ABSTRACT The increasing number of patients with developing osteoarthritis is accompanied by a gro... more ABSTRACT The increasing number of patients with developing osteoarthritis is accompanied by a growing scientific interest in non-operative early treatment strategies. It is generally believed that laterally wedged insoles can change the distribution of knee loading. However, the importance of footwear design/type on the effectiveness of lateral wedging has not been investigated so far. The Purpose of the present study was to explore alterations in knee loading due to lateral foot wedges in three different shoes. Methods: Thirteen healthy participants with no history of knee pain were tested using three-dimensional gait analysis. Barefoot walking, walking in a running shoe, an Oxford-type leather shoe, and a rocker shoe were analysed. The shoes were tested both with and without a 10-degree full-length laterally wedged insole. Results: There were significant shoe*wedge interactions on the first and second peak knee adduction moments. However, the variability of this moment between shoe designs was of similar magnitude as the effect of laterally wedged insoles. Only marginal changes in muscle activity for gastrocnemius when walking with the wedged Oxford shoe were revealed. Conclusion: Lateral wedging is effective regardless of shoe design. Differences between the three neutral walking conditions underline the importance of footwear choice in individuals. It is safe to apply lateral wedges without jeopardising muscular control during walking regardless of shoe type. Possible effects of altering neuromuscular control by shoe type needs further exploration in patient groups.
Hiking boots provide an interface for walking in challenging environments, typically equipped wit... more Hiking boots provide an interface for walking in challenging environments, typically equipped with a shaft to provide ankle joint stability in rough terrains. Currently it is unclear if the ankle joint is stabilized to an extent that protects against ankle injuries, and if so, to what degree this added ankle stability sacrifices ankle mobility and hence decreases efficient gait propulsion. The aim of the present study was to compare the effect of shaft construction and stiffness on lower extremity kinematics and kinetics during level and step-down walking to simulate hiking conditions. Thirteen healthy males walked in one low-cut and three shafted commercially available hiking shoes with varying shaft stiffness. Lower extremity kinematics and ground reaction forces were recorded simultaneously. During level walking, ankle plantar-dorsiflexion range of motion was significantly reduced for the stiffest shaft hiking shoe compared to the low-cut shoe. A reduction in the muscle contribution to ankle joint work was found for all shafted shoes compared to the low-cut shoe. The reduced ankle joint work for the shafted shoes conversely increased eccentric knee joint work. Kinematic and kinetic differences between shoes diminished during box step-down walking. The present study shows that shaft height and stiffness can influence ankle joint range of motion, and ankle and knee joint work, with the high-shaft shoes redistributing load from the ankle to the knee joint. This may have implications for gait efficiency and increase the risk of knee joint loading or injuries.
The impact maximum of the ground reaction force (GRF) has been discussed extensively in the conte... more The impact maximum of the ground reaction force (GRF) has been discussed extensively in the context of running injuries while numerous footwear-related papers aimed at modifying this parameter mainly by shoe construction. Several mechanisms have been proposed but to date the regulation of impact forces in running is not completely understood. In this paper findings on impact regulation will be reviewed and a statistical approach will be used to analyze variations in contact mechanics in 10 runners. Subjects were tested during running at 4 m/s on an instrumented treadmill. Sagittal plane kinematics, rearfoot eversion, tibial acceleration, pressure under the heel inside the shoe and vertical GRF were collected simultaneously over 19 ± 2 steps. Linear correlations were used to investigate relationships between single variables. A general regression model across the entire data set was employed and variable selection by backward elimination revealed the factors subject, minimum knee angle, rearfoot inversion at touch-down (TD) and the vertical velocity of the foot at TD as variables with the strongest contribution to the fit of the model. These four kinematic variables were re-entered in intra-individual regressions revealing an average R2 of 0.926 and an average power of the model of over 80%. The results support previous studies that suggest kinematic parameters to be linked to impact regulation. However, each subject appears to make use of individual combinations of mechanical impact modulation factors while some variables showed inverse relationships compared to results from intervention studies. Muscular activation remains as a possible factor in the regulation of touch-down mechanics in running and may be linked to running injuries.
