I think that anyone engaging physical activity in a more serious manner has heard the famous expression “watch out for overtraining” or “you must be in overtraining”. So, what is overtraining?
I think the feeling is common to all people. You’re excited with a new training phase, when usually by the end of the 6th week, something changes. It usually starts with a slight lack of energy, which progresses to a peculiar muscle pain, unlike anything you have ever experienced. Suddenly, motivation decreases and going to the gym becomes a torment. No matter what you do to drag you out of this lethargic state and generalized fatigue, this first stage of overtraining (called overreaching) will certainly defeat you.
It’s time to take a break or decrease the volume and intensity of your training, those who insist are usually caught in overtraining. Although brief periods of overreaching may be beneficial in terms of gains in strength and muscle mass, insisting in this case can lead you to tap out! Exercise physiology, has several strategies to fight out this extreme and very specific fatigue. Can nutrition also give you a hand on this?
“No single physiological measurement has proven 100 percent effective [to diagnose overtraining]. Since performance is the most dramatic indicator of overtraining, it is not surprising to find that overtraining has a dramatic effect on the energy demands for a standard, submaximal exercise bout. When runners show symptoms of overtraining, their heart rates and oxygen consumption during the runs are significantly higher.”
In: Wilmore JH, Costill DL. Training for Sport and Activity: The Physiological Basis of the Conditioning Process. 3rd Edition. Debuque: Wm. C. Brown Publishers, 1988.
There are two types of fatigue: acute fatigue and chronic fatigue (1). Acute fatigue appears to be specific to the performed task (2) and has been associated with neurophysiological factors, changes in intracellular and extracellular concentrations of calcium (Ca2 +) (3,4), inorganic phosphate increase (5), reduced glycogen levels and factors involved in the regulation of cyclic Ca2+ in the sarcoplasmic reticulum (6-8). Recovery time in acute fatigue is dependent of the type of training and type of muscle fibers that the athlete beholds (9).
Chronic fatigue occurs by the merging of stress factors both physical and psychological, which lead the athlete to enter in a situation where he cannot recover from training sessions. The lowered performance, may be associated with reduced overall strength, decreased rate of force progression and diminished energy stores (10), hormonal changes (1,11), factors involved in the metabolism of Ca2+ in the sarcoplasmic reticulum (13) and neurological fatigue (14). As chronic fatigue sets in, recovery decreases dramatically, leading ultimately to a reduced training adaptation in the athlete (1).
Beyond this point, any training session induces acute fatigue. Generally the athlete has the ability to recover and adapt over a short period of time (15). An overload resulting from a large volume or high intensity training in a short period of time (one microcycle for example) is called overreaching or if you prefer overload phase. When in overreaching for a long period of time, chronic fatigue sets in, leading to overtraining. Overreaching can be associated with reduced short-term performance, as a result of the accumulation of fatigue from agents related or not with exercise (16).
Symptoms and signs of overreaching and overtraining (18)
Symptoms / signs can vary significantly between individuals in overreaching / overtraining. These are just general guidelines
- Reduction of performance (without reducing performance it makes no sense to speak in overreaching or overtraining)
- The athlete feels exhausted, tired, dehydrated and lacking of energy
- Light myalgia in the lower limbs and general condition of muscle pain
- Joint pain
- Sleep disorders (insomnia etc..)
- Supressed immunity (colds, tonsillitis etc..)
- Decrease in training capacity or intensity, inability to complete training sessions
- Changes in mood and irritability
- Loss of enthusiasm for physical activity
- Loss of appetite and eating disorders
- Increased incidence of musculoskeletal injuries
- Reduction of maximum levels of lactate
- Reduction of maximum heart rate
- Increase of resting heart rate and increased heart rate during sleep
- Reduced levels of cortisol in response to strenuous exercise
Although there is much to discuss regarding the definitions of overreaching and overtraining, science decided to split overtraining into two paradigms: Overtraining originated from the sympathetic nervous system and overtraining originating from the parasympathetic nervous system (19,20). Simply put, and to avoid a longer approach on the physiology of overtraining, we can say that the first type is more associated with strength training (anaerobic), while the second is more associated with aerobic activities and endurance.
Nutritional strategies to prevent overtraining
One of the biggest concerns in regards to overtraining is the suppression of the immune system and the decrease of glycogen stores. Having this in mind we will try to study hypotheses that seem at first glance logical to prevent and reduce overtraining in the fields of nutrition and sports supplements.
Carbohydrates, glycogen and fatigue
Probably one of the first scientists to study the relationship of glycogen depletion with fatigue, was Costill et al. in 1988 (21). Looking at the performance in this study, the author failed to clearly relate low levels of glycogen with decreased performance. This led Snyder et al. again to analyze the relationship between glycogen and fatigue, also with no conclusive results (22). However, according to Jeukendrup and Gleeson (18) the unclear relationship between glycogen and performance in the two studies cited above, is due to the incorrect analysis of performance parameters in that research.
