Biomedical subjects

Uwe G Kersting

Publications and source records attributed to Uwe G Kersting.

4 recordsLinked to original sources

PubMed2005

Changes in knee cartilage volume and serum COMP concentration after running exercise.

OBJECTIVE: Investigate the relationship between running induced joint loading at the knee, changes in cartilage volume and serum cartilage oligomeric matrix protein (COMP) concentration. DESIGN: Serum COMP levels and knee cartilage volumes of experienced runners were tested before and after running. Joint loading was determined using a biomechanical model of the lower extremity. BACKGROUND: To date no biomechanical rationale has been identified to explain the role of mechanical load in the aetiology of running injuries. METHODS: Blood samples and magnetic resonance imaging scans were taken before and following a 1h training run. Knee cartilage volume and serum COMP concentration were determined. Individual knee joint loading parameters were calculated from positional data and ground reaction forces. Electromyography was employed to quantify activity of main muscle groups crossing the knee joint. RESULTS: Changes in cartilage volume and COMP showed significant correlations. Net joint forces did not explain the differences in cartilage changes. Multiple regression revealed that resting COMP, COMP change after exercise and the time of co-activation of flexor and extensor muscles explain the variance of cartilage volume changes. CONCLUSIONS: Muscular co-activation was the main mechanical parameter related to cartilage changes. The current investigation elucidates the interaction of factors related to cartilage degeneration on an individual basis. Applications to altered loading conditions such as equipment or training methods offer an auspicious way of quantifying effects of interventions.

Adult↗

PubMed2004

Adaptation of mechanical, morphological, and biochemical properties of the rat growth plate to dose-dependent voluntary exercise.

Mechanical loading has been shown to modulate longitudinal bone growth and cellular activity of the growth plate. Nevertheless, limited and controversial results exist regarding the effect of exercise on a physiological level on the growth plate. The present study investigated whether dose-dependent voluntary exercise has an influence on morphological, biochemical, and mechanical factors of the distal femoral growth plate of immature rats. Female growing Sprague-Dawley rats were randomly assigned to a unlimited exercise group (UE, n = 10), a limited exercise group (LE, n = 10), and a sedentary control group (CON, n = 10). The exercise groups were trained voluntarily in a running wheel for 8 weeks. The UE group could use the running wheel every time, whereas the LE group had timely restricted (50%) access. After sacrifice, the right femur was prepared for histomorphometric analysis and immunohistochemical staining of the distal growth plate. Mechanical testing was carried out on the distal growth plate of the left femur in shear direction. At the end of the study, the UE group had a significantly lower body mass than the CON group. There was no significant difference in overall femoral length between the groups. The height of the growth plate and the proliferation zone was significantly greater in the CON group than in both exercise groups. Only the LE group had a significantly lower hypertrophic zone and matrilin-3 staining pattern than the CON group. Osteonectin was located in the matrix of the upper hypertrophic zone in the UE group, whereas the LE and CON group showed more chondrocytes in the hypertrophic and lower proliferation zones stained for osteonectin, suggesting a higher level of mineralization in the growth plate of the UE group. No variations of mechanical properties of the distal femoral growth plate were detected. These results clearly demonstrate adaptations of morphology and biochemical parameters to the dose of running exercise, which do not result in significant differences in mechanical properties or bone length between the UE, LE, and CON groups.

Adaptation, Physiological↗

PubMedDate not supplied

Midsole material-related force control during heel-toe running.

The impact maximum and rearfoot eversion have been used as indicators of load on internal structures in running. The midsole hardness of a typical running shoe was varied systematically to determine the relationship between external ground reaction force (GRF), in-shoe force, and kinematic variables. Eight subjects were tested during overground running at 4 m/s. Rearfoot movement as well as in-shoe forces and external GRF varied nonsystematically with midsole hardness. Kinematic parameters such as knee flexion and foot velocity at touchdown (TD), also varied nonsystematically with altered midsole hardness. Results demonstrate that considerable variations of in-shoe loading occur that were not depicted by external GRF measurements alone. Individuals apparently use different strategies of mechanical and neuromuscular adaptation in response to footwear modifications. In conclusion, shoe design effects on impact forces or other factors relating to injuries depend on the individual and therefore cannot be generalized.

Adult↗

PubMedDate not supplied

The role of footwear-independent variations in rearfoot movement on impact attenuation in heel-toe running.

Impact forces and rearfoot eversion have been linked to overuse injuries in running. Modeling approaches suggest that both factors interact in that reduced foot eversion relates to increased impact maxima and vice versa. The aim of this study was to alter rearfoot eversion by applying three different combinations of ankle taping and bracing. Ten subjects were tested while running at 4 m/s on an instrumented treadmill. Sagittal plane kinematics, rearfoot eversion, tibial acceleration, pressure under the heel, and vertical ground reaction force (GRF) were collected simultaneously over 12 to 14 steps. All interventions reduced the maximum eversion significantly compared with unrestricted running. The largest effect was shown for combined bracing and taping, reducing rearfoot movement by 6.1 degrees while impact force varied only marginally. Overall, relationships between parameters contradict predictions by existing models of foot-ground interaction. Changes in muscular activation remain as a candidate in the regulation of impact mechanics in running.

Adult↗