For watching the video version of this article, click on the videos (2 part series) below:
What are the biological processes causing overreaching and overtraining syndrome?
What is the difference between overreaching and overtraining syndrome?
What are the signs and symptoms of overreaching and overtraining syndrome?
What are the tests (investigations) to diagnose overtraining syndrome?
What are the prevention and treatment strategies for overtraining syndrome?
Introduction
Physical exercise (aerobics and/or resistance training) is widely used for achieving goals like weight loss, staying fit, or improving performance in sports. Whenever a person exercises more than his capacity, positive adaptations take place in the body to increase performance. However, when the volume or intensity of the workout exceeds the adaptation capacity of the person, maladaptations occur. These maladaptations not only cause a fall in the performance of the athlete but also cause pathological changes in the organs of the body. The state of adaptation is defined as ‘overreaching’ and the state of maladaptation as ‘overtraining’. The systems best studied so far for the effects of too much exercise are the immune, endocrine, and nervous system.
What are the biological processes causing overreaching and overtraining syndrome?
Muscle does not contract on its own. For the muscle to contract, it has to receive signals from the brain. The signals from the brain pass through the spinal cord. From the spinal cord, they travel through the nerves. Finally, they reach the muscle. When fatigue arises in the brain or the spinal cord, it is called ‘central’ fatigue. When fatigue arises in the nerves or muscles, it is called ‘peripheral’ fatigue [Allen and colleagues, 2008]. The central fatigue may be responsible for the neurological and psychiatric symptoms of overtraining like the lack of motivation and depression.
Glycogen depletion
For contraction, muscle requires energy. This energy comes from glycogen. Glycogen is a polymer of glucose and is the main energy source of the muscle. Chronic depletion of muscle glycogen (due to increased exercise load without sufficient recovery period) can be an important contributor to fatigue [Cheng and colleagues, 2017]. Glycogen resynthesis in the muscle takes hours to a few days to restore to pre-exercise levels [Krustrup and colleagues, 2011]. However, symptoms of overtraining may go on for months. Thus, glycogen depletion alone cannot explain the prolonged periods of underperformance seen in overtraining.
Muscle damage
During exercise, muscles are damaged. Muscle damage is responsible for the reduction of strength, swelling, and the Delayed Onset Muscle Soreness (DOMS) after exercise [Chen and colleagues, 2019]. Muscle damage is especially severe after repeated eccentric muscle contractions (or lengthening) [Kamandullis and colleagues, 2019]. The muscle damage after exercise can last for prolonged periods, even lasting for months. Thus, muscle damage can explain the prolonged nature of symptoms seen in overtraining.
What is the difference between overreaching and overtraining syndrome?
Overreaching and overtraining are primarily divided into three categories [Meeusen and colleagues, 2013]:
Functional overreaching (FOR)
It is also called ‘short-term overreaching’. Excessive training leads to a fall in performance. However, if the person takes adequate rest, recovery takes place in a matter of days to weeks. The outcome of this condition is good, as the athlete super compensates and his performance becomes better than before.
Nonfunctional overreaching (NFOR)
It is also called ‘long-term overreaching’. Here, the recovery period, even after adequate rest, is usually weeks to months. The recovery is complete after this resting period. However, the athlete may experience some psychologic or neuro-endocrinologic (related to hormones) symptoms during this period.
Overtraining syndrome (OTS)
Here, the fall in performance despite rest goes on for months (usually more than 2 months). Generally, the overtraining syndrome is triggered by some external factor (like illness) or internal factor (like a psychological stressor). Apart from a drop in the athlete’s performance, other organ systems are affected. The athlete may have hormonal changes due to disturbance in the endocrine balance or frequent infections due to disturbance in the immune system. Additionally, the athlete may have psychological and neurological symptoms, the most common being depression and anxiety.
It is still unclear, whether overreaching progresses to overtraining, or overtraining syndrome can develop on its own without passing the stage of overreaching [Halson and colleagues, 2004].
What are the signs and symptoms of overreaching and overtraining syndrome?
Indicators of overtraining syndrome fall into three groups [Kreher and colleagues, 2012]:
In the first group, the symptoms are due to the balance tipping in the favor of the parasympathetic nervous system. These types of symptoms are seen in athletes involved in some form of aerobic or endurance training like cardio, high-intensity interval training (HIIT), and marathon running. As a result of overactivation of the parasympathetic nervous system, there may be negative symptoms like loss of motivation and depression. The resting heart rate may also be reduced.
