Normative trends in the gait patterns of modern man can be used to reconstruct crucial characteristics of the bipedal behaviour of Pliocene hominids from their fossilized footprints. In this reconstruction the interrelated parameters of velocity, stride-length, and cadence are determined from imprints made in damp volcanic ash some 3.7 million years ago. When early hominid footprint data is fitted to regression equations of high predictability for the interrelationship of these locomotor parameters in modern man, a pattern of gait emerges that contradicts previous reconstructions.

Pelvic rotation in the transverse plane is an energy-conserving mechanism employed during normal human locomotion. This mechanism functions to increase stride length and thereby decrease the cadence. II has been suggested (Ducroquel et "I. 1968) that the mechanism of pelvic rotation is lost during the metabolically expensive exercise of ascending or descending slopes. Fourteen healthy young adults were walked on a treadmill al five grades from 20%downhill to 20/:" uphill. Pelvicrotations in the transverse plane were measured. The results show that pelvic rotation is not substantially affected during uphill and downhill walking over the range of grades studied. I. IntroductionHuman locomotion is an extremely complex series of interactions, many of which work to keep energy expenditure to a minimum. Saunders et al. (1953) considered the behaviour of the centre ofmass in a model bipedal system in which the lower limbs were represented by simple, footless and rigid levers. In such a system the centre of mass will rise and fall twice during one complete stride (defined as the period from heel strike to the next heel strike by the same foot). The centre of mass is highest as it moves over the supporting limb, around mid-stance, and lowest at the time of heel strike. The energy cost of the rigid-lever system was high because of the large rise and fall of the centre of mass and was calculated to be almost double that found during normal human gait. Using this model Saunders et al. (1953) described six determinants of human gait which act to reduce the amplitude and/or frequency of the sinusoidal motion of the body's centre of mass and, in so doing, increase the efficiency of the gait. The result is that during normal level walking the centre of mass of the human body describes a sinusoidal path of approximately 5 em amplitude.The first 'determinant' to be isolated by Saunders et al. (1953) was the rotation of the pelvis in the horizontal plane, the others being pelvic frontal plane tilt, eccentric loading of the quadriceps during single support, lateral sway of the pelvis with each step and foot and knee mechanisms for smoothing out the otherwise jarring effect of the intermittent rise and fall of the centre of mass. Obviously each of the so-called 'six determinants of gait' is part of a functional whole in a normal human walker, but formulation of discrete determinants was more a means of breaking down the functional complexity of human locomotion, for reasons ofconvenience, rather than an assertion that there are six (neither more nor less) functionally discrete determinants. Thus the promotion of six determinants is as artificial as would be an attempt to show that the focus of this paper, the first determinant, can be related to each of the others. It is helpful, however, to note that pelvic excursions in the transverse plane occur in synchrony with the swinging leg with the left hip joint moving ahead of the right as the left leg swings. The swing phase on the left side coincides with single support on the right si...

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The purpose of this study was twofold: (1) to assess the reliability of both the psychophysical method in determining maximum acceptable loads (MAL) and the use of selected gait parameters in describing locomotor patterns; and (2) to describe and compare the locomotor patterns associated with a number of common load carriage strategies involving the hands and arms. A test-retest experimental design was utilized. Ten males performed five tasks comprising four load carriage conditions and one normal walking condition over a 10m walking distance. The MAL for each carriage task was determined using procedures modified from those described by Snook et al. (1970). Preferred walking speed was calculated from the time taken to cover a standardized portion of the walking distance. The other gait parameters-stride length, cadence and total and double support periods-were obtained using a footswitch technology as described by Wall et al. (1981). The results demonstrated that the procedures used in this study were reliable, in that no significant test-retest differences were found for any of the dependent variables (MAL and gait parameters). No significant differences in MAL were found between the carriage strategies involving two hands, but significantly less mass was chosen in the one-hand carriage condition. Only the two-handed arms-straight carriage condition resulted in significantly different preferred walking speeds. All load carriage conditions except the one-hand carriage condition resulted in significant changes in stride length and/or cadence when compared with normal walking. Only one condition, involving the heaviest MAL, resulting in significantly different total and double support periods when compared with normal walking. There appear to be discrepancies in the literature regarding the effects of load carriage on the various gait parameters. Specific task characteristics, such as the method of carriage, load mass, speed and walking medium, were discussed as potential contributors to the seemingly contradictory results. Subject characteristics, such as gender, age and occupation, may also be confounding factors.

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