Instructions: Kneel on the oor with your arms and thighs vertical and your toes just off the floor. (Only your knees and hands should be touching the ground) 1. Pay attention to the forces between the ground and your hands and knees. a) If the vertical component of the force on each appendage had the same magnitude (1/4 body weight) AND the four contact points lie on a rectangle, where would the CP be located? Draw a picture and indicate the CP location. b) In reality, you probably do not have this perfect distribution between your hands and knees. Where do you think the CP (of the net force of the floor on both hands + both knees) is located? Note that you cannot calculate an exact location because you don't know where your CM is located. 2. Resume the quadruped position with both hands and knees (and toes this time) in contact with the ground. a) With your right shoulder and hip against the wall, attempt to lift your left leg slightly off the ground while maintaining contact against the wall with your right shoulder and hip. Don't shift your torso in any direction! 1)) Now move away from the wall and repeat the left leg lift. Did you shift your torso? c) Using the terms base of support, center of pressure, and center of mass (as needed), what is the difference between these two attempts to lift the left leg, and why one was easy and the other impossible? 3. In quadruped support on hands and knees (no toes), attempt to lift both right hand and the opposite side (left) knee slightly off the ground without changing the location of any other part of your body. (this is sometimes called the bird-dog exercise) a) Were you able to stay upright or did you begin to tip over? b) Draw the outline of your 1308 for quadrupedal support: i) on knees without toes (as in #1), ii) on knees with toes touching (as in #2), iii) with left leg lifted off ground, and iv) the bird-dog (diagonal supports lifted). Assume that NONE of these positions were performed against a wall. c) Rank them from most to least challenging (1 being most challenging, 4 being least challenging) and explain what causes more or less difculty in these scenarios using biomechanical term reasoning (FED + equations). d) Focusing on the bird-dog exercise, use mechanical analysis to determine what your success in obtaining that position (whether you began to tip or not) tells you about the location of your CP? Location of your CM? 4. If you've made it this far, you now understand how to manipulate the base of support in quadrupedal postures to alter difculty, mainly by making the B03 smaller. What about making the B08 larger? Try Widening the stance of your palms on the ground to at least twice the Width of your shoulders, keeping elbows fully extended. Assume that you are pressing down on the ground with 25% of your body weight with each hand. a) Consider the impact of this stance on your shoulder joints. Below are FBD's of one arm from hand to shoulder joint in vertical arm quadrupedal support and in this wide-hand quadruped position. Using these diagrams, write out the sum of torques equation using the shoulder joint as the pivot in both scenarios. Note that we are assuming a purely vertical force under the hand in both cases. '3 Cu. F51 5'9 K x (an \"(S (LT-CT: k b) Discuss the pros and cons of choosing this wide stance over vertical arm when selecting a posture for performing exercises in quadruped (Keep in mind that in activity 1, we are manipulating BoS with the goal of targeting trunk muscle strength)