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Muscles and Recovery

Abstract

“Hans Selye, a Canadian endocrinologist, unknowingly provided the theoretical basis for periodization with his work on the adrenal gland and the role of stress hormones in the adaptation to stress, distress, and illness.

Former Eastern Bloc sport scientists and physicians found similarities between the pattern of the training responses in athletes and the stress patterns observed by Selye. Hans Selye coined the term General Adaptation Syndrome to describe how the adrenal gland responds with an initial alarm reaction followed by a reduction of an organism’s function in response to a noxious stimulus. The key to continued adaptation to the stress is the timely removal of the stimulus so that the organism’s function can recover.”[1]

Muscle recovery is one of the most important aspects to ramp up any bodybuilding activity whether the goal is increase strength or power or endurance. It is also important when there is an injury and a person wants to heal his muscles, manage fatigue and get back to his training with minimum down time. Treating an injury is only to be done under the guidance of the doctor. However, there are certain things which we can address via nutrition and rest that can help the treatment along. There are several aspects to address this process ranging from nutrition, role of nervous system and endocrine system and various practical approaches widely used to facilitate recovery and adaptation. In this article, we attempt to address the various aspects affecting muscle recovery and find the practical methods to be adopted for facilitating it.

Muscles and growth

When we talk of body building in terms of endurance or strength or power, we are concerned with muscle growth; particularly for the skeletal muscles that enable our movements. These muscles are composed of bunches of fibers made up of muscle cells. These cells are multinucleated.

Each nucleus (and hence our genetics) controls the protein metabolism in a particular region of the muscle cell called as nuclear domain. These cells have lots of mitochondria(known as the powerhouse organelle inside the cell which convert nutrients to ATP the energy currency of our body).

These cells also contain lots of myofibrils which are the parts of the cell that give it the distinct striated appearance. Myofibrils are the parts of the muscle cell which shorten and relax when we contract or relax a muscle. The myofibrils are made up contractile units called sarcomere.

The contraction of the sarcomere is due to two protein filament types: Actin and Myosin. These filaments move over each other in the presence of ATP due to the signalling from the neurotransmitters to contract or relax the myofibril. The Actin and Myosin protein filaments are held in place by a lattice of non-contractile proteins like Titin and Nebulin[2].

Irrespective of the type of activity we are involved in, muscle cells grow due to muscle damage and subsequent repair.[3] When we push our muscles to do more work than it is currently capable of, we damage the muscle fibers causing small breakages in the fiber called microtears. The body responds to the damage with the same mechanism for most soft tissues.

  • Inflammation: The immune system is involved in this phase as well as the endocrine system. This phase removes damaged cells and starts the repair process, improving blood circulation so that nutrients arrive at the scene of injury. It is characterized by pain/soreness, heat, swelling(resulting in stiffness)
  • Remodelling/Proliferation/Multiplication: Once the nutrients are available, the process of repair takes place with hormonal interactions and synthesis of new proteins which are then incorporated into the muscle fiber within existing or new sarcomere.

Depending upon the amount of injury, the duration of inflammation and remodelling phases will vary and they certainly have some amount of overlap. In the case of microtears from training a muscle, at the end of this process of recovery, we are aiming to recover as well as adapt to a stronger muscle. The increase in the strength of the muscle is most prominently due to increase in actin and myosin proteins. However, noncontractile proteins (like titin and nebulin present in the sarcomere) which form the support structure are laid down first. The type of muscle fiber may also change during this process of recovery.

So for anyone trying to increase performance and grow their muscles, this recovery process is key. Any ways that we can facilitate this process will help us advance in our goal whether it is muscle growth or recovering from an injury. Our body undergoes both proteolysis(protein degradation) and protein synthesis. After training, both these processes are found[4] to be heightened for around 48 hours for untrained individuals. Whether we have a resultant muscle hypertrophy or atrophy depends on which process is more prevalent in our body[5]. The extent of protein synthesis depends on a host of factors ranging from hydration level, nutrient uptake, hormone levels, nervous system and genetics[6]. Many of these factors are not completely understood today. For example, mTOR signaling is known to be of major importance in cell growth and hence muscle recovery.

