Hata-Yanagiya physical activity calculation system: a novel global positioning system-based method for accurate...

Marathon running has become increasingly popular among amateur athletes, many of whom maintain speeds of 8-9 km/h. However, existing methods for estimating oxygen consumption (VO₂) during running and walking-such as the American College of Sports Medicine (ACSM) equations and commercial activity monitors-often lack accuracy and transparency. This study introduces the Hata-Yanagiya Physical Activity Calculation (HYPAC) system, a novel approach for estimating VO₂ using Global Positioning System (GPS) and map data.

The HYPAC system was developed through regression equations based on metabolic equivalents (METs) and slope data. To validate the system, 10 university students (5 runners, 5 non-runners) completed a 5 km course while equipped with a GPS device and a portable metabolic measurement system. VO₂ estimates from the HYPAC system were compared with measured values and those calculated using ACSM equations.

The HYPAC system demonstrated high accuracy in estimating VO₂, with a relative error of -0.03 [95% confidence intervals (CI): -0.14, 0.08] compared to measured values. For the running group, the HYPAC system achieved the lowest absolute mean relative error (0.02). In the mixed running/walking group, the HYPAC system maintained strong performance with a relative error of -0.07 (95% CI: -0.26, 0.12).

The HYPAC system provides a transparent and accurate method for estimating VO₂ during walking and running, outperforming existing methods under varied conditions. Its open-source framework encourages further validation and improvement by researchers and practitioners. Future studies should address limitations such as sample size and population diversity to enhance the system's applicability.