Abstract
Objective: Although the propulsion distance of a wheelchair is measured by some devices, measuring self-propulsion distance, excluding assistance propulsion distance by the caregiver, is difficult. This is a pilot study conducted to verify whether the propulsion distance of wheelchair users, excluding the assistance propulsion distance, can be measured using a cycle computer by attaching the touch switch.
Methods: The wheelchair propulsion distance was measured using a cycle computer. We connected the touch switch and the cycle computer to the wheelchair to exclude assistance propulsion distance. We set the cycle computer to stop recording while the caregiver was touching the sensor. To confirm the propulsion distance using the cycle computer, the volunteer propelled the wheelchair on a rectangular facility with a total distance of 181 m, and the examiner confirmed the propulsion distance. The validation test to confirm the accuracy of the touch switch attached to the cycle computer was performed on a 50-m straight runway. The volunteer and caregiver propelled the wheelchair alternately by 10 m and continued until 50 m. The examiner confirmed the distance after 50-m propulsion.
Results: In the 181-m rectangular facility, the propulsion distance that the volunteer propelled the wheelchair with the cycle computer was 180 m. In the 50-m straight runway, the propulsion distance was 30 m with caregiver assistance for 20 m.
Conclusion: The present study showed that our modified device could measure the self-propulsion distance, excluding assistance propulsion distance in wheelchair users.
Keywords: Spinal cord injury, Wheelchair, Self propulsion distance, Cycle computer, Touch switch
Introduction
In the past decades, the World Health Organization (WHO) has shown that the interest in physical activity has been growing.1 One of the reasons is that the decline of physical activity (hypoactive) increases the incidence of diabetes and cardiovascular disease.2 Particularly, wheelchair users tend to have lower physical activity levels. Wheelchair users with spinal cord injury have a high prevalence of diabetes and cardiovascular diseases compared with healthy individuals as a result of wheelchair dependency.3–5 Therefore, the evaluation of their physical activity is important.
Propulsion distance is a factor of physical activity for wheelchair users.6 Although the physical activity of wheelchair users has been measured quantitatively using a variety of the active monitors,7–13 no method has been recommended as the different algorithms for wheelchair propulsion differ in accuracy. Among these methods, Levy et al.9 showed methods to measure the propulsion distance of wheelchair users by using a cycle computer for a bicycle. The cycle computer is a device that calculates the propulsion distance on the basis of the circumference and number of wheel rotations. The sensor attached to the wheel sends an electrical signal to the computer each time a spoke magnet passes the sensor. The computer defines the electric signal as the wheel rotation and multiplies it with the circumference to calculate the propulsion distance. Thus, a complicated algorithm is not necessary, and the method is easy to use.
However, the problem of previous studies is the inclusion of propulsion distances other than self-propulsion. For instance, those who move in a hospital, facility, and home using wheelchairs are usually assisted by a caregiver for movement in addition to self-propulsion. If the assistance propulsion distance by a caregiver is included, overestimation of the measured the propulsion distance is highly possible. Therefore, measurement of the propulsion distance, excluding assistance propulsion distance by a caregiver, is necessary to correctly evaluate propulsion distance.
Controlling the operation of the cycle computer during assistance propulsion is necessary to exclude the assistance propulsion distance. We thought that we could exclude assistance propulsion distance if the operation of the cycle computer was stopped while the caregiver held the push handle. Accordingly, we attempted to control the operation of the cycle computer by attaching a touch switch to a push handle. If we can measure the propulsion distance, excluding the assistance propulsion distance, it will help the activities of wheelchair users more accurately. Therefore, the purpose of this study was to verify whether the propulsion distance of wheelchair users, excluding the assistance propulsion distance, can be measured using the touch switch attached to the cycle computer.
Methods
Equipment and setting
The wheelchair propulsion distance is measured using a wired cycle computer for a bicycle (CC-VL 820 velo9, CAT EYE Co., LTD. Japan) (Fig. 1). Data are recorded when the magnet attached to the spoke passes the sensor. The distance is measured every 10 m. A previous study has reported that the propulsion distance for the wheelchair is measured using a cycle computer 9, and we have based our measurement on this method.
Figure 1.
The Equipment and setting of a cycle computer and touch-switch. A: Data are recorded when the magnet attached to the spoke passes the sensor fitted to the tipping lever. B: The cycle computer does not record the distance data while the touch switch is working.
Furthermore, in the present study, we used the seal-type touch switch (AD00018, Bit Trade One Co., LTD., Japan) to exclude assistance propulsion distance. The touch switch is a capacitance-type sensor that detects the change as an electric signal when the sensor is touched. We connected this switch and the electric wire of the cycle computer. Therefore, the cycle computer does not record the distance data while the touch switch is working (Fig. 2). The sensor of the cycle computer is attached to the right tipping lever of the standard manual wheelchair (outer diameter of tire: 55.9 cm) (BAL-1, Miki Co., LTD., Japan). Similarly, the magnet is attached to the spoke of the tire. In addition, the display of the cycle computer is attached on the upper edge of the back pipe ahead of the right push handle, and the touch switch is positioned on the push handle.
