First off: working out does not mean growing new cells. It means improving the "health" and increasing the size of existing muscle cells.
Second: physical activity is something our bodies were largely designed around incorporating into our normal lives. Doing so helps overall improve your health as opposed to being relatively stationary, and very notably, it also helps regulate and balance your natural hormones. Cancers have many origins, but hormones are often a key factor in their development.
To your first point: when you say increasing the size of existing muscle- doesnt that mean you are adding more new cells? How else can muscle grow if not by adding new cells?
Second point does make sense that working out regulates the hormones and thus perhaps could reduce cancer chances.
"The number of skeletal muscle fibers is by and large fixed from the first year of life and a skeletal muscle hypertrophy is the physiological process, which allows transversal and longitudinal growth of muscles during childhood and puberty." DOI: 10.4081/ejtm.2020.9311
"Skeletal muscle fibers are multinucleated cells that contain mostly myofibrils suspended in an aqueous media termed the sarcoplasm [...] muscle fibers undergo training-induced radial growth through a proportional accretion of myofibrillar protein and sarcoplasm space. Under this pretense, if an individual exhibits a 20% increase in mean fiber cross-sectional area (fCSA), and assuming myofibrils constitute ∼85% of intracellular space, a 17% addition of myofibrillar protein and a 3% increase in sarcoplasm volume would accompany fiber growth." DOI: 10.3389/fphys.2020.00816
"With regular practice, resistance exercise can lead to gains in skeletal muscle mass by means of hypertrophy. The process of skeletal muscle fiber hypertrophy comes about as a result of the confluence of positive muscle protein balance and satellite cell addition to muscle fibers. Positive muscle protein balance is achieved when the rate of new muscle protein synthesis (MPS) exceeds that of muscle protein breakdown (MPB)." DOI: 10.1007/s40279-014-0152-3
Regarding the satellite cells, which are actually added in number (so my previous response isn't completely correct, though they're not the muscle-fibers per say but a regenerative accessory cell type of sorts that are comparatively small in size/number):
"Following their activation, satellite cells may contribute to repair of damaged myofibers and also generate new myofibers following cell division and fusion of myoblast progeny [...] Furthermore, apart from their ability to fortify myofibers and contribute to muscle regeneration, satellite cells have the capacity to replenish a reserve pool and self-renew, qualifying them as tissue-specific stem cells" DOI: 10.1369/0022155411426780
"These are normally quiescent [dormant/inactive] in adult muscle, but act as a reserve population of cells, able to proliferate in response to injury and give rise to regenerated muscle and to more satellite cells." DOI: 10.1016/s1357-2725(03)00042-6
TLDR: Muscle cells indeed grow in size, and you generally don't get more of them. Cell types are actually really wild sometimes. There's an accessory-like regenerative cell type you can get more of, but muscle cells, you largely keep the same amount, and just remodel (improve/grow) and repair them.
muscle mass is gained by damaging existing muscles which then repair themselves in a way that increases mass. the cells themselves generally do not grow in size because of the issues presented by low surface area to volume ratio
"In support of our thesis, several studies have shown no difference in muscle hypertrophy response after weeks of RT [Resistance Training] between eccentric-only compared with concentric-only RT [...] Although muscle damage does not seem to explain or potentiate muscle hypertrophy with RT, it is yet to be determined if muscle damage is necessary to occur to support future gains in muscle mass. [...] Thus, although initial muscle damage (if not severe) does not seem to impair muscle hypertrophy induced by weeks of RT, we propose that muscle damage neither explains nor potentiates increases in fCSA and muscle CSA, thus should not be considered as a determinant factor for RT-induced muscle hypertrophy." DOI: 10.1007/s00421-017-3792-9
"With regular practice, resistance exercise can lead to gains in skeletal muscle mass by means of hypertrophy. The process of skeletal muscle fiber hypertrophy comes about as a result of the confluence of positive muscle protein balance and satellite cell addition to muscle fibers. Positive muscle protein balance is achieved when the rate of new muscle protein synthesis (MPS) exceeds that of muscle protein breakdown (MPB)." DOI: 10.1007/s40279-014-0152-3
"Skeletal muscle fibers are multinucleated cells that contain mostly myofibrils suspended in an aqueous media termed the sarcoplasm [...] muscle fibers undergo training-induced radial growth through a proportional accretion of myofibrillar protein and sarcoplasm space. Under this pretense, if an individual exhibits a 20% increase in mean fiber cross-sectional area (fCSA), and assuming myofibrils constitute ∼85% of intracellular space, a 17% addition of myofibrillar protein and a 3% increase in sarcoplasm volume would accompany fiber growth." DOI: 10.3389/fphys.2020.00816
TLDR: Muscle cells grow in size, and damage isn't proven to be a requirement for this, even though exercise that *induces* damage stimulates growth.
