Analytical Study for Some Variables of the Stride and Performance Level for the Racewalkers

Introduction

Racewalking is progressive striding executed while contacting the ground continuously, as the front foot contacts the ground before the back foot is lifted, and it is better not bending the knee when performing the columnar position (IAAF competition rule, no. 230, 2014)

This rule was introduced in 1995, and before 1995 the leg had to be straightened in a vertical position. The athletes had to develop the pattern of the special movements’ characteristics which is known as “race walking style”, although it has been used worldwide by all athletes. (Pavei, et al, 2012)

The stride length of the world’s best racewalkers ranges between 2.44m and 2.72m (for men). (Hanley, B. et al, 2008)

It is important to determine the variations in the angles of the upper and lower limb joints, and each individual’s points of strength and weakness to achieve the best performance for each racewalker.

The gait cycle has two strides – a left stride and a right stride. The basic description of the gait cycle is the cycle that includes a complete stride, the length of a single stride, and the foot angles. The length of the full distance stride is between the two successive heel contacts of the same foot, while the length of one stride is the distance between the two successive heel contacts of the two different feet. The main factor

that describes a gait cycle is the stride frequency (stride rate), and there is another factor to describe the gait cycle which is the stride time (full distance gait cycle), single stride time (the time of executing one stride with either the right or the left foot), speed of walking. A gait cycle can be divided into two major phases: the pulling phase which forms about 60% of the gait cycle (from the contact of the right heel to the right toe off) and the swing phase which forms about 40% of the gait cycle (from the right toe off to the next right heel contact). (Donald A. Neumann, 2010, pp631-637)

The principal aim of the relatively large amounts of pelvic rotation is to place the feet along a straight line to assist in increasing the stride length.

The stride width is sometimes referred to as the walking base or base of support (Levine et al., 2012). By contrast, by keeping the stride width narrow, less lateral movement is needed to maintain balance and therefore muscular energy is reduced (Levine et al., 2012). The normal width of the stride usually ranges between 5 and 13cm (Levine et al., 2012).

The ankle is obviously an important joint in all forms of gait. Its orientation can be defined by a line passing between the tips of the medial and lateral malleoli (Czerniecki, 1988), and Cairns et al. (1986). The normal state of the foot is when the ankle at 110°; as the angles get greater than this with plantarflexion and the angles get lesser with dorsiflexion. The range of ankle dorsiflexion during late swing was greater in the competitive pace condition (27° ± 7) than in normal walking, fast walking or running. The ankle joint is also considered important in late stance as plantarflexion aids the drive phase of the stride and the plantarflexion angle at toe-off in race walking was found to be higher than in normal walking (Preatoni et al., 2006).

Domestic researches on the athletic sports by kinematics and biomechanics have been continuously carried out in various forms such as the researches related to analysis of stride length, stride time, stride length, flight time, stride frequency, knee angle at contact, hip angle, pelvic rotation, shoulder rotation, leg pathway deviation, speed, performance time.

Therefore, the researcher conducted this study to identify the relationship between the angle of foot rotation at pushing off and the stride length and the time of performance for racewalkers.

This study aims to identify the relationship between the angle of foot rotation at pushing off and the stride length and the time of performance for racewalkers.

Methods

The researcher analyzed the stride of the racewalking competitors who participated in the republic’s competition of Egyptian racewalk championship in Cairo stadium from 28-30 October 2015.

Sample:

The sample consisted of (10) racewalkers from the Egyptian racewalk championship in Cairo stadium from 28-30 October 2015, the average age was (26.20 ± 3.99 years-old), body height (171.50 ± 3.54 cm) and body mass (67.10 ± 3.07 kg).

Data collecting tools

Data analysis: Dartfish v4.5 program was used to calculate the data. Racewalking speed was determined as the mean horizontal speed of the center of mass during one complete gait cycle (using Dartfish) 1 camera was placed approximately 12m from and perpendicular to the line of walking and another camera was placed approximately 5m from and perpendicular to the finish line, variables and gait events of interest were defined as follows:

• Angle of foot Rotation at pushing off.

• Stride length.

• Stride frequency.

• Stride time.

• Time of performance.

• Speed of performance.

Attachment (1) good Push off image and Bad push off Image.

Results:

Table ( 1 ) Race walking performance and some variables of stride for walker parameters ( Time of Performance, Speed of performance, Stride length, stride frequency , Stride Time and Angle of foot Rotation  at the push ).

Table ( 2 ) The relationship between Angle of foot rotation  at the push on some variables of stride and performance for walker ( Time of Performance, Speed of performance, Stride length, stride frequency , Stride Time and Angle of foot Rotation  at the push ).

P > 0.05