Where does muscle go when we take a fitness break? Is it true that either we use it, or we lose it? Explore strategies to protect your lean muscle mass and maintain a balanced body composition even when you can't pursue a vigorous regimen.

Does muscle tissue go away or shrink when we stop exercising? Does it turn into fat or simply disappear? Despite the common phrase “use it or lose it,” most people don't know what actually happens to lean muscle if something puts us on the sidelines and we can't keep up with our workout routines.

Research published by the journal Current Opinion in Clinical Nutrition and Metabolic Care shows that fat mass decreases as muscle mass increases with the shift from an active to a sedentary lifestyle. In other words, toning up and getting stronger drives away unwanted fat cells. On the other hand, a lack of exercise has the opposite effect. Even if you never missed a spin class before embracing a couch-potato philosophy, you'll quickly notice softer fat tissue taking over those lean muscles. 

Where does lost muscle go?

Despite the inverse relationship between lost muscle and increased fat, muscle cells don't actually transform into fat. Instead, when we stop exercising, muscle tissues atrophy or shrink as the number and size of their fibers decrease. This occurs at the molecular level and can start after just seven days of inactivity, according to the National Academy of Sports Medicine. 

What happens when we lose muscle?

Losing muscle can create a cascading impact on your health and fitness. Here are just a few of the possible negative effects:

We aren't as strong.

According to the journal Sports Medicine, athletes lose muscle strength just three weeks after they stop training. The researchers defined “athletes” as anyone who exercises vigorously at least five times a week, so you might qualify even if you don't compete in events or team sports. If you exercise fewer than five times a week or stick to low-impact activities like yoga or swimming, you may struggle to open that extra stubborn pickle jar or rearrange your furniture within just a month of stopping your workouts.

The good news? If you had a solid exercise routine in place before taking a short break, you'll be able to rebuild muscle faster than if you’d spent the last six months binging your favorite Netflix dramas. A study published in the journal Scientific Reports theorizes that genes within our muscles actually have memory. They "remember" what all those hours at Pilates felt like and trigger growth accordingly when we go back to similar activities. Without that memory, the process of building muscle takes longer.

Scientists think that genetic memory is passed down in our DNA through generations. This may explain cases when individuals have unexplained abilities in areas like math, music, or art.

We lose heart health.

If you stop exercising regularly, your body has to work harder when you return to physical activity. Cardiovascular fitness is the body's ability to take in oxygen and deliver it to tissues, organs, and muscles as you exercise. Your cardio fitness reflects your overall wellness. Unfortunately, at least 15% of American adults in every state get no physical activity, according to the Centers for Disease Control and Prevention. At least 30% of adults rarely exercise in Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Oklahoma, and Tennessee.

The Journal of Applied Physiology found that marathon runners see a drop in cardio fitness about three to four weeks after training ends. However, you don't have to run a marathon to be concerned about your heart health. The Centers for Disease Control and Prevention says that most healthy adults should engage in at least 150 minutes a week of moderate-intensity cardiovascular exercise (jogging or cycling, for example). If you struggle to exercise enough, talk to your health care provider about a routine that can help you build heart health and stamina. 

We're more likely to fall.

Even a minor fall can have a major impact on mobility and overall health, especially for elderly adults. A 2015 report from the American Society for Bone and Mineral Research found that seniors with low muscle mass have more than double the fracture risk from a fall than older people with healthy muscle strength. People who lose muscle with age may also struggle with balance and gait, further boosting fall risk. 

What factors influence muscle loss?

Age accelerates decreased fitness and metabolism when someone stops exercising. According to a study published by Muscles, Ligaments, and Tendons Journal, the older we are, the harder it is to regain lost muscle and heart health after a break of more than a week or two. 

After menopause, women lose strength faster than men. On the other hand, Harvard Health cites the role of testosterone in male muscle growth. As testosterone decreases, building lean muscle mass becomes more difficult for men.

How can we preserve muscle and prevent loss?

Even as you lose muscle mass with age, these strategies can keep your muscles healthy and strong. 

Strength and resistance training

Resistance training preserves muscle mass while keeping your resting metabolic rate elevated for up to 72 hours, which means you burn more calories during that interval. Most healthy adults should work out with resistance bands, lift weights, or do body-weight exercises like push-ups and sit-ups at least twice a week. The important thing is to work all major muscle groups. If you haven't exercised in several months, it can take up to six weeks to see results with a new strength training program. So, don’t give up too early!

Protein and nutrient intake

Try to incorporate protein-rich items such as beans, nuts, eggs, fish, quinoa, lentils, tofu, seafood, low-fat cheese, and lean meats in each of your daily meals. According to the Cleveland Clinic, you should strive for a daily intake of 0.45 g of protein for each pound you weigh. For example, if you weigh 160 pounds, you need about 75 g of protein a day. Eating one chicken breast or a serving of chickpea pasta can get you halfway to your daily goal. Spreading your protein intake across all your daily meals improves your body's ability to use it.

You may want to ask your health care provider about vitamin D or creatine supplements if you don't get enough dietary protein. These nutrients can help build muscle mass. You also need healthy carbohydrates from whole grains, vegetables, and fruits for the energy you need to drive a healthy fat burn.

Sufficient sleep

Getting enough sleep also supports a healthy body shape and composition. Most adults should get seven to nine hours a night, according to the National Sleep Foundation. If you have trouble sleeping, talk to your health care provider to figure out why. Try to keep a consistent sleep schedule and limit alcohol and caffeine.

Even with healthy lifestyle routines in place, we lose 3 to 8 percent of muscle mass per decade starting at age 40. Understanding this process can help you stay as healthy as possible, maintaining mobility and warding off obesity and chronic disease. 

It doesn't have to be a losing battle with time! Humans have the capacity to stay fit as we age. In the most famous example, Charles Eugster competed as a bodybuilder into his 90s and even gave a TEDx talk about his experience as the so-called world's oldest fitness man.

Tracking body shape and composition can identify a change in muscle mass that could affect your health. Get the insights you need by making an appointment at a Fitnescity location near you. Both the DEXA and BOD POD scans offer accurate ways to determine your proportion of lean muscle to body fat percentage. Get to the bottom of your body composition to realize real wellness results.

References:

https://www.medicalnewstoday.com/articles/318501

https://www.iofbonehealth.org/whos-risk-0 

https://www.cdc.gov/physicalactivity/basics/adults/index.htm 

https://health.clevelandclinic.org/how-can-you-avoid-muscle-loss-as-you-age/ 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3940510/ 

https://journals.physiology.org/doi/full/10.1152/japplphysiol.00911.2017 

https://www.researchgate.net/publication/322791398_Human_Skeletal_Muscle_Possesses_an_Epigenetic_Memory_of_Hypertrophy 

https://pubmed.ncbi.nlm.nih.gov/23529287/ 

https://blog.nasm.org/muscle-atrophy 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2804956/ 

https://www.health.harvard.edu/staying-healthy/preserve-your-muscle-mass 

https://www.sleepfoundation.org/how-sleep-works/how-much-sleep-do-we-really-need