Muscle memory (strength training)
Encyclopedia
Muscle memory has been used to describe the observation that various muscle
-related tasks seem to be easier to perform after previous practice, even if the task has not been performed for a while. It is as if the muscles “remember”. The term could relate to tasks as disparate as playing the clarinet
and weight-lifting, i. e. the observation that strength trained athletes experience a rapid return of muscle mass and strength even after long periods of inactivity. Until recently all such effects was largely attributed to motor learning
occurring in the central nervous system, but long term effects of previous training on the muscle fibers themselves have recently been observed, in particular related to strength training
.
Until recently it was generally assumed that the effects of exercise on muscle was reversible, and that after a long period of de-training the muscle fibers returned to their previous state. For strength training this view was recently challenged by using in vivo
imaging
techniques revealing specific long lasting structural changes in muscle fibers after a strength-training episode. The notion of a memory mechanism residing in the muscle fibers might have implications for health related exercise advice, and also for exclusion times after doping offences
. Muscle memory is probably related to the cell nuclei
residing inside the muscle fibers, as is described below.
The muscle cells are the largest cells in the body with a volume thousands of times larger than most other body cells. To support this large volume, the muscle cells are one of the very few in the mammalian body that contains several cell nuclei. Such multinucleated cells are called syncytia
. Strength-training increases muscle mass and force mainly by changing the caliber of each fiber rather than increasing the number of fibers. During such fiber enlargement muscle stem cell
s in the muscle tissue multiply and fuse with pre-existing fibers as to support the larger cellular volume. It has often been assumed that each nucleus can support a certain volume of cytoplasm
, and hence that there is a constant volume domain served by each nucleus, although recent evidence suggests that this is an oversimplification. Until recently it was believed that during muscle wasting (atrophy) muscle cells lost nuclei by a nuclear self-destruct mechanism called apoptosis
, but recent observations using time laps in vivo imaging in mice do not support this model. Direct observation indicated that no nuclei are lost under such conditions, and the apoptosis
observed in the muscle tissue were demonstrated to occur only in other cell nuclei in the tissue, e.g. connective tissue
and muscle stem cells called satellite cells
. Since in vivo imaging have confirmed that cell nuclei are added during strength training and not lost upon subsequent detraining, the nuclei might provide a mechanism for muscle memory. Thus, upon retraining the extra nuclei are already there and can rapidly start synthesizing new protein
to build muscle mass and strength. The extra muscle nuclei obtained by a strength training episode, seems to be very long lasting, perhaps permanent, even in muscles that are inactive for a long time. The ability to recruit new nuclei is impaired in the elderly, so it might be beneficial to strength train before senescence
. Doping with anabolic steroid
s also seem to act partly by recruiting new nuclei, so it is possible that doping give offenders a long lasting perhaps life long benefit compared to athletes not cheating.
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
-related tasks seem to be easier to perform after previous practice, even if the task has not been performed for a while. It is as if the muscles “remember”. The term could relate to tasks as disparate as playing the clarinet
Clarinet
The clarinet is a musical instrument of woodwind type. The name derives from adding the suffix -et to the Italian word clarino , as the first clarinets had a strident tone similar to that of a trumpet. The instrument has an approximately cylindrical bore, and uses a single reed...
and weight-lifting, i. e. the observation that strength trained athletes experience a rapid return of muscle mass and strength even after long periods of inactivity. Until recently all such effects was largely attributed to motor learning
Motor learning
Motor learning is a “relatively permanent” change, resulting from practice or a novel experience, in the capability for responding...
occurring in the central nervous system, but long term effects of previous training on the muscle fibers themselves have recently been observed, in particular related to strength training
Strength training
Strength training is the use of resistance to muscular contraction to build the strength, anaerobic endurance, and size of skeletal muscles. There are many different methods of strength training, the most common being the use of gravity or elastic/hydraulic forces to oppose muscle contraction...
.
Until recently it was generally assumed that the effects of exercise on muscle was reversible, and that after a long period of de-training the muscle fibers returned to their previous state. For strength training this view was recently challenged by using in vivo
In vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
imaging
Medical imaging
Medical imaging is the technique and process used to create images of the human body for clinical purposes or medical science...
techniques revealing specific long lasting structural changes in muscle fibers after a strength-training episode. The notion of a memory mechanism residing in the muscle fibers might have implications for health related exercise advice, and also for exclusion times after doping offences
Doping (sport)
The use of performance-enhancing drugs in sport is commonly referred to by the term "doping", particularly by those organizations that regulate competitions. The use of performance enhancing drugs is mostly done to improve athletic performance. This is why many sports ban the use of performance...
. Muscle memory is probably related to the cell nuclei
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
residing inside the muscle fibers, as is described below.
The muscle cells are the largest cells in the body with a volume thousands of times larger than most other body cells. To support this large volume, the muscle cells are one of the very few in the mammalian body that contains several cell nuclei. Such multinucleated cells are called syncytia
Syncytium
In biology, a syncytium is a large cell-like structure; filled with cytoplasm and containing many nuclei. Most cells in eukaryotic organisms have a single nucleus; syncytia are specialized forms used by various organisms.The term may also refer to cells that are connected by specialized membrane...
. Strength-training increases muscle mass and force mainly by changing the caliber of each fiber rather than increasing the number of fibers. During such fiber enlargement muscle stem cell
Stem cell
This article is about the cell type. For the medical therapy, see Stem Cell TreatmentsStem cells are biological cells found in all multicellular organisms, that can divide and differentiate into diverse specialized cell types and can self-renew to produce more stem cells...
s in the muscle tissue multiply and fuse with pre-existing fibers as to support the larger cellular volume. It has often been assumed that each nucleus can support a certain volume of cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
, and hence that there is a constant volume domain served by each nucleus, although recent evidence suggests that this is an oversimplification. Until recently it was believed that during muscle wasting (atrophy) muscle cells lost nuclei by a nuclear self-destruct mechanism called apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
, but recent observations using time laps in vivo imaging in mice do not support this model. Direct observation indicated that no nuclei are lost under such conditions, and the apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
observed in the muscle tissue were demonstrated to occur only in other cell nuclei in the tissue, e.g. connective tissue
Connective tissue
"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...
and muscle stem cells called satellite cells
Satellite cells
Myosatellite cells or satellite cells are small mononuclear progenitor cells with virtually no cytoplasm found in mature muscle. They are found sandwiched between the basement membrane and sarcolemma of individual muscle fibers, and can be difficult to distinguish from the sub-sarcolemmal nuclei...
. Since in vivo imaging have confirmed that cell nuclei are added during strength training and not lost upon subsequent detraining, the nuclei might provide a mechanism for muscle memory. Thus, upon retraining the extra nuclei are already there and can rapidly start synthesizing new protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
to build muscle mass and strength. The extra muscle nuclei obtained by a strength training episode, seems to be very long lasting, perhaps permanent, even in muscles that are inactive for a long time. The ability to recruit new nuclei is impaired in the elderly, so it might be beneficial to strength train before senescence
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...
. Doping with anabolic steroid
Anabolic steroid
Anabolic steroids, technically known as anabolic-androgen steroids or colloquially simply as "steroids", are drugs that mimic the effects of testosterone and dihydrotestosterone in the body. They increase protein synthesis within cells, which results in the buildup of cellular tissue ,...
s also seem to act partly by recruiting new nuclei, so it is possible that doping give offenders a long lasting perhaps life long benefit compared to athletes not cheating.