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Normal subjects were loaded with increasing weights (2-6 kg) applied around the ankles. During these conditions stride length increased in relation to velocity. The percentage duration of single support in relation to stride duration increased. Provided the same load was applied around both ankles increase was symmetrical. Consequently there was also an increase of swing as well as a decrease of stance and of double support. The results contrast in all respects to what was found in previous experiments when the load was carried in the hand. During these conditions stride length decreased as well as the duration of single support. The two experimental conditions differed in that with ankle loading the swing phase was loaded while in the other case stance was loaded. The two types of experiment may help to explain why some patients with paretic legs walk with short strides, while others walk with strides that are normal or slightly prolonged.

The gaits of 15 patients with peripheral and central paresis were studied. They were compared both with a control group of the same age and sex and with a group of nine subjects who carried varying weights. Velocity was low in the patients and this was due to decreases of both stride length and stride frequency. Load did not significantly decrease the velocity of the control subjects, since unlike the patients, they had the ability to compensate for a low stride length by significantly increasing stride frequency. The significant lowering of stride length in both groups was a similarity between them. The patients were also similar to the loaded normal subjects in having a shortened duration of the single support and a prolonged double support. The patients with hemisymptoms also showed significant differences between the two sides for the durations of both single and double support. The results obtained from this study justify our hypothesis that a subject who is carrying a load may in certain respects be considered as a model of a subject with paresis. The remaining differences may be explained by the fact that in the experimental situation, the leg was loaded only during stance, while in paresis the legs may be considered relatively loaded during the whole stride.

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