Fatigue: Processes, Side-effects and the Wingate Bicycle Test
When a person overexerts himself from doing strenuous activities through the say, he may feel sore and tired in each part of his body. This type of problem is called fatigue. Fatigue is mostly connected to the feeling of exhaustion because of the lack of energy and stress because of too much work, lack of sleep, lack of exercise or even because of boredom. But how exactly does this process work and how a person can discern fatigue once it is happening in the body. This paper will discuss the processes on how fatigue takes into place in the body, how it affects the muscles and if there is a possibility that muscle fatigue will take into place after doing the Wingate bicycle test. This paper will also note if there is a significant relationship between the max knee leg extension to the Wingate test.
In the analysis and discussion done by fatigue is a normal response of the body when the body experiences overexertion, stress and lack of sleep. Normally, sleep is an immediate remedy for fatigue but if the symptoms persist, the patient must be brought to a doctor for it may be a symptom of a serious disease. There are many causes that can make a person feel fatigue. Volek (1999) and Spence and Mason (1987) noted that muscle fatigue may be caused either because of the central nervous system or because of the muscles. Should it be caused by the central nervous system, it is the way the brain attempts to prevent muscle tearing from overexertion and to reduce the impulses sent to the muscles. Normally, fatigue that has been caused by the central nervous system would cause the body to completely feel tired or worn out before the feeling would settle in the particular area where the damage has taken place. The brain is also the one telling the affected muscles to temporarily shut down to prevent more action that may damage more muscles and cause more complications in the body. If fatigue is caused by the muscles themselves, it may mean that there are factors that influenced the muscle’s capability to perform functions and limit its capacity to do the activity for a given time. These factors include the body’s energy system, lactic acid accumulation in the body and muscle fiber failure. The body’s energy systems can only affect the body and cells depending on the activity being performed. The first type of energy system is called the ATP-CP system that is normally activated when it comes to short but very intense activities. In this cycle, ATP is broken down and rebuilt through creatine phosphate continuously. Fatigue would then be connected to the amount of creatine phosphate the body used in rebuilding ATP. The other types, glycolysis and oxidation energy systems are only used if the activity is done for longer periods of time. Like the ATP-CP system which depends on the body’s amount of creatine phosphate to identify if the person is fatigued from the activity, glycolytic and oxidative depends on the body’s amount of glycogen or glucose. For a person to be considered fatigued with this energy system, depletion of the glycogen of the body would be determined by the intensity of the activity and may limit the body’s performance should the body continuously do the activity for more than 30 minutes. Once the body completely reduces its glycogen supply, it would look for other energy minerals such as fat and protein to continuously sustain the body in finishing the task. For oxidation, it is mostly concerned with the levels of lactic acid and CO2 which reduces the body’s capacity to continue a particular activity in a given time. The body would automatically send signals to the brain and force the body to retire and rest because of too much exertion.
Muscle fatigue is a decrease in the capacity of muscles to handle physical actions and perform them properly. There are many possible definitions to muscle fatigue as noted by Enoka and Duchateau (2008) and it is connected to this decreased in muscle performance. Both authors noted that muscle fatigue can be a motor deficit that also affects mental and force function by the body because of an activity. It can be measured through muscle force, electromyographic activity and contractile functions. What makes the given definition of muscle fatigue to be completely unique is the capability to properly separate it from other similar body reactions. Unlike the other body reactions that are only aligned to the failure of the body to do a task, muscle fatigue is only a decrease in the force allotted by the body for a particular reaction and is then accumulated by the body after a strenuous activity. Authors such as Lorist et al. (2002), Kallenberg et al. (2007) and Cook et al (2007) cited factors pertaining to muscle fatigue in their given definition of the type. For the group of Lorist, performing a particular task that requires the use of motor skills for a long period of time would induce motor fatigue that may cause extra problems for the person to exert energy in continuing the task . The next group cited that through the use of EMG signals, fatigue can be identified if the amplitude of muscle energy increases as the spectral frequencies of the body decreases over a particular task . The last group notes that there is a relationship between mental fatigue and blood oxygen levels which sends out impulses to the brain to direct it to rest . Enoka and Duchateau also noted that to calculate the percentage of muscle fatigue in the body, there must be an interruption in the contractions so that an estimate can be done with regards to how much the body declined in inserting force in the body. The gravity of muscle fatigue may be affected by a particular interruption while the body is doing a strenuous activity .
According to Rohmert (1973), fatigue is closely related to stress and strain which can also explain how each aspect relates to recovery and acquiring fatigue. This can also be seen as the process on how fatigue takes into place in the body.
Figure 1. Diagram of the relationship of Fatigue, Stress and Strain. This figure depicts the relationship on how fatigue is closely related to stress and strain.
