Estimation of walking speed and stride length using accelerometer walking and nordic walking

The amount of daily physical activity is strongly associated with the prevalence of life-style associated diseases. Therefore, maintaining an appropriate level of physical activity is recommended for lifestyle associated diseases. Walking is a type of physical activity which most of people are capable in daily lives without any instruction. Recently a new style of walking using ski poles, namely Nordic Walking (NW) is becoming popular. NW is characterized by wide stride length due to thrust force produced by ski pole actions. Widening stride length may contribute to increasedwalking speedandconsequently to increasedexercise intensity in NW as well as in conventional walking. Estimation of walking speedandstrid e length using a wearable accelerometer may enable the users to evaluate their activities. Seventy-two healthy adult volunteers (age 18-78) were askedto walk a 40 m-stretch on a flat groundwith or without NW ski-poles. Three dimensional accelerometer was firmly attached to the center of low-back with a strap. Walking speed, stride length and cadence was calculated from the recorded movie data. A best-fit liner equation to estimate walking speed from acceleration, cadence, and body height was generated. Cross validation of the estimated walking speed revealed minimal errors (RMS 5.14 m/min, 5% of the mean). We propose a practical methodto estimate walking speed, cadence and stride length from three axis acceleration sensor signal.