The purposes of this study were to examine gender differences during drop jumps, to evaluate the ... more The purposes of this study were to examine gender differences during drop jumps, to evaluate the effect of a set of simple instructions on kinematic and kinetic parameters during a drop jump, and to determine if there are gender differences in the effects of instruction on those parameters. Twenty-five basketball players, 13 men and 12 women, performed drop jumps from a box (height 30.5 cm) after being asked to perform a land and jump movement as they normally would do when aiming at maximum jump height. The experimental group received a set of instructions designed to make them land softer. The measured parameters were impact force at landing, ground contact time, flight time, frontal plane knee angle, sagittal plane knee angle, and distance between the knees. When the groups were examined by gender, no differences in the parameters were seen in men after instruction, but in women the following significant differences were detected: an increase in contact time, a decrease in landing force, and a decrease in inward movement of the knees after landing. These data indicate that females respond differently to jumping/landing instructions.
This study compared metabolic power (MP) and time trial (TT) running performance between Adidas A... more This study compared metabolic power (MP) and time trial (TT) running performance between Adidas Adizero Adios (AAA) and Nike VaporFly 4% (NVP). Thirty-seven runners completed three laboratory sessions and two field sessions (n=30). After familiarization (visit 1), participants completed eight 6-min treadmill running bouts (four with each shoe, counterbalanced) at their preferred pace, and MP was assessed using indirect calorimetry (visits 2 and 3). During visits 4 and 5, participants completed two outdoor TTs (~3.5 km) in NVP and AAA (counterbalanced). Compared with AAA, NVP exhibited superior MP (NVP: median=13.88 (Q1–Q3=12.90–15.08 W/kg; AAA: median=14.08 (Q1–Q3=13.12–15.44 W/kg; z=−4.81, p<.001, effect size=.56) and TT (NVP=793±98 s; AAA=802±100 s, p=.001; effect size=.09). However, there was no relationship between changes in MP and changes in TT between shoes (r=.151 p=.425, 95% confidence interval=[−.22; .48]). Our results demonstrate that NVP, compared with AAA, improves M...
ABSTRACT The increasing number of patients with developing osteoarthritis is accompanied by a gro... more ABSTRACT The increasing number of patients with developing osteoarthritis is accompanied by a growing scientific interest in non-operative early treatment strategies. It is generally believed that laterally wedged insoles can change the distribution of knee loading. However, the importance of footwear design/type on the effectiveness of lateral wedging has not been investigated so far. The Purpose of the present study was to explore alterations in knee loading due to lateral foot wedges in three different shoes. Methods: Thirteen healthy participants with no history of knee pain were tested using three-dimensional gait analysis. Barefoot walking, walking in a running shoe, an Oxford-type leather shoe, and a rocker shoe were analysed. The shoes were tested both with and without a 10-degree full-length laterally wedged insole. Results: There were significant shoe*wedge interactions on the first and second peak knee adduction moments. However, the variability of this moment between shoe designs was of similar magnitude as the effect of laterally wedged insoles. Only marginal changes in muscle activity for gastrocnemius when walking with the wedged Oxford shoe were revealed. Conclusion: Lateral wedging is effective regardless of shoe design. Differences between the three neutral walking conditions underline the importance of footwear choice in individuals. It is safe to apply lateral wedges without jeopardising muscular control during walking regardless of shoe type. Possible effects of altering neuromuscular control by shoe type needs further exploration in patient groups.
Hiking boots provide an interface for walking in challenging environments, typically equipped wit... more Hiking boots provide an interface for walking in challenging environments, typically equipped with a shaft to provide ankle joint stability in rough terrains. Currently it is unclear if the ankle joint is stabilized to an extent that protects against ankle injuries, and if so, to what degree this added ankle stability sacrifices ankle mobility and hence decreases efficient gait propulsion. The aim of the present study was to compare the effect of shaft construction and stiffness on lower extremity kinematics and kinetics during level and step-down walking to simulate hiking conditions. Thirteen healthy males walked in one low-cut and three shafted commercially available hiking shoes with varying shaft stiffness. Lower extremity kinematics and ground reaction forces were recorded simultaneously. During level walking, ankle plantar-dorsiflexion range of motion was significantly reduced for the stiffest shaft hiking shoe compared to the low-cut shoe. A reduction in the muscle contribution to ankle joint work was found for all shafted shoes compared to the low-cut shoe. The reduced ankle joint work for the shafted shoes conversely increased eccentric knee joint work. Kinematic and kinetic differences between shoes diminished during box step-down walking. The present study shows that shaft height and stiffness can influence ankle joint range of motion, and ankle and knee joint work, with the high-shaft shoes redistributing load from the ankle to the knee joint. This may have implications for gait efficiency and increase the risk of knee joint loading or injuries.
