Physiological Reviews, Volume 84, Introduction Personal trainers and fitness professionals often spend countless hours reading articles and research on new training programs and exercise ideas for developing muscular fitness. However, largely because of its physiological complexity, few fitness professionals are as well informed in how muscles actually adapt and grow to the progressively increasing overload demands of exercise. In fact, skeletal muscle is the most adaptable tissue in the human body and muscle hypertrophy increase in size is a vastly researched topic, yet still considered a fertile area of research.
This column will provide a brief update on some of the intriguing cellular changes that occur leading to muscle growth, referred to as the satellite cell theory of hypertrophy. Trauma to the Muscle: Activating The Satellite Cells When muscles undergo intense exercise, as from a resistance training bout, there is trauma to the muscle fibers that is referred to as muscle injury or damage in scientific investigations.
This disruption to muscle cell organelles activates satellite cells, which are located on the outside of the muscle fibers between the basal lamina basement membrane and the plasma membrane sarcolemma of muscles fibers to proliferate to the injury site Charge and Rudnicki In essence, a biological effort to repair or replace damaged muscle fibers begins with the satellite cells fusing together and to the muscles fibers, often leading to increases in muscle fiber cross-sectional area or hypertrophy.
The satellite cells have only one nucleus and can replicate by dividing. After fusion with the muscle fiber, some satellite cells serve as a source of new nuclei to supplement the growing muscle fiber.
With these additional nuclei, the muscle fiber can synthesize more proteins and create more contractile myofilaments, known as actin and myosin, in skeletal muscle cells. It is interesting to note that high numbers of satellite cells are found associated within slow-twitch muscle fibers as compared to fast-twitch muscle fibers within the same muscle, as they are regularly going through cell maintenance repair from daily activities. Growth factors Growth factors are hormones or hormone-like compounds that stimulate satellite cells to produce the gains in the muscle fiber size.
These growth factors have been shown to affect muscle growth by regulating satellite cell activity. Hepatocyte growth factor HGF is a key regulator of satellite cell activity. It has been shown to be the active factor in damaged muscle and may also be responsible for causing satellite cells to migrate to the damaged muscle area Charge and Rudnicki Fibroblast growth factor FGF is another important growth factor in muscle repair following exercise. The role of FGF may be in the revascularization forming new blood capillaries process during muscle regeneration Charge and Rudnicki The IGFs play a primary role in regulating the amount of muscle mass growth, promoting changes occurring in the DNA for protein synthesis, and promoting muscle cell repair.
Insulin also stimulates muscle growth by enhancing protein synthesis and facilitating the entry of glucose into cells.
The satellite cells use glucose as a fuel substrate, thus enabling their cell growth activities. And, glucose is also used for intramuscular energy needs.
Wearing compression garments has become common among athletes over the past several decades. But a small study found that they lowered time for body muscle recovery in German handball players. In the study, the athletes wore the garments for 24 hours and then alternated between hour breaks and hour periods of wearing them for a total of 96 hours.
Contrast bath therapy involves alternating periods of submerging in very warm water and very cold water. This change in temperature stimulates the contraction and dilation of your blood vessels and changes your heart rate. Research has found that contrast bath therapy may help reduce muscle soreness post-workout. The results are limited and may only be relevant for athletes.
Cryotherapy is the technique of exposing your body to an extremely cold temperature for a few minutes. Research has found that it may be able to speed up recovery by reducing pain, inflammation, and muscle tiredness after strenuous activity.
Consuming alcohol is damaging to many aspects of your health. Alcohol also impairs protein synthesis in your muscles. Smoking tobacco negatively impacts your musculoskeletal system. Smoking tobacco is also associated with an increased risk of developing joint disease and an increased risk of fracturing a bone. The amount of time it takes for your muscles to recover from exercise depends on your fitness levels and the difficulty of your workout.
The volume, intensity, and duration of your workout all play a role in determining how taxing it is on your body. After a relatively light workout , your muscles may be able to recover in 24 hours, whereas a more challenging workout might take two to three days. Very intense workouts might take even longer. The basis of any good training program is small incremental increases in intensity or volume over time.
If you jump ahead too quickly, you put yourself at risk of injury or overtraining. Different trainers have different philosophies when it comes to training. Many agree that you should leave your workout session feeling challenged but not completely exhausted. Designing your program so you work alternate muscles groups in different workouts is a good way to increase the recovery period between sessions. For example, if you are lifting weights three times a week, try a schedule like this to give each muscle group a full week to recover:.
Athletes training for specific sports, like sprinters or Olympic lifters, often train the same body parts almost every day. They often alternate high- and low-intensity days to give their muscles time to recover. Repeated stress from exercise causes small tears called microtears that lead to muscles feeling sore and inflamed. An accumulation of tears puts you at risk of developing torn muscles, also called muscle strains or pulled muscles. Muscle strains can range from mildly uncomfortable to complete ruptures that may need surgery to repair.
Muscle injuries can range from mild to complete tears. American Fitness Magazine Recovery. Recovery from training is becoming recognized as one of the most important aspects of physical activity and overall wellness. The ideas outlined in this article cover an array of tactics for enhancing recovery. Keep in mind that the most effective strategy for you might be to experiment to determine which ones prove feasible and successful for the people you work with.
