Introduction: Emerging evidence suggests core stability is an important factor in high performance in sports. Although many clinical assessments of core stability exist, there is a lack of consensus on the most effective core exercises and their impact on specific sports strength and conditioning. The objectives of this study are to 1) determine a simple method to objectively quantify the trunk stability during core training, and 2) to evaluate the credibility of the core assessment criteria) using both qualitative and quantitative aspects.
Methods: The first part of the study established a method for quantitatively evaluating trunk stability using several inertial sensors (SABEL Sense), a 3D motion capture (OptiTrack), and a data analysis system (Motive). SABEL Sense is a wearable inertial sensor consisting of a tri-axial accelerometer, gyroscope and magnetometer developed within the SABEL laboratory at Griffith University. The motion capture (Mocap) data was recorded by 3 cameras (Flex3; OptiTrack) placed on the ground, and 12 cameras attached to a 3m height frame. The second part of the study evaluated core assessment criteria (pelvic tilt and rotation angles, etc.) during core training. Sixteen male healthy sub-elite soccer players (middle of the season) between 20 and 39 years old participated in this study (Institutional ethics approval no is 2022/135).
The participants performed three basic core training: plank, side plank, and one-legged bridge, and trunk stability was analyzed during these three training. These assessments consisted of both static and dynamic components. The static training required the participant to hold a neutral spine position for 20-seconds. The dynamic training required extending/ abducting their leg five times with constant-tempo (70 bpm). Different ankle weights were used during the dynamic assessment (zero, 2kg, and 4kg) in each leg while trunk stability was recorded.
Results: Strong correlation between the Mocap data and inertial sensor data demonstrated that accurate measurements using inertial unit alone were possible. The average pelvic tilt angle calculated from the Mocap data during static plank showed a mean value of 17.0 degrees (10.8-21.1). The relative angle change during plank with right leg extension using zero, 2kg, and 4kg ankle weight showed a mean value of 16.5 degrees (16.3-16.8), 19.7 degrees (15.6-22.0), 17.7 degrees (17.5-17.9) respectively. These values correlated with those obtained using inertial sensors.
Conclusion: Wearable inertial sensor is a useful tool same as the Mocap assessment and it is practical to evaluate core stability as a field level assessment. The relative change of pelvic tilt angle was difference in moving the legs and tends to increase pelvic angulation when increasing ankle weight.
Impact/Application to the field: The method might be useful for prevention of various musculoskeletal conditions such as low back pain and muscle strain, and for assessing the effect of rehabilitation. In addition, this method will help establish an evaluation criterion for trunk stability.
A conflict of interest statement: The authors of this abstract have no conflicts of interest to declare.