Leg cycling increases cardiorespiratory activity in tetraplegia


Lay summary and graphic by Preshon Pillay

Edited by Jocelyn Chan

This is a lay summary of the paper Jan Elaine Soriano, Rinaldo Romac, Jordan W. Squair, Otto F. Barak, Zoe K. Sarafis, Amanda H.X. Lee, Geoff B. Coombs, Bita Vaseghi, Christopher Grant, Rebecca Charbonneau, Tanja Mijacika, Andrei V. Krassioukov, Philip N. Ainslie, Kelly A. Larkin-Kaiser, Aaron A. Phillips, and Zeljko Dujic. Read the original article here.

People who have suffered a spinal cord injury (SCI) have an increased risk of heart disease and stroke. This is especially true for those who live with tetraplegia, a loss of function in all four limbs. Physical activity and exercise have been proven to benefit health outcomes in people living with an SCI such as reducing the elevated cardiovascular disease risk. However, most current recommendations are for moderate to vigorous exercise involving primarily the arms, which might be challenging for individuals with a cervical SCI to undertake. There has been new evidence suggesting that exercising paralyzed legs could provide similar health benefits.

How was the study done?

The study enrolled 12 individuals with a traumatic cervical SCI between the age of 18-65 years, in which the individuals sustained their SCI at least 1 year prior to inclusion in the study. Participants rested laying down for 15 minutes, during which a baseline measurement was taken including heart rate and blood pressure. The setup for passive cycling and the protocol used in this study can be seen in Figure 1 along with a video publicly available here.

Cycling was performed for 10 minutes at a speed of 29 ± 1 revolutions per minute in which cardiovascular and respiratory parameters were constantly monitored. These parameters included the following:

Figure 1 from original research article – Passive Cycling Protocol and Setup

What were the results of this study?

The results of this study showed that cardiovascular function was increased during passive leg cycling.  This was seen by elevations in many of the parameters discussed above such as blood pressure, heart rate, and FMD (flow-mediated dilation). Passive leg cycling also increased the respiratory drive with increases in minute ventilation and tidal volume. Please refer to the figure above for explanations of blood pressure, heart rate, FMD, minute ventilation, and tidal volume. These results show that passive leg-cycling is an effective exercise for people with cervical SCI.

Out of all twelve individuals that took part in the study, only one individual suffered a significant spike in blood pressure known as autonomic dysreflexia and therefore their involvement in the study was suspended. This individual’s blood pressure did not stabilize within the session timeline but was monitored closely by a team of physicians and returned to baseline before the participant left the laboratory. This form of exercise is therefore well-tolerated with a 92% success rate. However, the small sample size needs to be considered.

What does this mean for the SCI community?

This study showed that passive leg cycling safely increased the activity of the cardiorespiratory system and therefore can provide beneficial improvements to prevent cardiovascular disease. People with SCI who want to engage in exercise should therefore discuss it with their physicians to evaluate if passive leg cycling is a viable exercise option and how to partake in it.

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