Healthy Ageing requires strength training and a sufficient intake of protein. Many people lack both. In this article we explain why this is important, and what you can do about it.
Cicero (44 BC): It is our duty to resist old age, to compensate for its defects, to fight against it as we would fight a disease; to adopt a regimen of health; to practice moderate exercise; and to take just enough food and drink to restore our strength’.[2]
Old news to say it is important to stay active and to eat healthy as we age. Nevertheless, too many people seem to rely on just walking or biking at a certain age. Or they follow that same exercise routine over and over again. This is not enough to maintaining, not even improve (!), a good health.
About 46% of Dutch adults between the age of 18 and 64, and 38% of Dutch adults older than 65, meet the recommended guidelines for physical activity. [3] Of the total Dutch population, older people are the least active and more than 50% is overweight. These recommended guidelines only focus on maintain current health. Because to improve health, more needs to be done.[4]
Research shows that the combination of strength training and a sufficient intake of protein is necessary and effective in ageing strong and healthy. The problem is that many people lack both. In this article we explain why this combination is so important, and what you can do about it.
The highlights of this article
- Starting the age of thirty, people have to train harder and smarter, and have to eat more protein to stay healthy and strong.
- The combination of strength training and a high protein intake leads to the best results.
- Protein intake sometimes needs to be increased up to 200%, with 35 grams directly after training.
- Exercise should be constantly varied high intensity strength training with progressive loading, such as CrossFit
The importance of strength training
Ageing comes with decreased physical functioning and having more difficulty completing physical tasks. One important reason for this are changes in skeletal muscles.
Skeletal muscles are muscles that connect to bones and comprise 30- 40% of total body mass. Skeletal muscles have several important functions such as moving bones in the body, protecting joints, and supporting inhaling and exhaling. Skeletal muscles are voluntary, which means we control how and when they move. Such as ourleg muscles when we sit down and stand up.
Age- related degeneration is a common skeletal muscle conditioning that can significantly affect daily functioning. Weak muscles increase the risk of falling and getting injured for example, while strong muscles can prevent bone fractures and support a good breathing pattern. A combination of strength training and an adequate intake of protein keeps skeletal muscles strong and healthy, and supports physical functioning and the quality of daily life.[5]
Loss of muscle mass
After the age of 30, muscle mass decreases 3 to 8% per ten years under normal circumstances. In cases of immobilization such as due to inactivity or hospitalization, this decrease can accelerate. A young adult can lose 150 grams of lean leg muscle during one week of bed rest. For an older adult this can go up to 600 grams, for example because the older adult is already in a state of muscle mass reduction; stress hormones from being hospitalized increase the loss of muscle mass; and older adults often have a higher rate of inflammation leading to reduced muscle mass. Regaining 600 grams of lean muscle mass requires an intense program of strength training and nutrition for at least three months.
Loss of muscle strength and power
Muscle strength and power decrease faster than muscle mass, up to 30% per ten years. The decline of muscle power (peak power), for example picking up a heavy object, is greater than the decline of muscle strength (isometric force) for example pressing against a wall (3-4% respectively 1-2% per year). A 74-year-old man has 40% less muscle strength and 60% less muscle power than a 26- year- old man. This implies muscle mass alone is not the holy grail. Muscle strength and power are at least as important for daily functioning. The main reason for the faster decrease in muscle strength and power is age- related sarcopenia that comes with the loss of muscle fibres and fat infiltrating in the muscle.[6]
Sarcopenia
Sarcopenia is the age- related loss of skeletal muscle tissue and decreased capacity of muscle cell regeneration. From the second to the eight decade of life the decline in lean body mass in men is 18% and in women 27%, especially after the age of 45. The decrease is the greatest in the lower limbs compared to the upper limbs. One of the possible reasons for this is detraining.
Sarcopenia can be accelerated by inactivity or a disease such as anorexia nervosa. Women are more at risk of dropping below the critical level of muscle mass needed for independent living because they live longer than men; have lower muscle mass; and are less responsive to strength training and protein intake to maintain muscle mass.[7]
Loss of muscle fibres
Skeletal muscles are made up of two types of muscle fibres: Type I and Type II (IIA and IIB).
Muscle fibre types
Type I muscle fibres (slow twitch fibres) support aerobic metabolism and fatigue resistance. They produce less force, are slower in producing maximal tension, but they can maintain longer- term contraction. Type 1 muscle fibers are important for example for core stability and for prolonged submaximal aerobic activities.
Type II muscle fibres (fast twitch fibres) are larger in size, more anaerobic, create more powerful forces and maximum contractions, but for a shorter duration and faster fatigue. Type II muscle fibres are importan tfor example for power activities such as weightlifting and sprinting. There are two categories of Type II muscle fibres: Type IIB creates the most power but fatigues the fastest. Type IIA is considered an intermediated type that fatigues slower than type IIB but not as slow as Type 1.
