Biomechanics of the running gait.ppt
- 1. By : Jemini Parmar
- 2. Gait • Gait is described as the translatory progression of the body as a whole, produced by coordinated , rotatory movements of body segments.
- 3. Gait cycle • The gait cycle is the time interval or sequence of motion occurring between two consecutive initial contact of the same foot. • A gait cycle spans two successive events of the same limb: 1. Stance phase – 60 % 2. Swing phase – 40%
- 4. Phases and events in gait • Stance phase Initial contact Foot flat Midstance Heel off Toe off • Swing phase Early swing Mid swing Late swing
- 6. The Running Gait Cycle • Running is defined as a gait wherein the swing phase is longer than stance phase, and there are two periods within the gait cycle when neither lower limb is in contact with the ground. • Running requires: 1. Greater balance 2. Greater muscle strength 3. Greater joint range of movement
- 7. • Greater balance is required because running is characterized not only by a considerably reduced base of support but also by an absence of the double-support periods observed in normal walking and the presence of float periods in which both feet are out of contact with the supporting surface. • Muscles must generate greater energy both to raise HAT higher than in normal walking and to balance and support HAT during the gait cycle. • Muscles and joint structures also must be able to absorb more energy to accept and control the weight of HAT. • As the body transitions from walking to running , changes occur in spatial and temporal variables of gait.
- 9. Phases of running gait cycle Stance phase Absorption Propulsion Swing phase Initial swing Terminal swing
- 10. Stance phase 1.Absorption •The time from initial contact of the foot to the time of midstance. •About 80% of runners make initial contact on the heel. •As the name of this phase implies, its purpose is to absorb the forces of the foot impacting with the ground. 2.Propulsion •Body’s COM moves over the weight-bearing foot at midstance, the opposite limb is swinging forward.
- 11. • While the stance heel is moving off the ground as it initiates its forward propulsion, the swing leg continues its forward advancement and begins preparations for stance. • Once the foot leaves the ground, the stance phase ends, and the limb moves into the first double float phase.
- 12. Swing phase 1. Initial swing • The first half of initial swing is the first double float phase when both limbs are off the ground. 2. Terminal swing • The second half of the swing phase is marked by a change from acceleration to deceleration in preparation for initial contact.
- 13. Kinematics • kinematics deals with movement without consideration of the forces that cause that movement.
- 14. Joint motion Initial contact to midstance Midstance to toe off Initial swing Mid swing Terminal swing Hip joint 45° - 20° flexion 20° flexion - 5° extension 5° - 20° extension 5° - 20° extension 65° - 40° flexion Knee joint 20°- 40° flexion 40° - 50° flexion 15°- 5° flexion 15°- 5° flexion 130°- 20° flexion Ankle joint 5° PF - 10° DF 10°-20° DF 20°-30° PF 20°-30° PF 0 - 5° DF to 5° PF
- 15. Trunk & pelvis Hip joint Knee joint Ankle & foot Sagittal plane Increase speed , Lowered COM, Progressive forward lean of trunk, Anterior pelvic tilt, Similar to walking, Except extension in toe off, Terminal swing – hip moves towards extension , Maximum flexion – terminal swing Similar to walking, Stance phase – knee moves from 45° (absorption) to 20° extension (propulsion), Midswing – knee flex 90° to 130° flexion, 20° dorsiflexion before midstance , Propulsive phase , Plantarflexion Frontal plane Trunk lean towards weight bearing foot, Adduction – initial contact , Propulsive phase , Abduction – toe off Foot hits ground- knee abduction , Then 12° adduction by midstance Subtalar joint - 10° inversion , Immediately eversion, Transverse plane Upper spine - rotates forward in with the arm on(ipsilateral ), Lower spine - backward Medial rotation – absorption phase , Midstance , Lateral rotation – toe off Initial contact – lateral rotation , Medial rotation – absorption phase Weight bearing talus adducts causing the tibia medially rotate,
- 16. Muscle activity • Gluteus maximus and gluteus medius are both active at the beginning of stance phase, and also at the end of swing phase. • Tensor facia lata is active from the beginning of stance, and also the end of swing phase. It is also active between early and mid swing. • Adductor Magnus is active for about 25% of cycle, from late stance to early part of swing phase. • Iliopsoas activity occurs during swing phase for 35- 60% of cycle.
- 17. • Quadriceps works in an eccentric manner for the initial 10% of the stance phase. It stops being active after the first part of the stance phase, there is then no activity until the last 20% of swing phase. At this point it becomes concentric in behaviour so it can extend the knee to prepare for heel strike. • Medial Hamstrings become active at the beginning of the stance phase(18-28% of stance), they are also active throughout much of the swing phase(40-58% of initial swing then the last 20% of swing).
- 18. • Gastrocnemius muscle activity starts just after loading at heel strike, remaining active up until 15% of the gait cycle . It then re-starts its activity in the last 15% of the swing phase. • Tibialis anterior muscle is active through both stance and swing phases in running. It is active for about 73% of the cycle (compared to 54% when walking). The swing phase when running, is 62% of the total gait cycle, compared to 40% when walking, so TA is considerably more active when running. Its activity is mainly concentric or isometric, enabling the foot to clear the support surface during the swing phase of the running gait.
- 19. Kinetics 1. Internal forces • important muscle groups producing power for running comprise the hip flexors, extensors, abductors, knee extensors, and gastrocnemiussoleus groups. • During the first part of stance when the COM is behind the foot, the gluteus maximus and hamstrings must extend the hip to move the body forward. • Once the COM moves over and past the foot, the quadriceps extends the knee and calf muscles plantarflex the ankle to continue to propel the body forward by pushing it ahead.
- 20. 2 . Ground reaction force •Created between foot and the ground , in which the foot and ground exert an equal and opposite force on each other. •The direction and magnitude of the ground reaction force is determined by the position and acceleration of the runner’s center of mass. •After maximum velocity is reached, the center of mass moves backward. •A forward trunk lean and pelvic tilt keep the GRF in a position to allow forward acceleration.
- 21. Elastic Support Strategy • In runners the diagonal elastic support mechanism is utilised. This is produced by a constant diagonal stretch and release that is enabled by the body’s counter rotation. • The force continually flows up and down these force pathways alternately. The pattern of force distribution prevents force being concentrated in one area, but allows wide distribution of force throughout the body.
- 22. Rotation through the Kinetic Chain • The kinetic chain can be described as a series of joint movements, that make up a larger movement . • Running mainly uses sagittal movements as the arms and legs move forwards. • There is also a rotational component as the joints of the leg lock to support the body weight on each side. • There is also an element of counter pelvic rotation as the chest moves forward on the opposite side.
- 23. References • Levangie, Pamela K., and Cynthia C. Norkin. Joint structure and function: a comprehensive analysis. FA Davis, 2011. • Houglum PA, Bertoti DB. Brunnstrom's clinical kinesiology. FA Davis; 2011 Dec 7. • Houglum PA. Therapeutic exercise for musculoskeletal injuries 4th edition. Human Kinetics; 2016 May 18.
Editor's Notes
- #18: Concentric – initial and mid swing , Eccentric – controls knee extension also cause hip extension simultaneously