“mTORC1 positively controls protein synthesis, which is required for cell growth, through various downstream effectors. mTORC1 integrates four major signals – growth factors, energy status, oxygen and amino acids – to regulate many processes that are involved in the promotion of cell growth. It has been demonstrated that mTORC2 plays key roles in various biological processes, including cell survival, metabolism, proliferation and cytoskeleton organization.”[7]

Still the factors regulating mTOR and the biological processes it controls are not fully understood. More and more research indicates that any aspect of the human body cannot be sufficiently understood in parts and a holistic view encompassing the signalling, hormones, genetics as well as dietary intake is important to be able to make practical progress in the field of fitness.

Overreaching and Overtraining

Overreaching and overtraining are terms used to define various degrees of accumulation of training/non-training stress resulting in decrease in performance capacity of an athlete. While overreaching is recovered in short term (several days to few weeks), overtraining recovery takes several weeks or months[8]. Only the amount of time needed for performance restoration has been used to distinguish the two cases and not the nature or extent of training. The psychological signs of these effects have also not been distinguished. While there are numerous studies regarding these states, there is a large degree of variation in the usage of these terms and methods of study. So it is a very broad definition of the two terms which can be found to match much of the literature regarding this.

Overreaching is often a desired goal while training athletes because the recovery time is short enough and there is often ‘supercompensation’ effect after recovery that enhances performance more than the baseline levels. However, overtraining is not desirable since athletes cannot afford to be in recovery for months together and it may adversely affect their careers. There is no data whether a ‘supercompensation’ effect is observed from overtraining.

Beginners typically do not have to worry about either condition. These are seen in elite athletes. Only anecdotal evidence exists for overtraining and though there is wide consensus among elite athletes about it, it has not been studied extensively. There is a great degree of variation in the definition, measurement, type of activity, extent of training, individual capacity. Further, most studies do not measure performance continually during training but rather only report a before and after effect. Importantly, it is not possible/ethical to intentionally overtrain an athlete for the sake of study. So most studies on overtraining, are based on deliberately overreached athletes.

In search of clear and measurable markers of overreaching, several studies have been conducted on blood tests and a few of them such as decrease in blood lactate concentrations, indicators of suppressed immune system are found to partly indicate overreaching in combination with performance decrease and mood disturbances but further studies are required to clearly classify the markers with the type of activity.

However, it is clear from the literature and the studies that continual application of training stress without adequate recovery results in symptoms of overreaching such as reduced performance and psychological disturbances as well as decreased immunity. So the athlete/coach needs to watch and recognize these symptoms and allow adequate recovery in such cases.

Recovery

Sleep and recovery

There is fatigue as a result of training activities. This is partly an impairment of muscle function and partly a reduction in the capacity of the central nervous system to activate the muscle voluntarily. This fatigue has been studied for decades and papers have been written on various aspects as the cause, effect and methods of measurement of fatigue. Central and peripheral neuromuscular fatigue has been dealt with in several studies and reviews. Here are a couple of definitions of the same:

“Peripheral mechanisms of fatigue refer to adjustments in contractile function, whereas central mechanisms of fatigue refer to an inability to voluntarily activate the involved muscles.”[9] 

“The term “peripheral fatigue” is typically used to describe force reductions due to processes distal to the neuromuscular junction, whereas those due to processes within motoneurons and the central nervous system are commonly known as “central fatigue.””[10]

The type and extent fatigue is very much dependant on the class of exercise undertaken. Measurement methods for fatigue are not direct and while CNS fatigue is a much talked about term amongst athletes and coaches; scientific basis and measurement in this area is still lacking.

