Many characteristics of the human body play major roles in the action of sprinting. The apparently simple skill of sprinting is actually dependent on an “athlete’s ability to combine the actions of the legs, arms, trunk and so on into a smoothly coordinated whole” (Hay, 1993). We have to consider aspects of human anatomy, such as body height, stride frequency, stride length, speed, energy production, somatotype, anthropometry, power and muscle fibre composition, when analysing such an event. We should also consider external contributing factors such as footwear, state of fatigue, injury history, the running surface and variation in horizontal forces (Hall, 1999), if we are to truly analyze the runner within the 100-meter sprint.
The 100-meter sprint is naturally an explosive event incorporating several factors as an athlete moves through the following three phases:
- Acceleration, 0-30m (sub-divided into pure acceleration and transition).
- Maximum Velocity, 30-60m.
- Speed Maintenance, 60-100m (Jarver, 1995). The athlete must continue a cycle of movement throughout the 100 meters in the fastest possible way. This cycle can be subdivided into the following:
- A supporting phase that begins when the foot lands and ends when the athlete’s centre of gravity passes forward of it.
- A driving phase that begins as the supporting phase ends and ends as the foot leaves the ground.
- A recovery phase during which the foot is off the ground and is being brought forward preparatory to the next landing.
Throughout this paper, we will analyse the 100-meter sprint, considering the different aspects of the activity and the ideal physiological make-up of the sprinter.
REVIEW OF LITERATURE
A review of literature (Baechle 1994; Crowder et al. 1992; Dintiman et al. 1997; Javer 1995; Tellez 1994) concluded that there are many factors that determine an athlete’s success in the 100m sprint, these include physiological, morphological, and anatomical aspects. The literature identified seven specific mechanisms of performance.
1. Stride Frequency
It is the belief of Tellez (1984) that the ability to move the legs faster through the full running motion is limited by the physiology of the athlete. Each individual has a different ratio of Type II fast twitch fibres to Type I slow twitch fibres. The higher the ratio of Type II fibres to Type I fibres, the greater the ability to move quickly.
The identification of biomechanical factors and their effect on stride frequency is of utmost importance. Tellez (1984) identified improper technique as the major influence, resulting in slower leg turnover. For example, a low heel kick on the recovery phase of the stride will cause the leg “lever” to lengthen, which will reduce the angular velocity. Overstriding, projecting the foot too far in front of the body causes a breaking effect, which will also cause slower leg turnover. Deshon and Nelson, cited in (Hay, 1993) concluded, “efficient running is characterised by…placement of the foot as closely as possible beneath the centre of gravity of the runner”.
2. Stride Length
With proper technique, a sprinter can achieve optimal stride length. Dintiman et al. (1997) describes ideal stride length as a length that is as long as is mechanically efficient, with the foot striking the ground with the lower leg at 90° to the ground. Flexibility and strength both influence stride length. If the leg is free to move through the range of motion, an optimal stride is possible. If the restricted range of motion is restricted, due to lack of flexibility, the stride length will be lessened. Likewise, as strength increases, the amount of force applied to the ground with each stride should increase, resulting in the sprinter travelling further with each stride.
Baechle (1994) defines speed as the ability to move the body or body parts through a required range of motion in the fastest possible time. Speed comprises of reaction time, acceleration, maximum speed and speed endurance. It can also be considered as two separate components:
- The speed of a single movement (motor speed).
- Capacity to move at the highest possible velocity (considered as acceleration locomotor velocity).
Another desired aspect of speed is increasing the coordination of muscles. Dintiman et al. (1997) found increases in speed can be achieved when one contractile force arrives at the peak of velocity of the previous force, consequently the second force is more effective. Deshon and Nelson (Hay, 1993) found a significant positive correlation between (1) the angle the leg made with the ground at the instant the foot landed; and (2) the speed of running. The agonistic and antagonistic muscles also become better coordinated, the antagonists furnish less resistance to the contractile efforts of the agonists. For an increase in speed in sprinting, the skills should be practised at rates equal or exceeding those used in competition.
4. Energy Production
Sprinting requires repeated muscle contractions with ATP needing to be replenished from other fuel sources. Initially these sources are found within the muscle, they include ATP-PC (the phosphagen system) and the lactate system (anaerobic glycolysis). These systems require no oxygen in order to produce ATP, a third pathway used to produce ATP is the aerobic system, and this pathway requires oxygen.