According to these authors, restocking glycogen is essential to performance. A previous study carried out in runners showed that a diet rich in carbohydrates helped maintain glycogen levels (23). Although some authors defend the relationship glycogen/fatigue, some continue to argue that there are other unknown and more complex mechanisms related to overtraining which obviously require further investigation.
Thus it seems obvious that the evidence with regards to glycogen and overtraining is at least controversial. Looking at the research you will find that some authors advocate increasing the intake of carbohydrates when overreaching, to prevent progression to overtraining, while others prefer a more conservative and skeptical approach. I’ll tell you what I think: the analysis of overreaching and overtraining is based on symptoms and signs, any healthcare professional will tell you that symptoms are subjective, and signs are objective. Caution is required when analyzing symptoms due to obvious subjectivity; also the statistical approach should be suitable, something that frequently does not happen in some research.
A 2003 study established a relationship between glycogen and performance, suggesting the intake of a recovery supplement rich in carbohydrates and protein in order to fully restore glycogen levels (12,25). One effective way to prevent overtraining might be increasing the intake of 200-300 g of carbohydrates through regular meals and/or supplements with protein, in the days before competition or loading phase.
This nutritional strategy is usually applied during or after training or competition (26). The use of carbohydrates during exercise bouts should be 8-10 g during high intensity training or competition (27,28). During this phase, sources of low to moderate glycemic index carbohydrates such as fruit, whole grains and starches should be used (29). Obviously a diet with such density of carbohydrates requires the use of dietary supplements. Please be guided that this diet should only be used accordingly with the training phase and in athletes involved in high intensity workouts.
The recommended protein intake for athletes is not at all a matter of consensus. It seems logical though, that athletes have higher protein requirements but how much is optimal? According to some research, to increase protein synthesis, drop recovery time and sustain a positive nitrogen balance in athletes engaged in high intensity training, an intake of 1.5-2.0 g/kg/day is necessary (30,31).
When these amounts of protein intake are not achieved the risk of reducing performance and overtraining rises (26). The intake varies with the intensity of the workout, so there is no “one size fits all” in this matter. The type of protein used is also crucial in regards to prevent overtraining. Whey and micellar casein digestibility rates are different and this can be quite valuable in the athlete’s nutritional strategy (32-35).
Important sources of dietary protein are: fish, egg whites, skimmed milk and poultry (without the skin). In regards to food supplements your best choices should be: ovalbumin, whey, bovine colostrum and milk proteins in geral (32,36).I would also like to draw attention to the fact that eating excess protein will not bring any additional benefits in terms of increasing strength or increasing muscle mass (37,38).
If you speak with a dietitian, an exercise physiologist or a doctor specialized in sports medicine, they will probably agree that athletes have higher requirements in terms of macro and micronutrients than sedentary individuals. This notion derives essentially from distinct biochemical and physiological environments resulting from engaging physical activity. However, fat was so heavily marked as hazardous that recommendations for athletes are only slightly higher than those for sedentary populations (39).
In my opinion, fat intake depends on the training phase of the athlete related to his annual plan, something that we at the Tudor Bompa Institute call periodization (17). I think that even a 3 year old child can tell you that “fat is bad”. Although it is tempting to address this issue and the inherent fallacy within, exploring this topic is not the goal of this article. Most people tend to forget that fat is essential in the synthesis of hormones, including steroids that are synthesized in the adrenal glands and gonads from cholesterol (42,43).
High fat diets have shown in several research papers, the ability to raise decreased testosterone levels in athletes involved in high intensity training (38,40,41). Suppression of testosterone levels is common in athletes with low caloric intake especially when engaged in high intensity exercise or during competitions (44). Currently fat recommendation for athletes is of approximately 30% of the caloric intake. In athletes who wish to reduce body fat, values are typically 0.5-1.0 g/kg/day (45,46). Omega-3 fatty acids are very important for their well-known anti-inflammatory properties and should be a primer on the athlete’s nutritional plan (45-47).
I decided to only address 3 macronutrients, however the issue of hydration should also be spoken. The loss of only 2% of the athlete’s body weight from dehydration will significantly decrease his performance (29). Water is undoubtedly the fluid of life, not only for being the main constituent of the human body, but mainly because most of the biochemical and metabolic reactions occur in aqueous environment. Dehydration and performance will be discussed in another article I intend to write soon.
Can dietary supplements have an important role in overtraining?
Glutamine is the most abundant semi-essential amino acid in the body, and has the potential to assist in the regeneration of glycogen levels, not increasing insulin in the same way as glucose supplements (48). The conversion of glutamine to α-ketoglutarate, makes it preferential fuel for cells with high mitotic activity, such as leukocytes and enterocytes (49).