Human beings have intuitively understood and used sleep as an effective tool for recovery(be it training related, injury related or disease related). However, the complete explanation of why sleep influences recovery so much is still hypothetical and elusive. Substantial studies indicate that a sleep debt(deprivation of sleep)  results in impairments in many aspects, such as cognitive, immunological, metabolic and hormonal functions. The medical hypotheses[11] suggests that sleep debt damages muscle physiology and impairs muscle recovery because of increased stimulation of protein degradation, which is detrimental to protein synthesis and promotes muscle atrophy. It was found that in humans, sleep debt causes increase in body mass. However, an interesting study[12] indicated that over just 14 days sleep deprivation of 3 hours (5.5h vs 8.5h) along with a caloric deficit induced significant decrease in lean mass(60% higher) and retained significantly more fat(55% lower) than the group with normal sleep. The paper[13] explains these results by the following simplified diagram:

It references studies that show that in humans, sleep deprivation, sleep restriction and poor sleep quality is associated with two distinct outcomes: increases in the secretion of catabolic hormones such as cortisol and changes in the pattern of rhythmic secretion of anabolic hormones such as testosterone. IGF-1, ( Insulin-like Growth Factor 1: a hormone secreted predominantly by liver) which plays a central role in protein synthesis is also found to be rapidly reduced under conditions of sleep deprivation.

There are also studies which prove that sleep debt causes a loss of athletic performance[14] and that sleep debt impairs recovery[15]. Hence, sleep, relaxation and stress avoidance is of utmost importance in the path of muscle recovery.

Diet and recovery

Fluid intake

Our body circulates nutrients, immune cells, hormones via aqueous dispersion. Recovery after an injury or training, obviously requires proper hydration.[16] Performance of an athlete is heavily dependant on hydration levels. It has been seen to drop significantly in as little as 2% drop in hydration level.

Energy status

Our cells store information about the energy status[17] in the body. This information is a factor that affects the mTOR signalling[18] and hence it is of prime importance that our energy intake is not low during recovery. This is relevant to persons attempting to improve body composition or prepare for a competition because, calorie deficits have a detrimental effect of muscle recovery. Recovery also needs energy and while the energy intake could be decreased according to the reduced activity level during recovery, it should also allow for the sedentary maintenance intake and incorporate a boost in basal energy needs in proportion to the extent of injury to provide for recovery.

Protein intake(Amino acids)

Studies[19],[20] show that amino acids are required for activation of the mTOR which regulates protein translation, cell growth, and autophagy. It is found[21] that during recovery after resistance exercise, muscle protein turnover is increased because of an acceleration of synthesis and degradation. Dietary recommendations for protein range from 0.8 to 1.8g of protein per kg lean mass depending on level of activity beyond which, there is no observed benefit of higher protein intake[22]. This is important for recovery and adaptation[23],[24] of muscle after training.

Carbohydrates

There are studies presenting contrasting viewpoints when it comes to the role of carbohydrates in muscle recovery. While carbohydrates provide easily usable energy and are the preferred fuel source of the body, it is not very clear whether carbohydrates influence muscle recovery. One review[25] examines several studies and addresses recovery of immune system after exercise. Some of these studies show considerable alleviation in immune system and stress related overreaching symptoms due to carbohydrate intake. Another study[26] concludes that there is a minor advantage and this study is inherently flawed because the caloric intake between the test and control group is not equated. The control group got a placebo beverage with artificial sweeteners while the test group got a beverage with 100g of fast acting carbohydrates. A study[27] which equated calorie intake among test and control groups and measured response over 11 days found that among runners, a higher carbohydrate intake(65% of energy intake) reduced overreaching symptoms due to running in comparison with lower carbohydrate intake(40% of energy intake). Glycogen replenishment therefore had a considerable effect on recovery for runners. A study[28] shows that for high intensity resistance training activity, the energy source is partly from glycogenolysis and partly from fat oxidation. For athletes involved in activities majorly dependant on glycogen stores, a higher carbohydrate intake can help in recovery.

Other dietary considerations

Many supplements that are marketed for promoting recovery are basically multivitamins or anti-inflammatory food extracts. It is important to understand that inflammation is a natural part of the recovery process though it comes with discomfort, pain, swelling, heat etc. Inflammation is found to have a positive relation with mTOR activation. The goal during recovery is not to avoid inflammation completely, but to provide a degree of comfort and mobility to the affected person so that active recovery is possible.