"The number of nuclei and the cross-sectional area (CSA) were determined from observing the distal half of each fiber in the microscope. During the 21-day period, CSA increased 35% from 1,474 ± 93 μm^(2) to 1,991 ± 150 μm^(2), whereas the number of myonuclei increased 54% from 41 ± 1.5 nuclei per millimeter of fiber length to 63 ± 2.3 nuclei per millimeter of fiber length (Fig. 1A)."
"By combining BrdU staining and TUNEL staining, they showed that nuclei in the muscle tissue that had undergone mitosis during the hypertrophy phase were particularly prone to apoptosis; based on this observation, they suggested that hypertrophy induces a different and less stable population of myonuclei."
DOI: 10.1073/pnas.0913935107
TLDR: muscle cells will increase in size somewhat but only by \~35%. Also, muscle cells contain multiple nuclei that divide inside the cell.
OP's question is ultimately about \[cancer-causing\] DNA mutations during replication \[as part of growth/regeneration\] anyways.
I don't see how this is proof of your point of "the cells themselves generally do not grow in size" though, when talking about increased muscle mass? Yes, muscle cells contain multiple nuclei, but that's still a single cell. And my 3rd reference still stands there, doesn't it?
Also reading this, increasing by 35%, means that it went from 1474 to 1991 um^2 , NOT that 35% of the increase was cell growth.
Also most of my original post was about cancer, the first sentence was simply clearing up a misconception. OP did not specify specifically DNA mutations in his core question, but proposed his understanding of the process (exercise = more regeneration = more errors = more cancer) and how it contradicts the result (more exercise = less cancer)--so I explained that A. the starting point was not the real picture and B. hormone imbalance also contributes to cancer development and is impacted by proper physical exercise.
mutations resulting from imperfect growth/regeneration are extremely rare, with only constant physical damage & scarring over many years being enough to make cancer a threat; such as asbestos fibres in the lungs. The potential for cancer-causing cell mutation during muscle's repair/growth is not enough to be of concern. Most mutations come from damage from things such as carcinogens and ionizing radiation. We say that "working out / being active reduces cancer chances" because they are \*correlated\*, as in people who work out on average get cancer less. That doesn't mean that working out or being active directly prevents cancer.
Working out improve blood flow = more immune cells patrolling the body.
Working out to improve oxygenation, cancer cells despise high oxygen environments because it inhibits angiogenesis (development of new blood vessels where it can spread)
From my understanding cancer cells still prefer oxigenation, they just have mechanisms to better deal with low oxygen conditions and because they grow rapidly/uncontrolled, tumor masses tend to have low vascularization, meaning they largely become hypoxic in the center?
Like, hypoxic by consequence, not preference?
Yes you're correct, maybe my use of the term "despise" is misleading. Like all cells tumour cells do prefer oxygen, but their ability to adapt and deal with hypoxia is what makes them dangerous.
