Warm-up effect on active and passive arthrometric assessment of knee laxity

Objective: To determine the influence of a warm-up protocol suitable for us e in clinical settings on tibial displacement and muscle activity during ar thrometric knee laxity assessment. Design: Intervention study in which the subjects served as their own contro ls. Setting: The Biomechanics Research Laboratory, University of Wollongong, Wo llongong, New South Wales, Australia. Subjects: Ten volunteers who reported no history of knee trauma or disease. Intervention: A warm-up consisting of 10 minutes of ergometer cycling (60rp m) followed by two sets of three hamstring muscle stretches. Main Outcome Measures: Outcome measures were: (1) anterior tibial translati on and knee extension force assessed using a Dynamic Cruciate Tester(R) for each subject's right knee during active and passive testing, and (2) inten sity of quadriceps and hamstring muscle activity during knee laxity testing . Results: There was significantly less quadriceps activity after warm-up (t = 2.419, p = .039). However, there was no significant difference between an terior tibial translation, knee extension force, or hamstring muscle activi ty results before and after warm-up in either active or passive tests. Conclusion: A warm-up suitable for use in a clinical setting is not require d before arthrometric assessment of knee laxity. (C) 1999 by the American C ongress of Rehabilitation Medicine and the American Academy of Physical Med icine and Rehabilitation.