The science is pretty clear regarding muscles: if you don’t use them, you lose them - particularly as you age. Luckily, there’s a lot you can do to keep your muscles strong and functioning at their best.
As the largest organ in the human body making up around 40% of total body weight, muscle plays a significant role in how we expend energy, exercise, and function daily. Muscle tissue can change and adapt in response to the physical demands placed on it. For example, when muscle tissue is met with external forces, such as during exercise, it can grow. And when it is not used all that much, it can weaken and diminish.
As we age, we naturally begin to lose muscle tissue mass and strength, making maintaining muscle health a priority if we want to continue to perform our daily activities independently.
Fortunately, muscle loss does not have to be inevitable. With a two-pronged approach, including nutrition and exercise, it is possible to maintain and even enhance muscular strength throughout your lifetime.
Why maintaining muscle strength is so important
After you reach the age of 30, you start to lose 3% to 5% of your muscle mass for each decade going forward. In fact, men can expect to lose as much as 30% of their muscle mass during their lifetimes. This progressive decline in muscle mass and function is called sarcopenia. While this condition is most commonly attributed to aging, experts have discovered that it may also be promoted by a physically inactive lifestyle.
There are many reasons to prioritize preserving muscle mass. Not only is maintaining muscle mass critical for the way the body functions and moves physically, but having low muscle mass is also linked to a variety of conditions that threaten to diminish the quality of life, like disability, a higher likelihood of falling, osteoporosis, increased risk of cardiovascular disease, and lower immunity.
Understanding muscle protein synthesis
If you have ever spent any time at the gym lifting weights, you are probably all too familiar with the muscle soreness that sets in a day or two later. Delayed-onset muscle soreness, as it is called, feels uncomfortable, to say the least, and indicates a breakdown of muscle due to exercise. While muscle soreness is not necessary for muscle growth, damage to the muscle cells is necessary for muscles to grow. This is because of a process called muscle protein synthesis.
About 20% of muscle tissue is made up of protein, and during any type of movement, when muscles are stressed, muscle protein breaks down. This results in mechanical damage to the muscle proteins which stimulate a repair response in the body, causing ensuing soreness. To counteract this damage, the body produces amino acids that then bind to muscle proteins to repair it - a process called muscle protein synthesis. As a result, the muscle builds back larger.
Whether muscle tissues grow or weaken depends on how much muscle protein is produced versus how much muscle protein is broken down. Muscles grow if more protein in the muscle is produced than broken down.
Strategies for gaining muscle
Getting enough of the right nutrition and exercise is key to maintaining and growing muscle mass throughout your lifetime.
Protein. Known as the “building blocks of life,” protein is vital to survival because they are found everywhere: in our bones, cells, hormones, enzymes, and muscles. Protein is especially critical for muscle growth because it is needed for muscle protein synthesis to help repair muscle tissue from damage. So getting enough daily protein in your diet is important if you are training to build muscle.
How much protein do you need? Dietary protein requirements vary from person to person, but generally speaking, for most people who do not live a particularly active lifestyle, the minimum recommended daily amount of dietary protein to prevent muscle mass loss is 0.8 g of protein per kilogram of weight per day. That is, a person who weighs 150 lb (68 kg) should aim to consume at least 54 g of protein each day to maintain muscle mass. For people who exercise regularly, the amount of daily protein needed increases. Most people who are strength training to build muscle should aim to get as much as 1.6 g of protein per kilogram of weight per day. So, a 150 lb (68 kg) person who exercises should consume 108 g of protein each day and may spread this out over the course of the day if that is preferred.
Dietary protein sources are animal-derived foods like meat, eggs, and dairy products, as well as plant-based foods, including lentils, beans, nuts, seeds, quinoa, and soy products. As a guideline, the highest-protein foods are lean chicken breast (54.5g in 6 oz.), lean pork chop (52.7g in 6 oz.), tuna fillet (50.8g in 6 oz.), beef skirt steak (48.7g in 6 oz.), firm tofu (43.5g in 1 cup), lentils (17.9g in 1 cup), low-fat yogurt (14g in 1 cup), pumpkin seeds (8.5g in 1 oz.), and egg (6.3g in 1 large egg). Whole milk and soy protein products are shown to be especially useful for supporting muscle protein growth following resistance exercise.
