Alec Titan
Muscle growth, or hypertrophy, is a well-known and proven process in humans. However, the existence of another process, muscle hyperplasia, is highly contested. Hyperplasia is the increase in the number of muscle fibres, as opposed to hypertrophy, which is the increase in the size of muscle fibres. While hyperplasia has been observed in animals, it is unclear whether it occurs in humans. Some evidence suggests that it may be possible, while other studies refute this claim. The controversy surrounding hyperplasia has led to a multitude of questions and the development of various training strategies to potentially induce it.
Explore related products
$12.26 $21.99
What You'll Learn
Muscle hyperplasia vs hypertrophy
Muscle hypertrophy and hyperplasia are two mechanisms that explain the increase in muscle mass. Hypertrophy refers to an increase in the size of individual muscle fibres, which can be achieved by increasing the size of contractile proteins or intracellular space, or increasing the fluid and enzyme content of the muscle cell. This increase in diameter of muscle fibres leads to greater power of contraction and, therefore, greater force. Research over the past 40 years has shown that hypertrophy is the predominant mechanism for increasing muscle size.
On the other hand, hyperplasia refers to an increase in the number of muscle fibres. This can occur through muscle fibre splitting, a process observed in animals under extreme mechanical overload. Hyperplasia has been observed in birds, mice, cats, and fish, but evidence of hyperplasia in humans is lacking. Some studies suggest that hyperplasia may contribute to muscle mass increases in human athletes, but it likely contributes very little (less than 5%) to absolute muscle growth. The controversy surrounding hyperplasia in humans stems from the difficulty in measuring muscle fibres and counting errors that can occur when counting by hand.
The distinction between hypertrophy and hyperplasia is important when considering training strategies. Hypertrophy is associated with strength training and resistance training, which optimise muscle mass gains. Strategies such as training close to failure are important for increasing muscle mass. In contrast, acute training strategies for inducing hyperplasia may include weighted stretching, Intraset stretching, and stretch-pause reps, which involve extreme mechanical overload at long muscle lengths.
While hypertrophy and hyperplasia represent two distinct processes of muscle growth, they may also occur simultaneously. For example, satellite cell activation, which is necessary for hypertrophy due to the Nuclear Domain Theory, may also lead to hyperplasia if the muscle reaches a theoretical growth limit and the satellite cells split to form new fibres. However, it is unclear whether hyperplasia can occur in humans, and further experiments are needed to provide a definitive answer.
Locating the Piriformis Muscle: A Guide to Finding This Elusive Muscle
You may want to see also
Explore related products
Animal models of muscle hyperplasia
Animal models have been used to study muscle hyperplasia, which is the increase in the number of muscle fibres, as opposed to hypertrophy, which is the increase in the size of individual muscle fibres.
The use of animal models has allowed researchers to induce and study rapid and extensive muscle hypertrophy, and some models allow precise control of the exercise parameters. By examining the animal models of muscle hypertrophy, clinicians may be able to evaluate and use relevant data from these models to design new strategies for humans.
Scientists have used three models to study the cellular mechanisms of muscle enlargement: compensatory hypertrophy, stretch, and exercise. Each of these models has provided direct as well as indirect evidence supporting the occurrence of muscle fibre hyperplasia. Direct counts of muscle fibres using nitric acid digestion techniques have shown that both exercise and stretch overload result in significant increases (ranging from 9-52%) in fibre number. Indirect fibre counts using histological cross-sections have suggested fibre hyperplasia (ranging from 10-82%) in all three models.
In addition, the expression of embryonic myosin isoforms has provided indirect evidence for new fibre formation in stretch-overloaded muscle. Furthermore, satellite cells have been shown to be involved in muscle fibre hyperplasia in stretch and exercise.