Low levels of glutamine lead to the suppression of the immune system, particularly during overtraining. Reduced levels of glutamine resulting from intense exercise, may persist until 6 h, so it is very important to restore levels of this amino acid to optimize recovery and decrease overtraining risk (50). This supplement is widely addressed in the Sports Nutrition Certification Course (TBI-CSNE) from Tudor Bompa Institute, my opinion is very clear: There are no proven anti-catabolic effects with enteral (through the digestive system, per os) glutamine (51-53).
The few studies that show an anti-catabolic effect of glutamine are made by parenteral administration (intravenous), which doesn’t apply to regular supplements (54, 55). However having unproven anti-catabolic effect doesn’t make glutamine useless. Some research shows very important effects preventing leaky gut and the suppression of the immune system.
Although there is no evidence to support glutamine’s anti-catabolic actions, the possibility of being useful in preventing overtraining exists due to its action on the immune system (56).
Protein supplements – whey, casein and ovalbumin
For obvious reasons I cannot address these protein sources in full detail, so I’ll use a general approach for protein supplements. Proteins are known to enhance the immune system (32,57,58). They are fundamental in maintaining a positive energy balance during exercise, promoting the proper function of the immune system also presenting interesting results in many aspects of performance.
Protein supplementation has shown beneficial effects on the immune system of patients with protein malnutrition (32). Maintaining a positive nitrogen balance seems to me of the outmost importance in optimizing the immune system, so in this context protein supplementation seems logical and useful.
For decades, Linus Pauling spoke of the importance of this is vitamin (59).It is thought that vitamin C has the ability to positively influence the immune system after intense exercise (60). It is highly soluble in water, has antioxidant capacity, supports iron absorption and reduces susceptibility to upper respiratory tract infections in elite endurance athletes (61).
Research shows capacity of vitamin C to improve neutrophils and lymphocytes response, when administered after high intensity exercise protocols (62). Another study suggested that there is greater suppression of the immune system by athletes involved in intense physical exercise, when compared to moderate exercise. Again the hypothesis of vitamin C aiding in the prevention of lower respiratory tract infections in athletes is shown (62).
I don’t advise anyone to go over 200 mg/day of vitamin C unless if in a pathological state. Some recent research shows higher risk of getting kidney stones at chronic doses of 1000 mg/day.
This mineral is present in the vast majority of enzymes involved in the digestion process and is also a component of many enzymes involved in metabolic regulation. Like vitamin C, zinc supplementation (25-100 mg /day) has demonstrated the ability to boost the immune system, preventing the onset of colds and upper tract respiratory infections (63-65).
In hospital context zinc supplementation not only optimized the immune system of elderly patients but also improved hepatocyte plasticity (66,67). Scientific evidence to use zinc to prevent overtraining is lacking however the vast majority of athletes involved in high intensity protocols have serious deficiencies of this mineral (68).
Administering vitamin C with zinc, seems to be much more effective than giving vitamin C or zinc alone (69). Just out of curiosity, it is often mentioned the importance of zinc in the synthesis of the enzyme superoxide dismutase (SOD) as for the prevention of gonadal atrophy, etc. Any biochemist will tell you something more important: zinc within the cell’s nucleus guarantees the integrity of your DNA since histones are proteins combined with zinc. This seems very important, wouldn’t you agree?
This plant was dubbed by naturopaths and other complementary medicine practitioners as the “immunity plant”. As someone from the so called core sciences, it really intrigues me that some of my colleagues do not even consider the possibility of a plant having milder actions (or even equal) to some drugs. Many pharmaceutical compounds are synthesized from plants; off course this doesn’t mean that they have the same magnitude of therapeutic effect.
Not having the same magnitude of effect however doesn’t necessarily means “no action”. This plant has shown to act close to an antibiotic, both in animals and in humans by improving the symptoms of colds and upper respiratory tract infections, optimizing the immune system (70-72). Although some evidence backs up this plant in the improvement of the immune system we have to acknowledge that some evidence shows the opposite.
In my opinion some of these papers do not use the right species of Echinacea however since I am no expert in the area I will refrain myself from this discussion. So far I’m unaware of studies with this plant in athletes, so further scientific evidence is mandatory. In terms of antioxidants from plants, the flavonoid rutin shows very promising results in several pathological states (73).
I realize that this article is extremely extensive and even boring for most of you. When I decided to write about overtraining and nutrition I was aware that this would make me travel through several areas of science; from exercise physiology to nutrition and food supplements. Obviously it would not be possible to do so without making this text longer, please have in mind that the intricacy of the issues involved has been only superficially addressed. I do not hold a quarter on the Truth, so always have in mind that this is my best interpretation of the available data.
All the best,
The opinions contained herein reflect only the opinion of the author and not necessarily of the Tudor Bompa Institute. Always consult your doctor or healthcare practitioner before embarking on any supplement, dietary plan or treatment.
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