If you surf the internet, you’ll see a lot of references to the importance of detoxing. Many of these recommendations, particularly those that advertise detox supplements and potions, aren’t backed by science. As many dietitians point out, detox teas and homemade detox recipes are more of a gimmick than they are a legitimate way to eliminate toxins from your body. In fact, your body has the ability to process and eliminate toxins on its own. Most of the breakdown and elimination of toxins takes place in in the liver, kidneys, and lungs. To get these systems to work properly, support your body with proper nutrition. Of course, it’s also important to reduce your exposure to obvious toxins, such as cigarette smoke, excessive alcohol, air pollution etc.
Your cells are already trained in the art of detoxifying. In fact, every cell in your body has mechanisms for detoxifying as well, even muscle cells. In fact, a recent study showed that exercise enhances a muscle cell’s ability to “detox.” What exactly does detox mean with regard to a muscle cell?
If you looked inside a muscle cell, you would see it’s a busy place. Muscle contractions require the constant production of ATP. During the making of ATP, the cell’s energy currency, free radicals are produced that can damage proteins inside the muscle cell. Unless these damaged proteins are removed, they can injure important structures, including the contractile proteins inside the muscle cell. Muscle cells need a way to “keep house” and remove damaged proteins that are no longer needed. The way it does this is through a process called autophagy. It’s a mouthful to say, but it has important implications for the health of a cell.
Autophagy literally means self-eating. It’s the process by which cells remove misfolded, damaged proteins and it’s an important function. What would happen if you never cleaned house? “Stuff” would keep accumulating until you couldn’t carry out your daily activities as efficiently. The same happens when damaged proteins and organelles build up in a muscle cell. The “junk” needs to be removed for the health of the muscle and to optimize its efficiency. All cellular systems from fruit flies to humans have this housekeeping ability. Even fungi, mold, and plants use autophagy to clean up old material inside their cells.
The Role of Exercise in Cell Clean-Up
How does this pertain to exercise? A new study suggests that exercise enhances a muscle cell’s ability house clean or remove damaged proteins. Although this is a rodent study, it likely also applies to human muscle cells. In the study, researchers looked at rats with nerve injuries to their sciatic nerve. Due to the injury and lack of muscle stimulation and movement, the stimulation the muscle cell needed to do autophagy, or clean up, was impaired. As a result, old, damaged proteins built up in the muscle cell, like trash and waste that accumulates in a house we never clean up. In the case of a house, trash can accumulate quickly just as it can inside a muscle cell.
Sadly, the muscle cells of rats in the study that experienced no muscle stimulation weren’t able to clean-up the muscle cells. However, rodents that did aerobic exercise prior to the injury didn’t experience the same impairment in autophagy. The clean-up system inside their muscle cells continued to do its job of culling damaging protein. How much exercise did the rats do beforehand? They ran on a wheel at 60% of their V02 max, or aerobic capacity, for 60 minutes five days per week for 4 weeks prior to their injury.
What can we conclude from this study? Exercise provides a signal that keeps the autophagy system inside a muscle cell primed and capable of doing its clean-up job. Without this stimulus, damaged proteins can build up and interfere with muscle function. If too many abnormal proteins build up, it can kill the muscle cell. That’s not what we want! It’s another example of “use it or lose it.” If you don’t use a muscle, systems that keep it healthy start to fail.
All in all, Inactivity is Bad for Your Muscles
You lose strength and muscle size when you don’t move your muscles for extended periods of time. If you’ve ever broken an arm or a leg, you probably know this. Once the cast comes off, the muscle is weaker and smaller in size. In animal studies, even one week of immobilization causes changes to sarcomeres, the contractile elements inside a muscle cell. In addition, the elastic properties of a muscle change so that muscle fibers break with lesser degrees of force once the muscle moves again.
Some research even shows that muscles can atrophy in as little as a few days after being immobilized. When a muscle is immobilized, the muscles that help resist the force of gravity most are impacted the most. For example, the quadriceps muscles atrophy faster than the hamstrings since the quadriceps are anti-gravity muscles.
What do you see at a microscopic level when you don’t move a muscle? As the muscle atrophies, the size of the muscle fibers decreases, but the number of muscle fibers doesn’t typically change. In contrast, as muscles age, the number of muscle fibers also decrease in number. Muscles can also atrophy when there’s damage to the nerve that leads to the muscle and with certain health conditions that cause muscle wasting. Malnutrition, burns, injuries, and the use of corticosteroids to reduce inflammation can also trigger muscle atrophy and wasting.
Even if you don’t have an illness that’s harmful to the health of your muscles, you lose muscle mass over time due to the aging process itself and that’s why strength training is so important. It helps preserve muscle and reduce its age-related loss. If you should ever be confined to bed rest for a period of time, you will likely experience a loss of muscle tissue, but regaining that muscle will be easier after you’ve recovered, thanks to muscle memory. But, it’s best to keep those muscles contracting on a regular basis and to challenge them against resistance to keep them healthy. Muscles are too important to let them wither away. Keep training!
Science Daily. “Physical exercise improves the elimination of toxic proteins from muscles”
FEBS Letters. Volume 584, Issue 7, 2 April 2010, Pages 1411-1416.
J Physiol. 2016 Feb 1;594(3):745-61. doi: 10.1113/JP271405.
BMC Research Notes20125:166. “Effects of 2 weeks lower limb immobilization and two separate rehabilitation regimens on gastrocnemius muscle protein turnover signaling and normalization genes”
Massage Today. “Understanding Disuse Atrophy”