In Figure 1, stress is the sum of all the used energy of the body, which is then sensed by the receptor system in the brain. This is also the factor that sends signals to the body’s effector system to understand the body’s current status. Stress can be acquired by a person as a result of physical, chemical and mental activities caused by various tasks in doing these activities and by the conditions in the environment such as noise, climate and daily chores. Stress is then combined depending on the intensity and duration of the activity that would also contribute to the body’s fatigue. Combined stress may be categorized into two depending on the person’s behavior. If a person has an active lifestyle, stress can be combined as the person involved himself into activities that would require the function of muscles throughout the body. If a person has a passive lifestyle, it would enable the body to reduce stress and would only need to use a few muscles to create a voluntary and involuntary response. Activity and stress is also influenced by the needs of the person once the activity is given as it would vary per person. The person’s performance may also be dependent on the person’s motivation and concentration.
In regards to strains, they may manifest in particular events that may cause a person to have a varied reaction compared to the usual reaction a person would depict in the situation. Strains are usually noted upon the identification of a person’s physiological and biochemical reaction such as increased in heart rate and breathing. It can also be determined through the use of scaling that can identify how much strain is being experienced and the presence of strain in the body. Strains, like stress, can be influenced by the intensity and duration of the activity and the exact requirement of the person to enact a particular action. The author noted that for the body to return back to its original performance rate, a person must allow some time to rest and do activities that would give less stress .
Laurig (1970) notes that despite the general symptoms and influences fatigue could take, there are specific symptoms that correspond to how fatigue has been developed. The first category is the physiological symptoms that results to physiological reactions of the body such as heart and breathing rate. This category also notes that fatigue is already taking into place in the function in the certain parts of the body. The second category of symptoms is called the behavioral symptoms which are usually connected when a person’s performance continuously causes errors in activities which can easily be solved. Fatigue can then be identified through this category as the change in performance done by the body. The final category of symptoms is called psycho-physical symptoms influenced by the intensity of stress and the activity. Fatigue manifests itself in the person’s perception for a particular action that may require exerting force. Each symptom of fatigue may play different roles in the process of fatigue settling but they would only manifest itself in various instances and not at once .
Romer and Polkey (2005) notes that there have been many several studies that have been done in determining whether muscle fatigue affects a person’s tolerance to exercise. The first noted approach is by resting the muscles and observes if the body tolerance is weakened and turned off. This method can be tested using resistance loads and by voluntary hyperpnea when it comes to checking the respiratory muscle. This study has shown that there is a significant decrease in muscle capacity to exert energy but sometimes, there is no change in the output. But this type of test has a lot of limitations in identifying muscle fatigue due to the inability of the test into identifying the levels of fatigue before the exercise or activity is done.
There are certain kinds of exercise and resistant tests that are available in the market today that accurately estimates the amount of muscle fatigue and energy capacity of a person. This exam is called the Wingate Test. According to Gullstrand and Larsson, the Wingate Test is the most popular way to test a person’s anaerobic capability and muscle fatigue that cannot be normally documented by other exercise equipment at present. A person must pedal using a bicycle ergometer with all the energy he has for at least 30 seconds. Each exam is normally done in this time span after the person has successfully done warm-up exercises and a cool-down recovery exercise. While the person is pedaling, there is no resistance in the ergometer to exactly test how many revolutions the person has done within the test. Depending on the person who has done the test, computing the scores will depend on the ergometer used and the weight of the athlete. Geron and Inbar (1980) states that the Wingate test can be done by others and can work properly better with them as compared to athletes who are required to take the test. The test itself is quite rigorous as it would require great focus and readiness in both physiological and mental aspects in facing the exhaustion that would be felt after the test. For athletes to feel better after taking this test, they are always requested to rest immediately before continuing any other form of exercise. The 30 second test is also the toughest exams athletes would have to take as it would take out every amount of energy they have in the body .
Brown and Weir (2001) cites that the Wingate Anaerobic Cycle Test is used to measure the lower part of the body and its capability in producing anaerobic power. The result of the very strenuous test is somewhat an estimate of the subject’s lower body capacity to produce power in any given time. In computing the results of the test, the result is divided to six periods of 5s with the peak power is the highest power output during the 5 second interval and the mean power is the mean of all the periods into one. Fatigue would come into play as the difference between both types of power. The authors note that the test is very reliable as the ratio of its accuracy is up to .94% higher than the other exams. However, the validity of the exam can be questionable as there is no specific measurement of the perfect anaerobic performance of the body. Many studies have been done in trying to identify the limitations of the Wingate test and there have been some particular points raised regarding the improvements needed to place in the test. One limitation of the Wingate test is the resistance setting needed when the test is being done as it would demonstrate the capability of the subject in the amount of power he or she can produce when there is a force hindering his overall output. Another limitation is the exact measurement needed to determine if the athlete is qualified for long periods of continuous strenuous activity. The Wingate test is completely computerized to compute the number of revolutions done in each pedal and converts each signal in revolutions. Computerized nerves are also placed into the test subject to monitor his body rate. After each test, the subject is ordered to stop by the system as it slowly decreases the amount of calibrated mass and resistance. This would then help the subject to relax and recover from the test and prevent complications in the legs.
