Causes of Sarcopenia – What Drives Muscle Loss?

---

Sarcopenia is rarely the result of a single cause – it is an interplay between biological ageing, lifestyle factors and disease. Understanding what drives muscle loss is the first step towards slowing it down.

---

Primary and secondary sarcopenia

Sarcopenia is clinically divided into two types:

Primary sarcopenia arises as a direct consequence of ageing, with no other identifiable cause. The body’s ability to build and maintain muscle tissue naturally declines with age, independent of lifestyle.

Secondary sarcopenia is caused or worsened by disease, inactivity or malnutrition. It is more amenable to intervention – and this is where most measures can make a difference [1].

In practice, the two often coexist: biological ageing initiates the process, and lifestyle factors determine how quickly it progresses.

1. Ageing – the primary driver

From approximately age 30, the body begins to lose muscle mass gradually – 3–8 % per decade. After 60, the process accelerates markedly, and in people over 80, muscle loss can be visible and functionally significant.

Several mechanisms underlie biological ageing:

• Fewer and smaller muscle fibres – fast-twitch fibres (type II) decrease more rapidly than slow-twitch fibres (type I), affecting strength and reaction speed
• Anabolic resistance – older muscles respond less effectively to protein stimulation and exercise, making it harder to build new muscle tissue
• Reduced nerve signalling – the number of motor neurones declines with age, impairing communication between the nervous system and muscles

2. Physical inactivity

Muscles that are not used atrophy – they shrink and weaken. Periods of bed rest, injury or sedentary living can cause muscle mass loss of 1–3 % per day in severe cases.

A vicious cycle often develops: sarcopenia causes fatigue and difficulty moving → the person moves less → muscle loss increases further. Physical activity is therefore both prevention and treatment [2].

3. Insufficient protein intake

Muscle protein is constantly being broken down and rebuilt. In older adults, breakdown is relatively stronger and synthesis weaker – and adequate protein intake is crucial to keeping the balance positive.

The recommendation for older adults is 1.0–1.2 grams of protein per kilogram of body weight per day – considerably more than for younger people. Despite this, many older adults consume too little protein, often due to reduced appetite, social isolation, financial constraints or difficulty cooking [1].

The distribution of protein intake also matters. Consuming at least 25–30 grams of protein per meal is more effective for muscle synthesis than concentrating the same amount into one or two daily meals.

4. Hormonal changes

Several hormones that regulate muscle building decline naturally with age:

• Testosterone – decreases by 1–2 % per year in men after age 30, directly affecting muscle mass and strength
• Oestrogen – influences muscle function and bone; declines sharply at menopause
• Growth hormone (GH) and IGF-1 – stimulate muscle protein synthesis; levels fall with age
• Insulin – older muscles are often more insulin-resistant, impairing post-meal muscle synthesis

Hormonal changes are difficult to influence directly without medical treatment, but exercise and adequate protein intake can partly compensate for reduced hormonal stimulation.

5. Chronic low-grade inflammation

The ageing immune system continuously produces low levels of inflammatory substances – a phenomenon known as inflammaging. These substances, including cytokines such as IL-6 and TNF-α, actively break down muscle tissue and inhibit its rebuilding.

Chronic inflammation is worsened by diabetes, heart disease, COPD and obesity – conditions more common in older adults that all accelerate the sarcopenia process [1].

6. Chronic diseases

Several conditions drive muscle loss directly or indirectly:

• Parkinson’s disease – reduced mobility and tremors lead to inactivity
• COPD – breathlessness limits physical activity; systemic inflammation breaks down muscle
• Diabetes – insulin resistance impairs muscle synthesis; neuropathy affects mobility
• Dementia – forgetting to eat, reduced willingness to move and dependence on care
• Osteoporosis – sarcopenia and osteoporosis frequently coexist, a condition known as osteosarcopenia

7. Malnutrition and vitamin D deficiency

Beyond protein, overall energy balance and specific micronutrients are important:

• Vitamin D – deficiency is common in older adults, particularly in northern latitudes during winter. Vitamin D deficiency is linked to reduced muscle strength and increased fall risk [3]
• Omega-3 fatty acids – have anti-inflammatory effects and may support muscle protein synthesis
• B12 and folate – deficiency affects nervous system function and indirectly impairs muscle control

Can the causes be influenced?

Yes – but to varying degrees:

Read more about symptoms of sarcopenia and what sarcopenia is.

Sensorem’s personal alarm features GPS, medication reminders and automatic fall detection

Sensorem’s personal alarm for the elderly is a technical aid specifically developed for people with a heightened risk of falling. The alarm works outdoors and has built-in GPS positioning so that relatives can see the user’s location on a map in the Sensorem app. Relatives are automatically called by the alarm (two-way communication) if the user leaves a pre-set geographical area. The alarm also features a medication reminder – the watch emits a sound telling the user it is time to take their medicine. The alarm can also detect falls automatically using the built-in fall sensor.