In the second group, the symptoms are due to the overactivation of the sympathetic nervous system. These types of symptoms are seen in athletes involved in anaerobic or strength training like bodybuilding and weightlifting. As a result of overactivation of the sympathetic nervous system, there may be positive symptoms like restlessness, irritability, agitation, and insomnia. The resting heart rate and the blood pressure may be elevated.
The third group of symptoms is unrelated to the above two. These include fatigue, a feeling of exhaustion, stiff and sore muscles, loss of appetite, weight loss, not feeling fresh after waking up, and others.
What are the tests (investigations) to diagnose overtraining syndrome?
To date, no tests have been validated for diagnosing overreaching. Because of this, it is difficult to come up with exact prevention strategies [Meeusen and colleagues, 2013].
Two Bout Maximum Exercise Protocol
However, there are some performance tests, which can be used to differentiate the above three conditions. The best test so far available is the ‘Two Bout Maximum Exercise Protocol’ [Meeusen and colleagues, 2010]. In this protocol, two exercise sessions of maximum intensity are separated by a rest period of 4 hours. At the end of each session, the levels of two hormones are measured. These are the adrenocorticotrophic hormone (ACTH) and prolactin. Depending on the level of hormones at the end of both sessions, a person is categorized into FOR, NFOR, or OTS.
It is interesting to note that as per this study, subjects who fell in the category of nonfunctional overreaching had symptoms that lasted in the range between 6 weeks to 8 months, and those that fell in the category of overtraining had symptoms that lasted for more than 2 years. Thus, this study challenges the conventional period of 2 months used for defining overtraining syndrome.
Tests for ruling out other medical conditions
Overtraining syndrome may be severe enough to bring about the end of an athlete’s sporting career. However, before labeling any athlete with overtraining syndrome, it is important to rule out other medical conditions by appropriate tests. This is because many medical conditions can also cause a fall in athlete’s performance, and mimic the symptoms seen in overtraining syndrome.
What are the prevention and treatment strategies for overtraining syndrome?
The primary aim of preventing the development of overtraining syndrome is to avoid excessive training that exceeds the body’s ability to recover.
Education
This begins with the education of coaches and athletes about the risk factors that may lead to the development of overtraining syndrome.
Individualized training regimens
Every athlete has a different stress handling capacity, and consequently, a different ‘tipping point’ for progressing to overreached and over-trained states [Kreher and colleagues, 2012]. Therefore, a training log should be kept for every athlete. This log should contain the measure of Rate of Perceived Exertion (RPE) for that athlete. Coaches and athletes should use this measure for individual athletes, to decide the volume and intensity of exercise for them [Fry and colleagues, 1994]. Thus, every athlete should have an individualized training prescription. Furthermore, sudden increments in training load should be avoided. The weekly increments should be less than 10% [Schwellnus and colleagues, 2016].
Early detection of warning signs
Coaches and athletes should be aware of some early signs of overtraining. Firstly, if the athlete is overtrained, there is an increased effort required by the athlete to complete a particular task, that he would have completed without the need for increased effort under normal conditions. Furthermore, despite the increased effort, the athlete’s performance for that particular task is lower. Secondly, there is a loss of vigor during training [Meeusen and colleagues, 2013, and others]. Thirdly, the athlete may be able to begin a training session, but unable to complete it or give it that ‘finishing kick’ [Budgett and colleagues, 1998].
Other simple measures that the athletes can use to detect overreaching are weight, morning heart rate, and maximal heart rate. Weight measurement can give clues regarding the hydration and nutrition status of the athlete. Morning heart rate can give clues to the function of the sympathetic and parasympathetic nervous system. Overactivity of the sympathetic nervous system causes the resting heart rate to be higher, and overactivity of the parasympathetic nervous system causes the resting heart rate to be lower than normal. Overactivity of the sympathetic nervous system, and consequently, a higher heart rate is frequently seen in athletes doing weight training. On the contrary, in endurance athletes involved in sports like marathon running, the parasympathetic nervous system is more active, and the morning heart rate may be lower. Maximal heart rate can also indicate the status of sympathetic and parasympathetic balance [Meeusen and colleagues, 2013 and Urhausen and colleagues, 2002].
