With the ITUG, the most common cause of this is if you perform the TUG test using the "standard" 3m walkway instead of the 7m walkway that we suggest and have used for our normative data collection. The reason for this is that the 3m test does not have enough "steady-state" gait cycles for us to report on. Gait cycles that occur during the sit to stand event, the turn, and the turn to sit event are removed from the gait analysis as they are often irregular and significantly reduce the reliability of the reported measures.
Another less common cause is having the subject perform a turn where they make a rounded corner about a fixed point or object (e.g., cone) instead of a pivot turn at the end behind a marked line. The effect of this can sometimes be a long turn that takes up a significant amount of the recording. Sometimes, even with a 7m walkway, enough of the gait cycles are removed from lying within the turn that no gait measures will be reported.
If you believe you are experiencing a different issue, please create a support ticket on this site or email firstname.lastname@example.org