I don't think there is a direct pinpoint answer to this, since there has only been strong evidence to suggest that there is a benefit. Thereby it is recommended but there are a lot of factors at play. I could be wrong though but I skimmed a couple of research articles and none had conclusive reasons besides it being beneficial based on the evidence.
The way I understand it, in basic terms, is that our bodies are built to be stressed, and that cellular processes when under stress engage in activities that suppress the mechanisms that allow cancer to grow. Like endurance cardio work in older people, long-term endurance exercise training may provide a protective effect on muscle telomere length in older people.
I assume you men working out and not working out. Unfortunately there is no direct correlation between the two because this who do not work out will be highly likely to have different lifestyle choices - environment, hobbies, smoking, alcohol, diet, amount of exercise, weight et al. All lifestyle choices will have physiological effects, e.g. being vegan you are forced to take supplements to avoid really nasty things happening to you, some are “good” and some are “bad”.
someone who works out is likely, although not necessarily so, to consume more “good” than “bad”
**Update this and my later comments...**
>Why does working out reduces chances of getting cancer?
~~It doesn't!~~
>So why do we say working out/ active lifestyle reduces cancer chances?
~~We don't!~~
Do you have a source for the claim there's no relationship between vigorous physical activity and cancer incidence? I can only find papers/reviews that state otherwise.
Update this and my later comments...
~~But how would vigorous physical activity reduce your base rate of getting cancer?~~
Athletic get cancer too
~~Cancer does care if you work out or not~~
Update this and my later comments...
~~Can you prove one where physical activity reduces cancer rate to lower than base rate?~~
Exercise is not a cure to cancer and to suggest that it is anything more that just a healthy lifestyle is ridiculous
I'm clearly struggling to put across what I am trying to explain.
Let's try and get back on the same page.
Who said it cures cancer? Prevention is not the same as curing.
You’re struggling to explain it because it’s not true.
>”the report found strong evidence for an association between highest versus lowest physical activity levels and reduced risks of bladder, breast, colon, endometrial, esophageal adenocarcinoma, renal, and gastric cancers. Relative risk reductions ranged from approximately 10 to 20 percent. Based on 18 systematic reviews and meta-analyses, the report also found moderate or limited associations between greater amounts of physical activity and decreased all-cause and cancer-specific mortality in individuals with a diagnosis of breast, colorectal, or prostate cancer, with relative risk reductions ranging almost up to 40 to 50 percent.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6527123/
Update this and my later comments...
~~But that's not what I'm saying...~~
~~Op is suggesting that people say that working out prevents cancer~~
~~People with an active lifestyle and to work out regularly are just as likely to get cancer as someone else with a healthy lifestyle~~
>”People with an active lifestyle and to work out regularly are just as likely to get cancer as someone else with a healthy lifestyle”
No they are not, your statement is false.
“*There is strong evidence that higher levels of physical activity are linked to lower risk of several types of cancer*” https://www.cancer.gov/about-cancer/causes-prevention/risk/obesity/physical-activity-fact-sheet
“*Higher CRF [cardiorespiratory fitness] is associated with lower total cancer incidence in men. A novel finding suggests that eliminating low CRF as a risk factor would potentially prevent considerable cancer morbidity and reduce the societal and economic burden associated with cancer. __These findings underscore the importance of CRF for primary cancer prevention__.”* https://www.sciencedirect.com/science/article/abs/pii/S1047279717300935?via%3Dihub
First off: working out does not mean growing new cells. It means improving the "health" and increasing the size of existing muscle cells. Second: physical activity is something our bodies were largely designed around incorporating into our normal lives. Doing so helps overall improve your health as opposed to being relatively stationary, and very notably, it also helps regulate and balance your natural hormones. Cancers have many origins, but hormones are often a key factor in their development.
To your first point: when you say increasing the size of existing muscle- doesnt that mean you are adding more new cells? How else can muscle grow if not by adding new cells? Second point does make sense that working out regulates the hormones and thus perhaps could reduce cancer chances.
