Gait and motion Biomechanics

Note: This webpage is incomplete, please refer to the pdf version of the notes on blackboard

Gait Biomechanics

University of Reading references are

Definitions and concepts

gait cycle A complete stride from initial contact to initial contact
Step length distance between left and right foot placement
Stride lengthdistance covered in one gait cycle
stride 2 steps or 1 pace
Cadence steps per second

The roman definition of a pace is two steps. Since a roman mile is defined as 1 mile=1000 paces this gives a step as approx 800mm

Animal Gaits

Gaits can be static or dynamically stable, symmetrical or asymmetrical and mostly involve an even number of legs[Alexander92:_explor_biomec].

A gait is described by two variables for each foot:

  1. Relative phase, phase shift between the different feet
  2. Duty factor (fraction of the time spent on the ground)

Quadruped gaits

some animals
Trot Pig
Canter equine
Transverse gallopElk
Rotary gallop
Rack/Pace Giraffe/Camel
Pronk
Walk
Bound/Buck

See Gresham Lecture[stewart13:_how_mathematicians_think_about_patterns] "How Mathematicians think about patterns" (at 55:00 mins)

Examples of cheetah running gait with Hildebrande diagram, also zebra running gait in (https://mammals-locomotion.com/walking.html)

Symmetrical gaits

Footfalls of a pair of feet are equally spaced in time

Asymmetrical gaits

Footfalls of a pair are not equally spaced in time

Muybridge galloping horse (wikimedia.org)
Statically stable tripod gait. Toni Wöhrl, CC BY-SA 3.0, via Wikimedia Commons

Figure t.b.d. (fig:tripod) is from Alexander 1992[Alexander92:_explor_biomec]

Figure 1: Symmetric and asymmetric animal gaits. (Wikimedia, `Gait graphs' ronhjones 2012, after Hildebrand)

Human gaits

Biped gait can be considered as several states in two phases

Stance phase

Swing phase

Whittle's figure 5, position of the legs during a single gait cycle (right leg blue)
Eadweard Muybridge the man who started it all

There is discussion as to the principles of human walking in particular do we walk to save energy or to avoid accelerating our head and body[kuo2007six]

Section missing

Ground reaction forces

Ground reaction forces (GRF) during walking. (AP-shear is anterioposterio forces i.e. the GRF pushes you back as your foot strikes the ground, and you push against this force as foot leaves the ground. From (http://doi.org/10.1177/0309364613485112)
Ground Reaction Force (GRF) measured below a foot while walking. From (http://doi.org/10.1007/978-1-4419-8432-6_3) adapted from Winter DA (1991) The biomechanics and motor control of human gait: normal, elderly and pathological. University of Waterloo press, Ontario.
Sagittal plane ground reaction force `Butterfly diagram' (Juan Carlos Muñoz 2012, Research Gate)

Force plate butterfly

bare foot running

Gait initiation and termination

Initiation requires

Termination

Age and pathology determinates of gait

Gaits evidently change with age and with conditions such as cerebral palsy, muscular conditions such as SMA or MD, Parkinson's disease, stroke, orthopaedic difficulties, etc. For details see texts such as Whitaker, Perry etc.

Young gaits

Parkinson's

Appendix, passive dynamic walkers

Knees

No knees

Ruina lab Cornell

28/11/2023