Yuichi Fujiki

NEAT-o-Games: blending physical activity and fun in the daily routine

This article describes research that aims to encourage physical activity through a novel pervasive gaming paradigm. Data from a wearable accelerometer are logged wirelessly to a cell phone and control the animation of an avatar that represents the player in a virtual race game with other players over the cellular network. Winners are declared every day and players with an excess of activity points can spend some to get hints in mental games of the suite, like Sudoku. The racing game runs in the background throughout the day and every little move counts. As the gaming platform is embedded in the daily routine of players, it may act as a strong behavioral modifier and increase everyday physical activity other than volitional sporting exercise. Such physical activity (e.g., taking the stairs), is termed NEAT and was shown to play a major role in obesity prevention and intervention. A pilot experiment demonstrates that players are engaged in NEAT-o-Games and become more physically active while having a good dosage of fun.

iPhone as a physical activity measurement platform

iPhone is emerging as a ubiquitous physical activity measurement platform due to its incorporated accelerometer sensor. The iPhones capacity to accurately measure physical activity has not been put to scrutiny up to now, despite claims from an increasing number of applications. This study examines ways to perform accurate physical activity measurements with the iPhone, at various positions on the users body. The study focuses on walking and running - the two most prevalent aerobic activities. For walking, a methodology has been developed that translates accelerometer values from peripheral body locations to equivalent readings on the waist and from there to metabolic units. For running, the limitation of iPhone to perform accurate metabolic measurements is documented. The formulas and results in this paper can readily be used by developers to increase the accuracy of fitness applications and improve user experience.

Evaluation of the Accuracy of a Triaxial Accelerometer Embedded into a Cell Phone Platform for Measuring Physical Activity

BACKGROUND Physical activity is important in health and weight management. Several cell phone platforms integrate an accelerometer onto the motherboard. Here we tested the validity of the cell phone accelerometer to assess physical activity in a controlled laboratory setting. METHODS 31 subjects wore the cell phone on their waist along with the validated Physical Activity Monitoring System (PAMS) with different body postures and during graded walking. Energy expenditure was measured using indirect calorimetry. 11 subjects also wore the iPhone at different locations such as arm, hand, pant pocket, etc. RESULTS The cell phone accelerometer was accurate and precise compared to the PAMS, with an intra-class correlation coefficient (r2> 0.98). The cell phone accelerometer showed excellent sequential increases with increased in walking velocity and energy expenditure (r2>0.9). CONCLUSION An accelerometer embedded into a cell phone was accurate and reliable in measuring and quantifying physical activity in the laboratory setting. Data from free-living users shows promise for deployment of a comprehensive integrated physical activity promoting and weight loss platform using such mobile technologies.

Making sense of accelerometer measurements in pervasive physical activity applications

In the last few years, accelerometer-based entertainment and health applications have been receiving increased attention in the research and commercial worlds. The effect of accelerometer placement on different parts of the body, despite its apparent significance, received little consideration. This paper documents through experimentation the different characteristics of accelerometer output on the waist, arm, wrist, thigh, and ankle in the context of translational body motion (walk). Furthermore, it offers experimental formulas that transform peripheral body measurements to more reliable, center body (i.e., waist) measurements, and these in turn to caloric measurements, which are the standard physical activity units. The importance of these results on the design of ubiquitous health applications and the ensuing user experiences cannot be underestimated. The papers methodology can be used in further studies in other physical activity contexts, where more elaborate body motion patterns are involved.