Muscle hypertrophy
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[edit] Muscular hypertrophy
Muscular hypertrophy is most effectively done by undertaking strength training, though it can also occur during other short duration, high intensity anaerobic exercises such as interval training, rowing, cycling and sprinting. Lower intensity, longer duration aerobic exercise generally does not result in organ hypertrophy, instead causing greater storage of fats and carbohydrates within the muscles, as well as neovascularization.
For hypertrophy to occur in the skeletal muscles, the muscle must be directly stimulated. Hypertrophy can be pathological in many organs; for example in the heart, non-exercise based hypertrophy of the left ventricle can be associated with up to a four fold risk of dying over the following 5 years. In skeletal muscle, it is usually helpful and increases strength.
Two different types of muscular hypertrophy are common; sarcoplasmic hypertrophy, in which sarcoplasmic fluid in the muscle cell increases rather than the contractile protein, and hence no increase in contractile strength, and myofibrillar hypertrophy, in which there is an increase in myofibrils, and hence increase in muscular contractile strength. Myofibrillar hypertrophy can, in theory, arise through two processes: increase in the number of nuclei within each muscle fiber, or increase in the amount of contractile material supported by each nucleus. The former is the usual means of muscle hypertrophy.
[edit] Strength training
Strength training typically produces a combination of the two different types of hypertrophy; contraction against 80-90% of the one repetition maximum for a lower number of repetitions causes myofibrillated hypertrophy to dominate (as in powerlifters, olympic lifters and strength athletes), while several repetitions (generally 12 or more)against a sub-maximal load facilitates mainly sarcoplasmic hypertrophy (professional bodybuilders and endurance athletes).
'Neural Response'
The first measurable effect is an increase in the neural drive stimulating muscle contraction. Within just a few days, an untrained individual can achieve measurable strength gains resulting from "learning" to use the muscle.
Genetic Response
As the muscle continues to receive increased demands, the synthetic machinery is upregulated. Although all the steps are not yet clear, this upregulation appears to begin with the ubiquitous second messenger system (including phospholipases, protein kinase C, tyrosine kinase, and others). These, in turn, activate the family of immediate-early genes, including c-fos, c-jun and myc. These genes appear to dictate the contractile protein gene response.
Protein Synthesis
Finally, the message filters down to alter the pattern of protein expression. It can take as long as two months for actual hypertrophy to begin. The additional contractile proteins appear to be incorporated into existing myofibrils (the chains of sarcomeres within a muscle cell). There appears to be some limit to how large a myofibril can become: at some point, they split. These events appear to occur within each muscle fiber. That is, hypertrophy results primarily from the growth of each muscle cell, rather than an increase in the number of cells.
[edit] Muscular hypertrophy through anaerobic training
Experts and professionals differ widely on the best approaches to specifically achieve muscle growth (as opposed to focusing on gaining strength, power, or endurance), it is generally considered that doing anaerobic strength training consistently will result in hypertrophy in the long term (as well as strength and endurance gains). Because testosterone is one of the body's major growth hormones, men tend to find hypertrophy much easier to achieve than women. Taking additional testosterone will increase results, but the psychological and physiological side-effects can cause health issues, and it is considered a performance-enhancing drug, and could thus get one suspended from sporting events, in addition to being illegal in most countries.
In order to get the best gains out of training sessions, experts agree on some basic principles, however some are contradicted by other research:
- Strength Training: it is doing "weights", targeting specific muscle groups, that best stimulates muscle growth, as opposed to aerobic training. Even though runners, swimmers and cyclists have all been known to be very muscular, it is generally the shorter distance / sprinters that tend to develop muscle, so the type of training they do could be seen as a type of "resistance training", and is mostly anaerobic, as opposed to long distance swimmers/runners/cyclists, that tend to be slim and lean.
