Introduction

Muscle atrophy is a phrase used to describe the wasting or thinning of muscle mass. Many factors cause this, including ageing, a sedentary lifestyle, genetic factors, nutritional deficiencies and medical conditions. 

Muscle atrophy often occurs after prolonged periods of inactivity or when muscles are not used enough. The body eventually breaks the muscle down to conserve energy – essentially use it or lose it! Some loss of muscle is normal and natural as people age, but excessive muscle loss can be a problem if it leads to decreased strength and inability to complete day-to-day tasks. Especially in older people, muscle atrophy can leave you more vulnerable to falls and injuries.

The good news is that muscle atrophy can be reversed through lifestyle changes, such as physical therapy involving exercises to use and strengthen muscles, and ensuring your diet is nutritionally complete and healthy. 

Links have been made between cardiovascular health and muscle atrophy. Studies have shown that a loss in muscle mass can increase the risk of cardiovascular events such as heart attacks, strokes and cardiovascular disease.¹ Conversely, there has also been a link found between severe heart failure and an increase in muscle wasting and weakness.²

Symptoms

What are the symptoms of muscle atrophy? It is important to understand what to look out for if you think you or someone you know might have muscle atrophy. The symptoms can differ based on what is the cause of atrophy, with the most obvious being reduced muscle mass, however, other symptoms can include the following:

• One arm or leg looks smaller than the other 
• Weakness in one arm/leg
• Numbness/tingling in arms/legs
• Difficulty speaking or swallowing
• Trouble balancing or walking
• Gradual memory loss
• Facial weakness

What does muscle atrophy feel like?

Muscle wasting can feel like tingling, numbness or weakness in your arms and legs. If you have an atrophied face and throat muscles, this could feel like weakness in your face and difficulty in swallowing and speaking. 

Types of muscle atrophy

Disuse atrophy 

Muscle atrophy commonly is caused by not using your muscles enough in everyday life. The body’s response to using muscles less is to break them down to save energy, causing the muscles to become smaller and, thus, have reduced strength. Loss of muscle is also common in clinical settings following surgeries or medical conditions requiring bed rest.

You could be affected by disuse atrophy due to the following:

• Living a sedentary lifestyle
• Not exercising and using your muscles enough
• Being malnourished
• Being on bedrest following illness, surgery, etc.
• Sitting at a desk job all-day
• Having genetic disorders such as muscular dystrophy or Charcot-Marie-Tooth disease
• Not being able to move your limbs due to medical conditions such as a stroke

Neurogenic atrophy 

This type of atrophy can occur due to injury or disease affecting the nerves that stimulate muscles to contract. Without these nerves telling the muscles to contract, your body thinks they are no longer needed and starts breaking them down, causing them to reduce in strength and size. 
Diseases and conditions that can affect these nerves and cause this type of atrophy include:

• Motor neurone disease (MND)
• Polio
• Multiple sclerosis
• Guillain-Barre syndrome
• Spinal cord injury
• Carpal tunnel syndrome

Sarcopenia (age-related muscle loss)

Sarcopenia is the term used to describe muscle wastage that is associated with ageing. It most often affects the elderly, sedentary individuals and those who may have comorbidities that affect the musculoskeletal system or prevent adequate physical activity. Most people start gradually losing muscle mass as they age, starting in their thirties. 

The level of muscle loss correlates with the level of inactivity, meaning that this type of muscle wastage can be prevented and combatted through physical activity, such as strength training, and good nutrition.³ 

Diagnosis 

Physical examination and diagnostic tests

The amount of time taken for the muscle to atrophy depends on factors such as your fitness level, your age, and the cause of the atrophy. If due to disuse, the muscle wastage can start as early as two weeks. It is important to get a diagnosis as early as possible, in order to have the best chance of diminishing the effects of the condition. 

To diagnose atrophy, a healthcare professional will often conduct a physical exam and ask about your symptoms. Commonly, your arms and legs will be examined and your muscle mass measured. Additional tests that could be carried out by your healthcare provider could be:

• Blood tests
• Muscle or nerve biopsy
• Electromyography (EMG)
• Nerve conduction studies
• X-rays
• Computed tomography (CT) scan
• Magnetic resonance imaging (MRI) scan

Factors influencing cardiovascular health

Physical activity and exercise

It is widely accepted that regular exercise is beneficial for cardiovascular health and is strongly associated with a decrease in death due to cardiovascular issues as well as a reduced risk of developing cardiovascular disease.⁴ The heart is a muscle, and exercise helps to strengthen it, as well as improve circulation, and ensure that blood vessels can properly constrict and dilate to regulate the flow of blood around your body and to your tissues such as your muscles.

