Step-down-Answers-Biomechanics-Worksheet copy PDF

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Biomechanics Worksheet: Movement analysis step down Preparatory work: watch someone perform a stepping down movement (from a standard height step), focussing only on the leg which is on the step. Complete the questions below to guide your analysis. Guide to movement analysis; 1. Name the joints involved in the activity Hip, knee, ankle 2. For each joint identify what movement is occurring and in what order Hip: neutral, then flexion Knee: extension, then flexion Ankle: neutral (plantargrade) then dorsiflexion (? May start to PF as the other leg comes in to contact with the ground depending on where the foot is positioned on the step) 3. For each movement identify what axes/planes the movement is occurring in All sagittal plane, frontal axis 4. Name which muscle/muscle groups are bringing about each movement Hip: initial contraction from hip flexors, then eccentric control by glutes and hamstrings Knee: Initial contraction from hamstrings/gastroc then eccentric control by quads Ankle: initial dorsiflexors (primarily tib ant) then eccentric gastroc/soleus 5. What range is the muscle/muscle group working in (inner/middle/outer)? Hip: Glutes – mid, towards outer Knee: Quads – (VL, VM and VI) inner towards mid. RF: mid (due to inner at knee, then mid/outer at hip) to mid (towards outer at knee and inner at hip) Ankle: gastroc mid to mid (as initially outer at knee, mid at ankle. Then inner at knee and outer at ankle) 6. What type of muscle contraction is occurring around the ankle joint? Initial concentric DFs, followed by eccentric control of PFs. 7. Define the type of muscle contraction and explain how this relates to torque? Define in relation to cross bridge movement, sarcomere length, balance of ext and int torque

8. Explain the impact of the calcaneus on torque, and why this provides an biomechanical advantage Anatomical torque – increases PD of insertion point of Achilles from axis of rotation at the TCJ, therefore greater internal torque generated by PFs. 9. Can you give an example of an (open chain) 2 nd class lever using one of the joints involved? Any open chain example using 1, 2, 3, F, L, E. 10. Put Gastrocnemius into a position of potential passive insufficiency – explain the concept and explain why this does not happen during step down Knee ext with ankle DF. Explain concept with idea of restricted movement in to further DF due to passive insufficiency. Avoided throughout the movement, as the 2 joint muscles are doing opposite movements (i.e. lengthening and shortening) at each end of the muscle, therefore remaining in optimal (mid) range throughout. 11. Can you give an example of a local and a global stabiliser for this movement? Global = mm’s of the trunk, or could argue hip abductors to avoid Trendelenburg and therefore maintaining CoG within BoS (could also argue as local stabiliser if considering position of pelvis in relation to being an attachment point for hip mm’s!) Local = could be intrinsic mm’s of the foot which provide a stable base for the DFs/PFs to work from 12. Are there any examples of origin to insertion reversed? O to I reversed at ankle with DFs Activity 1: Watch the video clip of the model doing a step down and identify and differences from ‘normal’ movement. Restricted ankle DF, also valgus knee dip Consider why this may be happening (from a mechanical point of view) and form a potential problem list Restricted ankle DF – could be stiffness in joint, tightness of PFs, possible weakness in glutes/quads/PFs in controlling the movement Valgus knee – could be overpronation at foot causing internal rotation femur, ext rotn tibia. Or, weakness in abductors/lateral rotators at hip. Activity 2:

Using your list, prescribe exercises which would help to address the potential problems identified. Teach (explain, demo, feedback) these to your partner considering the following areas: 1. Aim of the exercise 2. Dosage (to include repetitions, sets, frequency) and justification of this

3. What would your outcome measure be? 4. Can you demonstrate how you would test this? 5. How long would the exercises take to be effective (approx.)?

6. Demonstrate and justify a progression and a regression...