Wearable Inertial Sensor for Jump Performance Analysis

Wearable devices enable the unobtrusive sensing of a wide range of human activities and the development of innovative applications. While the consumer market is pushing them particularly as activity or heart rate trackers, their adoption in healthcare is still restricted to few cases, primarily due to their limited accuracy and reliability. An interesting field of application is the jump performance assessment. It is frequently used by therapists to estimate neuromuscular imbalances, since it helps to monitor training progress in athletes or injured patients. Measurements are typically captured with accurate but expensive instrumentation (e.g. force plates). In this work, we propose the use of a versatile low-cost wearable device equipped with inertial sensors for the evaluation of jump height, which can be easily employed at home. We consider two categories of jumps, the counter-movement jump (a single vertical jump) and the plyometric jump (the fast repetition of 4 jumps). The proposed approach, after an initialization phase, uses gyroscope data to continuously track the orientation of the device and align it with the vertical plane and the accelerometer data to estimate the jump trajectory. To validate the system, we collected 200 jumps performed with our device and the Myotest and we observed a mean difference of 0.7 cm (max. 1.9 cm) for the counter-movement jumps and 0.6 (max. 2.1 cm) for the plyometric jumps.