All skeletal muscles consist of a combination of Type I and Type II fibres. Depending on several factors such as genes, training and age, the ratio of muscle type fibres can vary per person. Type 1 muscle fibres can be developed through endurance training such as longer duration running or exercises at low intensity with high repetitions. Type II muscle fibers can be developed through power training.
The effect of strength training
Strength training increases the size of both Type I and Type II muscle fibers. Type II fibers can also recruit Type I fibers such as during high intensity interval training for a longer duration. Deload phases in a training program, where volume and intensity are decreased for a certain period, can improve the strength and power of Type IIA fibers without compromising Type I fibers. Studie has shown that recreational runners who were training for a marathon improved the function of Type I and Type IIA muscle fibers during the 13-week training program. During the 3- weeks deload- phase of the training program,Type IIA continued to significantly improve.[8]
Muscle fibre changes with ageing
With ageing, Type IIB muscle fibres are more likely to decrease in size than Type IIA and Type I. On average, Type II fibers are 30% smaller in older adults than in younger adults. Furthermore, there seems to be a shift in muscle fibers type in older people towards Type I, as a result of a combination of age- related neuro- degenerative changes and physical activity status. Up to the age of 60, the number of motor units (the neuron and all its related muscle fibres) remains the same. From the age of 60 this number declines with 3% per year, up to 60% at the age of 80. To that age, the loss of muscle fibres Type II is greater than of Type I. After the age of 80, Type I fibres are also lost.[9]
Fat infiltration
The loss of muscle fibres is accompanied by fat infiltration in the muscle and in connective tissue. In older people this is about 15% of muscle area, compared to 6% in young adults. Fat infiltration is inversely related to physical activity: The more you exercise, the lower the amount of fat infiltration in the muscle will be.
Fat infiltration is not exclusively related to ageing. Itcan also take place in younger adults who do not use their muscles. For example, research shows a correlation between low back pain and fat infiltration in core muscles.[10]
Fat infiltration is related to low grade chronic inflammation and insulin resistance, increasing the risk of metabolic syndrome, a combination of obesity, diabetes type 2, high blood pressure and high cholesterol. The increasing global obesity rate is considered a compounding factor of sarcopenia and contributes to the loss of muscle mass and impaired physical functioning.[11]
In short
Neuropathic, hormonal, immunological, nutritional, and physical activity factors contribute to sarcopenia. Ageing comes with the loss of Type II muscle fibres, the loss of motor units, changes in the ratio of muscle fibres, and decreased muscle regeneration capacity.[12] Strength training and nutrition are necessary to prevent or slow down the process of sarcopenia.
Use it or lose it!
Muscles that are not used or trained become smaller and weaker. Muscle that are trained can become bigger and stronger under the right conditions. Skeletal muscle protein metabolism is a dynamic process of muscle synthesis (growth) and muscle breakdown. In muscle synthesis, new muscle proteins are formed from building blocks, amino acids, mostly delivered by eating protein. In muscle breakdown, muscle proteins are broken down into amino acids. Some of those amino acids can be re-used, others are burned to generate energy for the body. Skeletal muscles are constantly renewed and within 3 months all muscle proteins are replaced by new ones.
The right conditions
The right conditions for muscles to grow and become stronger refers to the combination of a sufficient intake of protein and resistance training. The intake of protein is discussed later.
Chronic resistance training increases muscle mass and muscle strength in older people, provided the muscles are progressively stimulated and exposed to a sufficient variety of stimuli. Strength training can increase the rate o fmuscle protein synthesis about two to five times directly after the exercise and the synthesis can persist up to 48 hours. Chronic resistance training helps to prevent age- related loss of muscle strength and fat infiltration in the muscles. This emphasizes the importance of constantly varied training sessions with progressive loading. If muscle synthesis is greater than muscle breakdown, muscle mass increases.[13]
The need to work harder
Muscle mass decreases with ageing and in general, older muscles are weaker muscles. One important explanation is that older people respond differently to the intake of protein (discussed later) and to exercise compared to younger adults.[14]
Research has shown that older men (average age of 70) have a 30% lower response of muscle protein synthesis to resistance training than younger men (average age of 24).[15] Furthermore, in younger adults, muscle protein synthesis peaks higher one to two hours after exercise, compared to older adults. Simply said: Strength training leads to more gains in younger adults.[16]
Loss of muscle quality
Reasons for the reduced responsiveness to exercise in older people is, as mentioned, the decline in the size of Type II muscle fibres and the changes in the ratio of types of muscle fibres, that come with ageing. Muscle strength and power decline more than muscle mass, which implies a decline in force and power older muscles can produce. This is also known as a loss in muscle quality. A loss of Type II muscle fibres and a decline in the function of muscle fibers to generating force at high speed are possible explanations for the loss of muscle quality.
