative and objective estimation of physical strain and may therefore be a useful tool to identify task difficulty during rehabilitation and to evaluate the results of task and physical training on the physical strain during ADL.