We eat, sleep, train, repeat—constantly striving to get bigger, stronger, faster or slimmer—but is there a point where too much becomes harmful? Many recognize the need for recovery after exercise, but do we understand what it takes to fully recover and whether we have actually achieved that state?
Answering these questions starts with a basic understanding of homeostasis, stress and recovery within the body. An intense, acute bout of physiological stress followed by adequate recovery, which enables adaptation and restores homeostasis, is generally considered healthy Sapolsky However, physiological stress that is not followed by adequate recovery can, over time, compromise homeostasis and immune function, increasing the probability of injury, illness and the onset of nonfunctional overreaching or overtraining.
Though recovery is a critical phase of the exercise-adaptation cycle, it is among the least understood and most under-researched components of training. Essentially, recovery is a process that includes rest, refueling through nutrition , rehydration, regeneration repair , resynthesis, reduction of inflammation and restoration that ultimately returns the body to homeostasis. Focusing on training recovery offers the greatest potential benefit because everything that happens outside of an exercise session—i.
Furthermore, how do we measure or monitor recovery? Usually, an evening of restful sleep coupled with good nutrition and hydration will restore homeostasis and full recovery Pocari et al.
However, we can now monitor various physiological parameters in real time to validate recovery and improve the recovery process. For example, measuring resting heart rate RHR , heart rate variability HRV and ventilation breathing patterns can provide valuable information on the dominance of our sympathetic nervous system SNS or parasympathetic nervous system PNS , the latter of which is responsible for rest, repair and recovery.
Two studies highlight the value of active recovery, which typically uses movements ranging from spurts of anaerobic activity to very light-intensity activity e. One study found that active recovery after repeated intense exercise resulted in faster returns to homeostasis compared with passive recoveries that used no movement Ahmaidi et al. Advocates of massage say it decreases muscle soreness, pain and stress, improves circulation and lymphatic flow, and creates an enhanced perception of recovery.
Researchers, however, have questioned its value and warn of its potential to create more muscle damage if performed too aggressively or too soon after exercise Schaser et al. One study discovered that massage performed immediately after exercise resulted in reduced blood flow and impaired removal of lactate and hydrogen ions from muscles, thereby slowing recovery Wiltshire et al.
Consequently, we still cannot say if massages are truly effective at influencing muscle and overall recovery. Delivered via clothing or through inflatable devices e.
Various studies examining the effects of elastic compression i. Elastic compression clothing which incorporates constant pressure appears to reduce some muscle soreness and perception of fatigue, but it also slows the removal of metabolic byproducts. Pneumatic compression which incorporates pulsatile pressure tends to have a greater effect on increasing blood flow and decreasing muscle stiffness, but it offers little or no improvement in power, strength or performance.
Miyamoto et al. Although research is somewhat minimal on the true effects of compression, there appear to be some small recovery benefits with little concern about harmful side effects Hill et al.
Cryotherapy temporarily reduces muscle temperature, stimulating vasoconstriction and reducing inflammation and pain. Critics of cryotherapy point to an overall slowing of normal regenerative inflammation and an increasing risk of further injury from extended exposure of skin and nerves to cold temperatures Schaser et al.
Some practitioners now advocate alternating hot and cold applications, but little research supports this practice. Although post-exercise cryotherapy remains popular, the reality is that temporary muscle cooling is unlikely to have a significant influence on muscle repair or recovery. Furthermore, in animal-based studies, it did delay recovery Schaser et al. The cardiovascular system responds to hydrotherapy water immersion by changing heart rate, peripheral blood flow and resistance to flow.
It also changes the temperature of the skin, muscles and core, influencing inflammation, immune function, muscle soreness and perception of fatigue. The three most common immersion techniques are cold water immersion CWI , hot water immersion HWI and contrast water therapy CWT , which alternates immersions between hot and cold water. In one study, CWI treatment demonstrated lower perceptions of muscle soreness and smaller decrements in muscle strength 24 and 48 hours post-exercise versus CWT Ingram et al.
The fields of health and medicine recognize the importance of sleep upon overall health and wellness. Sleep and recovery depend on two vital data points:.
If sleep debt piles up, rising stress and cortisol accumulation in the body will impair recovery and threaten our health. Considering how much psycho-emotional stress people deal with every day, trainers should take time to inventory the stress their clients or athletes face outside of their workouts and consider the ramifications on recovery and performance.
Disregarding or underestimating the importance of sleep may expose your clients to a higher risk of nonfunctional overreaching or overtraining. Read also: Recovery Techniques for Athletes. That phase is synonymous with overtraining.
Though several signals point to overtraining, an elevated resting heart rate RHR coupled with a decrease in exercise performance over 7—10 days are perhaps the easiest to monitor Pocari et al. By contrast, strength recovery is a consistent and effective marker of muscle recovery. Although objective markers of muscle recovery like creatine kinase CK are considered valid, the utility of CK is reduced by several variables including gender, age and individual biological responses.
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