Vitamin D. Like protein, vitamin D fills several essential roles in the human body, like boosting the immune system and assisting in the absorption of calcium for the growth and maintenance of bone. Being deficient in this important nutrient is linked with the risk of obesity, cardiovascular disease, and cancer. Vitamin D is also shown to play an essential role in the growth and development of muscle and its ability to contract, which means that maintaining healthy vitamin D levels can also help preserve and restore muscle mass and strength. A simple blood test can determine whether your vitamin D levels are in the healthy range, which is any level above 20 ng/mL. A vitamin D level below 12 ng/mL suggests a deficiency.
How can you get enough daily vitamin D? There are three primary ways.
Some foods, like dairy milk, plant-based milk alternatives, and certain cereals, yogurt, and orange juice products, are fortified with vitamin D. Fatty fish like salmon, tuna, trout, and egg yolks all naturally contain vitamin D.
Likewise, exposure to the sun allows your body to make its own vitamin D. Exposing your bare skin for 10 to 15 minutes in the spring and summer sun each day can generally do the trick.
But the easiest, most reliable way to ensure you’re getting all the vitamin D you need is to take a daily supplement. Both vitamin D2 and D3 supplements are commercially available, but D3 may be more effective in raising and maintaining vitamin D at healthy levels for longer. If you choose to supplement, take the recommended 600 IU amount each day if you are an adult under the age of 70, and take 800 IU if you are older than 70.
Resistance training is the most effective way to maintain and build muscle mass. Maintaining muscle mass happens when the ratio between muscle protein breakdown and muscle protein synthesis is balanced. For a muscle to grow, muscle protein synthesis must exceed protein breakdown, and for that to occur, muscles must be intensely stressed to stimulate their repair and growth.
Unlike aerobic exercises like walking, cycling, or running, resistance exercises such as weightlifting, working with resistance bands or free weights, yoga, squats, and push-ups increase muscle strength by making the muscles contract against a force or a weight. If you do not have access to free weights, lifting soup cans or milk jugs you have at home can easily fill in too. Carrying groceries, performing wall push-ups, and gripping a tennis ball can even offer strength training.
Starting a resistance training routine
Ready to get started on a new resistance training routine? Here are the guidelines from The American College of Sports Medicine (ACM), which also include recommendations for those who wish to advance their progress down the road. If you are just starting out with a new resistance training routine, start out by making small changes at a time. This way, you're more likely to prevent injury.
- Before starting any exercise program, please consult your healthcare provider to ensure that starting a new routine is safe for you.
- Set a goal to train the entire body two to three nonconsecutive days per week, targeting the major muscle groups (hips, legs, chest, back, shoulders, arms, and abdomen).
- Over time and as your strength and endurance grow, you can progress by modifying the load (amount of weight lifted), volume (total number of exercises, repetitions, and sets), the time period between each set, and frequency (number of sessions per week) of your sessions.
- To gain muscular strength
- Novice to intermediate: load 60-70% 1RM, where 1RM (one repetition maximum) is the maximum amount of weight a person can lift for one repetition. 1-3 sets of 8-12 repetitions. 1-2 minute rest period between exercises.
- Advanced: load 80-100% 1RM. 2-6 sets of 1-8 repetitions. 2-3 minute rest period between exercises.
- To gain muscle mass size
- Novice to intermediate: load 70-85% 1RM, 1-3 sets of 8-12 repetitions. 1-2 minute rest period between exercises.
- Advanced: load 70-100% 1RM, 3-6 sets of 1-12 repetitions. 2-3 minute rest period between exercises.
- To gain muscle endurance
- Load less than 70% 1RM, 2-4 sets of 10-25 repetitions. 30 seconds to 1-minute rest period between sets.
The bottom line
Just as it is important to get at least 150 minutes of moderate-intensity physical activity into your week to keep your heart and lungs healthy, it is equally important to maintain your muscle mass and strength so that you can continue to do all the things you enjoy doing. As we age, we tend to lose muscle mass, which can lead to a lower quality of life. But the encouraging news is that just because you lose muscle mass does not mean it is gone for good. By incorporating enough protein in your diet, vitamin D, and regular resistance training into your lifestyle, you can ensure your muscles will stay in tip-top shape for the long run.