Energy Expenditure during Wheelchair Propulsion in Different Levels of Paraplegics Using Physiological Cost Index

Background&objective

Wheelchair is considered as an efficient means of locomotion with optimal independence for a subject with paraplegia. This study was aimed to evaluate the energy expenditure during standard wheelchair propulsion in different levels of paraplegics using Physiological Cost Index (PCI). It also aimed to correlate the energy expenditure to various levels of spinal injury and to the duration since wheelchair use.

Methodology

Male subjects with paraplegia (n =24) between T7 to T12 spinal level injury, who were using wheelchair were included in the study. Patients were given 5 minutes rest at the starting line in order to attain a steady resting heart rate, which was measured by the palpation of radial pulse. Subjects were instructed to propel the wheelchair at their normal propulsion speed on a standard leveled corridor (walkway of 25 m) for a minimum duration of 5 minutes to attain a steady physiological heart rate. At the end of 5 minutes, they were instructed to stop and steady propulsion heart rate was measured. Energy expenditure (PCI) was calculated by: PCI (beats/ meter) = Steady propulsion heart rate - Resting heart rate (beats per min) / Propulsion speed (meter/min).

Results

Descriptive statistics was used to calculate the mean and standard deviation of PCI in different levels of paraplegics. Pearson correlation was used for correlating the PCI values to level of injury and weeks since use of wheelchair. Mean PCI during wheelchair propulsion was 0.67 (SD ± 0.37) beats/meter. There was no correlation between different levels of spinal injury and energy expenditure (p value = 0.511), but there was a strong correlation between weeks since use of wheelchair after injury and energy expenditure (p value = 0.000).

Interpretation&conclusion

The mean PCI during wheelchair propulsion in different levels of paraplegics (T7-T12) was found to be 0.67 (SD± 0.37) beats/meter. There is a strong correlation between the duration since use of wheelchair and the energy expenditure. This suggests that with longer usage, wheelchair propulsion may become a more energy efficient form of ambulation in paraplegics.