Decreased tendon stiffness
Furthermore, ageing also affects tendons, the connective tissue that attached muscle to bones. Tendon stiffness decreases with age. This directly affects the contraction capabilities of muscles, leading to loss of muscle force.
Changes in neural drive
Also, with ageing the brain to muscle connection changes. The neural drive to the agonist muscle, the prime muscle that contracts during a movement, is reduced, and the neural drive to the antagonist muscle, the opposite muscle that relaxes during that movement, is increased. For example: the neural drive to the biceps muscle when drinking a glass of water is reduced, while the neural drive to the triceps muscle is increased. This change in neural drive leads to a loss of force of the prime mover and eventually to distorted movement patterns.[17]
Decreased energy function
During ageing the number and the function of mitochondria in muscle cells decrease. Mitochondria are, in a nutshell, parts of a muscle cell needed for energy availability in the cell. In the mitochondria, the energy containing nutrients from food are metabolized to energy that muscle fibres can use to contract and relax. Ageing therefor leads to a decline in the muscle function.
Hormonal changes
Older women (65 and older) have a 33% lower increase in muscle mass in response to resistance training than men of the same age. Furthermore, the basal rate of muscle protein synthesis in response to resistance training increases with 50% in older men, but only with 15% in women. One possible explanation is that men are better in maintaining the adaptive responses to resistance training. [18] On the other hand, women have less muscle than men, but they lose it more slowly during aging. Although the intake of protein leads to less muscle protein synthesis in woman than men, research shows that women of 65 to 80 years of age have a 30% higher overall basal rate of muscle protein synthesis than men. This means sex differences in muscle protein metabolism come with age and are probably the result of age-related hormonal changes. [19]
The importance of high protein intake
The combination of strength training and an adequate intake of protein is key for strong and healthy ageing. The type, amount and timing of the intake of protein matter, as well as combining the intake with carbs and maintaining a qualitative and quantitive well balanced diet.
Type of protein
When we eat, protein synthesis increases and protein breakdown decreases. This decrease of protein breakdown is due to the increase of the hormone insulin. Insulin is responsible for regulation of blood glucose levels and for suppressing protein breakdown.
Essential amino acids
The increase of protein synthesis leads to the gain of muscle protein, known as ‘fed gains’. Crucial for protein synthesis is the intake of essential amino acids, amino acids that cannot be made by the body but must be provided via nutrition. Especially leucine, isoleucine and valine stimulate muscle protein synthesis, with leucine being the strongest of the three. Leucine is in products such as meat, dairy, eggs, soya, and beans. The amount of leucine is higher in animal-based products than in plant- based products. Research shows that the type of protein ingested is matters. Whey protein is superior to casein and soy. High quality proteins that contain all essential amino acids such as whole milk, beef, egg, and soy supply everything need to muscle protein synthesis. [20]
Amount of protein
The Recommended Daily Allowance (RDA) for healthy adults is 0.8 grams of protein per kilogram body weight per day. According to the RDA, a healthy woman with a body weight of 65 kg should eat 52 grams of protein per day. For example: 150 grams of quark, 2 eggs, 100 grams of chicken breast and 1 spoon of chickpeas. The RDA is the level that is sufficient to cover the needs for the majority of a population. RDAs can vary between countries and authorities on nutrition. This is due to differences in dietary habits, different interpretations of data and the use of different ranges or different values on vitamin and mineral intake. This implies that the RDA does not apply to everyone in all situations.
Studies show that older people eat on average 0,9 grams of protein per kilogram body weight per day, and that protein intake takes place mostly during lunch and dinner, and not during breakfast. This average intake is far too low to prevent the loss of muscle mass, undernutrition, and the risk of several diseases. [21]
Up to 2 grams per kilogram body weight per day
Based on research, the recommended intake of protein fo rolder people, not necessarily athletes, is higher than the RDA: At least 1,2 grams protein per kilogram body weight per day and in case of regular strength trainingup to 2 grams per kilogram bodyweight per day. The intake should be divided into portions of 25 to 30 grams of protein divided over several meals during the day.
35 grams directly after exercise
The intake of protein directly after exercise should be up to 35 grams compared to 10 to 20 grams for younger athletes. In the example of the healthy woman with a body weight of 65 kg this means eating at least 1,5 times more protein per day. [22]
Ageing requires higher intake of protein
The reason for this higher intake of protein is that older people respond differently to exercise and nutrition than younger people. They have a reduced sensitivity and responsiveness to the intake of amino acids, as well as a reduced sensitivity to the suppressing effect of insulin on protein breakdown.
