Dr
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01 during the study, the head, arms and trunk accounted for about 68% of the total body mass
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The researchers thought they were shocked by the relationship between stride frequency and stride length
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When the trunk tilts forward, the leg swing faster may mean higher exercise cost,” the researchers said Figure 4 increased torso flexion angle (a) increased landing rate (b) increased impact transient | Anna Warren et al
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The introduction study found that a larger trunk flexion angle had a significant impact on stride, joint motion and ground reaction force
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The more the body leans forward, the legs need to be extended further to prevent the center of gravity from falling outside the support area
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When Lieberman was preparing for the marathon, he noticed that others leaned forward a large distance when running, which may have a great impact on the lower limbs
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Figure 2 (a) with the increase of trunk flexion angle, hip jump significantly increased (b) flexion angle increased and step frequency increased (c) standing phase duration increased with the increase of trunk flexion degree | Anna Warren et al
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The way the body tilts may be one of the causes of knee pain, medial tibial pressure syndrome or back pain
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The more common overuse injury perplexing runners may stem from an unlikely cause: the forward tilt angle of the trunk during running
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“The leg swing is very important when running
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Therefore, the stride and stride frequency will increase
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Figure 3 (a) hip extension torque increases with the increase of trunk bending degree (b) knee extension torque decreases with the increase of trunk bending degree (c) ankle plantar flexion torque decreases with the increase of trunk bending degree | The researchers believe that this may be due to the shortening of the swing phase time (if runners don’t get enough swing time, they will take a smaller stride), which means that the leg swing speed will increase due to the reduction of forward movement
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They recorded each participant’s 15 second test in their chosen torso position and three other torso flexion angles: 10 °, 20 ° and 30 °
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Torso bending (the angle at which the runner bends forward from the hip) ranges widely – the runner’s own description of the angle is about – 2 degrees to more than 25 degrees
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Increased torso flexion resulted in increased hip and knee flexion angles compared to participants’ natural torso flexion
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Greater trunk tilt angle also changed the position of runners’ feet and lower limbs, resulting in an increase in the impact of GRF on the body (load rate increased by 29%; Vertical ground reaction impact transients increased by 20%)
Figure 1 Biomechanical model of trunk bending related to lower limb dynamics and kinematics, it: impact transient peak | Contrary to the team’s initial hypothesis, the results of Anna warreneretal.02 showed that when leaning forward, the average stride decreased by 13 cm, the stride frequency increased from 86.3 steps / min to 92.8 steps / min, and the stride relative to the hip increased by 28%
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Liberman is a collaborator of Warren’s preliminary study at Harvard University
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Dr
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Small changes in trunk flexion angle may significantly change lower limb kinematics and ground reaction force (GRF) during running
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Generally speaking, running is not just a movement from the trunk down – it is a whole body experience
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But for the study to be effective, they must first figure out how to get each runner to bend at the right angle
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The way the body tilts may be one of the causes of knee pain, medial tibial pressure syndrome, or back pain
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A new study by the University of Colorado Denver found that greater trunk flexion had a significant impact on stride, joint motion and ground reaction forces
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The team suspended a lightweight plastic pin from the ceiling above the runner’s head, which can move up or down as needed
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However, this is not the case
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Anna Warren is the first author of the study and assistant professor of anthropology at Denver
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The combination of trunk flexion angle, foot and leg position and GRF variables shows that excessive trunk flexion may be one of the causes of running injury
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To study the impact, Warren and her team recruited 23 non-invasive leisure runners aged 18 to 23
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The stride decreases and the stride frequency increases
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Researchers should consider the impact of trunk flexion on lower limbs when studying running biomechanics
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Researchers believe that they must create a method that can reasonably force subjects to tilt forward without making them feel uncomfortable and affecting their gait during running
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Content source https://www.sciencedaily.com/releases/2021/07/210712092216.htm
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