Validation of an inertial measurement unit for the measurement of jump count and height.

OBJECTIVES

To validate the use of an inertial measurement unit (IMU) for the collection of total jump count and assess the validity of an IMU for the measurement of jump height against 3-D motion analysis.

DESIGN

Cross sectional validation study.

SETTING

3D motion-capture laboratory and field based settings.

PARTICIPANTS

Thirteen elite adolescent volleyball players.

INDEPENDENT VARIABLES

Participants performed structured drills, played a 4 set volleyball match and performed twelve counter movement jumps.

MAIN OUTCOME MEASURES

Jump counts from structured drills and match play were validated against visual count from recorded video. Jump height during the counter movement jumps was validated against concurrent 3-D motion-capture data.

RESULTS

The IMU device captured more total jumps (1032) than visual inspection (977) during match play. During structured practice, device jump count sensitivity was strong (96.8%) while specificity was perfect (100%). The IMU underestimated jump height compared to 3D motion-capture with mean differences for maximal and submaximal jumps of 2.5 cm (95%CI: 1.3 to 3.8) and 4.1 cm (3.1-5.1), respectively.

CONCLUSION

The IMU offers a valid measuring tool for jump count. Although the IMU underestimates maximal and submaximal jump height, our findings demonstrate its practical utility for field-based measurement of jump load.