Certain foods such as turmeric, garlic and berries are supposed to have an anti-inflammatory effect which can be beneficial to alleviate inflammation.[29] Including anti inflammatory foods in our diet is a good way to alleviate some of the troublesome symptoms of inflammation. There is no need for expensive supplementation to reduce inflammation unless it is part of a medical issue prescribed by the doctor. Non-steroidal anti-inflammatory medication (NSAID) should also be avoided unless necessary and used with moderation.

Meeting certain nutrient requirements like Vitamins A, B, C, and D as well as calcium, copper, iron, magnesium, manganese, zinc and Omega 3 fatty acids have higher importance in the perspective of recovery. In general, a nutrient rich diet is always needed for our body to be able to function well and this holds good for the aspect of recovery as well.

Active recovery

Active recovery focuses on completing a workout at a low intensity, but just high enough that it gets the blood moving and helps reduce residual fatigue[30] in the muscle. It could also refer to including massages[31], deloads during the recovery period to improve circulation and aid in recovery. Active recovery is recommended over passive rest in most studies in this area.

Conclusion

There are several other strategies used to promote recovery such as compression garments, heat/cold therapies and various supplements.[32] The results show that some of these techniques are useful in reducing inflammation, perceived fatigue etc though all these methods do not have the same success rate. Methods which are targeted at reducing inflammation may also hinder the adaptation an athlete is targeting via his training. Hence, for such techniques, a balance must be made between reducing excessive discomfort and immobility due to inflammation while allowing the body to recover from training such that it can adapt to higher intensity/duration workouts that the athlete is targeting. Fulfillment of the most essential and basic requirements for recovery like hydration, sleep, energy intake, protein intake, micronutrient rich diet and active recovery techniques like light exercise and massage should be prioritized over any supplements and therapies.


[1] “Essentials of Strength Training and Conditioning-3rd Edition – NHSSCA.” https://nhssca.us/wp-content/uploads/2017/10/Essentials-of-Strength-Training-and-Conditioning-3rd-Edition.pdf. Accessed 12 Oct. 2018.

[2] “Exercise Physiology: Integrating Theory and … – Google Books.” 19 Feb. 2015, https://books.google.com/books/about/Exercise_Physiology.html?id=kjn0ngEACAAJ. Accessed 12 Oct. 2018.

[3] “Essentials of Strength Training and Conditioning-3rd Edition – NHSSCA.” https://nhssca.us/wp-content/uploads/2017/10/Essentials-of-Strength-Training-and-Conditioning-3rd-Edition.pdf. Accessed 12 Oct. 2018.

[4] “Mixed muscle protein synthesis and breakdown after resistance ….” https://www.physiology.org/doi/10.1152/ajpendo.1997.273.1.E99. Accessed 18 Oct. 2018.

[5] “Exercise, protein metabolism, and muscle growth. – NCBI.” https://www.ncbi.nlm.nih.gov/pubmed/11255140. Accessed 16 Oct. 2018.

[6] “Postexercise hypertrophic adaptations: a reexamination of the … – NCBI.” https://www.ncbi.nlm.nih.gov/pubmed/23442269. Accessed 16 Oct. 2018.

[7] “mTOR signaling at a glance – Journal of Cell Science – The Company ….” http://jcs.biologists.org/content/122/20/3589. Accessed 16 Oct. 2018.

[8] “Does overtraining exist? An analysis of overreaching and … – NCBI.” https://www.ncbi.nlm.nih.gov/pubmed/15571428. Accessed 18 Oct. 2018.

[9] “Modulation of specific inhibitory networks in fatigued … – NCBI – NIH.” 6 Dec. 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5809538/. Accessed 15 Oct. 2018.

[10] “Recovery of central and peripheral neuromuscular fatigue after exercise..” 8 Dec. 2016, https://www.ncbi.nlm.nih.gov/pubmed/27932676. Accessed 15 Oct. 2018.

[11] “Sleep and muscle recovery: endocrinological and molecular basis for ….” 7 May. 2011, https://www.ncbi.nlm.nih.gov/pubmed/21550729. Accessed 16 Oct. 2018.

