The start of a sprint race is that part of the race from the firing of the gun to the departure from the starting blocks and the term usually includes the first strides out of the blocks.
James C. Hay in “Biomechanics of Sports Techniques” (1994) describes: “At the starter’s command ‘on your marks’ the athlete moves forward and adopts a position with his hands just behind the starting line, the feet on the starting blocks and the knee of the back leg resting on the ground. On the ‘set’ the athlete lifts the knee of the back leg off the ground, thereby elevating the hips and shifting the centre of gravity forward. Finally, when the gun is fired, the athlete lifts his hands from the track, swings the arms vigorously (one forward and one backwards), and with a forceful extension of both legs drives the body forward away from the blocks and into the running strides.”
The above describes the motion of the athlete from the time he prepares for the start until he leaves the blocks in the first phase of the race.In preparing for the start the athlete must consider a range of variables from where to position his blocks in relation to the starting line and each other, what angles he should have his blocks set, the position he assumes before and after the gun is fired, and the force he applies as he leaves the blocks. In this paper I would like to consider some of these variables and their effect in improving the start, with reference to some of the literature written on the subject.
STARTING OBJECTIVES
The principal purpose of the sprint start is to facilitate rapid clearance from the blocks and acceleration to maximum speed. There are a number of broad objectives of the sprint start.
Firstly, the athlete must establish a balanced position in the starting blocks. He must also make sure that suitable force is applied to the blocks. There must be correct positioning of the body in the blocks to ensure that the hips rise to the same height each time. The athlete must establish a foot position which enables
him to come out of the blocks well balanced and with the greatest possible velocity, as he moves into full sprinting position. Finally the athlete must attempt to clear the starting blocks in the shortest possible time after the firing of the starters gun.
TYPES OF STARTS
There are three main types of starting positions for the sprint start. The principle difference between these starts is basically the horizontal distance between the front and back feet of the athlete.
1. The Bunch Start : (Sometimes referred to as the Bullet start) This is where the feet are close together with the toes of the back foot opposite the heel of the front foot. Sometimes the feet are even closer together. This would usually involve a block spacing of less than 30cm.
2. The Medium Start : the feet are further apart. The knee of the back leg is placed opposite a point towards the toes of the front foot. The inter-block distance of this start has been described as approximately shin length apart. Arnold (1992) describes a position many athletes use these days which is slightly
less than shin length apart, but not so close as to call a Bunch or Bullet start. This position could be referred to as a ‘Short Medium Position’. An inter-block distance of somewhere between 30 to 50cm could be described as a medium start.
3. Elongated Start : the knee of the back leg is placed level or slightly behind the heel of the front foot. It has been described as a position where the inter-block distance is well in excess of shin length. An inter-block distance in excess of 50cm could be described as an elongated start.
BLOCK SPACING
The most common factor studied has been the effect of block spacing on the start. The major research studies support the use of a medium anteroposteior spacing between the feet. ( Henry 1952, Menely & Rosemier 1968, Sigerseth & Grinaker 1962 ).
In some very early studies, ( Dickson 1932) it was found the bunch start ( foot spacing 10 inches apart ) yielded faster starting times than the medium or elongated starts. This study, like a number of other early studies was conducted under the belief that the start was a distinct division of the race and disregarded
the influence of the start on the complete race. Henry (1952) presented evidence that the use of the 11 inch bunch start resulted in the faster block clearance, but with less velocity than those achieved from the medium position, resulting in significantly slower times for the 10 and 50 yards. The highest proportion of best runs were from the 16 inch block spacing, which would be classified as a medium start. Sigerseth & Grinaker (1962) findings after studying times for 10, 20, 30, 40 and 50 yards supports those reported by Henry. The medium start offers the greatest advantage to the sprinter.
BLOCK ANGLES
Much has been written and discussed about distance between front and back blocks, but ignores the effect of differing block angles.
A recent study by Guissard, Duchateau & Hainaut 1992 has shown that variation in block angles can have a profound effect on starting velocities. In the study 17 athletes used their own preferred distance between blocks and starting line. They all used a rear block angle of 70 degrees, but tested three angles with the front block : 30, 50 & 70 degrees.
It is concluded that decreasing front block obliquity increase the start velocity of a sprinter without any prolongation of the push-off. The effect of reducing the front block angle induces both neural and mechanical changes in relation to the recorded increase in starting velocity when block angles are decreased. However it is predominantly mechanical changes in relation to the recorded increase in starting
velocity when block angles are decreased.
The explanation for this improvement is that the ankle joint is in a more effective position in that the ankle is dorsiflexed. Dorsiflexion of the ankle pre-stretches the calf muscle and the Achilles tendon. The lower the block angle ( down to 30 degrees ), the greater the Achilles and calf muscle stretch and the greater the force the ankle joint can generate.