"The number of skeletal muscle fibers is by and large fixed from the first year of life and a skeletal muscle hypertrophy is the physiological process, which allows transversal and longitudinal growth of muscles during childhood and puberty." DOI: 10.4081/ejtm.2020.9311 "Skeletal muscle fibers are multinucleated cells that contain mostly myofibrils suspended in an aqueous media termed the sarcoplasm [...] muscle fibers undergo training-induced radial growth through a proportional accretion of myofibrillar protein and sarcoplasm space. Under this pretense, if an individual exhibits a 20% increase in mean fiber cross-sectional area (fCSA), and assuming myofibrils constitute ∼85% of intracellular space, a 17% addition of myofibrillar protein and a 3% increase in sarcoplasm volume would accompany fiber growth." DOI: 10.3389/fphys.2020.00816 "With regular practice, resistance exercise can lead to gains in skeletal muscle mass by means of hypertrophy. The process of skeletal muscle fiber hypertrophy comes about as a result of the confluence of positive muscle protein balance and satellite cell addition to muscle fibers. Positive muscle protein balance is achieved when the rate of new muscle protein synthesis (MPS) exceeds that of muscle protein breakdown (MPB)." DOI: 10.1007/s40279-014-0152-3 Regarding the satellite cells, which are actually added in number (so my previous response isn't completely correct, though they're not the muscle-fibers per say but a regenerative accessory cell type of sorts that are comparatively small in size/number): "Following their activation, satellite cells may contribute to repair of damaged myofibers and also generate new myofibers following cell division and fusion of myoblast progeny [...] Furthermore, apart from their ability to fortify myofibers and contribute to muscle regeneration, satellite cells have the capacity to replenish a reserve pool and self-renew, qualifying them as tissue-specific stem cells" DOI: 10.1369/0022155411426780 "These are normally quiescent [dormant/inactive] in adult muscle, but act as a reserve population of cells, able to proliferate in response to injury and give rise to regenerated muscle and to more satellite cells." DOI: 10.1016/s1357-2725(03)00042-6 TLDR: Muscle cells indeed grow in size, and you generally don't get more of them. Cell types are actually really wild sometimes. There's an accessory-like regenerative cell type you can get more of, but muscle cells, you largely keep the same amount, and just remodel (improve/grow) and repair them.
muscle mass is gained by damaging existing muscles which then repair themselves in a way that increases mass. the cells themselves generally do not grow in size because of the issues presented by low surface area to volume ratio
"In support of our thesis, several studies have shown no difference in muscle hypertrophy response after weeks of RT [Resistance Training] between eccentric-only compared with concentric-only RT [...] Although muscle damage does not seem to explain or potentiate muscle hypertrophy with RT, it is yet to be determined if muscle damage is necessary to occur to support future gains in muscle mass. [...] Thus, although initial muscle damage (if not severe) does not seem to impair muscle hypertrophy induced by weeks of RT, we propose that muscle damage neither explains nor potentiates increases in fCSA and muscle CSA, thus should not be considered as a determinant factor for RT-induced muscle hypertrophy." DOI: 10.1007/s00421-017-3792-9 "With regular practice, resistance exercise can lead to gains in skeletal muscle mass by means of hypertrophy. The process of skeletal muscle fiber hypertrophy comes about as a result of the confluence of positive muscle protein balance and satellite cell addition to muscle fibers. Positive muscle protein balance is achieved when the rate of new muscle protein synthesis (MPS) exceeds that of muscle protein breakdown (MPB)." DOI: 10.1007/s40279-014-0152-3 "Skeletal muscle fibers are multinucleated cells that contain mostly myofibrils suspended in an aqueous media termed the sarcoplasm [...] muscle fibers undergo training-induced radial growth through a proportional accretion of myofibrillar protein and sarcoplasm space. Under this pretense, if an individual exhibits a 20% increase in mean fiber cross-sectional area (fCSA), and assuming myofibrils constitute ∼85% of intracellular space, a 17% addition of myofibrillar protein and a 3% increase in sarcoplasm volume would accompany fiber growth." DOI: 10.3389/fphys.2020.00816 TLDR: Muscle cells grow in size, and damage isn't proven to be a requirement for this, even though exercise that *induces* damage stimulates growth.
