Muscle recovery mechanisms can vary, according to the individual level of physical preparation, age, intensity and duration of exercise, and environmental conditions.
In order to understand the strategies that we must implement for adequate and prompt muscle recovery after a workout, a competition or between stages of a multi-day race, it is absolutely necessary to know the mechanisms by which fatigue and muscle damage are generated.
Fatigue must be recognized as an adaptive and protective process, which limits muscle activity that can lead to tissue injury, with irreversible changes, so that the muscle is able to adapt and improve its performance and resistance to fatigue.
Physical activity must always generate a certain degree of injury, so that the muscular adaptive mechanisms can be expressed. Although its exact physiology has not been fully determined, fatigue originates in two ways:
The decrease in the ability to maintain the level of effort occurs in skeletal muscle, caused by various pathways that affect the propagation of the action potential in the sarcolemma and the contractility of the muscle fiber. The best studied causes, in greater or lesser extent contribute to peripheral fatigue are:
· Biochemical imbalance in myofibrils
· Depletion of energy substrates.
It is the set of alterations in the functioning of the central nervous system (CNS), which can generate a failure, voluntary or not, in the transmission of the nerve impulse to carry out muscle contraction and muscle mechanical work.
Although there is much controversy, central fatigue can be explained by the following mechanisms:
- Ammonium accumulation
- High plasma levels of pro-inflammatory substances, such as interleukin – 6 (IL6), IL 1 and tumor necrosis factor (TNF), induce that muscle damage and interfere with the performance of GAP junctions
- During exercise, body temperature increases. When the core temperature exceeds 38 ° C, sweating increases for thermoregulation. This causes hydro electrolyte imbalances and finally produces an alteration of the activity in the prefrontal cortex and the motor cortex.
What is muscle recovery all about?
Recovery is the process by which the body returns to homeostasis and goes back to its normal state. Scientific evidence indicates that aerobic physical condition (APC) is the basis for power, and it allows us to recover from fatigue after exercise.
The APC can be determined, practically, through the recovery heart rate (RHR), which in trained athletes is much higher during the first minute after the end of the effort. This also explains their low heart rates not only at rest, but also during exercise. The lower HR as a training effect, the better oxidative capacity.
The oxidative capacity depends on the efficiency of the oxygen usage to obtain energy to perform an exercise, and to recover from it. When we start an exercise, the oxygen demands increase, but its contribution to organs and tissues does not. Immediately leading to an initial oxygen deficit, since the cardiorespiratory system must take a few minutes to respond to the demand imposed by the effort.
While this happens, oxymyoglobin is responsible for providing the oxygen that the muscles need in their mitochondria. The opposite occurs at the end of exercise: oxygen consumption will remain high for a period of time after physical activity has ended, as part of the organic muscle recovery strategy. This is known as “oxygen recovery”, “oxygen debt”, or “excess post-exercise oxygen consumption”.
How does muscle damage occur?
It occurs as a response to the overstretching of certain sarcomeres during eccentric contraction, since they are not all the same length, nor are they equally strong. Basically, they are stretched beyond the overlap of actin and myosin filaments.
When the rupture is very large, the organelles or structures of the myocyte, and the sarcomere are also damaged. Thus, proteins such as tinin, inside the sarcomeric region, and desmin and dystrophin, which are found outside, are altered.
Tinin is responsible for muscle stiffness and passive resistance of the fibers. Desmin forms a mesh around the sarcomere in the region of the Z lines, joining the discs with each other and with the plasma membrane. This forms cross-bridges between myofibrils. Dystrophin binds laminin to actin. Damage to these proteins produces muscle weakness.
Now comes the inflammation…
The metabolic products resulting from muscle damage generate an inflammatory response. This activates chemotaxis, which is favored by the increase in calcium concentrations. Then activates the transcription of genes that are responsible for attracting macrophages and polymorphonuclear cells to the damaged muscle.
The role of the humoral and cellular inflammatory response is to cleanse the injured muscle tissue of debris and prepare its repair. This inflammatory phase is what causes delayed muscle pain, known as “stiffness or grinding.”
Some techniques that can be useful to reduce inflammation and pain are hydrotherapy, massages, stretching, and the use of pharmacological strategies such as AM3, antioxidants, B vitamins, and the use of cannabidiol (CBD).
Scientific studies show that CBD may help with pain. It is a cannabinoid that has been shown to have promising potential for treating inflammation by inhibiting the production of pro-inflammatory cytokines. Also, CBD may help with inflammation, since T- regulatory cells are known to work to suppress inflammation, and this cannabinoid has the ability to upregulate these kinds of cells.
The use of non-steroidal anti-inflammatory drugs or analgesics such as ibuprofen, naproxen, acetylsalicylic acid, diclofenac, acetaminophen (paracetamol) only mask possible symptoms of injuries that must be treated, but that also alter kidney function. They do not help muscle recovery or prevent muscle damage.
With a better level of training (oxidative capacity), you will gradually start experiencing less fatigue, more efficient recoveries and greater resistance, because the concept of recovery is linked to the concept of resistance, understanding this last one as the possibility of resisting fatigue and recovering faster from a physical effort. Resistance is subject to the organic adaptations imposed by the intensity and duration of the exercise to which it is subjected.
Recovering quickly and optimally from fatigue will improve our endurance and athletic performance. I hope this article was useful to you, and always remember that just as fatigue and muscle damage have multiple causes, muscle recovery strategies must be multiple.