Figure 2.
The measurement of propulsion distance using a cycle computer. A: During self-propulsion. B: During assistance propulsion. While touching the switch, the computer does not record the distance (velocity is zero).
Measurement of self-propulsion distance of wheelchair using cycle computer
First, the examiner marked each side of the rectangular facility and measured the distance on the marked line using the walking measure (WM-10KL, MURATEC-KDS Co., Japan). Subsequently, the healthy volunteer propelled the wheelchair equipped with a cycle computer on a marked line for five laps clockwise and five laps counterclockwise. The volunteer was instructed (a) to propel on a marked line with the right tire in the clockwise direction and (b) to propel on a marked line with the left tire in the counterclockwise direction (Fig. 3). The volunteer propelled the wheelchair with their upper limbs. The examiner recorded the propulsion distance every lap.
Figure 3.
Measurement of self-propulsion distance of wheelchair using a cycle computer.
Excluding assistance distance by touch switch
The validation test run was performed on a 50-m straight runway. Six markers were placed on a runway every 10 m. The validation test run, where the volunteer and caregiver propelled the wheelchair 10 m each, was repeated until 50 m (Fig. 4). The volunteer propelled the wheelchair with their upper limbs and propelled on a marked line with the right tire, and the caregiver propelled the wheelchair while gripping the push handle attached to the touch switch. The volunteer was instructed not to propel the wheelchair while the caregiver was propelling the wheelchair. While the caregiver was touching the touch switch, the light-emitting diode (LED) lamp attached to the electronic board was turned on. The caregiver used the LED to confirm that the touch switch on the push handle is being activated. The examiner confirmed the distance after the 50-m propulsion by using the cycle computer.
Figure 4.
The measurement of distance of wheelchair propulsion without assisted distance using a cycle computer and touch switch. The cycle that the volunteer and caregiver propel the wheelchair at 10 m each was repeated until 50 m.
Results
The distance on the marked line in the rectangular facility using the walking measure was 181 m per round. The distance on the line propelled by the volunteer was 180 m for all 10 laps (Fig. 3), and the error was 1 m compared with the distance by walking measure. In the 50-m straight runway, the propulsion distance was 30 m when the caregiver assisted 20 m.
Discussion
In the present study, we measured the self-propulsion distance, excluding assistance propulsion distance in wheelchair users, by using our modified device that is connected to the cycle computer and touch switch. The results of this study showed that our method could measure the self-propulsion distance, excluding assistance propulsion.
Measurement of the activity of wheelchair users using the activity monitor is considered a valid method because the output of the activity monitor has been reported to be in good agreement with video analysis.10,14 However, the measurement of wheelchair activity using the activity monitor has problems with accuracy because the algorithm for calculating the amount of activity from a specific pattern of wheelchair propulsion is not as accurate as that used for pedestrians.6 Thus, we measured the propulsion distance of wheelchair by using the cycle computer for a bicycle. Because the cycle computer calculates the propulsion distance by multiplying the circumference and the number of wheel rotations, a special algorithm is not necessary. This method is easy to use in a clinical setting.
Furthermore, the present study used the touch switch to exclude the assistance propulsion distance. Our results showed a new result. Our method can reduce an overestimation of measurement of wheelchair propulsion distance in hospital and institutions where wheelchair users may receive assistance propulsion. Using this method, further study is needed to examine the relationships between self-propulsion distance and several adverse health outcomes in wheelchair users with spinal cord injury.
The present study has several limitations. First, there is a problem due to the measurement environment. The cycle computer calculates the propulsion distance by multiplying the circumference and the number of wheel rotations. Thus, measurement of slight movements of wheelchair users, such as backward and forward movements in a narrow space, such as in a hospital room, is difficult. Second, a caregiver must touch the touch switch during the assistance propulsion. However, this problem will be easily solved by guiding the caregiver. In addition, obtaining other indicators of physical activity is difficult because the data obtained by our method are only distance. Finally, detecting the differences in the propulsion strategy of the wheelchair is difficult. For example, wheelchair users generally propel the wheelchair by using the upper limbs, whereas stroke patients sometimes propel the wheelchair by using one side of the upper and lower limbs.15 Participants who used their arms covered more distance than did those who used a combination of the upper and lower limbs.16 However, the developed device cannot capture the propulsion strategy.
Conclusion
The present study showed that our modified device, which was connected to the cycle computer and touch switch, could measure self-propulsion distance, excluding assistance propulsion distance in wheelchair users. Our methods can reduce an overestimation of measurement of wheelchair propulsion distance in hospital and institutions where wheelchair users may receive assistance propulsion.
Disclaimer statements
Contributors None.
Funding None.
Conflicts of interest Authors have no conflicts of interest to declare.
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