The impact maximum of the ground reaction force (GRF) has been discussed extensively in the conte... more The impact maximum of the ground reaction force (GRF) has been discussed extensively in the context of running injuries while numerous footwear-related papers aimed at modifying this parameter mainly by shoe construction. Several mechanisms have been proposed but to date the regulation of impact forces in running is not completely understood. In this paper findings on impact regulation will be reviewed and a statistical approach will be used to analyze variations in contact mechanics in 10 runners. Subjects were tested during running at 4 m/s on an instrumented treadmill. Sagittal plane kinematics, rearfoot eversion, tibial acceleration, pressure under the heel inside the shoe and vertical GRF were collected simultaneously over 19 ± 2 steps. Linear correlations were used to investigate relationships between single variables. A general regression model across the entire data set was employed and variable selection by backward elimination revealed the factors subject, minimum knee angle, rearfoot inversion at touch-down (TD) and the vertical velocity of the foot at TD as variables with the strongest contribution to the fit of the model. These four kinematic variables were re-entered in intra-individual regressions revealing an average R2 of 0.926 and an average power of the model of over 80%. The results support previous studies that suggest kinematic parameters to be linked to impact regulation. However, each subject appears to make use of individual combinations of mechanical impact modulation factors while some variables showed inverse relationships compared to results from intervention studies. Muscular activation remains as a possible factor in the regulation of touch-down mechanics in running and may be linked to running injuries.
The purposes of this study were to examine gender differences during drop jumps, to evaluate the ... more The purposes of this study were to examine gender differences during drop jumps, to evaluate the effect of a set of simple instructions on kinematic and kinetic parameters during a drop jump, and to determine if there are gender differences in the effects of instruction on those parameters. Twenty-five basketball players, 13 men and 12 women, performed drop jumps from a box (height 30.5 cm) after being asked to perform a land and jump movement as they normally would do when aiming at maximum jump height. The experimental group received a set of instructions designed to make them land softer. The measured parameters were impact force at landing, ground contact time, flight time, frontal plane knee angle, sagittal plane knee angle, and distance between the knees. When the groups were examined by gender, no differences in the parameters were seen in men after instruction, but in women the following significant differences were detected: an increase in contact time, a decrease in landing force, and a decrease in inward movement of the knees after landing. These data indicate that females respond differently to jumping/landing instructions.
This study compared metabolic power (MP) and time trial (TT) running performance between Adidas A... more This study compared metabolic power (MP) and time trial (TT) running performance between Adidas Adizero Adios (AAA) and Nike VaporFly 4% (NVP). Thirty-seven runners completed three laboratory sessions and two field sessions (n=30). After familiarization (visit 1), participants completed eight 6-min treadmill running bouts (four with each shoe, counterbalanced) at their preferred pace, and MP was assessed using indirect calorimetry (visits 2 and 3). During visits 4 and 5, participants completed two outdoor TTs (~3.5 km) in NVP and AAA (counterbalanced). Compared with AAA, NVP exhibited superior MP (NVP: median=13.88 (Q1–Q3=12.90–15.08 W/kg; AAA: median=14.08 (Q1–Q3=13.12–15.44 W/kg; z=−4.81, p<.001, effect size=.56) and TT (NVP=793±98 s; AAA=802±100 s, p=.001; effect size=.09). However, there was no relationship between changes in MP and changes in TT between shoes (r=.151 p=.425, 95% confidence interval=[−.22; .48]). Our results demonstrate that NVP, compared with AAA, improves M...
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Papers by Uwe Kersting