After eating protein, the uptake of amino acids is delayed, with lower levels of amino acids in the blood stream. This implies that more amino acids are required to stimulate muscle growth in older athletes than in younger athletes.
Furthermore, directly after absorption, a higher portion of the amino acids is used as a source of energy. In younger athletes this is around 30%, in older athletes this is 50%. This means a smaller portion is left to stimulate muscle growth. Also, in older people blood flow (containing amino acids from food) to and in the muscles is reduced and muscle cells are less sensitive to insulin which is needed for the uptake of amino acids and the suppression of protein breakdown. This results in less amino acids entering muscle cells. [23]
Supplements
Increasing the intake of protein, sometimes up to 200%,can be a challenge. Many older people suffer from a loss of taste, dental problems, or mental issues that hinder healthy nutritional habits and appetite. A dietary supplement can help to increase the intake of protein. Although it does not improve muscle mass, it can improve muscle strength and physical performance.[24]
Protein and carbs
Additional to a higher intake of protein, insulin sensitivity is key to support the uptake of protein in the muscle cells. This means the intake of protein should be combined with the intake of glucose. Furthermore,the daily caloric intake should consist of around 50% carbohydrates, mostly in the form of unprocessed whole wheat products, vegetables, and some fruit. Sugara nd processed foods should be avoided to prevent insulin resistance, which blocks muscle build. A healthy body weight and regular exercise support insulin sensitivity and do not worsen the risk of fat infiltration in the muscle of acceleration of the loss of muscle mass.
Timing of protein
Nutrition and exercise work together to increase muscle protein synthesis. Only nutrition or only exercise does not lead to the same results. Research shows muscle protein synthesis increased with 145% with the intake of leucine enriched amino acids solution with carbohydrates directly after resistance training and a longer period of remaining increase of muscle protein synthesis, compared to an increase of 41% without the intake of nutrition after training and less hours of remaining increase.[25]
Before and during exercise
During exercise muscle protein synthesis is suppressed and muscle protein breakdown increases. The intake of amino acids with glucose one hour before strength training can result in less decrease of muscle protein synthesis during exercise compared to no intake. Also protein intake during resistance training can increase muscle protein synthesis. [26]
Directly after exercise
The stimulation of muscle protein synthesis is enhanced when protein in consumed directly after exercise, rather than hours later. This is achieved via the intake of amino acids and glucose directly after the exercise. The intake of amino acids increases muscle protein synthesis and the production of the hormone insulin because of the intake of glucose suppresses muscle protein breakdown. In healthy young adults 20 grams of high-quality protein is the optimal dose to maximize muscle synthesis. In older adults this optimal dose is on average 35 grams. Eating only a regular meal without the essential amino acids will not result in the same muscle synthesis.[27]
During the day and before bed
With a regular intake of healthy meals with 20 grams of protein every 3 to 5 hours after the exercise, protein synthesis can continue up to 24 hours after the exercise. Research shows that protein ingestion before sleep could be a ‘window of opportunity’ for athletes. During sleep, a period of fasting, protein balance can be improved when eating 20 grams of protein just before going to bed.[28]
Food quantity and quality
It seems so obvious, that eating enough calories a day is essential, a prerequisite for daily functioning. Nevertheless, research shows that, on average, 1 in 10 older individuals living at home is malnourished. This percentage increases from about 3% aged 65-69 years to 15-20% aged 75 years and older. Among older people receiving home care, 30% is malnourished.[29] More than 50% of the Dutch adult population is overweight. Malnutrition and overweight/ obesity can go hand in hand and are an indication of insufficient intake of high quality food.[30]
Low energy availability and low quality of food likely impact performance. Muscle protein synthesis decrease, neuromuscular performance is diminished, recovery is delayed, the risk of injury increases, and the risk of metabolic syndrome and several chronic diseases increases. All reduce the capacity to maintain or improve daily physical functioning and the quality of life.[31]
Concluding and final comment
To age healthy and strong, a loss of muscle mass, muscle strength and muscle power needs to be prevented. The combination of consistent and constantly varied strength training with progressive loading at high intensity, with a sufficient daily intake of high-quality protein and a well-balanced diet, is the most effective strategy. The synergy between resistance training and healthy nutrition is key. [32]
CrossFit offers constantly varied strength training with progressive loading at high intensity, and can be a great choice for everyoine even at an older age, provided they receive professional guidance from educated coaches and are not deterred by the sometimes-daunting image of the sport.
Coaches and health professionals can play a supporting role in developing and maintaining sustainable exercise and nutritional habits. Especially since the combination of both is key and older people have to work harder to get the same results as younger people, yet also experience several age-related limitations that can hinder both. The master body and mind cannot be compared to that of a younger individual, and require a different approach.
Create your own health!©
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