TIME OF FLIGHT, FREQUENCY AND LENGTH OF STRIDE IN WALKING

Abstract

competitive walking requires the athlete to keep up a high speed throughout the race. This, however, must be done while abiding by the regulations according to which the athlete is required to remain in contact with the ground at all times. 0~ingt o the obvious energy saving and speed gain that can be achieved through short flight phase all too often athletes attempt to remain temporarily in fli ght or, at least, are unable to prevent themselves from doing so. the times of flight, the length and frequency of stride of 16 (10 men and 6 women) international level walkers were evaluated. The subjects were required to cross twice - while walking - a 8 m conductance-footboard (connected with a stopwatch) placed at ground level and covered with the same material as the race track, over a 200 m course completed at increasing speeds: 5 for male athletes - 12, 12.65, 13.3, 14.1, 15; and 3 for female athletes - 12.65, 13.3, 14.1 km/h. Flight phases were noticed in all athletes, at all speeds and almost in all strides. It was also observed that flight times tended to increase on a rather steady basis as the speed itself increased - (mean values ±SD) for male athletes: 30.2 ±12.7, 32.7 ± 10.9, 35.6 ±7.9, 39.5 ± 6.9, 43.3 ± 6.3 ms, coefficient of correlation r = 0.999 (SEE = 0.21),coefficient of regression b=4.43;for female athletes:39.2±4.2,41.3±4.4,45.3±3.7ms,r=0.993 (SEE=0.52), b=4.23 - this also involving an increase in frequency - male athletes: from 3.23 to 3.49 steps/s, r = 0.997 (SEE = 0.94, b = 0.09, female athletes: from 3,47 to 3,62 steps/s, r a 0.990 (SEE =0.01), b = 0.10; -and in the length of stride - male athletes: from 102 to 118 cm, r = 0.926 (SEE = 0.47), b = 5.54. The times of flight and frequency of stride were observed to be clearly greater among female athletes, while the length of their stride showed to be shorter. We also asked a coach of high international status to visually evaluate any occurrence of flight phases. Generally, the athlete was evaluated by the coach in lifting when the time of flight as measured with the platform approached and/or exceeded 40 ms. The coach's evaluation on the occurrence and/or the extend of flight phases, however, did not always tally with instrumental findings, as differences - at tines even substantial -were noted between the objective and subjective assessment. In this connection, a role is also likely to be played by an “aesthetic” kind of subjective assessment on the walking technique, which, however, can mislead the judge as far as the-actual lifting is concerned. Speeds as currently observed during international competitions and the technique required to reach such speeds do not enable the athlete to avoid flight phases altogether. In the light of this investigation, we believe that the regulations should be changed. Indeed, leaving the assessment entirely up to the judge's sight seems to be rather unsatisfactory. We also feel that an apparatus such as the one we used or any other equipment of today's technology could be easily used to make evaluation more objective.