It is hugely important that our client considers the biomechanics of running a marathon, in order to improve his running ability. Our client should investigate kinematic analysis to improve his performance. Kinematic analysis describes the positions, velocities and acceleration of bodies in motion. The most important aspect of kinematics to consider in this instance is ‘the gait cycle’. Most people will believe that running is a natural skill and that athletes will naturally find their preferred stride and this should not be changed. However, if we investigate at the biomechanics behind running, it is clear that just like a golfer’s swing can be improved and perfected in golf, a runner can also learn to improve the technique of his stride (1). If we look at the stride parameters used in running and walking, the body moves in a cyclic motion where the body is supported by one leg and then the other before the cycle is repeated. The distance covered by one stride (the time between an event occurring on one limb and it being repeated on the same limb) is described as the stride length and the number of strides per minute is the stride rate. The relationship between stride rate and stride length can be used to calculate running speed (Running speed = Stride length X stride rate). Many studies have shown that both stride length and stride rate increase with velocity, but the relationship is only linear up to a certain point (roughly 7m/s), after this point there is a smaller increment in stride length and a greater increment in stride rate. We can conclude from this that in order to run faster, our client must lengthen his stride. However, running a marathon is not about running at the fastest speed possible, it is about finding a speed you are comfortable with and maintaining that speed over a long period of time. Other research has found that runners have a preferred walking speed, a preferred running speed and a preferred stride length at each speed. If an individual deviates from the preferred stride length at the preferred speed there could be serious consequences in terms of energy expenditure as shown in the graph. (2).
(3).
Another adjustment our client could make to improve his performance involves the time spent in contact with the ground. Whilst research into this area has found contradictory results, we can conclude that short ground-contact times can cause a higher metabolic cost because there is a need for force to be produced at a more rapid rate. One study that supports the idea that a shorter contact time of the foot can improve running economy is a This in turn improves the ‘running economy’ of a runner. Running economy is typically defined as the energy demand for a given velocity of submaximal running. It is generally accepted that being able to reduce the amount of speed lost during ground contact is the most important aspect of the length of time the foot is in contact with the ground’s relationship to running economy. For this reason it would be advisable that our client adopts a running style that allows him to remain in contact with the ground for the least amount of time possible. (4).
Selecting the appropriate footwear is important to not only improve performance but also to decrease the chance of sustaining an injury during training which could potentially prevent our client from running the marathon. A lot of research into the biomechanics of running a centred around the different phases of running, known as ‘the gait cycle’. The cycle starts at the moment one of the feet first touches the ground, this is known as ‘the foot strike’ stage, this leads into the ‘mid-support’, this occurs after impact and is characterised by the shortening of the overall length of the support limb towards the centre of mass. Next is the stage known as ‘take-off’, at the start of this phase the supporting limb increases and finishes at the moment the toe is no longer in contact with the ground. During the phase the hips and knees extend. This leads into ‘the follow-through’, the phase starts as the last phase ends and is characterised by the slowing of the hip extension and the start of the hip flexion. The final stage of the cycle is the ‘forward swing’. The phase starts with the foot moving forward relative to the body with the hip and knee both flexing. It’s main function is to enhance forwards-upwards reaction. (5). A number of studies have been conducted into the rearfoot angle of the foot relative to the surface during the foot strike stage. Excessive rearfoot motion during running has been linked to causing a variety of different injuries, particularly in the leg and foot. Runners with a softer midsole have reported more extreme eversion angles in the rearfoot when compared to runners with a firmer midsole. Hamill et al found that running in shoes with a soft midsole could alter the rearfoot angle when running but not the knee angle. In their summary of their findings they outlined that as a result of over-rotation of the tibia inside the knee, a potentially training inhibiting injury can occur. We can conclude from this that it would be advisable for our client wear footwear with a soft midsole. Also, we can say that our client should be aware of the effects of over-training and the injuries that it can cause and take the necessary steps to insure it does not happen. He should do this by making the most of his relaxation periods in between training and not pushing himself too hard during training. Another study, conducted by Sobhani et al investigated the benefits of running in so called ‘rocker shoes’. Rocker shoes are different to normal different to normal shoes because of the fact that they have a rounded heel and the sole of the shoe is considerably thicker. It Is claimed that rocker shoes help to prevent injury in athletes by absorbing some of the pressure exerted on the feet whilst running, however the effect of rocker shoes on hip and knee biomechanics remains unclear. Furthermore, it is also unclear whether the rocker shoe has an effect the different running strike types displayed whilst running. The results of the study were very interesting. It was found that the rocker shoes decreased the loading force exerted on the ankle by a considerable amount. However, the loading force exerted on the knee increased when using the rocker shoes. This suggests that running in rocker shoes can significantly increase the chance of the runner sustaining a serious injury. These findings suggest that it is not advisable for our client to wear rockers shoes as the effect that rocker shoe have on an athlete is clearly very debatable and may even cause injury to an athlete. (6).
From the research into the biomechanics of running outlined above, we know that our client can adjust both his running technique and the type of footwear both in training and during the actual marathon. From research of the gait cycle and the kinetics of running, it is clear that our client can make very slight adjustments to his running technique that could prove to cause a very effective improvement to his running economy. For example decreasing the time his foot is in contact with the ground and maintaining the same stride length and stride rate throughout the marathon. This technique can be worked on and improved during training. The other area outlined was the effect of different types of footwear on running performance and their effectiveness in preventing injury during training. Our client should be advised to wear footwear with a soft midsole to alter the angle that the rearfoot makes with the ground at the foot strike phase of the gait cycle. However, the research also showed that certain types of footwear would be unadvisable for our client to wear, namely the so called rocker shoe. The research “ how the shoe has an unclear effect on preventing injury that actually the shoe can have the opposite effect and cause serious injury to the runner. Our client should therefore avoid training in rocker shoes. From the research we can also conclude that our client should be wary of the dangers of overtraining and take the relevant steps outlined above to prevent them.
- Science of Running (2017). How to Run: Running with proper biomechanics [online]. Available: http://www.scienceofrunning.com/2010/08/how-to-run-running-with-proper.html [accessed on 12th May 2017].
- Hamill, J. Knutzen, M. (2009) Biomechanical basis of human movement: Wolters Kluwer.
- Research Gate (2013) Stride frequency in relation to oxygen consumption in experienced and novice runners [online]. Available: https://www.researchgate.net/publication/236197725_Stide_frequency_in_relation_to_oxygen_consumption_in_experienced_and_novice_runners [accessed on 12th May 2017].
- Moore, I.S. Sports Med (2016) 46: 793. doi:10.1007/s40279-016-0474-4
- Bartlett, R. (1997) Introduction to Sport Biomechanics: Routledge
- Sobhani, S. (2017) “Biomechanics of running with rocker shoes”, Journal of Science and Medicine in Sport, 20 (6).