A Method for Quantifying Upper Limb Performance in Daily Life Using Accelerometers

The overall goal of this Accelerometer methodology is to quantify upper limb performance in daily life and thus track rehabilitation progress and outcomes. This method can help answer key questions in stroke rehabilitation. Such as whether an intervention can improve someone’s function in the real world not just in the clinic or laboratory.

The main advantage of this technique is that it provides a numeric quantification of upper limb performance and doesn’t rely on self report. Although this method was originally developed for stroke rehabilitation, it can also be applied for other individuals receiving physical and occupational therapy services. Such as those with brain injury or multiple sclerosis, and even children with cerebral palsy.

At first the methodology may seem difficult because there are so many steps, but after you use it a few times the steps become much more routine. Demonstrating this method will be Maggie Bland, a member of our laboratory. Begin by connecting the two accelerometers to the computer via the docking station to charge their batteries and ensure recording during the entire experiment.

After the accelerometers are connected to the computer, open the appropriate software to initialize them. Then, in the software select Initialization to synchronize the accelerometer clocks to each other and to the local computer. Enter the start time and date of data collection based on when the accelerometers will be placed on the participant, and an end date and time at least 24 hours later.

Next, select 30 Hz from the dropdown menu for sampling rate and leave LED options and wireless options unchecked. Enable Idle Sleep Mode to extend battery life and select Enter Subject Info to complete the initialization process. Then, enter subject-specific information for the location of the accelerometer the wrist, and the body side, right or left.

Choose to fill in other subject specific information as desired. Entry will be for identification only, and will not affect the data analysis. Finally, select Initialize Devices to complete the process.

Once initialization is confirmed, disconnect the accelerometers from the computer. Begin by placing one accelerometer on each wrist of the participant. Then, ask the participant to do their regular activities throughout the day and inform them that the accelerometers may feel strange at first but they will soon get used to them.

Inform the participant that the accelerometers are waterproof and can be worn while showering or doing the dishes. However, instruct them to not wear the accelerometers during extended periods of swimming. Additionally, ask them to keep the accelerometers on during naps and overnight.

Finally, provide instructions about when to take the two accelerometers off and how to bring or mail back the accelerometers and wearing log. Then, send the participant home with encouragement to engage in normal daily activities. After the accelerometers have been returned, following a wearing period of 24 hours or more, connect them to the computer to download the recorded data.

Within the software, select Download and then choose a location to store the data on the computer, using the Change Location button. Select the option to create AGD File. For files that are small enough to be quickly inspected, choose 10 seconds from the Epoch dropdown menu and select Download All Devices.

Next, in order to confirm that the accelerometers were worn for the planned time period, and that the data matches the wearing log, visually inspect the data by clicking File, Open AGD File, and selecting the files to open. Then look at the daily graphs to see the collected data. Confirm that the activity occurred during typical waking hours and that there are not extended periods of no activity, except in the night time.

If desired, scale down the graph to focus on smaller increments of time. Finally, to generate files for calculations, repeat the download process but choose one second from the Epoch dropdown box in order to bin the data in to one-second epochs. This symmetrical plot from a healthy adult indicates that the upper limbs are active together throughout the day.

With the Dominant and Non-Dominant limbs used similarly. The symmetry is contrary to common perceptions about hand dominance. Secondly, the plot is tree-shaped with a wide bottom portion and rounded edges, in which these rounded edges represent activity where one limb is moving while the other is relatively still.

The symmetry in the rounded edges indicates that both hands are active to perform and to stabilize similarly over the course of the day. Lastly, the warm glow in the center indicates that the most frequent upper limb movements are low intensity, with approximately equal contributions from both limbs. Other results show upper limb activity for an individual with a stroke that caused moderate paresis and disfunction to his left limb.

The asymmetrical plot indicates that the paretic upper limb was rarely active during daily life and the low-peak means only low-intensity activities occurred. Lastly, the cool colors in the middle indicate a low frequency of movement. Once mastered, the setup for this technique can take about 10 minutes.

Once the accelerometers are returned, the processing will take about 20 minutes. When doing this procedure, it’s really important to visually inspect the data once the accelerometers have been returned. After its development, this technique paved the way for stroke researchers to explore arm and hand activity in daily life, outside of the clinic or laboratory.

After watching this video, you will know how to use accelerometery to quantify upper limb performance in daily life. And thus, be able to track the progress and outcomes of rehabilitation.