Higher quality of skeletal muscle in the chest and back is associated with a significantly lower risk of heart attack, according to medical research analyzing muscle composition via CT scans. This finding suggests that the infiltration of fat into muscle tissue, known as myosteatosis, serves as a critical predictor for myocardial infarction independently of traditional cardiovascular risk factors.
For decades, cardiovascular risk assessments have prioritized arterial health, cholesterol levels, and blood pressure. However, new evidence indicates that the “quality” of skeletal muscle—specifically in the upper body—provides a window into systemic metabolic health and the likelihood of a cardiac event. While muscle mass refers to the total volume of muscle, muscle quality refers to the density of the tissue and the absence of intramuscular fat.
Researchers utilizing computed tomography (CT) scans have found that patients with lower muscle attenuation—meaning higher fat content within the chest and back muscles—face a higher probability of heart attack. This relationship remains significant even after adjusting for age, sex, and existing comorbidities, suggesting that muscle quality is a distinct biomarker for heart health.
Why Muscle Quality Differs From Muscle Mass
Medical professionals distinguish between muscle quantity and muscle quality to better assess a patient’s physiological state. Muscle mass is the total amount of muscle tissue present, while muscle quality describes the functional integrity and composition of that tissue. When fat begins to infiltrate muscle fibers, a condition called myosteatosis, the muscle’s ability to contract and metabolize glucose decreases.
According to the National Library of Medicine, myosteatosis is often linked to insulin resistance and chronic systemic inflammation. These conditions are primary drivers of atherosclerosis, the buildup of fats and cholesterol in artery walls that leads to heart attacks. Consequently, a person may appear to have significant muscle mass but still possess “poor quality” muscle that correlates with high cardiovascular risk.
In clinical settings, this quality is measured using Hounsfield Units (HU) on a CT scan. A higher HU value indicates denser, leaner muscle, while a lower HU value indicates the presence of fat. Data shows that those with lower HU values in the pectoralis and paraspinal muscles are more susceptible to acute myocardial infarction.
The Connection Between Upper Body Muscle and the Heart
The specific focus on chest and back muscles is not incidental. These muscle groups are proximal to the heart and are heavily involved in the body’s overall metabolic regulation. Poor muscle quality in these areas often reflects a systemic failure in lipid metabolism and an increase in pro-inflammatory cytokines.
When muscle quality declines, the body’s capacity to clear glucose from the bloodstream is impaired. This metabolic dysfunction increases the risk of type 2 diabetes and hypertension, both of which are established precursors to heart disease. According to guidelines from the American Heart Association, managing metabolic health is essential to reducing the risk of heart failure and stroke.
Furthermore, the infiltration of fat into the skeletal muscles of the chest and back often mirrors the infiltration of fat into the epicardial space—the area surrounding the heart. This visceral fat accumulation can exert direct pressure on the heart and release inflammatory chemicals that damage the coronary arteries.
How Myosteatosis Increases Heart Attack Risk
The mechanism linking poor muscle quality to heart attacks involves a cascade of metabolic failures. Myosteatosis disrupts the normal function of mitochondria, the powerhouses of the cell, leading to oxidative stress. This stress damages the endothelium, the inner lining of the blood vessels, making them more prone to plaque rupture.
Patients with low muscle quality often exhibit higher levels of C-reactive protein (CRP), a marker of inflammation. High CRP levels are closely associated with the instability of arterial plaques. When a plaque ruptures, it triggers a blood clot that can block blood flow to the heart muscle, resulting in a heart attack.
Research indicates that the predictive power of muscle quality is particularly strong in older adults and those with existing metabolic syndrome. In these populations, the density of the chest and back muscles can be a more accurate predictor of short-term cardiac events than traditional body mass index (BMI) measurements, which do not distinguish between fat and muscle.
Practical Strategies to Improve Muscle Quality
Improving muscle quality requires a combination of targeted physical activity and nutritional intervention. Unlike simply “bulking up,” the goal of improving quality is to reduce intramuscular fat and increase mitochondrial efficiency.
Resistance training is the most effective method for reversing myosteatosis. Strength training, particularly exercises that target the upper body such as rows, presses, and pulls, encourages the hypertrophy of lean muscle fibers and the oxidation of intramuscular lipids. The Mayo Clinic recommends a combination of aerobic exercise and strength training to optimize cardiovascular and metabolic health.
Nutrition also plays a critical role. Diets high in refined sugars and saturated fats contribute to the accumulation of lipids within muscle tissue. Increasing the intake of omega-3 fatty acids and lean proteins helps maintain muscle density and reduces systemic inflammation. Maintaining a caloric balance that prevents excessive visceral fat accumulation is essential for preserving the quality of skeletal muscles.
Measuring and Monitoring Cardiovascular Risk
While CT scans provide the most accurate measurement of muscle quality, they are typically performed for other diagnostic reasons and are not used as routine screening tools for muscle quality. However, clinicians are increasingly using these “opportunistic” scans to identify patients who may be at higher risk for heart disease despite having a normal weight.
Patients are encouraged to monitor traditional risk factors—blood pressure, LDL cholesterol, and fasting glucose—while incorporating strength training into their routines. For those with a family history of heart disease, focusing on the functional quality of their muscles can provide an additional layer of protection.
The shift toward analyzing muscle quality represents a broader trend in precision medicine, where the focus is moving from general population averages to the specific biological composition of the individual. By understanding the link between myosteatosis and heart health, physicians can better tailor preventative strategies to high-risk patients.
The next step in this research involves longitudinal studies to determine if improving muscle quality through targeted exercise can directly lower the measured risk of heart attack in high-risk populations. Official updates on these clinical trials are expected in upcoming cardiology symposiums.
Do you incorporate strength training into your heart-health routine? Share your experience or ask a question in the comments below.