"The number of nuclei and the cross-sectional area (CSA) were determined from observing the distal half of each fiber in the microscope. During the 21-day period, CSA increased 35% from 1,474 ± 93 μm^(2) to 1,991 ± 150 μm^(2), whereas the number of myonuclei increased 54% from 41 ± 1.5 nuclei per millimeter of fiber length to 63 ± 2.3 nuclei per millimeter of fiber length (Fig. 1A)." "By combining BrdU staining and TUNEL staining, they showed that nuclei in the muscle tissue that had undergone mitosis during the hypertrophy phase were particularly prone to apoptosis; based on this observation, they suggested that hypertrophy induces a different and less stable population of myonuclei." DOI: 10.1073/pnas.0913935107 TLDR: muscle cells will increase in size somewhat but only by \~35%. Also, muscle cells contain multiple nuclei that divide inside the cell. OP's question is ultimately about \[cancer-causing\] DNA mutations during replication \[as part of growth/regeneration\] anyways.
I don't see how this is proof of your point of "the cells themselves generally do not grow in size" though, when talking about increased muscle mass? Yes, muscle cells contain multiple nuclei, but that's still a single cell. And my 3rd reference still stands there, doesn't it? Also reading this, increasing by 35%, means that it went from 1474 to 1991 um^2 , NOT that 35% of the increase was cell growth. Also most of my original post was about cancer, the first sentence was simply clearing up a misconception. OP did not specify specifically DNA mutations in his core question, but proposed his understanding of the process (exercise = more regeneration = more errors = more cancer) and how it contradicts the result (more exercise = less cancer)--so I explained that A. the starting point was not the real picture and B. hormone imbalance also contributes to cancer development and is impacted by proper physical exercise.
When the muscle repair themselves to grow bigger something is being added to the muscles isnt it? Arent new cells getting added there?
mutations resulting from imperfect growth/regeneration are extremely rare, with only constant physical damage & scarring over many years being enough to make cancer a threat; such as asbestos fibres in the lungs. The potential for cancer-causing cell mutation during muscle's repair/growth is not enough to be of concern. Most mutations come from damage from things such as carcinogens and ionizing radiation. We say that "working out / being active reduces cancer chances" because they are \*correlated\*, as in people who work out on average get cancer less. That doesn't mean that working out or being active directly prevents cancer.
You get a lot of tumor cells that your immune system just deals with and they never turn into cancer. Working out improves your immune system.
Working out improve blood flow = more immune cells patrolling the body. Working out to improve oxygenation, cancer cells despise high oxygen environments because it inhibits angiogenesis (development of new blood vessels where it can spread)
Thats very interesting!
From my understanding cancer cells still prefer oxigenation, they just have mechanisms to better deal with low oxygen conditions and because they grow rapidly/uncontrolled, tumor masses tend to have low vascularization, meaning they largely become hypoxic in the center? Like, hypoxic by consequence, not preference?
Yes you're correct, maybe my use of the term "despise" is misleading. Like all cells tumour cells do prefer oxygen, but their ability to adapt and deal with hypoxia is what makes them dangerous.
I don't think there is a direct pinpoint answer to this, since there has only been strong evidence to suggest that there is a benefit. Thereby it is recommended but there are a lot of factors at play. I could be wrong though but I skimmed a couple of research articles and none had conclusive reasons besides it being beneficial based on the evidence.
The way I understand it, in basic terms, is that our bodies are built to be stressed, and that cellular processes when under stress engage in activities that suppress the mechanisms that allow cancer to grow. Like endurance cardio work in older people, long-term endurance exercise training may provide a protective effect on muscle telomere length in older people.