[12] “Insufficient sleep undermines dietary efforts to reduce adiposity..” https://www.ncbi.nlm.nih.gov/pubmed/20921542. Accessed 16 Oct. 2018.

[13] “Sleep and muscle recovery: endocrinological and molecular basis for ….” 7 May. 2011, https://www.ncbi.nlm.nih.gov/pubmed/21550729. Accessed 16 Oct. 2018.

[14] “Sleep and athletic performance: the effects of sleep loss on exercise ….” https://www.ncbi.nlm.nih.gov/pubmed/25315456. Accessed 15 Oct. 2018.

[15] “One night of partial sleep deprivation impairs recovery from a single ….” 28 Feb. 2017, https://www.ncbi.nlm.nih.gov/pubmed/28247026. Accessed 15 Oct. 2018.

[16] “Water: Nature’s Most Important Nutrient – UNM.” https://www.unm.edu/~lkravitz/Article%20folder/WaterUNM.html. Accessed 16 Oct. 2018.

[17] “AMP-activated/SNF1 protein kinases: conserved guardians of … – Nature.” 1 Oct. 2007, https://www.nature.com/articles/nrm2249. Accessed 16 Oct. 2018.

[18] “mTOR signaling at a glance – Journal of Cell Science – The Company ….” http://jcs.biologists.org/content/122/20/3589. Accessed 16 Oct. 2018.

[19] “Bidirectional transport of amino acids regulates mTOR … – Science Direct.” 6 Feb. 2009, https://www.sciencedirect.com/science/article/pii/S0092867408015195. Accessed 16 Oct. 2018.

[20] “Amino acids mediate mTOR/raptor signaling through … – PNAS.” http://www.pnas.org/content/102/40/14238.short. Accessed 16 Oct. 2018.

[21] “Increased rates of muscle protein turnover and amino acid transport ….” https://www.physiology.org/doi/10.1152/ajpendo.1995.268.3.E514. Accessed 18 Oct. 2018.

[22] “The short-term effect of high versus moderate protein … – NCBI – NIH.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5697135/. Accessed 16 Oct. 2018.

[23] “Postexercise net protein synthesis in human muscle from orally ….” https://www.physiology.org/doi/full/10.1152/ajpendo.1999.276.4.e628. Accessed 17 Oct. 2018.

[24] “Dietary protein to support anabolism with resistance exercise in … – NCBI.” https://www.ncbi.nlm.nih.gov/pubmed/15798080. Accessed 16 Oct. 2018.

[25] “Recovery of the immune system after exercise | Journal of Applied ….” 1 May. 2017, https://www.physiology.org/doi/full/10.1152/japplphysiol.00622.2016. Accessed 17 Oct. 2018.

[26] “Effect of carbohydrate intake on net muscle protein synthesis during ….” https://www.ncbi.nlm.nih.gov/pubmed/14594866. Accessed 17 Oct. 2018.

[27] “Higher dietary carbohydrate content during intensified running training ….” https://www.physiology.org/doi/10.1152/japplphysiol.00973.2003. Accessed 18 Oct. 2018.

[28] “Glycogen and triglyceride utilization in relation to muscle … – NCBI.” https://www.ncbi.nlm.nih.gov/pubmed/2289498. Accessed 17 Oct. 2018.

[29] “Nutrition for Injury Recovery: Part 2 – Precision Nutrition.” https://www.precisionnutrition.com/nutrition-for-injury-part-2. Accessed 12 Oct. 2018.

[30] “The Comparative Effects of Sports Massage, Active … – NCBI – NIH.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1320372/. Accessed 18 Oct. 2018.

[31] “Effectiveness of Sports Massage for Recovery of … – Semantic Scholar.” https://pdfs.semanticscholar.org/d1d3/cf96cab8bded24955a2f8500297901c80d68.pdf. Accessed 18 Oct. 2018.

[32] “An Evidence-Based Approach for Choosing Post-exercise Recovery ….” 26 Apr. 2018, https://www.ncbi.nlm.nih.gov/pubmed/29755363. Accessed 15 Oct. 2018.

Muscles and Recovery

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