Lateral foot placement analysis of the sprint start 

By Tom E. Parry, Phillip Henson, John Cooper 

ABSTRACT     Ever since starting blocks were introduced in 1928-29 to facilitate more reliable starting in the sprint events, substantial research has been conducted to evaluate the relationship between the start and overall sprint performance. However, the design of the starting blocks has received little modification from the earliest models. This study investigated the effect of alternative foot-width placements in modified starting blocks on performance at distance interval split times up to 30 metres. The findings suggest that a wider foot placement leads to a more effective start because it reduces the lateral deviation of the initial step, thus optimising the athlete's linear momentum.  

INTRODUCTION    Throughout the history of track and field, speed has been the quality man has most endeavored to conquer. Within the athletics realm, the 100 metres is perceived as the definitive test of human speed. The grandeur associated with success in the event has led to the investigation of the various elements involved, specifically the sprint start.    Ever since starting blocks were introduced in 1928-29 to facilitate more reliable starting in the sprint events (IMF, 2000), substantial research has been conducted to evaluate the relationship between the sprint start and overall sprint performance (Baumann, 1976). However, the structure of the starting blocks has received little modification from the earliest models. Research has covered many areas related to the sprint start, with longitudinal block spacing (Harland Et Steele, 1997), block angle obliquities (Guissard, Duchateau Et Hainaut, 1992), types of start (Stock, 1962; Sigurseth Et Grinaker, 1962; Mendoza Et Sch61lhorn, 1993), the biomechanics of the start (Mero, luhtanen Et Komi, 1983; Schot Et Knutzen, 1992), acceleration (Menley Et Rosemier, 1968; Murase, Hoshikawa, Yasuda, Ikegami Et Matsui, 1975; Van Coppenolle, Delecluse, Goris, Diels, Sea- grave Et Kraayenhoff, 1989), muscular strength, power, and force production (Henry, 1952; Mero Et Komi, 1990; Guissard Et Duchateau, 1990; Young, Mclean Et Ardagna, 1995), being the main topics of the literature. Only very limited research currently exists on foot placement width and its relation to sprint start effectiveness (Biancani, 1975).    A high-quality sprint start can be summarised as the product of effective drive from the blocks and transition to maximal running speed as rapidly as possible. Although a number of variables can positive- ly or negatively affect the effectiveness of the sprint start, it is established that technique is the underlying factor of success. Research has demonstrated movement in a straight line is the optimal path to attain maximal speed. Deviation from a straight line will elicit a loss in horizontal forward force and therefore loss in speed (Biancani, 1975; Mero, luhtanen Et Komi, 1983; Schot Et Knutzen, 1992). However, observational

analysis shows a deviance from the centerline of the lane when exiting the starting blocks at the first or second steps. This movement could be a product of narrow foot placement in the starting blocks and the physical response the body makes to maintain balance. The question of the width of foot placement on the starting blocks was originally conceived at the 1996 Olympic Games in Atlanta, where several athletes mentioned that the starting blocks being used appeared to be very narrow and hence uncomfortable. This raised the question as to whether optimal exit from the starting blocks could be achieved with the current stance or if a greater lateral spacing would provide equal or improved exit and transition to maximal running speed.     The purpose of this study was to investigate the effectiveness of the current starting block design, in particular the relationship between width of foot placement employed and start performance at distance interval split times up to 30 metres.

Methods

Participants    12 male and 10 female varsity level sprinters gave informed consent to participate in the study. For the males the mean (SD±) agewas 20.1 ±1.1 years, height 172.89 ±14.89cm, and weight 73.29 ±5.83kg; for the females the mean (SD±) age was 19.4 ±2.32 years, height 161.8 ±9.45cm, and weight 58.7 ±5.39kg.

Instrumentation     A conventional Pacer® starting block was modified by Gill Athletics® by extending the width of each foot pedal to 30cm rather than the normal 15cm found on a regular block. Three different toe-to-toe foot widths 24cm, 38cm and 52cm, were investigated on the modified block as a determinant of reaction time and start speed.    A Reactime® reaction time monitor (Image 1) with automated start sequence was used to determine reaction time and provide a randomised order of start sequence length. This eliminates any anticipation and learning effect, of the start signal on the results obtained. 