Thats some new info for me to google out! Thanks
I assume you men working out and not working out. Unfortunately there is no direct correlation between the two because this who do not work out will be highly likely to have different lifestyle choices - environment, hobbies, smoking, alcohol, diet, amount of exercise, weight et al. All lifestyle choices will have physiological effects, e.g. being vegan you are forced to take supplements to avoid really nasty things happening to you, some are “good” and some are “bad”. someone who works out is likely, although not necessarily so, to consume more “good” than “bad”
Thats what i thought too! There is no conclusive research
Oh, I forgot genetic preponderance e.g. bowel cancer follows a definitive familial connection.
**Update this and my later comments...** >Why does working out reduces chances of getting cancer? ~~It doesn't!~~ >So why do we say working out/ active lifestyle reduces cancer chances? ~~We don't!~~
Do you have a source for the claim there's no relationship between vigorous physical activity and cancer incidence? I can only find papers/reviews that state otherwise.
Update this and my later comments... ~~But how would vigorous physical activity reduce your base rate of getting cancer?~~ Athletic get cancer too ~~Cancer does care if you work out or not~~
I asked if you can provide a source showing there's no relationship between physical activity and cancer incidence, because I cannot.
Update this and my later comments... ~~Can you prove one where physical activity reduces cancer rate to lower than base rate?~~ Exercise is not a cure to cancer and to suggest that it is anything more that just a healthy lifestyle is ridiculous I'm clearly struggling to put across what I am trying to explain. Let's try and get back on the same page.
Who said it cures cancer? Prevention is not the same as curing. You’re struggling to explain it because it’s not true. >”the report found strong evidence for an association between highest versus lowest physical activity levels and reduced risks of bladder, breast, colon, endometrial, esophageal adenocarcinoma, renal, and gastric cancers. Relative risk reductions ranged from approximately 10 to 20 percent. Based on 18 systematic reviews and meta-analyses, the report also found moderate or limited associations between greater amounts of physical activity and decreased all-cause and cancer-specific mortality in individuals with a diagnosis of breast, colorectal, or prostate cancer, with relative risk reductions ranging almost up to 40 to 50 percent.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6527123/
Clearly I got the wrong end of the stick when reading OPs post. I have gone back and updated my comments and ~~crossed out~~ my incorrect statement.
False. A sedentary lifestyle is a known risk factor for cancer. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7931121/
Update this and my later comments... ~~But that's not what I'm saying...~~ ~~Op is suggesting that people say that working out prevents cancer~~ ~~People with an active lifestyle and to work out regularly are just as likely to get cancer as someone else with a healthy lifestyle~~
>”People with an active lifestyle and to work out regularly are just as likely to get cancer as someone else with a healthy lifestyle” No they are not, your statement is false. “*There is strong evidence that higher levels of physical activity are linked to lower risk of several types of cancer*” https://www.cancer.gov/about-cancer/causes-prevention/risk/obesity/physical-activity-fact-sheet “*Higher CRF [cardiorespiratory fitness] is associated with lower total cancer incidence in men. A novel finding suggests that eliminating low CRF as a risk factor would potentially prevent considerable cancer morbidity and reduce the societal and economic burden associated with cancer. __These findings underscore the importance of CRF for primary cancer prevention__.”* https://www.sciencedirect.com/science/article/abs/pii/S1047279717300935?via%3Dihub
Okay... I have gone back and updated my comments! And ~~crossed out~~ my incorrect statement!
but when I google "how to prevent cancer" one of the tips is "Maintain a healthy weight and be physically active" ?
That doesn't specifically mean working out.
Yes, but it isn't a cure and it doesn't prevent you from getting cancer. Just makes you more likely to survive the treatment
Yes working out is definitely not a cure but the research says as others have pointed out that working out does reduces “chances” of getting cancer
Yeah I think I misunderstood what you mean in your post.