Consistently engaging in aerobic exercises that raise your heart rate, such as walking, running, or swimming increases your cardiovascular endurance and promotes your body to efficiently use oxygen.

Strength training exercises, such as weightlifting, not only build muscle mass, combatting disuse related atrophy but also boost metabolism and improve overall physical performance. Moreover, incorporating flexibility and balance exercises like yoga and stretching can enhance overall bodily function and reduce the risk of injuries.

Diet and nutrition

A heart-healthy diet plays an important role in maintaining cardiovascular health. It is essential to prioritise the consumption of fruits, vegetables, whole grains, lean proteins, and healthy fats, particularly omega-3 fatty acids found in fish. Limiting the consumption of saturated fats, trans fats, sodium, and added sugars is crucial in preventing cardiovascular diseases. Essential nutrients like antioxidants (e.g., vitamins C and E) help reduce oxidative stress, while fibre improves cholesterol levels and supports gut health. Potassium is also important in regulating blood pressure, contributing to overall cardiovascular wellness.

Lifestyle factors

Cardiovascular health can be greatly influenced by lifestyle. Smoking is a major risk factor for atherosclerosis as it causes damage to blood vessels and reduces the delivery of oxygen tissues. 

Excessive alcohol consumption is associated with hypertension (high blood pressure), heart failure, and stroke. Chronic stress can also lead to hypertension and other cardiovascular issues, meaning stress management techniques, such as mindfulness and relaxation exercises, are essential for maintaining good cardiovascular health.

Interaction between muscle atrophy and cardiovascular health

Physiological links

Muscle atrophy and cardiovascular health are interconnected through several physiological mechanisms. They share common risk factors, such as inactivity and poor diet, which can exacerbate both conditions. Additionally, they involve similar pathways, including inflammation and metabolic dysfunction. For example, chronic inflammation can contribute to both muscle degradation and the development of cardiovascular diseases, while metabolic issues such as insulin resistance can impact both muscle and cardiovascular health.

Impact of muscle atrophy on cardiovascular health

Muscle atrophy negatively impacts cardiovascular health in multiple ways. Reduced physical activity, a consequence of muscle atrophy, leads to cardiovascular deconditioning (which can be seen by an increase in resting heart rate and a decrease in physical capability), weakening the heart and reducing its efficiency. This increased inactivity also elevates the risk of cardiovascular diseases such as high blood pressure and heart failure. Furthermore, muscle atrophy is often accompanied by impaired metabolic function and increased fat deposition, which contribute to the development of cardiovascular conditions.

Impact of cardiovascular health on muscle atrophy

Conversely, poor cardiovascular health can exacerbate muscle atrophy. Reduced blood flow and nutrient delivery to muscles, resulting from cardiovascular issues, impair muscle function and regeneration. Increased inflammation and oxidative stress, common in cardiovascular diseases, can further accelerate muscle degradation. Additionally, cardiovascular conditions such as heart failure can lead to muscle wasting, creating a vicious cycle that further deteriorates both muscle and cardiovascular health.

Clinical evidence and research findings

Numerous studies have established a link between muscle atrophy and cardiovascular outcomes.⁵ Research shows that individuals with muscle atrophy are more likely to develop cardiovascular diseases. Patient case studies also illustrate the clinical interplay between these conditions, demonstrating how muscle degradation can lead to worsened cardiovascular health and vice versa.

Summary

Muscle atrophy is the loss of muscle mass due to ageing, inactivity, or medical conditions. It leads to weakness, reduced strength, and increased risk of falls. Disuse atrophy results from a sedentary lifestyle, while neurogenic atrophy stems from nerve damage. Age-related sarcopenia affects the elderly but can be managed through exercise and a healthy diet. The interconnectedness of muscle atrophy and cardiovascular health shows the importance of prevention and management to prevent and treat this condition. Regular exercise, proper nutrition, and lifestyle modifications are all essential to maintain both muscle mass and cardiovascular function which is important to significantly enhance overall well-being and reduce the risk of related diseases.