No description available.

Running popularity has led to a rise in chronic lower limb injuries resulting from cumulative loading. Many of these injuries are tibial stress fractures. Tibial accelerometers are commonly used to measure tibial stress and may even be predictive of injury at the distal limb. Lower body positive pressure (LBPP) treadmills have become increasingly popular amongst athletes and practitioners to prevent and treat lower limb injuries by reducing effective body weight (BW) through mechanical support. The purpose of this thesis is to investigate if BW unloading affects tibial acceleration (TA) and shock attenuation. Twelve trained distance runners (Sex: 6 males and 6 females; Age: 18-30 years) were recruited for this study. TA was measured through two Blue Trident, IMeasureU step units located at the distal tibiae. A STATSports Apex unit was also used to measure acceleration at the superior trunk and calculate shock attenuation for each limb. It was found that BW unloading had no discernable effect on mean peak TA and shock attenuation, bone stimulus, or contact time, regardless of running speed. However, a significant relationship was observed between running speed and both mean peak TA and bone stimulus where an increase in speed led to an increase in TA and bone stimulus. Furthermore, running speed did not affect shock attenuation or contact time. In conclusion, BW unloading did not alter gait kinematics in trained distance runners. / Master of Science / Running popularity has led to a rise in chronic lower limb injuries, particularly stress fractures at the shin or tibia bone, due to greater impact forces and "stiffer" landings. Tibial accelerometers are commonly used to measure these impact forces and may even be predictive of injury at the tibia bone near the ankle. The process of reducing these impact forces is called shock attenuation. Lower body positive pressure (LBPP) treadmills have become increasingly popular amongst athletes and practitioners to prevent and treat lower limb injuries by unloading body weight (BW) through mechanical support. The purpose of this thesis is to investigate if BW unloading affects tibial acceleration (TA) and shock attenuation. Twelve trained distance runners (Sex: 6 males and 6 females; Age: 18-30 years) were recruited for this study. TA was measured through two Blue Trident, IMeasureU step units located at the shin. A STATSports Apex unit was also used to measure impact at the upper trunk and calculate shock attenuation for each limb. It was found that BW unloading did not affect mean peak TA and shock attenuation, bone stimulus, or contact time, regardless of running speed. However, running speed significantly affected both mean peak TA and bone stimulus where an increase in speed led to an increase in TA and bone stimulus. Furthermore, running speed did not affect shock attenuation or contact time. In conclusion, BW unloading did not alter impact forces in trained distance runners. Caution is advised for individuals with injuries at the shin when using LBPP treadmills.

No description available.

Previous studies have used accelerometers with various operating ranges (ORs) when measuring biomechanical parameters. However, it is still unclear whether ORs influence the accuracy of running parameters, and whether the different stiffnesses of footwear midsoles influence this accuracy. The purpose of the present study was to systematically investigate the influence of OR on the accuracy of stride length, running velocity, and on peak tibial acceleration. Twenty-one recreational heel strike runners ran on a 15-m indoor track at self-selected running speeds in three footwear conditions (low to high midsole stiffness). Runners were equipped with an inertial measurement unit (IMU) affixed to the heel cup of the right shoe and with a uniaxial accelerometer at the right tibia. Accelerometers (at the tibia and included in the IMU) with a high OR of ±70 g were used as the reference and the data were cut at ±32, ±16, and at ±8 g in post-processing, before calculating parameters. The results show that the OR influenced the outcomes of all investigated parameters, which were not influenced by tested footwear conditions. The lower ORs were associated with an underestimation error for all biomechanical parameters, which increased noticeably with a decreasing OR. It can be concluded that accelerometers with a minimum OR of ±32 g should be used to avoid inaccurate measurements.

