Intra- and Inter-Session Reliability of Methods for Measuring Reaction Time in Participants with and without Patellofemoral Pain Syndrome

To evaluate the relative and absolute reliability of reaction time measuring methods during differentconditions in participants with and without patellofemoral pain syndrome (PFPS).

30 patients with PFPS and 30 healthy controls were recruited in the present study. The upper extremityreaction time, upper extremity error rate, involved and non-involved lower extremity braking reaction times, and involvedand non-involved knee extension reaction times were measured. Each condition was repeated three times, 2 sessionswith a 5-7 days interval. The intra-session reliability was evaluated in three-trial (A), second- and third-trial (B) modes.In addition, the inter-session reliability was evaluated in mode A, mode B, and best score (C) mode.

The result of inter-session reliability of mode A showed that all measurements except upper extremity reactiontime in PFPS group showed high to very high relative reliability (ICC: 0.74-0.94). In mode B, all measurements exceptnon-involved knee extension reaction time in PFPS group showed high to very high relative reliability (ICC: 0.71-0.93).In mode C, all measurements showed high to very high relative reliability (ICC: 0.70-0.94) except upper extremity errorrate and non-involved knee extension reaction time in PFPS group. The result of intra-session reliability showed thatall measurements had high to very high relative reliability (ICC: 0.78-0.94) in mode A. In mode B, all measurementsshowed high to very high relative reliability (0.78-0.94).

The braking time seems more reliable than other reaction time tasks. In addition, the results showedthat mode A is more reliable than other modes. The newly designed package is a reliable tool to measure the kneeextension reaction time in patients with knee musculoskeletal disorders.Level of evidence: II