Tellez & Doolittle suggest that angles in both ankles should be close to at least 90 degrees, helping the athlete to feel pressure in the rear block to a greater degree.
FOOT POSITION
Mero, Komi & Gregor 1992 report
In order to get more pre-tension in the calf muscles, the first spikes of both feet should be positioned on the track. With pre-stretched calf muscles, it is possible to get a more efficient start. If the body mass is centred more on the legs than on the arms, pre-tension may be increased.
Tellez & Doolittle (1984) recommend a similar foot position in the front block with the toes on the track surface, while in rear block, they suggest the tip of the toes of the shoe touching the track. This variation of rear toe position may emphasise the speed of departure of the rear foot from the block.
DISTANCE FROM STARTING LINE
In deciding the distance between the front foot and the starting line, ( Barbaro 1983)mentions that weight distribution, hip position and the effect of foot drive must be considered. If the front foot is too close to the starting line, much of the body weight will rest on it and the knee angle will be less than 90 degrees.
This will result in an inefficient front foot drive. If the body mass is centred more on the legs than
arms, pre-tension of the calf can be increased. ( Mero ).
In a study by Schot & Knutzen (1992) four sprint start positions were analysed with particular attention to ground reaction forces, horizontal forces and velocity. It was found that those with a greater distance between the front foot and starting line resulted in a greater propelling impulse, first step toe off velocity and a greater average velocity through a 2 metre speed trap.
KNEE ANGLES
An important factor in determining the power and momentum developed in the sprint start is the angle of the front leg in the set position. Most literature accepts that an angle close to 90 degrees is the ideal angle in this position. It allows the knee extensors to work best at the correct time for maximum power and momentum to be developed. An angle in excess of 90 degrees may allow a faster leg speed out of the blocks but will not develop the same power and momentum.
Borzov (1980) in his investigations into an optimal starting position, varies a little, with a suggested ideal front leg angle of 100 degrees. Opinions on rear leg angle vary between 110 degrees and 135 degrees. Tellez & Doolittle (1984) suggest an optimal angle of about 135 degrees for the rear leg because it allows the lever to move more quickly and allows greater impulse from a static position. They also suggest that an early body velocity provided by the rear leg drive past the front leg is a better mechanical position to accelerate through a more prolonged application of force.
HIPS
The height of the hips and the amount of forward lean in the set position is of paramount importance. This is obviously interrelated with the leg angles. If the hip height is too low the leg angles are too closed and the centre of mass is not in a good position to displace in the direction of the run. If they are too high the
angles are too open affecting the optimal force against the blocks. Barbaro suggests the hips should be 6-12cm higher than shoulders. The degree of forward lean should be such that it is not too far to put pronounced pressure on the hands or too little that it inhibits forward displacement of the centre of gravity. If the hips are too far forward it will diminish front fast drive. If they are just above or behind the front foot their will be more vertical component instead of horizontal component in the drive out. The hips should be therefore just in front of the foot in the set position.
ARMS
The arm should be shoulder width or slightly wider. If they are too narrow the set position becomes unstable. If they are too wide, the head and shoulders drop too far below hip height.
REACTION TIME
Reaction time has been described as the time elapsed between the firing of the starters gun, and the first reaction of the athlete.
When automatic blocks are used in major championships it is deemed an athlete cannot react faster than 0.1 of a second.
(Mero, Komi & Gregor 1992) defines reaction time as the time between the sound of the starter’s gun and the moment the athlete is able to exert a certain pressure against the starting blocks.
Reaction time measurement currently includes the time it takes for the sound of the gun to reach the athlete, the time it takes for an athlete to react to the sound and the mechanical delay of measurements inherent in the starting blocks.
Reaction time can be divided into:
1. Premotor time: the time from the gun until the onset of EMG activity in skeletal muscle.
2. Motor time: delay between the onset of electrical activity and force production by the muscle.
(Payne & Blader 1971) described an average Reaction time of about 0.09 seconds from the sound of the gun and the first rise by the force trace – this time was considerably faster than reaction times of the same athletes obtained by conventional methods. Possibly indicating a measurement of ‘ Pre-motor ‘ period of total reaction time. This theory was supported by the fact that this first rise in the trace did not coincide with perceptible movement of athlete.
Various conclusions have been made regarding reaction times, they include:
i. In all sprint events, reaction times of best athletes is less than 200m/sec.
ii. In the same events, reaction times of females is greater than those of males.
iii. Reaction times grow in proportion to the length of the race.
iv. Reaction time plays only a very small part in the overall race performance.
BLOCK CLEARANCE
As the athlete drives from the blocks, the rear leg is pulled through fast; the front leg fully extends; the arms drive vigorously in a short arm action; while the head remains in a natural line with the trunk.