Muscle fatigue does occur when taking this particular exam and affects the body in specific instances. However, when it comes to the factor of maximum knee leg extension, studies show that it does not affect the results when it comes to the wingate bicycle test and there are other factors that affect muscle fatigue when doing the test. In the study conducted by Martin, Davidson and Pardyjak (2007) in identifying how cyclists get their extra energy by performing the Wingate anaerobic test, they noted that subjects perform better when standing up which can be seen in the hip alignment of the body. As the study notes where the power is coming from while in standing position, they also noted that their power would only decrease because of fatigue and it happen both in the bouts of maximum sprinting and the pedaling rate of the cyclist.
The Wingate test also recorded that the fatigue index for both men and women are about 38% and 35% respectively and denotes this is the same percentage on how fatigue affects the person’s body. The authors had a very hard time in interpreting the results from the Wingate test because of the varied pedaling rate done by each subject in the test. It is also due to this varied pedaling rate which makes it hard to determine the fatigue index from the pedaling rate and the manifestation of fatigue that takes place. To resolve this limitation raised by Martin and his co-authors, some studies have used isokinetic cycling to control pedaling rate. For Jones and his team (1985), they noted that when the pedaling rate reaches up to 140 rpm, the fatigue index is far greater than its usual rate when pedaling is at 60 rpm . Beelen and Sargeant (1991) stressed from their review that cyclists produce large quantities of power and fatigue when using a higher rate of pedaling. As long as this is done, it may have been influenced by the body’s anaerobic metabolism . Martin, Davidson and Pardyjak also added that cyclist’s maximum pedaling rate and energy may depend on the terrain and environment around the cyclists. Once sprints have been done in a couple of rounds, stress would affect the body’s maximum power by increasing the body’s temperature, changing the hydration status in the body and by muscle strain due to pedaling
In the study done by Jereb and Strojnik (1995), they have observed that fatigue, despite in its lowest form, is dominant throughout the entire test. However, they have found that there are differences on how intense the fatigue is when it comes to how long the Wingate test has been done by each subject. However, they have concluded that the test itself is not the test to use in determining high-frequency fatigue happening in the body. Throughout the test that has been performed, they have cited that fatigue indexes of all participants of the study have decreased per duration of the Wingate Test. The decrease amounted to 15.5% for 15 seconds, 35.77% for 30 seconds and 51.27% for 45 percent. They have also noted that for fatigue to manifest itself in the Wingate test, there must be some form of contraction happening. If there is a maximal muscle action, there will always be an appearance of low-frequency fatigue. Stretch-shortening cycles will, however, create high-frequency fatigue .
The maximum knee leg extension factor plays a key role in the isokinetic knee extension test as noted by Gill, Shield, Blazevich, Zhou and Weatherby (2000) which is an important aspect in understanding muscle activation. In this test, torque is computed through an electrode placement and determines the contraction done at a particular knee angle. An isokinetic dynamometer is used in assessing the strength of the leg extensor at a 90 degree angle. Muscle activation would be triggered by electrical stimulation and apply the needed impulse to get relaxed muscles moving . For Klasnja, Drapsin, Lukac, Drid, Obadov and Grujic (2010), they presented a modified Wingate test that uses dynamometers that would be able to measure the body’s anaerobic capacity and leg extension. Leg extension measurements were taken through the use of an isotonic apparatus and three trial contractions were done to test the strength of the knee extensors. Results of these tests were done separately from the original Wingate test under the same conditions and time. They have noted that with a classic Wingate test and a modified version with few modifications to accommodate leg extension, there are only a few similarities in both tests in certain areas. The first possible explanation on why there is difference is because of the inertia present in a classic Wingate test and would only be similar to the modified test on the second and third intervals. There is also a faster process of muscle fatigue on the modified test as the maximum capacity of the body is immediately reached on the first seconds in the dynamometer machine. Another possible reason why there is no similarity between these two is because of the information provided by the dynamometer in terms of the person’s athletic status. Thanks to the American College of Sport Medicine, it is very important that a person be active before partaking into a very strenuous exercise such as the Wingate test. The modified Wingate test of leg extension through the use of would enable regular citizens in conditioning their health. The original version would be suitable for precise measurements for anaerobic capacity.
Lemon (1998), Itil (1996) and Wager-Srdar (1983) cited a couple of ways to allow muscles to properly relax and recover. The most obvious way to recover from muscle fatigue is through the use of a suitable diet and plenty of rest to strengthen the body’s energy supplies and build up the body’s supplies of carbohydrates, fat and protein that helps in the endurance and strength of the body. There are supplements that help in delaying fatigue by activating the hormones in the body that would then release excess body fat and decrease the level of difficulty of the activity being done. Supplements also help in increasing mental alertness and delay the signals that the body is experiencing significant amounts of fatigue because of a workout or activity . It is very important to understand that muscle fatigue may cause complications if it is not prevented and is continuously overexerted.
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