Static versus dynamic kinematics in cyclists: A comparison of goniometer, inclinometer and 3D motion capture

Jed Williams Research Review

Holliday 2017 looked in to the efficacy of measuring joint angles in both a static and a dynamic setting for bike fitting. The study looked at 3 different methods of measuring angles; a goniometer (GM), electric inclinometer (IM) and an 8-camera three-dimensional motion capture system (3DMC).

The study had 19 participants complete 3 different trials each one 10 minutes long at a fixed intensity of 70% of peak power output, the joint angles were measured after each test to compare the repeatability of the different methods of data collection. The joints measured were the ankle, knee, hip, shoulder and elbow, the GM was operated by the primary researcher over three different measurements to achieve a standard error of less than a degree.

The IM and the GM had a good correlation across all the joint angles suggesting that as measurement tools both the GM and the IM are interchangeable. The only significant relationship between GM, IM & 3DMC was across the knee, shoulder and elbow joints. When comparing the static measurement methods to the dynamic however do not correlate so well, the highest correlation from dynamic to static was at the shoulder, the ankle joint had the poorest correlation.
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The error in the measurement was found to be low across all methods meaning that provided a fitter was using the same measurement device results would be consistent across all joints.

The researchers take into consideration that the disparity between the static measures and the 3DMC could be caused by the different landmarks used for measuring joint angles. The difference in the static and dynamic measures have been attributed to the different ankleling patterns engaged during the pedal stroke. Previous studies have found that when moving measurement from static to dynamic average knee flexion angle at optimal saddle height moves from 25-35 to 30-40. The implication of this is that when setting a bike up using dynamic measures that a different range of joint angles should be used.

Limitations of this study are that a the 3rd motion capture time trial had an incomplete data-set due to illness and injury, meaning that the averages were taken over just the first 2 trials reducing the reliability of the research. You can find the study at the link below

Static versus dynamic kinematics in cyclists: A comparison of goniometer, inclinometer and 3D motion capture

W. Holliday, J. Fisher, R. Theo & J. Swart European Journal of Sport Science Vol. 17 , Iss. 9,2017

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