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External loads throughout a 45 minute run in stress fracture and non-stress fracture runners
668
The Kinetics Cycling
Abstracts-InternationalSocietyof BiomechanicsXIV Congress1993
of Shoe/Pedal
Interface
and Load on Pedaling Kinetics
in
Gregor, R.J., Wheeler, J.B., *Broker, J.P. and Ryan, M.M. Departmentof PhysiologIcal Science,UCLA, Los Angeles,CA and *Athletic PerformanceDivision, USOTC, ColoradoSprings,CO, 80909
Knowledgeof applied loads betweenthe foot and pedal is significant to our understandingof lower extremity function during cycling. While three dimensionalpedalreactionforce componentshave been reportedby several investigators,little attention has beengiven measurementof the applied torsion at the shoe/pedalinterface. This is true despitethe recentexplosion in the bicycle componentdesignindustry resultingin the new “float” pedal designsintendedto reducemusculoskeletaltrauma.In the presentinvestigationthe applied torsional moment at the pedalsurfacewas studiedin 27 subjectsreportedlyfree of knee pain. A standardroad racing bicycle equipped with speciallydesignedforce pedalsand loadedusing a Schwinn VelodyneTrainer was set-upfor each subject accordingto their own bicycle dimensions. All subjectswere studiedusing three separateshoe/pedalinterface conditions(toe-clip and strap, clipless fixed and clipless float) at 150,250 & 35OWof power. The applied torsionalmoment (Ma, its time derivative and integral were measuredthroughoutthe pedalling cycle for all subjectsduring all conditions. Resultsindicate that the power phase(O-18@)beginswith an externally applied momentfollowed by an internally applied momentlastingjust prior to the recoveryphase(180-3600)for eachof the threeshoe/pedalinterfacetypesat all power output conditions. An externally applied moment was recorded throughoutrecovery for all subjectsat all conditions. The lowest peak momentswere recordedduring the “float” shoe/pedalinterfacecondition for all subjects. Thesedata supportthe contentionthat “float” designsminimize torsion loadson the leg during cycling. Remainingquestionsnow focus on the magnitudeand absoluterangeof fioai that is bestfor each cyclist. EXTERNAL LOADS THROUGHOUT A 45 MINUTE RUN IN STRESS FRACTURE AND NON-STRESS FRACTURE RUNNERS. SusanK. Grimston, Benno M. Nigg, Veronica Fisher, and Stanley V. Ajemian Human Performance Laboratory, Faculty of Physical Education, The University of Calgary, Calgary, AB., T2N lN4, CANADA. External loading kinetics were measured using a Kistler force plate embedded in an indoor track, thoughout a 45 minute run and results for runners with a history of tibial stress fracture (SF, n=5) and runners with no stress fracture history (NSF, n=S) compared. External loads were also compared within and between groups during early and late stages of the run. All forces were normalized to a ratio of body weight and controlled for differences in running speed. Average forces during the entire run showed no significant differences between groups. However when forces for the early stage plate contacts were compared, NSF recorded significantly greater vertical impact (2.24f.12 vs 1.84&.06), maximum vertical (2.68f.04 vs 2.48+.04),anterior (0.47f.02~0.37~.02)andposterior (0.35f.01 vs0.28f.02)forces thanSF. Therewere no significant differences in external forces for NSF during the course of the run. In contrast, maximum vertical (2.48f.04 early and 2.51k.03 late) and anterior (0.37f.02 early and 0.4Ok.02 late) forces were significantly increasedin the late stagesof the run for SF. All other forces for SF showed a consistent trend for increasing later in the run. Maximum lateral forces were significantly greater for SF during both early and late stagesof the run compared to NSF, confirming previous laboratory findings. The finding of increased external loads during the course of a 45 minute run in SF, and constant or decreasedloads in NSF, may be indicative of differences in fatigue adaptation and warrants further study.
FORCES IN THE KNEE JOINT DURING THE STEERING PHASE IN ALPINE SKIING Ch. Haid, E. Mtiller*, Ch. Raschner*, Universitdtsklinik fi.ir Orthopadie, l lnstitut ftir Sporlwissenschaft, Innsbruck, Austria The objectives of this study were to analyse the external forces and the body position during the steering phase in alpine skiing and to calculate the internal forces in the knee joints. 6 subjects were used in this study, three very high and three low standard skiers. All the skiers had to pass the same gate combination on a medium steep slope (20”) with packed snow. The steering phase between gate two and three was analysed. Ground reaction forces and plantar pressure distribution were measured with two EMED insoles with a maximum sampling rate of 40 Hz. At the same time the skiers were filmed -with ~VVO video cameras with a nominal frame rate of 50 112.The video data were analysed hccoidics to the 3D- programme of the PEAK-System. The centre of mass of the skier-ski system was calculate. The distance between the knee joint and the acting external force was calculated to estimate the turning moment in the knee. In the mathematical model the knee was built as a four joint connecting rod according to Menschik (1976) to calculate the joint kinematics. The position of the patella and the force of the M. quadriceps were calculated for static equilibrium in the knee joint. These results made it possible to calculate the internal forces of the knee joint, such as the force of pressure in the femoro-patellar and tibia-femoral joints as well as the tension in the anterior cruciate ligament. The knee joints forces in the steering phase in alpine skiing are not very high for highly skilled skiers. But due to the fact that badly skilled skiers tend to lean far more backwards their knee joint forces increase heavily. This study was supported by a grant of the Austrian Research Foundation.