Questionnaires
Various questionnaires have been developed for the early detection of overreaching and overtraining. Some prominent ones include the Recovery-Stress Questionnaire for Athletes, Profile of Mood States (POMS), and the Training Distress Scale. According to the POMS questionnaire, measures like ‘fatigue’, ‘vigor’, and ‘depression’ were most commonly associated with overtraining syndrome. Furthermore, a POMS index energy measure, which was a measure derived from POMS to differentiate between fatigue and vigor in overtraining states, found that loss of ‘vigor’ was more strongly associated with overtraining than ‘fatigue’ [Kentta and colleagues, 2001]. However, in one study, the Training Distress Scale questionnaire outperformed the Profile of Mood States (POMS) questionnaire in identifying overtrained swimmers [Raglin and colleagues, 1994].
Nutrition
For the repair and regeneration of muscle, adequate macronutrients (like carbohydrates, proteins, and fats) and micronutrients (like vitamins and minerals) are required. Thus, proper nutrition plays an important role in the recovery. Inadequate nutrition can delay the recovery process, and this effect can pile up over a period, eventually leading to the development of overtraining syndrome. If the requirement for macro- and micro-nutrients cannot be achieved through diet alone, protein and vitamin and mineral supplements specially designed for muscle recovery can be taken.
One common misconception is that carbohydrates should be avoided in trainers, as they may cause weight gain. However, it is important to note that glycogen (which is a form of carbohydrate) is the main source of energy for the exercising muscle, and chronic glycogen depletion can significantly contribute to muscle fatigue. Thus, optimum amounts (that is, not more, and not less) of carbohydrates should be included in the diet of trainers.
Hydration
Another factor, which is often overlooked, is adequate hydration. Dehydration can increase the viscosity of the blood. This can lead to reduced blood circulation of the muscle tissue. The reduced blood circulation of the muscle can contribute to the impairment of muscle repair and regeneration.
Rest and Sleep
Adequate resting periods are required between the training sessions for recovery. Sleep is the best form of rest. It is during these resting periods, that repair and regeneration of the muscle take place. However, there is still insufficient scientific data regarding the optimum duration of these periods of rest.
Stress reduction
Reducing other stressors (like work pressure, interpersonal conflicts, illness, etc.). Psychological stressors, in the background of excessive exercise, are important triggers for the development of overtraining syndrome [Meeusen and colleagues, 2013]. In times of increased life stressors (like infections), training regimens should be temporarily reduced or halted altogether. This is known as ‘periodization’ and is a proven intervention for reducing the occurrence of overtraining syndrome [Meeusen and colleagues, 2013]. In addition to this, psychological interventions like education in stress management and relaxation techniques should be undertaken under the guidance of a sports psychologist. Too frequent sports competitions should be avoided as these also add up to the total number of stressors and may take a toll on the athlete’s health.
Summary
Overtraining is a real possibility in an athlete’s career, and if not detected and treated early, can have devastating consequences for the athlete. Muscle damage plays an important role in the development of overtraining syndrome. Athletes most commonly experience increased effort and decreased performance, inability to complete a training session, fatigue, loss of vigor, and other symptoms like depression. It is important to rule out other medical conditions before diagnosing an athlete with overtraining syndrome. Currently, there are no validated tests for the diagnosis of overtraining syndrome, but the ‘Two Bout Maximum Exercise Protocol’ may differentiate the conditions of overreaching and overtraining. Some prevention strategies include education of coaches and athletes about the risk factors and signs and symptoms of overtraining for early detection of this condition, individualized training regimens of athletes based on their capacities, avoidance of sudden increments in training load, proper nutrition and hydration, sleep and rest, and management of life stressors.
If you found the information in this article useful and would like to receive updates on health-related articles in the future, consider subscribing by providing your e-mail.
Attributions for images used in this article:
Featured image. https://pxhere.com/en/photo/825379
Image for first part of YouTube video
Image for second part of YouTube video
Disclaimer:
The information on this website is strictly for educational purposes only. This information is not a substitute for professional medical advice, diagnosis, and treatment. Always consult a qualified medical professional for any advice regarding a medical condition. Do not disregard any professional medical advice or delay in seeking medical help because of any content on this website. Although every effort is made to provide the latest, accurate, and comprehensive information in this content, the author does not take any liability for any damage arising from any use of this content. The content is provided as-is and without any warranties.
RELATED POSTS: