Reliability and Validity of a Wireless Inertial Sensor for Assessing Vertical Jump Biomechanics

Abstract

PURPOSE: Compare vertical jump metrics measured using force plates (FP) versus a wireless inertial sensor (IS). METHODS: 9 men (age 35±14 yr, height 178±8 cm, mass 84±9 kg) performed 3 vertical countermovement jumps with arms akimbo (CMJ) and with arm thrust (CMJAT) while standing on force plates (BTS 6000D, BTS Bioengineering, Brooklyn, NY) and wearing a wireless inertial sensor (BTS G-Sensor 2, Brooklyn, NY) placed on the lumbar spine. CMJ and CMJAT biomechanical metrics were compared between FP and IS using paired t-tests, with reliability assessed using Pearson correlation coefficients. The following metrics were assessed: flight height, jump height (flight height + difference between standing height and takeoff height), low force (unweighting during initiation of countermovement), countermovement distance dropped, force at low point (end of countermovement), rate of force development, eccentric power, peak propulsive force, peak and takeoff velocity, maximum power, and peak landing force. RESULTS: For CMJ there was good agreement between FP and IS for most parameters (Table 1); all metrics were significantly correlated between the FP and IS, but the IS significantly underestimated flight height, low force and force at low point. For CMJAT there was poor agreement for most jump parameters.Table: No title available.CONCLUSIONS: This wireless inertial sensor was effective for quantifying the countermovement and propulsive phases of a CMJ, but was not effective for quantifying landing force. The sensor was not effective for quantifying CMJAT parameters.