Sarcopenia and loss of muscle mass

Sarcopenia means the age-related loss of muscle strength and muscle mass. It is not just a concern for older people: it is a process that can begin quietly much earlier in life. The good news is simple: strength training, eating enough and staying consistently active help slow it down.

Why does sarcopenia matter?

Sarcopenia has been described as the age-related decline in strength and muscle mass (Waters, Baumgartner & Garry 2000; Vandervoort & Symons 2001). It is not easy to establish a precise threshold for when someone can be said to have sarcopenia (Roubenoff 2001). Even so, any clear loss of muscle mass deserves to be taken seriously, because muscle mass and strength usually go hand in hand (Roth, Ferrell & Hurley 2000).

In everyday life, this means much more than how you look in the mirror. When the muscles in your thighs, buttocks, back and shoulder girdle weaken, climbing stairs, carrying shopping bags, getting out of a chair and keeping your balance become harder. So what is actually happening? Your body is losing some of the reserve that helps you move independently.

Sarcopenia becomes more apparent from your forties onward and accelerates significantly from the age of 75 (Waters, Baumgartner & Garry 2000). Age and a lack of physical activity particularly affect fast-twitch muscle fibers. These fibers work when you need strength, speed and a sudden burst of movement: for example, when standing up, preventing a fall or lifting a heavier object.

However, inactivity cannot take all the blame. Studies have also found signs of sarcopenia in physically active people. This suggests that several factors interact. Changes in motor units, declining hormone levels, slower protein synthesis, insufficient strength training load and sometimes eating too little all play a part.

How does sarcopenia develop in the body?

A muscle does not work alone. The brain sends a signal through a nerve to the muscle, triggering movement. A motor neuron and the muscle fibers it controls form a motor unit. In some muscles, such as those of the eyes, motor units are small and precise. In larger muscles, such as the quadriceps, a single motor unit can contain hundreds or even thousands of fibers.

As you age, motor neurons become less effective. Roth, Ferrel & Hurley 2000 and Roubenoff 2001 describe a gradual loss of motor neurons and their function. When a motor neuron no longer controls a muscle fiber, that fiber loses its usual signal. This is called denervation. Over time, the affected muscle fiber may atrophy, or waste away.

Your body does have a backup plan. Sometimes a neighboring motor neuron takes over some of the work, innervating fibers previously controlled by another nerve cell. This is called motor unit remodeling. Slow motor units usually take over this work. They are resistant to fatigue, but they do not produce as much strength or speed as fast motor units.

This is one reason why explosive strength, movement speed and balance decline as you age. The number of fast motor units decreases, and the new connections do not fully replace them. If fast-twitch muscle fibers lose their nerve supply faster than slow motor neurons can reinnervate them, atrophy may worsen further (Roth, Ferrel & Hurley 2000).

Protein synthesis and recovery

Muscle protein is not static tissue. It is constantly being broken down and rebuilt. Nair 1995 describes how the balance between protein breakdown and synthesis largely determines the body’s protein content. With aging, the main change is a slowdown in protein synthesis, rather than simply an increase in breakdown (Vandervoort & Symons 2001).

Several studies have confirmed this (Nair 1995; Yarasheski et al. 1999; Hasten et al. 2000; Roth, Ferrel & Hurley 2000). Slower muscle protein synthesis makes maintaining muscle mass harder. Muscles also become less able to recover after a training load or injury as you age. Satellite cells play an important role here, helping muscle fibers repair and regenerate (Roth, Ferrel & Hurley 2000).

Hormones and metabolism

Hormone levels also change with age. Concentrations of growth hormone, testosterone and insulin-like growth factor decline. These hormones are involved in protein metabolism, a positive nitrogen balance and the synthesis of myofibrillar proteins such as actin and myosin (Waters, Baumgartner & Garry 2000).

There is an important qualification: administering supplemental hormones has not produced consistently positive results. Roubenoff 2001 notes that trials in older people have yielded mixed results. Growth hormone administration has been studied more extensively, but it has not always helped maintain or increase muscle mass (Roubenoff 2001; Waters, Baumgartner & Garry 2000). The effects of estrogens in women have also been discussed, but little research has been done in this area.

What can you do if you are at risk of sarcopenia?

The simple truth is that progressive strength training is the most practical way to counter it. This does not mean that an older person needs to start lifting heavy weights straight away. Quite the opposite. Training must take account of age, health status, previous experience and the ability to recover.