There are a variety of animal models that exist to investigate the underlying pathophysiology of neointimal hyperplasia, which can be traced back to four main mechanisms: endothelial damage and activation; monocyte accumulation in the subintimal space; fibroblast migration; and the transformation of vascular smooth muscle cells. Mouse models, for example, enable cell- and molecular-focused fundamental research due to their ease of genetic manipulation.
Flexing Muscles: Techniques for Showing Off Your Physique
You may want to see also
Explore related products
Training strategies for muscle hyperplasia
Hyperplasia is the increase in the number of muscle fibres. While hyperplasia is a controversial topic, studies have shown that it may contribute to muscle mass increases in adult humans. Training strategies that may induce hyperplasia include:
Weighted stretching
This involves performing a specific stretch while holding weights. For example, a chest stretch can be achieved by performing a dumbbell chest flye to the greatest range of motion you can withstand and holding that position for as long as possible.
Intraset stretching
This is similar to weighted stretching, but instead of holding the stretch position, you perform a normal chest flye set, then immediately do a chest stretch for about 30 seconds, before returning to the flyes as soon as possible.
Stretch-pause reps
This method involves performing a stretch during the pause between repetitions of an exercise.
Accentuated eccentric loading (AEL)
AEL leverages the ability of muscles to generate greater force during maximal eccentric contractions. This strategy is associated with significant exercise-induced muscle damage and mechanical tension, which have been linked to hypertrophic response.
Low-load resistance training under blood flow restriction (BFR)
This method involves applying a restrictive device to the proximal part of the limb to reduce arterial blood flow and occlude the venous return. This allows for the avoidance of the high mechanical stress associated with high-load resistance training.
Progressive overload
This is described as the "bread and butter of muscle building".
Diet
Increasing muscle size requires energy and the building blocks for new protein growth, which come from a properly designed and well-balanced diet that incorporates adequate calories and nutrients.
Defeating Masked Muscle: Strategies for Unmasking the Mystery
You may want to see also
Explore related products
Muscle memory and hyperplasia
Muscle growth can be achieved through two primary mechanisms: hypertrophy and hyperplasia. Hypertrophy is the increase in diameter of a muscle fibre, achieved through increasing the size of the contractile proteins or increasing the fluid and enzyme content of the muscle cell. Hyperplasia, on the other hand, is the increase in the number of muscle fibres. Hyperplasia is a controversial topic, with research over the past 40 years showing that hypertrophy is the predominant mechanism for increasing muscle size.
Muscle memory is a process in which information is encoded, stored, and retrieved. In the context of muscle memory, it refers to the ability to reperform certain movements or motor skills, such as riding a bike. Muscle memory can be classified into two main types: cellular muscle memory and epigenetic muscle memory. Cellular muscle memory relates to the accrual of new nuclei within muscle fibres (myonuclei) following a period of muscle growth, which may be retained even during subsequent periods of muscle loss. This results in enhanced adaptation to later regrowth. Epigenetic muscle memory, on the other hand, relates to modifications in the DNA of skeletal muscle following earlier exercise-induced muscle growth, which are retained even after ceasing exercise and are associated with enhanced molecular responses to later retraining.
The concept of muscle memory is supported by research in both animal and human models. Animal studies have shown that myonuclei added during muscle fibre growth are not lost during muscle atrophy, a phenomenon referred to as "muscle memory by myonuclear permanence". This allows the muscle fibre to regrow more efficiently during retraining. While the muscle memory hypothesis has been primarily based on data from rodent models, there is also evidence from human studies that may support or contradict the hypothesis. However, translating results from animal studies to humans can be challenging due to differences in muscle architecture and metabolism between species.
The idea of muscle memory has important implications for optimising exercise interventions and training programs, as well as developing therapeutic strategies to counteract muscle wasting conditions and age-related muscle loss. For example, muscle memory may promote quicker muscle regrowth in older adults who participated in resistance-type exercise training earlier in life. Additionally, the concept of muscle memory highlights the importance of early strength training as a public health advice, as myonuclei are harder to recruit in the elderly.
