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Biomechanics of Locomotion D. Gordon E. Robertson, PhD, FCSB Biomechanics, Laboratory, School of Human Kinetics, University of Ottawa, Ottawa, Canada D.

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Presentation on theme: "Biomechanics of Locomotion D. Gordon E. Robertson, PhD, FCSB Biomechanics, Laboratory, School of Human Kinetics, University of Ottawa, Ottawa, Canada D."— Presentation transcript:

1 Biomechanics of Locomotion D. Gordon E. Robertson, PhD, FCSB Biomechanics, Laboratory, School of Human Kinetics, University of Ottawa, Ottawa, Canada D. Gordon E. Robertson, PhD, FCSB Biomechanics, Laboratory, School of Human Kinetics, University of Ottawa, Ottawa, Canada

2 Quantitative Domains Temporal –phases (stance/swing) and events (foot- strike, toe-off), stride rate Electromyography –muscle activation patterns Kinematic (motion description) –stride length, velocity, ranges of motion, acceleration Kinetic (causes of motion) –ground reaction forces, pressure patterns, joint forces, moments of force, work, energy and power

3 Temporal Analysis Stride time (s) Stride rate = 1/time (/s) Stride cadence = 120 × rate (b/min) Instrumentation –Photocells and timers –Videography (1 frame = 1/30 second) –Metronome

4 Donovan Bailey sets world record (9.835) despite slowest reaction time (0.174) of finalists

5 Electromyography Delsys electrodesMega system Noraxon systemBortec system

6 EMG of normal walking gait initiation rectus femoris vastus lateralis tibialis anterior gastrocnemius biceps femoris heel switch strides

7 EMG of normal walking rectus femoris vastus lateralis tibialis anterior gastrocnemius biceps femoris heel switch rectus femoris contracts twice per cycle, once in early stance and once in late stance

8 EMG of normal walking rectus femoris vastus lateralis tibialis anterior gastrocnemius biceps femoris heel switch biceps femoris has one longer contraction in late swing and early stance, synchronous with one burst of rectus femoris

9 EMG of normal walking rectus femoris vastus lateralis tibialis anterior gastrocnemius biceps femoris heel switch tibialis anterior has two bursts of activity one in mid-swing and one during early stance. It is very active at initiation.

10 EMG of normal walking rectus femoris vastus lateralis tibialis anterior gastrocnemius biceps femoris heel switch gastrocnemius has one long contraction throughout stance. It is asynchronous with tibialis anterior.

11 Kinematic Analysis Linear position –Ruler, tape measure, optical Linear velocity –radar gun, photo-optical timer Linear acceleration –Accelerometry, videography miniature accelerometers radar gun

12 Motion Capture Cinefilm, video or infrared video Subject is filmed and locations of joint centres are digitized Panasonic videocamera Basler charge-coupled device (CCD) camera Vicon infra-red camera

13 Gait Characteristics - Walking

14 Gait Characteristics – Running/Sprinting

15 Motion Capture (e.g., SIMI or Vicon) 3D motion data EMG data F-Scan data Force platform data Video data

16 Passive Infrared Motion Capture (e.g., Vicon or M.A.C.) Infrared video cameras Kistler force platforms M.A.C. system

17 Active Infrared Motion Capture NDI’s Optotrak Infrared video cameras Infrared emitting diodes

18 Gait and Movement Analysis Laboratory Motion capture system for marker trajectories Force platforms for ground reactions Electromyography for muscle activity Pressure mapping systems for in-shoe pressure patterns

19 3D Geometric Model (Visual3D) from stick-figures to geometrical solids of revolution with known inertial properties from markers to joint centres and stick-figure of body

20 Kinetic Analysis Causes of motion Forces and moments of force Work, energy and power Impulse and momentum Inverse Dynamics derives forces and moments from kinematics and body segment parameters (mass, centre of gravity, and moment of inertia)

21 Normal Walking Example Female subject Speed was 1.77 m/s (fast) IFS = ipsilateral foot-strike ITO = ipsilateral toe-off CFS = contralateral foot-strike CTO = contralateral toe-off

22 Results Trial: 2SFN3 Ang. velocity Moment Power CFS ITO IFS CTO CFS ITO Dorsiflexion Plantar flexion Dorsiflexors Plantar flexors Concentric Eccentric Angular velocity tells whether joint is flexing or extending Moment of force records whether flexors or extensors are performing work Power quantifies whether work done was positive or negative

23 Ankle angular velocity, moment of force and power Dorsiflexors produce dorsiflexion during swing Plantar flexors control dorsiflexion Large burst of power by plantar flexors for push-off Trial: 2SFN3 Ang. velocity Moment Power CFS ITO IFS CTO CFS ITO Dorsiflexion Plantar flexion Dorsiflexors Plantar flexors Concentric Eccentric

24 Knee angular velocity, moment of force and power Negative work by knee extensors to control flexion at push-off another to cushion weight-acceptance Negative work by knee flexors to control knee extension prior to foot-strike Trial: 2SFN3 Ang. velocity Moment Power CFS ITO IFS CTO CFS ITO Extension Flexion Extensors Flexors Concentric Eccentric

25 Hip angular velocity, moment of force and power Time (s) Power (W) Moment (N.m) A ng. Vel. (rad/s) Trial: 2SFN3 Ang. velocity Moment Power CFS ITO IFS CTO CFS ITO Flexion Extension Flexors Extensors Concentric Eccentric Positive work by hip flexors to swing thigh & flex knee Positive work by hip extensors to extend hip in early stance Negative work by hip flexors to control extension

26 Solid-Ankle, Cushioned Heel (SACH) Prostheses

27 Ankle angular velocity, moment of force and power of SACH foot prosthesis No power produced during push-off Trial: WB24MH-S Ang. velocity Net moment Power ITO IFS CTO CFS ITO Dorsiflexing Plantar flexing Dorsiflexor Plantar flexor Concentric Eccentric Power dissipation during weight acceptance and push-off

28 FlexFoot Prostheses (energy-storing) Recent models Original model

29 Ankle angular velocity, moment of force and power of FlexFoot prosthesis Some energy returned during push-off Time (s) Trial: WB13MH-F Ang. velocity Net moment Power ITO IFS CTO CFS ITO Dorsiflexing Plantar flexing Dorsiflexor Plantar flexor Concentric Eccentric

30 Above-knee Prostheses

31 Running Prostheses


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