Physically inactive people lose 3 – 5% of their muscle mass per decade after the age of 30 (Nair 1995). Strength declines along with it. This makes strength training a key tool in preventing and treating sarcopenia, not just a hobby for athletes.

According to Roth, Ferrel & Hurley 2000, strength training has a positive effect on neuromuscular factors, hormone concentrations and protein synthesis. Roubenoff 2001 and Roth et al. 2000 confirm that a properly structured program improves muscle fiber recruitment and the conduction of nerve impulses. This can result in faster contractions and greater strength.

Hasten et al. 2000 observed a 182% increase in the rate of protein synthesis after two weeks of strength training. The participants were older adults aged 78 – 84. Yarasheski 1993 also found that just two weeks of strength training affected the rate of protein synthesis in people aged 63 – 66. These figures do not point to a miracle solution, but they show that muscle responds to training load even in old age.

Structuring your training

If you are an older adult, you should have a medical checkup before starting strength training, especially if you have concerns about your heart, joints, bones or blood pressure. If you experience pain, dizziness or another health problem, stop your workout and consult your doctor again (Porter 2000).

The recommendation was to choose 8 – 10 exercises targeting the major muscle groups: the pectorals, latissimus dorsi, deltoids, abdominals, glutes and thigh muscles. Prioritize compound exercises that work several muscles at once (Balady 2000). At first, technique matters more than the weight you lift.

Choose a weight that allows you to complete 10 – 15 reps per set. Reps 12 and 13 should require considerable effort, but you should still be able to complete a set of 15 reps. As your strength improves, increase your rep count first, then the resistance (Balady 2000). This is gradual progress, not a competition.

At least one set per muscle group has been recommended. Most observations and studies have used 2 – 3 sets per muscle (Porter 2000). Higher volume may produce better results, but only if you recover adequately and maintain control of your technique.

For frequency, 2 workouts per week is a sensible starting point. Allow at least 48 hours of recovery between workouts. Porter 2000 notes that 1 strength training workout per week maintained strength measures and overall strength levels in older adults. If your goal is to improve, 2 workouts per week is generally a better starting point.

Practical recommendations for sarcopenia

Safety starts with the basics. Learn the correct exercise technique before adding weight. Do not hold your breath. Use a range of motion that does not cause pain or place harmful stress on your joints (Balady 2000).

If you are an older adult returning to training after a long break, use 50% or less of your previous resistance (Balady 2000). For the first 8 weeks, keep your training load minimal to allow your joints and connective tissues to adapt gradually. Repetition maximum testing should be avoided in older adults unless it is part of a research study (Porter 2000).

Approach eccentric training with caution, as it can cause severe muscle soreness and fatigue (Pollock et al. 1998). Standing exercises and moderate use of free weights can help maintain balance and coordination (Porter 2000). Workouts should last 20 – 30 min. Long sessions lasting 50-60 minutes can cause excessive exhaustion and put you off training (Balady 2000).

Nutrition cannot be overlooked either. If you consume too little energy or protein, maintaining muscle mass becomes harder (Evans 1995). The aim is not to overfeed older adults, but to ensure that training is followed by the nutrients needed for recovery.

If you cannot access a gym, you can still train. At home, you can use resistance bands, whatever weights you have available and your own body weight. What matters is that your training load is consistent, controlled and increases slightly over time. This approach helps slow the effects of sarcopenia and, in some cases, partially reverse them.

FAQ: sarcopenia

What is sarcopenia?

Sarcopenia is the age-related decline in muscle mass and strength. It affects movement, balance, your ability to manage everyday activities and your risk of falling.

Does strength training help with sarcopenia?

Yes, strength training is one of the most important practical tools. It helps maintain muscle strength, supports protein synthesis and improves neural control of muscles when the training is structured to suit your needs.

Can older adults train at home?

Yes, as long as the exercises are safe and your health allows it. Resistance bands, your own body weight and light weights are all suitable options, especially at the start.

References

This article retains the references used in the original text: Waters, Baumgartner & Garry 2000; Vandervoort & Symons 2001; Roubenoff 2001; Roth, Ferrell & Hurley 2000; Nair 1995; Yarasheski et al. 1999; Hasten et al. 2000; Balady et al. 2000; Porter 2000; Pollock et al. 1998; Evans 1995; Yarasheski 1993.

Author: Janar Rückenberg

Source: WHO – physical activity.

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