Tellez & Doolittle suggest that as a result of the drive from the blocks, the force that has been applied through the front block travels in one direct line through the body. An angle of 45 degrees being suggested as the optimum angle for the most efficient drive from the blocks. It would appear that an angle much
greater than 45 degrees would lend itself to too much vertical component and thus sacrificing some early acceleration. An angle of less than 40 degrees may cause a stumbling effect necessitating short strides to correct the imbalance. However, Payne & Blader (1971) suggest that provided the athlete does not trip or interfere too much with subsequent running, it would seem that on the whole, as much horizontal impulse as possible should be striven for during the start.
It was found that when athletes complained of stumbling out of the blocks, they had the best starts as measured by the mean horizontal acceleration and mean velocity over 20 feet.
Payne & Blader (1971) also found that in general both rear and front feet started to exert forces on the blocks at the same instant. Athletes with the best starts usually had strong rear leg action. However, it was the front foot with its much longer contact time which provided the greater part of the acceleration of the body.
Arnold (1992) decries how, after the firing of the gun, the focus of attention should be trained on a particular thought. Five basic thoughts were suggested (but concentrating on only one at a time). They include driving hard with the front leg, moving the rear leg as quickly as possible into the first stride, driving the arms
into the first stride, keeping the shoulders low for the first few strides, and driving hard, without overstriding for the first few strides.
After the blocks are cleared the first couple of strides set up the pattern of acceleration. The athlete needs pronounced body lean when the acceleration is greatest in the first strides. Each successive stride in the acceleration phase will be slightly longer than the previous one while the athlete is accelerating from the
blocks.
RECENT STUDIES
In a recent study (1995) conducted by Martin Harland of the University of Wollongong, Australia, 26 athletes were filmed and recorded by instrumented starting blocks. From the moment force was exerted on the blocks until they passed the 2.5 metre mark (about three strides from the blocks.) A variety of data was
recorded, the athletes were split into fast and slow groups depending on the time taken to pass the 2.5 metre mark. Harland found that higher speeds the faster starters could produce was due to the fact that the faster starters applied more force in a horizontal direction than the slower ones while pushing off the blocks.
Time taken for the fast group to produce this force was less, and the average acceleration attained for this group when leaving the blocks was higher.
Harland also found once the athletes had left the blocks, the faster athletes were able to position their centre of gravity significantly further ahead of the toe of their support foot at the moment of contact of the first step than the slower athletes, thus greater horizontal forces could be applied.
Harland concluded that faster starters were able to exert a greater average horizontal force while on the blocks, in less time than the slower starters. This enabled the faster starters to leave the blocks with higher acceleration combined with a more effective alignment of their body at first contact. This created a
superior start.
CONCLUSION
As can be seen there are a whole range of variables that effect the sprint start.
As a coach it is wise to consider the studies described and apply any information gained to the benefit of your own athletes.
All too often we find athletes may observe a block position or technique of a particular elite athlete, and apply it to themselves unsuccessfully. An obvious case is the number of young athletes attempting to copy the starting position of Ben Johnson. This athlete had incredibly fast reaction times and very high strength
levels that assisted in his particular start being so successful.
Johnson used a relatively high block angle and a short interblock distance (about 28cm), which would be classified as a Bunch start. With this type of start problems can arise in the push off because of the small angle of flexion in the knee joints.
Johnson solved this problem by increasing the distance between his hands on the track and lifting his hips on set to give an optimal knee-joint angle.
This type of start technique would be unsuitable for most elite athletes and not an advised technique for developing athletes who would have much lower strength levels than Johnson.
The technique of athletes such as Linford Christie or Colin Jackson, who use lower block angles and a wider interblock distance would be more suitable as models for developing athletes. These athletes have a more balanced starting position and use the start very effectively to set themselves up for the rest of the
race.
With my own athletes I have a preference for low block angles and a medium interblock distance. This type of position appears to be supported by much of the research described.
When I have had occasion to modify an athletes starting position from a higher block angle and closer interblock distance, I have found that once the athlete becomes used to the new position, although their block clearance is no faster, their twenty metres times have improved.
However it must be remembered that there is no one block position or starting technique that suits every athlete, and a coach must take into consideration the individual characteristics of the athlete.
As Barbaro states “A coach can do no worse than start with the best mechanical position and then modify if necessary, to suit the characteristics of his athletes.”
As can be seen , there are a whole range of variables that affect the sprint start. Each of these variables can play a signifigant role in the overall performance of the sprint start.It can also be seen that some of these variables are directly related with others.
As a coach , it is wise to consider the studies described in this paper and apply any information gained to the benefit of your athletes.
by Dr Martin Lynch © 2003
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