The Kinetics Cycling
Abstracts-InternationalSocietyof BiomechanicsXIV Congress1993
of Shoe/Pedal
Interface
and Load on Pedaling Kinetics
in
Gregor, R.J., Wheeler, J.B., *Broker, J.P. and Ryan, M.M. Departmentof PhysiologIcal Science,UCLA, Los Angeles,CA and *Athletic PerformanceDivision, USOTC, ColoradoSprings,CO, 80909
Knowledgeof applied loads betweenthe foot and pedal is significant to our understandingof lower extremity function during cycling. While three dimensionalpedalreactionforce componentshave been reportedby several investigators,little attention has beengiven measurementof the applied torsion at the shoe/pedalinterface. This is true despitethe recentexplosion in the bicycle componentdesignindustry resultingin the new “float” pedal designsintendedto reducemusculoskeletaltrauma.In the presentinvestigationthe applied torsional moment at the pedalsurfacewas studiedin 27 subjectsreportedlyfree of knee pain. A standardroad racing bicycle equipped with speciallydesignedforce pedalsand loadedusing a Schwinn VelodyneTrainer was set-upfor each subject accordingto their own bicycle dimensions. All subjectswere studiedusing three separateshoe/pedalinterface conditions(toe-clip and strap, clipless fixed and clipless float) at 150,250 & 35OWof power. The applied torsionalmoment (Ma, its time derivative and integral were measuredthroughoutthe pedalling cycle for all subjectsduring all conditions. Resultsindicate that the power phase(O-18@)beginswith an externally applied momentfollowed by an internally applied momentlastingjust prior to the recoveryphase(180-3600)for eachof the threeshoe/pedalinterfacetypesat all power output conditions. An externally applied moment was recorded throughoutrecovery for all subjectsat all conditions. The lowest peak momentswere recordedduring the “float” shoe/pedalinterfacecondition for all subjects. Thesedata supportthe contentionthat “float” designsminimize torsion loadson the leg during cycling. Remainingquestionsnow focus on the magnitudeand absoluterangeof fioai that is bestfor each cyclist. EXTERNAL LOADS THROUGHOUT A 45 MINUTE RUN IN STRESS FRACTURE AND NON-STRESS FRACTURE RUNNERS. SusanK. Grimston, Benno M. Nigg, Veronica Fisher, and Stanley V. Ajemian Human Performance Laboratory, Faculty of Physical Education, The University of Calgary, Calgary, AB., T2N lN4, CANADA. External loading kinetics were measured using a Kistler force plate embedded in an indoor track, thoughout a 45 minute run and results for runners with a history of tibial stress fracture (SF, n=5) and runners with no stress fracture history (NSF, n=S) compared. External loads were also compared within and between groups during early and late stages of the run. All forces were normalized to a ratio of body weight and controlled for differences in running speed. Average forces during the entire run showed no significant differences between groups. However when forces for the early stage plate contacts were compared, NSF recorded significantly greater vertical impact (2.24f.12 vs 1.84&.06), maximum vertical (2.68f.04 vs 2.48+.04),anterior (0.47f.02~0.37~.02)andposterior (0.35f.01 vs0.28f.02)forces thanSF. Therewere no significant differences in external forces for NSF during the course of the run. In contrast, maximum vertical (2.48f.04 early and 2.51k.03 late) and anterior (0.37f.02 early and 0.4Ok.02 late) forces were significantly increasedin the late stagesof the run for SF. All other forces for SF showed a consistent trend for increasing later in the run. Maximum lateral forces were significantly greater for SF during both early and late stagesof the run compared to NSF, confirming previous laboratory findings. The finding of increased external loads during the course of a 45 minute run in SF, and constant or decreasedloads in NSF, may be indicative of differences in fatigue adaptation and warrants further study.
FORCES IN THE KNEE JOINT DURING THE STEERING PHASE IN ALPINE SKIING Ch. Haid, E. Mtiller*, Ch. Raschner*, Universitdtsklinik fi.ir Orthopadie, l lnstitut ftir Sporlwissenschaft, Innsbruck, Austria The objectives of this study were to analyse the external forces and the body position during the steering phase in alpine skiing and to calculate the internal forces in the knee joints. 6 subjects were used in this study, three very high and three low standard skiers. All the skiers had to pass the same gate combination on a medium steep slope (20”) with packed snow. The steering phase between gate two and three was analysed. Ground reaction forces and plantar pressure distribution were measured with two EMED insoles with a maximum sampling rate of 40 Hz. At the same time the skiers were filmed -with ~VVO video cameras with a nominal frame rate of 50 112.The video data were analysed hccoidics to the 3D- programme of the PEAK-System. The centre of mass of the skier-ski system was calculate. The distance between the knee joint and the acting external force was calculated to estimate the turning moment in the knee. In the mathematical model the knee was built as a four joint connecting rod according to Menschik (1976) to calculate the joint kinematics. The position of the patella and the force of the M. quadriceps were calculated for static equilibrium in the knee joint. These results made it possible to calculate the internal forces of the knee joint, such as the force of pressure in the femoro-patellar and tibia-femoral joints as well as the tension in the anterior cruciate ligament. The knee joints forces in the steering phase in alpine skiing are not very high for highly skilled skiers. But due to the fact that badly skilled skiers tend to lean far more backwards their knee joint forces increase heavily. This study was supported by a grant of the Austrian Research Foundation.