Correction for the errors by riding vehicles to estimate VO2 during walking by tri-axial accelerometry

 

Toshiaki Yamazaki^1,2, Hirokazu Gen-no^2,3, and Hiroshi Nose^1,3

¹Department of Sports Medical Sciences, Shinshu University Graduate School of Medicine, Matsumoto 390-8621, Japan; ²Kissei Comtec Co., Ltd., Matsumoto 390-1293; ³Jukunen Taiiku Daigaku Research Center, Matsumoto 390-8621, Japan

 

Recently, we have developed a device to estimate VO₂ during uphill and downhill walking by using tri-axial accelerometry and barometry (MSSE, in press). Here, we propose an algorithm to correct the errors by passive body movement by riding vehicles in the measurement. Forty two subjects with tri-axial accelerometer (JD Mate, Kissei Comtec, Japan) on their waist walked on a treadmill while tri-axial accelerations (A_x, A_y, and A_z) were measured every min. Other 5 subjects with JD Mate rode on a car, a train, and a bike while the accelerations were recorded as in the walking test. Then, we performed discriminant analysis on acceleration data. The rates of correct classification were 98.5%, 93.8%, 89.4%, and 95.3%, for walking and riding a car, a train, and a bike, respectively.  The wrong classification into walking category from riding a car, a train and a bike were 3.9%, 0.0%, and 1.6%, respectively.  Thus, this algorithm made it possible to estimate mere VO₂ by walking in our daily activity.

 

Keywords: triaxial accelerometer, discriminant analysis