Article Figures & Tables
Figures
- Fig. 1.
The orientation of the equine digit during foot on and foot off. The accelerometer is mounted axially on the dorsal hoof wall with the sensitive axis orientated disto-proximally. Critically, the foot acceleration vector (indicated by the red arrows) is orientated along the sensitive axis of the accelerometer at foot on (d) and at foot off (g). However, during roll over (f), when the heel of the foot (the most rearward point of the ground-bearing surface) has left the ground and the foot is rotating around the toe (the most forward point of the ground-bearing surface), the vector is orientated orthogonal to the sensitive axis.
- Fig. 2.
An accelerometer and telemetry unit in place on the distal limb of a horse. The telemetry unit and battery are contained within the exercise bandage and mounted on the lateral aspect of the third metacarpal bone. The accelerometer is encased in epoxy and Kevlar fibres, mounted on the dorsal surface of the hoof and protected from abrasion by the exercise surface with electrical insulation tape.
- Fig. 3.
Representative graphs of simultaneous peak vertical ground reaction force (GRFz) and accelerometer data collected during walk (A), trot (B) and canter (C) locomotion. For walk and trot trials, force plate data were collected for both front limbs (red broken line) and hind limbs (green broken line) during the same trial. Beneath the force outputs, the corresponding accelerometer traces are shown. Vertical broken lines indicate the timing of foot on (a) and foot off (b). The red solid line indicates the output from the forelimb accelerometer, and the green solid line the hind limb accelerometer data. Note the precipitous rise in force at foot on and the rapid drop in force at foot off, which allow the accurate determination of foot on and foot off from vertical force data alone. Also note the absence of features in the accelerometer trace during the stance phases, except a minor undulation shortly prior to foot off, corresponding to heel off and foot rotation. The automatic gain control in the telemetry link means that whilst the accelerometer signal amplitude is the same in all three plots, the actual acceleration will differ.
- Fig. 4.
Comparison of different accelerometer mounting positions by simultaneous collection of data from several accelerometer locations. The output for the hoof-mounted accelerometer is always shown in green, and the comparison location in red. The output during locomotion on a hard surface of an accelerometer mounted on the lateral aspect of the third metacarpal bone (MCP) at walk (A) and trot (B), and the output of an accelerometer mounted on the proximal phalanx (prox. phalanx) during walk (C) and trot (D) are shown. The output during soft surface locomotion of an accelerometer mounted on the proximal phalanx during walk (E), trot (F) and canter (G) is also shown. Vertical broken lines indicate the time of foot on (a) and foot off (b). Accelerometer output in volts cannot be converted to m s–2 due to automatic gain control within the analogue telemetry system used.
- Fig. 5.
Mean (± s.d.; broken lines) vertical ground reaction force (blue) relative to percentage of stance duration for the forelimb and hind limb at walk (A,B) and trot (C,D), and lead and non-lead forelimbs at canter (E,F). A sine wave of equal base and area is superimposed in red over the ground reaction force. Values in the upper left corner of each graph indicate the percentage of the stance time for which the sine wave lies within 1 s.d. of the mean force.
- Fig. 6.
Histograms showing the distribution of errors in peak limb force prediction for individual stance phases using a sine wave of same base and area at walk (A) and trot (B) and for the non-lead (C) and lead limbs (D) at canter.
- Fig. 7.
(A) Plot of front:hind ratio of peak vertical ground reaction force (GRFz) versus peak forelimb GRFz, expressed as percentages. Data are shown for walk (red diamonds), trot (green triangles) and canter non-lead leg (filled blue circles). The linear regression line is fitted to all data (y=1.6198–0.0358x, r2=0.2722, P<0.0000). (B) Plot of front:hind vertical impulse ratio versus peak GRFz, expressed as percentages. Symbols are as for A. The horizontal red solid line shows the mean ratio across all speeds (1.33). The red broken lines indicate ± s.d., and the blue broken lines indicate the inter-quartile range.
- Fig. 8.
Scatter plot of predicted peak vertical ground reaction force (GRFz) versus actual peak GRFz. Both are normalised to body mass. Data are shown for walk (red diamonds), trot (green triangles), non-lead leg at canter (blue circles) and lead leg at canter (black squares). The red line indicates the function y=x. The red star shows the position of the mean of the average lead and non-lead limb data.
- Fig. 9.
Difference in metacarpophalangeal (MCP) joint extension angle between left and right forelimbs during treadmill locomotion at a range of speeds and gaits for four horses. Colours indicate individual horses.
Article navigation
Related articles
Cited by...
More in this TOC section
Similar articles
Other journals from The Company of Biologists
Predicting the Future: Species Survival in a Changing World
Read our new special issue exploring the significant role of experimental biology in assessing and predicting the susceptibility or resilience of species to future, human-induced environmental change.
Big Biology Podcast - Hollie Putnam and coral bleaching
Catch the next JEB-sponsored episode of the Big Biology Podcast where Art and Marty talk to Hollie Putnam about the causes of coral bleaching and the basic biology of corals in the hope of selectively breeding corals that can better tolerate future ocean conditions.
Read Hollie's Review on the subject, which is featured in our current special issue.
Stark trade-offs and elegant solutions in arthropod visual systems
Many elegant eye specializations that evolved in response to visual challenges continue to be discovered. A new Review by Meece et al. summarises exciting solutions evolved by insects and other arthropods in response to specific visual challenges.
Head bobbing gives pigeons a sense of perspective
Pigeons might look goofy with their head-bobbing walk, but it turns out that the ungainly head manoeuvre allows the birds to judge distance.