Image 1-Block mounted Reatime start sequencer

    To measure the 5 metres, 10 metres, 15 metres, 20 metres, and 30 metres start split times, a photo-electric timing system was set up on the borders of a Mondo® indoor track lane, with the light on the left hand side of the lane and the light beam receiver (Image 2a) on the opposing side. At 30 metres, a strobe was placed directly opposite the finish line camera, enabling blip marks to be recognised on the data collection software (Image 2b). The lights and receivers were set at a height of 1.2 metres, with the exception of the first one, which was set at 1.0 metres to eliminate missed 5 metres split times from subjects who exit the blocks at a low angle. All split times from the photoelectric system and the photo finish camera were transferred to the Finishlynx® time analysis computer program, where they were analysed to the 1000th of a second.  

Image 2a-Distance interval timing sensor 

Image 2b-Finish line strobe 

Image 3-Foot placement grid 

Conditions of Testing    Each subject completed a total of twelve trials of sprint starts, split into two different sessions. Each session comprised two trials at each of the three separate foot spacing from the block centrepiece. The toe-to-toe foot spacings are classified as:

Conventional (Condition 1): 24cm    Intermediate (Condition 2): 38cm    Lateral (Condition 3): 52cm

 

Image 4- Top frame is 1, center frame is condition 2 and bottom frame is condition 3

    Each subject controlled their own start line to front block spacing, inter-block spacing and block angle obliquities to minimise the amount of manipulated variables and ensure that the main independent variable was foot width. The trials were completed in a randomised order to eliminate any learning effect. Three minutes of rest time were allowed between trials to remove the effects of fatigue. Subjects were started using an auditory start sequence from the Reactime® reaction time (RT) processor, with a randomised start sequence length. The first foot placement from exiting the starting blocks was recorded on a track mounted grid relevant to foot starting position and each start was gradedby each athlete on a perception scale of 1-5, 1 being a poor start and 5 being an excellent start.

Pilot Study    A number of pilot trials using the modified starting block were conducted using high jump athletes who had performed conventional sprint starts previously. The pilot study underlined a few refinements to the collection procedure needed to ensure comprehensive data collection.  

These were:1. Some female athletes were not powerful enough to trigger a reaction time

measure from the Reactime@ measuring device. 2. Foot placement grid squares needed to be in line with the three different

footing positions to obtain a relevant measure between foot placement on the blocks and first foot placement on exiting the blocks.

3. The photo electric timing lights positioned at 5 metres needed to be lowered by 20cm as some subjects exited the blocks at a low angle and therefore ran below the timing light beam not triggering a time.

4. Some subjects created multiple breaks in the timing light beam, therefore, in the cases of two and three flashes the second was taken, the assumption been that the lead arm broke the beam first.

Results    All results collected were recorded to 1/1000th of a second and are presented in mean scores and standard deviation across all three foot placement conditions for reaction time (RT) and the times for the 5 metres, 10 metres, 15 metres, 20 metres and 30 metres intervals (Table 1). 

Table 1  Condition Mean SDRT 1 0.184 0.040  2 0.196 0.064  3 0.210 0.072       5m 1 1.458 0.110  2 1.436 0.193  3 1.447 0.111       10m 1 2.184 0.153  2 2.178 0.153  3 2.190 0.151       15m 1 2.825 0.197  2 2.826 0.196  3 2.820 0.202       20m 1 3.396 0.404  2 3.423 0.243  3 3.432 0.240       30m 1 4.598 0.359  2 4.591 0.353  3 4.596 0.354

       Rating 1 3.370 0.881  2 3.359 0.909  3 2.924 0.947

      Table 1 illustrates a difference at the initiation of the start between the three foot placement conditions in reaction time. The mean time of Condition 1 (0.184s) exhibited a 0.012s and 0.026s, quicker reaction time than Condition 2 (0.196s) and Condition 3 (0.210s) respectively. Figure 1 displays the variance pictorially illustrating the faster initiation of movement from the blocks at Condition 1 and the differences observed at condition 2 and 3 respectively. 

    For the 5 metres interval the advantage gained in reaction time at Condition 1 has diminished with Condition 2 producing the fastest mean time (1.436s), 0.022s and 0.011s faster than condition 1 (1.458s) and condition 3 (1.447s) respectively. Differences are exhibited in Figure 2 below. 

    The difference gained at the 5 metres interval is emulated at the 10 metres interval, with Condition 2 once again providing the fastest mean time at 2.178s, however, the mean difference between Condition 2 and Condition 1 considerably decreased to 0.006S, with Condition 3 being 0.012s slower than Condition 2.  

    At the 15 metre interval from the starting blocks the fastest time was observed at the mean score of Condition 3 at 2.820s. This was faster than both Condition 1 and Condition 2 by 0.005s and 0.006s respectively, which were only separated by 0.001s at this interval. Figure 4 depicts the distinction between Condition 3 and Conditions 1 and 2. 