- Progressive overload is considered the most important principle behind hypertrophy, so increasing the weight, reps and sets will all have a positive impact of growth. Some experts create complicated plans that play around with weight, reps and sets, increasing one while decreasing the others, to constantly shock the body into growing. Keeping the sets and reps the same while just increasing weight will lead to growth, but will focus more on developing muscular strength; keeping the weight the same but doing more sets, or doing a few extra reps, may be more effective at stimulating growth for a few weeks, before a rise in weight is necessary. It is generally believed that with more than 15 repetitions per set, the weight will be too light to stimulate growth. Also leave about 45-60sec rest between sets.
[edit] Microtrauma
Microtrauma, which is tiny damage to the fibres, is seen as the basis for hypertrophy. When microtrauma occurs (from weight training or other strenuous activities), the body responds by overcompensating, replacing the damaged tissue and adding more, so that the risk of repeat damage is reduced. This is why progressive overload is essential to continued improvement, as the body adapts and becomes more resistant to stress.
Because microtrauma is physical damage to the muscle, rest and recovery are just as important as training. Leave at least 48 hours before training a muscle group again. Also stretch after training, as well as on rest days, to maintain/improve flexibility and range of motion.
[edit] Nutrition
Experts agree that nutrition is very important to hypertrophy, especially a diet high in protein, as protein is the main non-water constituent of muscle. There is disagreement over the necessity of artificial protein supplements (such as shakes and bars) versus maintaining a less processed diet high in lean meats such as fish or chicken.
Carbohydrates, broken down into glucose, construct glycogen stores in the muscles. These stores can have a are "protein sparing" effect. When energy is expended beyond the instant energy stores of the body (ATP, creatine, etc), if more energy is expended beyond the body's aerobic fat-burning system, it will require carbohydrates for energy. If the current glycogen stores cannot adequately provide this energy, protein's amino acids can be broken down to be utilized for this. Improving one's aerobic fat-burning system will greatly decrease the amount of carbohydrates needed in storage to avoid this, which is how low-carbohydrate athletes train. Eating extra protein can also do this by supplementing the amino acid pool. Carbohydrates tend to burn 'cleaner', however, with less byproducts, making them a favoured source of energy.
Carbohydrates also release insulin, which is an anabolic hormone, as opposed to glucagon, which is catabolic and turns protein into glucose when the body is deprived of carbs. Low carbohydrate diets are designed for weight (fat) loss, not muscle gain, though high glycemic simple carbohydrates such as sugary foods and drink should be avoided to limit fat gain for bodybuilders who want their muscular to be apparent. Despite the anabolic effect of insulin, spikes of it or high levels in general can put a strain on system to produce greater amounts of it as cells become desensitized to it. Some bodybuilders who do not manage this contract Type 2 Diabetes.
- Some scientific research on hypertrophy training is contradictory. For instance some studies have found that the anabolic stage lasts only 36-48 hours after a workout, while others have found that the body is still making adaptive changes after 1-2 weeks. Which study one chooses to believe will affect the training regime, for instance working a muscle group once a week in a 3 day split, or 3 times a week in a full body program. Therefore trying both types of programs for a few months each may help one determine which is better for the individual.
- Seek the advice of a professional trainer, especially trainers that have already achieved the results you wish to achieve, but be wary of those that use/recommend anabolic steroids, as these are illegal and entail many potential health risks such as damage to the liver.
- There are plenty of legal supplements that can help one get results quicker.Although considered by scientists to still be in testing, the three considered most effective are glutamine, creatine, and the humble multivitamin. The body needs vitamins and minerals to process the protein, carbohydrates, and fat that it gets from food, and getting enough vitamins will help the body function more efficiently and build more muscle. Glutamine is an essential amino-acid for building muscle, and taking supplements replenishes the stores that may be used up in heavy training. Creatine is used by the body to convert ADP back into ATP in the first 10-20 seconds of exertion, as is limited by the amount of creatine stored in your muscles. As a set in weight training doesn't usually last more than 10-15 seconds, this energy system is the dominant one, and so taking supplements will increase the amount of creatine available and can greatly increase muscular endurance, meaning one can do more reps and sets, fatiguing more muscle fibres.
