Introduction
How can biomechanics fulfil its goals?
Performance Improvement
Technique Improvement
In many sporting events technique is the major factor of performance. Martens (2004) defines sport technique as follows:
Sport technique is a physical action of an athlete which leads to the best possible execution of a physical motion, in conformity with a required task of a given sporting event.
Improvement of technique with the help of biomechanics can be used by teachers and coaches to correct motions of students or athletes. Moreover, research workers in the field of biomechanics may develop a new and more effective technique for better execution of a sport motion. In the former case teachers and coaches make use of the methods of qualitative biomechanics analysis in their every day practice to produce changes in the technique used by their charges. In the latter case research workers in the field of biomechanics use quantitative biomechanics methods to develop new techniques which can then be implemented into teaching and training processes.
For instance if a gymnastics coach sees that her charge has difficulties to turn a somersault she can come up with three recommendations to help the gymnast execute this exercise correctly: 1. to jump higher, 2. to fling arms with more energy before taking off, or 3. to curl up more tightly. All these recommendations can help to execute this task correctly and are based on the principles of biomechanics. If the gymnast jumps higher, she has more time to finish the turn during the flight phase. To curl up more tightly means to increase the speed of rotation while keeping the same angular momentum. To fling arms with more energy increases the angular momentum which helps the gymnast to rotate faster.
With the use of biomechanics it is possible to specify motor actions or positions that can increase sport performance.
I have already mentioned that with the use of biomechanics we can decide which technique is better than other and to justify such decision. Let us have a look at an example of quantitative biomechanics research. Researchers Estevan, Falco and Jandacka (2011) presented novel scientific information in taekwondo. The stance position is a factor that affects the mechanical performance of taekwondo athletes’ kicks. The 90° stance position of feet with regards to the rival involves longer execution and total time than the 0° and 45° stance positions in the roundhouse kick. They concluded that the 0° and 45° stance positions seem more appropriate than the 90° stance position.
Among sport events that saw in the past substantial changes in technique are javelin, high jump, and cross country skiing.
Equipment Improvement
Use of biomechanics can also lead to a better look and better functioning of sport equipment. For example ski boots can have a real impact on sport performance. Sophisticated sport equipment gives advantage to both elite and recreational athletes.
Artistic gymnastics offers good examples. An introduction of the new vaulting equipment (vaulting table) after the 2000 Olympics represents the most substantial transition in the development of gymnastics equipment in the last decades. New vaulting equipment allows gymnasts to produce bigger angular momentum and thus to execute more complex vaults with multiple rotations around horizontal and vertical axes (Farana and Vaverka, 2010).
Researchers have recently also developed a new swimming suit which helped swimmers at the Sydney Olympics in 2000 better several world records because it has a favourable influence on the draft force and buoyancy of water that is acting against swimmers. This swimming suit had such an influence on sport performance in swimming, in fact, that its use was later banned.
Training Improvement
Biomechanics can help improve training of athletes in two ways:
By the analysis of mechanical values a coach defines such training conditions that may lead to threshold stimuli.
We can use as an example the research project by Jandacka and Uchytil (2011) who carried out mechanical analysis of bench press with various loads in elite footballers. They discovered that the use of a load equalling to 30 – 50% of the load which the footballers were only able to lift once leads to maximal produced mechanical power output. The recommendation resulting from this research project was as follows: Soccer players should train maximal strength during the preparatory period for their competitive season along with training for speed and endurance. When athletes maximally develop muscular power toward the end of a season when the most important competitions are scheduled, dynamic effort strength training with loads from 30 to 50% of 1RM BP should be used. During the competitive season, loads of 50% of 1RM BP should be used to maintain muscular power over a wide load range.
By the analysis of technical imperfections of a given athlete the coach/teacher identifies the type of training needed for this athlete to improve.
An athlete is limited by strength or endurance of certain muscle groups, by speed of motion, or by specific aspects of motion technique. Sometimes the limits are quite obvious. For example a gymnast executing the crucifix on the gymnastic rings must have very strong shoulder adductors. In the case of certain sport skills the required abilities to execute a motor task are not easy to detect and quantitative biomechanics analysis must be used.
Injury Prevention
By injury prevention it is meant an attempt to prevent or to limit the seriousness of injuries before they are actually incurred.
The concept of injury prevention is part of public health and its goal is to improve the general health of the population and thus to increase the quality of life. Biomechanics is a tool that can be used in sport medicine to identify forces and mechanical energy that cause injuries. It helps to understand how injuries originate, how to avoid them during sport performance, and how to identify exercise suitable for injury prevention and rehabilitation. Biomechanics offers possibilities to create alternative techniques of executing specific movements, using new equipment, and carrying out more effective training methods, which also contributes to injury prevention.
Good examples of how biomechanics helps reduce the prevalence of injuries can be found in volleyball. Zahradník and Jandacka (2011) examined whether it is possible to adapt the landing after a volleyball blocking to reduce impact reaction forces acting on knee joints. They found that it is better for volleyball players to make one step back after blocking as opposed to staying on the landing spot and absorbing the relevant forces there.
Another interesting result of biomechanics analysis with the purpose of injury prevention was the causation study of the so-called iliotibial band syndrome. Research workers Hamill, Miller, Noehren, Davis (2008) allege that the lateral knee pain, typical for many distance runners who train regularly, represents roughly 12% of all injuries in runners. They also discovered that this syndrome may be caused by increased hip abduction and knee internal rotation during the stance phase, which causes strain in iliotibial band. From a large prospective study, female runners who incurred iliotibial band syndrome during the study were compared to a control group who incurred no injuries. Strain, strain rate and duration of impingement were determined from a musculoskeletal model of the lower extremity. This study indicated that a major factor in the development of iliotibial band syndrome was the strain rate. Therefore, Hamill et al. (2008) suggested that strain rate, rather than the magnitude of strain, could be a causative factor in developing the iliotibial band syndrome.
Injury prevention and rehabilitation are currently among very important goals of research in the field of biomechanics of sport and physical exercise.
Injury reduction through changes to equipment function
One of the examples of using the results of biomechanics research for improving the functioning of sport equipment can be found in running. The number of people who realize the importance of healthy life style is recently growing. Running, as an elementary human locomotion, is a legitimate part of healthy lifestyle. But the growing numbers of people engaged in running also brought higher prevalence of injuries. Running shoes at the beginning of the 1970s were too stiff for inexperienced runners. Among the injuries with growing prevalence were stress fractures and shin bone pain. Shoe manufacturers therefore started to market shoes with soft soles. However, soft soles did not offer good stability and motor control. Runners started to suffer from ankle, knee and hip injuries. Biomechanics research has made it possible to manufacture running shoes which reduce impact forces and, at the same time, offer good stability and motor control. With the help of biomechanics it is even possible to recommend custom made shoes for individual athletes. Prevalence of injuries in running has decreased again.
Isn’t human body itself the best equipment for running? People who wear shoes from very early age mostly touch the ground first with their rear foot when they walk. Lieberman et al. (2010) studied the style of running in Kenyans who never wore shoes and assert that in barefoot running people naturally touch the ground first with their forefoot. This produces slower loading rate in foot compared to running in shoes and touching the ground first with rear foot. Grand reaction forces during running may cause chronic injuries that runners often suffer from.