The Foot Classification Conference Proceedings provide a summary of the topics covered in the recent meeting sponsored by the Foot and Ankle Special Interest Group. These proceedings are presented to our readers in the form of keynote summaries and conference abstracts. The proceedings embody current thinking on the classification of foot disorders from experts in our profession and the abstracts are summaries of works in progress. All of the authors have accomplished the goal of presenting their ideas. The first Foot and Ankle Special Interest Group research retreat, "Static and Dynamic Classification of the Foot," sponsored by the Orthopaedic Section of the American Physical Therapy Association, was held at the Historic Inns in Annapolis, MD, May 19-20, 2000. Thirty participants, including registrants from Canada and Australia, attended the meeting chaired by Irene McClay, PhD, PT, and Tom McPoil, PhD, PT. The group was made up of podiatrists, physical therapists, biomechanists, and footwear specialists, all with an interest in foot and ankle research. The objective of the retreat was to examine classification of the foot through the presentation of research findings, with a view to developing a consensus regarding future research directions. J Orthop Sports Phys Ther. 2001;31(3):153-160.

Study Design: A cross-sectional, descriptive study of shoulder movements conducted on nonimpaired subjects. Objective: To investigate whether a single functional rotation axis about the shoulder complex can be determined during elevation in the coronal or sagittal planes, and to identify their location. Background: Accurate measurement of isokinetic torques about a joint requires alignment of the dynamometer axis with an assumed rotation axis of the joint. To assess shoulder function on a dynamometer, the location of a single rotation axis is not evident because the shoulder joint motion is based on several anatomical joints. Therefore, the rotation axis where humerothoracic movements occur should be judged as a functional rotation axis. Methods and Measures: During slow elevation movements in the sagittal and coronal plane, the position of the epicondyle and acromion were recorded with a motion analysis system. The motion trajectory of the elbow coordinates was fitted to a circle and considered an estimate of the functional shoulder joint rotation axis in the specified plane. Results: The fitted trajectory appeared to be very accurate (root-mean-square error < 2%; N = 7). In the sagittal plane, the estimated functional rotation axis was found at the humeral head; in the coronal plane, it was located about 13 centimeters medial relative to the acromion. Conclusion: The shoulder complex of nonimpaired subjects can act as a hinge joint of the upper arm relative to the thorax during elevation in each measured plane. J Orthop Sports Phys Ther. 2OO1;31(3):133-137. Key Words: biomechanics, isokinetics, movement analysis, upper extremity

Study Design: Single group repeated measures design. Objective: To determine if the rate of transition between knee flexion and extension influences the subsequent concentric activation of the quadriceps and knee extension torque during reciprocal movements. Background: Preloading a muscle by stretching, a prior isometric or eccentric muscle action, or a prior movement controlled concentrically by the antagonist muscle group increases the maximal torque-generating capability of the agonist. We hypothesized that the rate of transition from the prior movement may be the critical factor that influences the degree of muscle facilitation and torque potentiation. Rapid reversal of antagonistic movements has been postulated as a potential facilitatory mechanism. Methods: Knee extension torque and electromyographic (EMG) amplitude (dependent variables) from 2 of the vasti muscles were recorded while subjects (N = 20; 12 men, 8 women, mean age, 28.5 ± 2.68 years) maximally activated their quadriceps at 3 constant angular velocities, 100°/s, 200°/s, and 300°/s, and 2 preload conditions, SLOW and RAPID (independent variables). In the SLOW transition condition, subjects actively flexed their knee to 110° from an extended position, paused in this position for 3 seconds, and then extended to O°. In the RAPID transition condition, the same movement from knee flexion to extension was performed without a pause. Results: Peak torque, the root-mean-square (RMS) average, peak (peak rectified and smoothed), and initial (100 milliseconds prior to torque onset) EMG amplitudes were all significantly greater during the RAPID transition condition. Peak torque decreased with increasing movement velocity. There were no interactions between the preload conditions and angular velocity on peak torque or the EMG amplitude variables. There was also no influence of velocity on the EMG amplitude variables. Conclusions: The effect of preloading the quadriceps by prior concentric activation of the hamstrings is dependent on the rate of transition between the flexion and extension movements and is due primarily to neural facilitation. J Orthop Sports Phys Ther. 2001;31(4):122-132. Key Words: exercise, muscle training. proprioceptive neuromuscular facilitation, quadriceps