    Mean scores for the 20 metres interval demonstrate a faster time from Condition 1 (3.396s) than both Conditions 2 and 3 by 0.027s and 0.036s respectively. However, the standard deviation from Condition 1 is almost two times the size of its counter-parts. Figure 5 represents this difference graphically. 

  The differences observed for the 30 metres interval are again reversed to the common trend exhibited at earlier distance intervals, with Condition 2 providing the fastest time at 4.591s. Condition 3 provided the second fastest time with 4.596s and Condition 1 the slowest at 4.598s. Figure 6 represents the mean times observed at the 30 metres interval. 

    Using the time data collected at each distance interval, acceleration was calculated over four subsequent 5 metres intervals and the final 10 metres interval across the three footing conditions. Acceleration data is presented in Table 2. 

Table 2

    The data illustrates that a common curve exists amongst all three footing conditions up to the 20 metres interval where Condition 1 exceeds both Condition 2 and Condition 3 by 0.379 metres per second and 0.582m/s respectively. However, this appears to be the mean peak acceleration gained at Condition 1, with Condition 2 and Condition 3 continuing to accelerate over the 20 metres to 30 metres time period. A comparison of the acceleration curves of each footing condition is presented in Figure 7.  

    First foot placement from exiting the blocks was observed and recorded on a scaled version of the foot-placement grid. The co-ordinate points were then graphed in relation to foot-placement starting position to observe any variability from a straight line and observe the mean depth of foot placement into the track (Figure 8). 

    Data presented demonstrates the mean first foot placement of athletes whose initial foot plant is with the right foot. Left-footed exits did not provide enough data points to provide representative mean data.    The data shows Condition 2 deviated the least from the starting point centreline, only 0.02cm, with Condition 1 deviating a mean distance of 8.7cm to the right and Condition 3 deviating a mean distance of 1.65cm to the left from starting foot position to first foot placement. Depth of foot placement produced similar data with Condition 2 providing the longest distance at 48.10cm, 1.14cm and 4.74cm greater than Condition 3 and Condition 1 respectively.  

Discussion

    As the results illustrate, there is a marked difference between the three foot-placement conditions in reaction time. Condition 1 produced the mean fastest RT time at 0.184s, 0.012s and 0.026s faster than Condition 2 (0.196s) and Condition 3 (b.210s) respectively. However, this difference can be expected, with reaction time being a product of a learned motor programme. Schmidt ft Lee (1999) classify reaction time as a measure of movement programming with every movement having its own unique pattern. With training this pattern becomes more efficientand hence reaction time will become faster. Therefore, it can be assumed the reaction time of the extended foot-width placements at Condition 2 and Condition 3 could provide comparable reaction times to Condition 1 through a training regime.    Although reaction time results present an expected advantage exiting from the regular Condition 1 starting position, times recorded at 5 metres do not adhere to the advantage gained in reaction time. Condition 2 provided the fastest mean 5 metres time at 1.436s, over 0.022s faster Condition 1 (1.458s) and 0.011 seconds faster than Condition 3 (1.447s). Analysis of first foot placement from exiting the blocks (Figure 8) provides a probable cause for the distinction between conditions. Observational analysis has shown a deviation from the centreline of the lane when exiting the starting blocks at the first or second steps. Figure 8 demonstrates from a conventional (Condition 1) start the first foot placement deviates 8.7cm towards the border of the lane supporting the theory of lateral deviance and therefore loss of forward momentum. Exits exhibited from Condition 3 illustrate the opposite of Condition 1, by deviating towards the centre of the lane by a mean of 1.65cm providing a similar deficit in speed production.