Previous studies have used accelerometers with various operating ranges (ORs) when measuring biomechanical parameters. However, it is still unclear whether ORs influence the accuracy of running parameters, and whether the different stiffnesses of footwear midsoles influence this accuracy. The purpose of the present study was to systematically investigate the influence of OR on the accuracy of stride length, running velocity, and on peak tibial acceleration. Twenty-one recreational heel strike runners ran on a 15-m indoor track at self-selected running speeds in three footwear conditions (low to high midsole stiffness). Runners were equipped with an inertial measurement unit (IMU) affixed to the heel cup of the right shoe and with a uniaxial accelerometer at the right tibia. Accelerometers (at the tibia and included in the IMU) with a high OR of ±70 g were used as the reference and the data were cut at ±32, ±16, and at ±8 g in post-processing, before calculating parameters. The results show that the OR influenced the outcomes of all investigated parameters, which were not influenced by tested footwear conditions. The lower ORs were associated with an underestimation error for all biomechanical parameters, which increased noticeably with a decreasing OR. It can be concluded that accelerometers with a minimum OR of ±32 g should be used to avoid inaccurate measurements.

Im Fokus dieser kumulativ angefertigten Dissertation stehen vier methodenorientierte biomechanische Studien, in welchen die potentiellen Fehlerquellen analysiert werden, die beim Einsatz von Inertialsensoren in der biomechanischen Gang- und Laufanalyse auftreten können. In den einzelnen Beiträgen werden die Einflüsse der Inertialsensoraufnahmefrequenz (Studie I) und des Messbereichs der Beschleunigungssensoren (Studie II) auf die kinematischen, kinetischen und räumlich-zeitlichen Parameter systematisch untersucht. Des Weiteren wird sich kritisch mit der Genauigkeit verschiedener Detektionsmethoden des initialen Bodenkontaktes (Studie III) sowie mit der Aussagekraft der maximalen Eversionsgeschwindigkeit (Studie IV) auseinandergesetzt. Um ein umfassendes Bild der Einflussgrößen zu erhalten, wurde in den Studien II, III und IV untersucht, ob die Materialcharakteristik der Laufschuhsohle die Genauigkeit der biomechanischen Parameter beeinflusst. Zudem wurde in Studie III geprüft, welchen zusätzlichen Effekt der Laufstil (Vor- und Rückfußlaufen) auf die Genauigkeit der initialen Bodenkontaktbestimmung hat sowie welchen Einfluss die Bewegungsgeschwindigkeit (Gehen und Laufen) auf die maximale Eversionsgeschwindigkeit nehmen kann (Studie IV). Die Ergebnisse der vier Untersuchungen werden am Ende dieser Arbeit in einem gemeinsamen Kontext diskutiert. Auf Grundlage der Erkenntnisse konnte eine Übersicht erstellt werden, welche sowohl die Mindestanforderungen an Inertialsensoren als auch die Einflussgrößen auf die Genauigkeit der biomechanischen Parameter enthält. Mit diesem Überblick erhalten Nutzer von Inertialsensoren (z.B. Sportler, Trainer, Mediziner und Wissenschaftler) bei der Planung einer Bewegungsanalyse die Unterstützung, die Sensoren mit der passenden Sensorspezifikation in Kombination mit den präzisesten Auswertealgorithmen auszuwählen. Zudem können die Informationen aus dieser Dissertation dazu genutzt werden, Erkenntnisse bereits publizierter Studien kritisch zu hinterfragen. / In previous studies, inertial sensors were used to investigate kinematic, kinetic, and spatio-temporal parameters during walking and running. The present cumulative doctoral thesis consists of four methodological studies. Two of the studies examine the influence of inertial sensor sampling rate (study I) and accelerometer operating range (study II) on the accuracy of biomechanical parameters. Another study investigated whether different published foot strike detection methods can accurately detect the time of initial ground contact (study III). The final study examined whether a single gyroscope can be used to accurately determine peak eversion velocity (study IV). In order to obtain a comprehensive view of the influencing factors, studies II, III and IV also investigated whether the material characteristics of the running shoe sole also influence the accuracy of the biomechanical parameters. Additionally, the effect of running style (forefoot or rearfoot) on the accuracy of foot strike detection methods was investigated in study III, and the effect of locomotion speed (walking, running slow up to running fast) on the accuracy of peak eversion velocity was examined in study IV. The results of the four investigations will be summarized and discussed in a common context. Based on the findings, an overview was prepared which contains both the minimum requirements for inertial sensors and also the influencing variables on the accuracy of the biomechanical parameters. This overview may assist users of inertial sensors (e.g. athletes, trainers, physicians, or scientists) in planning gait and running analyses to select inertial sensors with the appropriate specification in combination with the most accurate algorithms. In addition, the information from this dissertation can be used to critically consider the findings of published studies.