Effects of Fatigue Running on Joint Mechanics in Female Runners: A Prediction Study Based on a Partial Least Squares Algorithm

Background: Joint mechanics are permanently changed using different intensities and running durations. These variations in intensity and duration also influence fatigue during prolonged running. Little is known about the potential interactions between fatigue and joint mechanics in female recreational runners. Thus, the purpose of this study was to describe and examine kinematic and joint mechanical parameters when female recreational runners are subject to fatigue as a result of running.Method: Fifty female recreational runners maintained running on a treadmill to induce fatigue conditions. Joint mechanics, sagittal joint angle, moment, and power were recorded pre- and immediately post fatigue treadmill running.Result: Moderate reductions in absolute positive ankle power, total ankle energy dissipation, dorsiflexion at initial contact, max dorsiflexion angle, and range of motion of the joint ankle were collected after fatigue following prolonged fatigue running. Knee joint mechanics, joint angle, and joint power remained unchanged after prolonged fatigue running. Nevertheless, with the decreased ankle joint work, negative knee power increased. At the hip joint, the extension angle was significantly decreased. The range motion of the hip joint, hip positive work and hip positive power were increased during the post-prolonged fatigue running.Conclusion: This study found no proximal shift in knee joint mechanics in amateur female runners following prolonged fatigue running. The joint work redistribution was associated with running fatigue changes. As for long-distance running, runners should include muscle strength training to avoid the occurrence of running-related injuries.

Reliability of Tibiofemoral Contact Area and Centroid Location in an Upright, Open MRI (UO-MRI)

Background: Biomechanical studies are often performed using conventional closed-bore MR, which has necessitated simulating weightbearing load on the joint. The clinical applicability of these biomechanical findings is unclear because of the limitations of simulating weightbearing. Upright, open MRI (UO-MRI) can be used to assess knee joint mechanics, in particular contact area and centroid location. However, it is not clear how reliably measurements of contact area and centroid location can be made in upright weightbearing postures. Methods: Manual segmentation of cartilage regions in contact was performed and centroids of those contact areas were automatically determined for the medial (MC) and lateral (LC) tibiofemoral compartments. To assess reliability, inter-rater, test-retest, and intra-rater reliability were determined by intra-class correlation (ICC 3,1 ), standard error of measurement (SEM), smallest detectable change with 95% confidence (SDC 95 ). Accuracy was assessed by using a high-resolution, 7T MRI as a reference and determined by measurement error (%). Results: Contact area and centroid location reliability (inter-rater, test-retest, and intra-rater) for sagittal scans in the MC demonstrated ICC 3,1 values from 0.95-0.99 and 0.98-0.99 respectively, and in the LC from 0.83-0.91 and 0.95-1.00 respectively. The smallest detectable change in contact area was 1.28% in the MC and 0.95% in the LC. Contact area and centroid location reliability for coronal scans in the MC demonstrated ICC 3,1 values from 0.90-0.98 and 0.98-1.00 respectively, and in the LC from 0.76-0.94 and 0.93-1.00 respectively. The smallest detectable change in contact area was 0.65% in the MC and 1.41% in the LC. Contact area segmentation was accurate to within 4.81% measurement error. Conclusions: Knee contact area and contact centroid location can be assessed in upright weightbearing MRI with good to excellent reliability and accuracy within 5%. The lower field strength used in upright, weightbearing MRI does not compromise the reliability of tibiofemoral contact area and centroid location measures.

Reliability of Tibiofemoral Contact Area and Centroid Location in an Upright, Open MRI (UO-MRI)

Background: Biomechanical studies are often performed using conventional closed-bore MR, which has necessitated simulating weightbearing load on the joint. The clinical applicability of these biomechanical findings is unclear because of the limitations of simulating weightbearing. Upright, open MRI (UO-MRI) can be used to assess knee joint mechanics, in particular contact area and centroid location. However, it is not clear how reliably measurements of contact area and centroid location can be made in upright weightbearing postures. Methods: Manual segmentation of cartilage regions in contact was performed and centroids of those contact areas were automatically determined for the medial (MC) and lateral (LC) tibiofemoral compartments. To assess reliability, inter-rater, test-retest, and intra-rater reliability were determined by intra-class correlation (ICC 3,1 ), standard error of measurement (SEM), smallest detectable change with 95% confidence (SDC 95 ). Accuracy was assessed by using a high-resolution, 7T MRI as a reference and determined by measurement error (%). Results: Contact area and centroid location reliability (inter-rater, test-retest, and intra-rater) for sagittal scans in the MC demonstrated ICC 3,1 values from 0.95-0.99 and 0.98-0.99 respectively, and in the LC from 0.83-0.91 and 0.95-1.00 respectively. The smallest detectable change in contact area was 1.28% in the MC and 0.95% in the LC. Contact area and centroid location reliability for coronal scans in the MC demonstrated ICC 3,1 values from 0.90-0.98 and 0.98-1.00 respectively, and in the LC from 0.76-0.94 and 0.93-1.00 respectively. The smallest detectable change in contact area was 0.65% in the MC and 1.41% in the LC. Contact area segmentation was accurate to within 4.81% measurement error. Conclusions: Knee contact area and contact centroid location can be assessed in upright weightbearing MRI with good to excellent reliability and accuracy within 5%. The lower field strength used in upright, weightbearing MRI does not compromise the reliability of tibiofemoral contact area and centroid location measures.