A more recent study (Crowder et al. 1992) determined that the creatine phosphate and ATP stored within the muscles are sufficient to enable maximal effort for 5-10 seconds. Beyond this time, energy is provided by anaerobic glycolysis. One of the by-products of anaerobic glycolysis is lactic acid, which results in higher muscle cell and blood acidity. It is important to note that all three systems are used simultaneously albeit at varying degrees. Crowder et al. (1992) estimates that during sprint events approximately 95% of energy production comes via the anaerobic system (85% phosphate, 10% lactic acid), and only 5% from aerobic oxygen. Thus, the 100m sprint is an anaerobic event relying heavily on energy supply from the ATP-PC system.
Somatotyping illustrates general trends of body shape and their suitability to particular sports. Somatotyping is used to assess the physical body shape and give a rating from 1 to 7 (least to most respectively) on the following characteristics - endomorph (roundness), mesomorph (muscularity) and ectomorph (leanness). Athletes are given a rating on all three. A study conducted by Pyke & Watson (1978) suggest that the average somatotype for sprinters entering the 100m sprint event is 2 : 5.5 : 3 (high in mesomorphy, low in endomrphy and ectomorphy).
Anthropometry assesses body size and composition with the aim of determining the compatibility between the athlete’s body and their chosen sport. Dintiman et al. (1997) concluded that athletes possessing shorter legs seem to have an advantage over an athletes with long legs. The shorter leg is more suited to sprints as - having a lower point of inertia - it is easier to move than a long leg. This is not to say that short legs and speed are directly associated, but when powerful muscles combine with a lower point of inertia, the result is a faster stride rate (even though stride length may be slightly reduced).
Power is described by Baechle (1994) as the rate at which work can be done, therefore power = work/time. The more work that can be done in a given amount of time, the greater the power. The sprinter out of the blocks at the start of a race exerts great muscle power to overcome gravity and body inertia in order to reach maximum velocity. The sprinter’s task as mentioned by Hall (1999) is to drive or thrust downward and backward against the ground.
This drive brought about by forceful extension of the hip knee and ankle joints, causes the body to project forward and upward into the next stride. Therefore sprinters require power to thrust each subsequent support leg against the ground and to propel their body forward. Sprinters with well-developed, strong muscles attached to shorter limbs promote rapid movements resulting in a great deal of power.
For elite sprinters to run efficiently they require a combination of physical and physiological characteristics. A greater percentage of Type II muscle fibres will enhance quicker movements and therefore increase the overall running speed. Optimal stride length has an impact on other areas such as speed, reaction and recovery time, and the rate of acceleration.
Greater relative muscle mass in the thighs with strong quadricep muscles will result in strong driving forces. Longer legs relative to body height and shorter thigh length relative to whole leg length is more suited to sprinters for fast recovery time and easier cyclical movement. Somatotype primarily of mesomorph is desired, where muscle mass is the greatest percentage and body fat and leanness contribute the least. The combination of these factors all play a role in analysing the performance of a 100m sprinter.
It was assumed that more power generated primarily in the legs would produce more force and therefore, greater speed. To fully benefit in the overall performance we found that the percentage of body fat is preferred to be minimal and the portion of muscle mass in relation to the rest of the body to be the greatest.
Predicting that a shorter thigh length would be a greater advantage for the runner was shown to be true as it had a lower point of inertia and therefore produced an increase in stride rate. In order to increase the efficiency of a sprinter the above characteristics need to be considered, and (where physiologically possible) adopted, to enhance performance.
Baechle, T.R. (1994). Strength Training and Conditioning. Human Kinetics: Champaign, IL.
Crowder, L, McKenna, K, & Plummer, L. (1992). Training for the 100m sprint. FIA Journal. Vol. August, pp.29-31.
Dintiman, G, Tellez, T, & Ward, R. (1997). Sports Speed 2nd Edition. Leisure Press, USA.
Hall, S.J. (1999). Basic Biomechanics 3rd Edition. McGaw-Hill, Singapore.
Hay, J.G. (1993). The Biomechanics of Sport Techniques 4th Edition. Prentice Hall Limited, USA.
Jarver, J. (1995). Sprints and Relays: Contemporary Theory, Technique and Training. Tafnews Press, USA.
Pyke, F, & Watson, G. (1978). Focus on Running. Harper and Row Publishers, Sydney.
Tellez, T. (1984). Sprint Training - including strength training. Track & Field Quarterly. Vol. 84, pp.9-12.
The author would like to thank Acushla Munday and Colleen Bray for their contributions in the above work.