Assessment of exercise intensity using the Phyphox Mobile App

Abstract

This study aimed to explore the use of a specific high-intensity interval training (HIIT) program, assess exercise using with the Phyphox mobile application, and evaluate the reliability of this measurement technique. In a single-participant case study, we designed a short burpee movement program (BMP) comprising 3 sessions of 3 minutes each, with a one-minute break, in between. Participants performed burpees at regular intervals upon hearing a sound signal. Three variants of the BMP were developed: based on the number of repetitions: B7 (26 repetitions per round, 78 repetitions per BMP), B6 (30/ repetitions per round, 90 repetitions) per BMP), and B5 (35/ repetitions per round, 105 repetitions per BMP). Each variant was performed 3 times with varying intensity (Bs – burpee performed slowly, Bf – burpee performed quickly, Bme – burpee performed with maximum effort). A total of 9 training units were completed in our research. The acceleration values, heart rate and jump height during the burpee were recorded. Subsequently, the round intensity, burpee intensity and fatigue index were determined. The slowly performed burpee ranged from 3.5 to 3.8 ms-2, the quickly performed burpee ranged from 9.2 to 10.6 ms-2, and the maximum effort burpee 10.9 to 12.9 ms-2. The fatigue index was slightly noticeable during the less intense variant, but maximum effort reached 25% in B5. Depending on the intensity, the heart rate ranged from 120 to 168 bpm and the jump height varied from 2 to 11.9 cm. A significant correlation was found between round intensity, burpee intensity, heart rate and jump height. When set to measure the acceleration values, the Phyphox mobile application can reliably assess exercise intensity.