While the exact mechanisms of muscle hyperplasia are still being studied, extreme mechanical overload at long muscle lengths has been shown to induce hyperplasia in animal studies. This can be applied to human training strategies through the use of weighted stretching, Intraset stretching, and stretch-pause reps. However, it is important to note that hyperplasia in humans is still controversial, and if it does occur, it likely contributes very little to absolute muscle growth.
Flexing PC Muscles: A Step-by-Step Guide to Strengthening Your Eyes
You may want to see also
Explore related products
Hyperplasia and anabolic drugs
Hyperplasia refers to an increase in the number of muscle fibres, as opposed to hypertrophy, which is an increase in the size of individual muscle fibres. Research over the past 40 years has shown that hypertrophy is the predominant mechanism for increasing muscle size. Hyperplasia in humans may exist but is still very controversial as a major mechanism for increasing the intact size of a muscle.
The anabolic stimulus for muscle growth appears to be related to the amount of resistance used in a lift and the associated neural activation in both men and women. Heavier resistance produces higher neural activation voltages in the recruitment of motor units. High voltage is needed for neural stimuli to activate high-threshold motor units, and this high voltage also exposes lower-threshold motor units to the neural stimuli. This was evidenced with biopsy training studies on the thigh muscle from Dr. Robert Staron’s research groups. These studies showed that when using only light weights (20-28RM), no hypertrophy of the Type I muscle fibres was seen. However, when using heavier resistance (9-11RM and 3-5RM), increases in cross-sectional area of all muscle fibre types were observed with training.
In this context, the most prolific stimulus for muscle growth is a well-designed resistance exercise program of sufficient volume and sufficiently high intensity. Increasing muscle size requires energy and the building blocks for new protein growth, which come from a properly designed and well-balanced diet that incorporates adequate calories and needed nutrients. Nutrient intake is vital for optimal muscle development, and the body needs carbohydrates, protein, and fat to repair and remodel muscle. Everyday dietary patterns (including the timing of nutrient intake around the workout), appropriate sleep, and a healthy lifestyle all contribute to the effectiveness of muscle repair and, therefore, muscle growth.
Anabolic steroids are one type of anabolic drug that can play a role in muscle growth. Testosterone is one of the body's major growth hormones, and taking additional testosterone, as in anabolic steroids, will increase muscle growth results. Anabolic steroid use can cause testicular atrophy, cardiac arrest, and gynecomastia. Anabolic steroids are also considered performance-enhancing drugs, and their use can cause competitors to be suspended or banned from competitions. Testosterone is also a medically regulated substance in most countries, making it illegal to possess without a medical prescription.
While hyperplasia has been observed in animal studies, it is unclear whether it occurs in humans. The largest increase in muscle fibre number in animal studies was brought about by extreme mechanical overload at long muscle lengths. Some fitness experts recommend stretching in between sets and using high-reps and light weights in an attempt to mimic the protocols used in animal studies. While at least one study has shown that stretching alone can cause muscle growth in humans (through hypertrophy), and several others have found an association between weighted stretching and an increase in anabolic hormones in the body, none have found that weighted stretching causes hyperplasia in humans.
The Benefits of Shaving for Muscle Builders
You may want to see also
Frequently asked questions
Muscle hypertrophy is the increase in size of muscle fibres, achieved through increasing the size of contractile proteins or increasing the fluid and enzyme content of the muscle cell.
Muscle hyperplasia is the increase in the number of muscle fibres.
Muscle hyperplasia has been observed in animal subjects, but its effect on humans is unclear. Some sources claim it is not possible in humans, while others state that it is possible but unclear if it can ever occur.
Extreme mechanical overload at long muscle lengths has been shown to increase muscle fibre number in animal studies. This can be applied to human training through strategies such as weighted stretching, intraset stretching, and stretch-pause reps.
Hypertrophy increases the thickness of muscle fibres, while hyperplasia increases the number of fibres.
