Visualization of Intensity Levels to Reduce the Gap Between Self-Reported and Directly Measured Physical Activity

This method can help to answer key questions in the field of physical activity measurement about whether a visualization of different intensity levels can improve the accuracy of self reported physical activity. The main advantage of this method is that it connects widely used communication techniques with the opportunity to achieve high level standardization within a randomized control trial. Visual demonstration is critical as the combination of the questionnaire and the video represents an innovative approach to measuring physical activity difficult to describe adequately by written text.

Demonstrating the procedure will be Margit Prystawik, a study assistant, and Elke Bandelin, a study nurse. Begin by selecting a publicly available or self produced video based on the specific experimental question. Have the presenter in the video explain the differences in heart rate, breathing frequency, and ability to talk normally in accordance with the intensity levels while simultaneously demonstrating these symptoms while walking or running on a treadmill at the corresponding pace.

Then integrate the video into a self administered tablet computer survey to be presented directly before the physical activity questionnaire making sure the participants cannot skip the video. Recruit participants in a setting that permits enough time to hand out the accelerometer and to prepare the accelerometer for data collection. Obtain written consent from each participant prior to their participation.

And select an accelerometer prepared with an appropriately sized elastic belt that will fit the participant comfortably. Give the participant adequate information about how to handle the accelerometer, instructing the participant to begin wearing the device from wake until sleep. Before giving the accelerometer to the participant, connect the device to a computer and initialize the accelerometer in the program software.

Schedule the participant for a follow up assessment session to obtain self reported physical activity and somatometry data. Then give the accelerometer to the participant and encourage the participant to engage in normal daily activities. Within three days of the last day that the participant has worn the accelerometer collect the accelerometer from the participant and set up a new tablet computer survey.

When the participant has completed the questionnaire, collect the tablet computer and have the participant remove their shoes before standing on a calibrated scale for a body weight measurement. Next, have the participant stand up straight in front of a mirror with their toes at a mark on the ground for body height measurement. Ask the participant to remove the upper layers of clothing for waist and hip circumference measurement.

Measure the waist circumference midway between the lowest rib and the iliac crest and measure the hip circumference about two inches below the iliac crest using the mirror to confirm an accurate positioning of the tape. Then enter the results into the tablet computer and thank the participant for their participation. For data analysis, use an appropriate software program to download the data from the device.

Then export the data to an appropriate program for further processing. When exporting the data, make sure to select the desired cut points to determine the non-wear time and to differentiate between the physical activity intensity levels. Import all of the relevant variables into a software program appropriate for creating a computerized feedback letter.

The letter may contain a number of graphs illustrating the accelerometer based physical activity outcomes as well as the sedentary time as desired. Each graph should be accompanied by a paragraph of three to five sentences explaining the content of the figures and providing any respective health recommendations. Then, deliver the feedback letter as soon as possible after the participant has completed the study.

In this representative study 52%of the participants were randomized to the experimental group who watched a video demonstration before completing the physical activity questionnaire and 48%of the participants were randomized to the control group who received the physical activity assessment only. Preliminary results of the interim analysis have revealed a lower formal mean difference in the video group compared to the control participants. After watching this video you will be more familiar with how to combine the questionnaire and the video to assess different levels of physical activity in human subjects.

The agreement between questionnaire and accelerometer data may be investigated further by integrating a protocol that covers activities not captured by the device, such as cycling or swimming. This method may pave the way for adopting and exploring the visualization of physical activity in populations at risk, such as in pre-diabetic or cardiac patients.