Do elite athletes exhibit enhanced proprioceptive acuity, range and strength of knee rotation compared with non-athletes?

The aims of this study were to compare proprioception in knee rotation in Olympic-level soccer players (N=18) with non-athletes (N=18), to explore between-limb differences in soccer players, and examine correlations between proprioception and years of playing, function, physical measures and skill level. The knee rotatory kinaesthetic device was used to present stimuli of different magnitudes to determine proprioceptive acuity for internal and external active rotation, and to measure active and passive rotation range of motion (ROM). Knee rotation strength was measured using a dynamometer. Proprioceptive acuity of the athletes was significantly (P=0.004) better than that of the non-athletes. Athletes displayed significantly less passive ROM (P=0.001), higher isometric muscle strength (P=0.006) and greater hop for distance (P=0.001) than non-athletes. No significant between-limb differences were found in the athletes in any objective outcome measure. Internal rotation proprioceptive acuity was negatively correlated with coach-rated ball skill (r=-0.52) and positively correlated with internal rotation ROM (r=0.59). Our findings suggest that highly trained athletes possess enhanced proprioceptive acuity and muscle strength that may be inherent, or may develop as a result of long-term athletic training.

Design of a knee rotatory kinaesthetic device.

The anterior cruciate ligament (ACL) constrains rotatory motion at the knee and is commonly injured during rotational movements in athletic activity. This densely innervated ligament is assumed to play a role in knee proprioception, however, no study has measured proprioception in a manner relevant to either the kinematics of the ligament or the mechanism of injury, partly because of a lack of suitable equipment. The aims of this technical note are to document the development of a novel knee rotatory kinaesthetic device, and to present details of its construction, reproducibility, accuracy and application. The purpose-built device allows rotational movements at the knee to occur with minimal frictional resistance and provides accurate limits to the magnitude of these movements. This allows analysis of subjects' ability to discriminate between movements of differing magnitudes and thus allows calculation of subjects' sensitivity to small differences in magnitude of active knee rotation. Measurements taken with the device had a high level of agreement with those of a calibrated digital inclinometer (ICC=0.99; 95% CI 0.88 to 0.99) with a mean error of 0.24 degrees . The device also demonstrated excellent reproducibility (Pearson's r=1.0). A single case study is presented to detail the clinical application of the device. This novel device allows subjects to perform active knee rotational movements in a closed kinetic chain with discrete, self-paced movement, enabling calculation of movement discrimination. The device is compact and portable enabling testing to be undertaken in remote settings enhancing its clinical applicability.