However, the first foot placement from Condition 2 demonstrated a deviation of only 2mm fromstarting point, providing an almost direct linear exit from the starting block position. The effects of such a deviation can be presented with the acceleration data, illustrating Condition 2 (3.48m/s) accelerating the fastest, followed by Condition 3 (3.46m/s) and finally Condition 1 (3.43m/s). The movement of the centre of mass in a direct linear path from starting position will provide an immediate advantage by moderating any lateral deviation observed from the centerline and optimising linear momentum.    The times at 10 metres illustrate the continuation of advantage gained at the 5 metres interval, although to a lesser degree. Condition 2 was again the fastest with 2.178s, followed by Condition 1 (2.184s) and then Condition 3 (2.190s). The difference between the fastest, Condition 2, and Condition 1 decreased by 16/1000ths to only 6/1000ths of a second, however differences observed between Condition 2 and Condition 3 increased from 11/1000ths of a second to 12/1000ths of a second. The conflicting differentiations between conditions, observed at the 5 metres and 10 metres intervals may be attributed to a learned motor programme. A programme has already been formed for the sprint start at Condition 1. Both Conditions 2 and 3 are adaptations of this programme and therefore a specific motor programme has to be developed for the movement. It is evident from the data that a sprint start executed from Condition 1 has an assembled movement pattern for the acceleration phase of the start and hence has recovered some of the detriment over the first ten meters. But, with a training programme of sprint starts exiting from the Condition 2 and Condition 3 starting positions, time differentials will be held if not increased through the ten meter mark with Condition 2 maintaining the advantage gained through the first 10 metres.    The sprint times observed at the 15 metres and 20 metres marks appear to deviate from the trend developing. Prior to this point, Condition 2 provided the greatest mean benefit at both the 5 metres and 10 metres distances, an advantage maintained over the conventional Condition 1 and the greater width of Condition 3. The digression of these times from the norm can be associated with subject variance within the trials and therefore the disruption of the developing trend. At 15 metres the distinction between conditions is not significantly large, with Condition 3 (2.820s) holding a 5/1000ths and 6/1000ths advantage on conditions 1 and 2 respectively. Such a difference could establish Condition 3 as the most effective, however, the gain possesses no rationale for being fastest at this interval, being defeated at every interval excluding the fifteen meter point.    At the 20 metres point it appears that Condition 1 (3.396s) has surpassed the other conditions between 15 metres and 20 metres, with a time 0.027s and 0.036s faster than both Condition 2 (3.423s) and Condition 3 (3.432s) respectively. However, analysis of the distribution of times of each condition at this interval, illustrates a greater inconsistency of times attained at the Condition 1 foot position than both the Condition 2 and 3 times. This is displayed through the standard deviation from the mean times, with scores being 0.404s, 0.243s and 0.240s for the three conditions respectively. Such a difference in variability

demonstrates subjects are less consistent from the Condition 1 start position therefore, producing an extensive range of times.    The classification of this interval as a divergence from the developing pattern is substantiated with the advantage once again returning to Condition 2 at the final 30 metres interval. The fastest time is 4.591s, achieved from Condition 2, with Condition 1 (4.598s) and Condition 3 (4.596s) trailing by 7/1000ths and 5/1000ths respectively. The evident advantages gained from a wider than conventional foot placement position, demonstrate the prospect of improved block exit from this position. The earlier time measurements at 5 metres and 10 metres provide a strong case for the use of a wider lateral foot position on the blocks, by giving the greatest advantage immediately after block exit. This proposal is also supported by direction of the first foot placement following block exit, illustrating a direct linear movement of the body mass, and hence a highly effective sprint start.

Conclusions

    The present study provides relevant information on the optimal foot-width position to attain the most efficient sprint start. From this data it can be postulated that the conventional start (Condition 1) may not provide the optimum exit from the starting blocks, and may in fact hinder optimal block exit and consequently speed production. A possible rationale for the choice of Condition 2 could suggest the feet in the conventional start position being too close together, and therefore creating an unbalanced "Set" position. This in turn will cause deviance from the centreline onblock exit, as the foot has to achieve a greater lateral plant position to compensate for the unbalanced exit. This is clearly observable from analysis of the times collected at the 5 metres and 10 metres points. Data accumulated from the Condition 2 starts exemplify the direct linear exit generated (Figure 8), and the subsequent advantage in speed production in the early stages following block exit. This can be highly related to the elimination of lateral deviance at the start.    Condition 3 provides ambiguous results related to its effectiveness as an adaptation of a sprint start. It would appear that Condition 3 places the athlete at the opposite end of the continuum to Condition 1, with the initial foot placement deviating towards the centre- line of the lane, creating a comparable unbalanced situation observed at Condition 1.    In conclusion, Condition 2 provided the optimum sprint start up to the 30 metres mark. Direct linear exits from the blocks and transition to rapid acceleration distinguish Condition 2, as the most effective of the three starts investigated.     The present study has explored lateral foot- width placement as a potential variable of success of an athlete's sprint start. Further studies are to be completed on the development of technique and movement patterning related to the additional starting block width at Condition 2 and Condition 3. In addition to further studies, a new starting block design is currently under construction in conjunction with Gill Athletics, with an endeavor to further improve the initial

gains observed.  Thanks are forwarded to Indiana University and Indiana State University track coaches and athletes for their help and participation, and to the Indiana University Grant-in-Aid Program for their financial support of this research paper.  A follow up study is to be conducted to assess the effects of a learning schedule on early sprint start characteristics, in conjunction with Gill Athletics. 

FROM: IAAF NEW STUDIES IN ATHLETICS 1.2003