Relationship between forelimb coordination and movement asymmetries during fast gaits, canter and gallop

The coordination and control of human creeping with increases in speed

Changes were documented in the inter-limb and intra-limb timing of well trained adult males creeping at increasing speed on a motor-driven treadmill. A power function (y = axb) showed a good fit to hand and foot stride and support duration (y) and speed (x), a finding that parallels the changes expected in normal upright walking. Similarly, limbs of the same girdle maintained a half-cycle phase lag as speed increased. Swing duration, however, showed cyclical changes with increasing speed, a phenomenon not previously reported either for quadrupedal gait or normal upright gait. Ipsilateral hands and feet abruptly changed their phase-lags at a constant percentage of maximum speed in a manner similar to gait transitions observed in quadrupedal species. Explanations for these transitions were suggested, such as physical constraints on the speed of limb movement and the organism's biomechanical adaptation to increased metabolic energy expenditure.

Effects of growth and speed on hindlimb joint angular displacement patterns in vervet monkeys (Cercopithecus aethiops)

Hip, knee, and ankle joint displacement patterns are compared across both age and speed for five immature vervet monkeys sampled approximately every 6 months over a 3 year period. The analysis indicated that, as a group, the animals displayed no consistent changes in joint patterns as they grew. However, individual animals showed consistent patterns. There were also no consistent effects of size across animals at the walk-gallop transition. This is contrary to McMahon's prediction (J. Appl. Physiol. 39:619-627, 1975) based upon his elastic-similarity model of animal scaling. With increasing speed, when symmetrical gaits were used, all of the animals tended to show a decrease in the relative positions of the hip, knee, and ankle maximum values. Furthermore, across the walk-gallop transition, the animals tended to show a decrease in the range of ankle and knee movements.

A test of Raibert's symmetry equations in animal and human running

Based upon his work with robots, Raibert proposed that a specific class of symmetry equations may be important to animals and humans during steady-state running. In a test of this hypothesis, Raibert found good agreement with his predictions. However, his test was limited to one cat at two speeds and a human at a single speed. For the present study, we duplicated Raibert's methodology and tested his predictions for three cats, two monkeys, and a human at a variety of speeds. Our results indicate that body and limb movements in animals and humans generally are not in agreement with predictions based on the symmetry equations.

Gait characteristics of two macaques, with emphasis on relationships with speed

The gait of a juvenile rhesus monkey as he walked, ran, underwent a run-gallop transition, and galloped on a motor-driven treadmill is described. Additionally, gait data for an adult animal during walking are also presented. Footfall sequences, stride durations, and absolute and relative swing and stance durations for all four limbs are reported, and, where possible, correlated with speed. Furthermore, support patterns and delays between footfalls are presented as a function of speed. The analysis revealed many similarities with previous studies on both primates and other species, but additionally demonstrated that the fore- and hindlimbs may not relate to speed in an identical manner and that galloping is initiated asymmetrically by a single diagonal couplet. The implications of these results in terms of understanding the neural mechanisms by which quadrupeds increase speed are discussed.

The locomotion of the low spinal cat. II. Interlimb coordination

The interaction of the two hindlimbs were investigated by an analysis of the muscular activity and the movements in 14 chronic spinal kittens during treadmill locomotion (i.e. in kittens subjected to a transection of the spinal cord (Th10--12)) one or two weeks after birth). At low speed the limbs were alternating (walk or trot). At higher they were activated more simultaneous, as during gallop. The two limbs could walk at different velocities, as during walking in a circle, when the two belts of the treadmill were driven at different speeds. The duration of the support phases was mainly influenced by the speed of the belt on which the limb was walking. The limbs could still maintain a common rhythm up to a two or three fold speed difference, as the flexion or the first extension phase of the limb walking on the "fast" belt was prolonged and the flexion phase of "slow limb" was shortened. At extreme speed differences the limb on the "fast belt" performed 2, 3 and even 4 steps during one stepcycle of the "slow limb". The placement of the feet was found to maintain the most stable relationship during alternating gaits at different speed differences. It is concluded that all phases of the step cycle are modifiable and that there are several mechanisms coordinating the limbs within the spinal cord.