A research team from the Kitasato University School of Medicine in Japan analyzed the association between leg muscle strength and the risk of heart failure in 932 patients (average age 66) hospitalized for acute myocardial infarction between 2007 and 2020. Myocardial infarction, commonly known as a heart attack, occurs when the coronary artery suddenly becomes blocked, leading to damage to the heart muscle. It is the most common cause of heart failure, affecting approximately 6-9% of myocardial infarction patients.
The research team measured the maximum strength of the quadriceps femoris muscle, located in the front of the thigh, as an indicator of leg muscle strength. Patients were divided into two groups based on their measurements. During the assessment, patients sat in a chair and contracted their quadriceps muscles forcefully for 5 seconds, which was then measured using a portable dynamometer attached to the ankle. Approximately 52% of the patients had strong leg muscles, while 48% had weak leg muscles.
The follow-up observations revealed that 67 patients (7.2%) developed heart failure. Patients with stronger leg muscles had a 41% lower probability of heart failure compared to those with weaker leg muscles. Furthermore, for every 5% increase in leg muscle strength, the likelihood of heart failure decreased by 11%. The research team speculated that the quadriceps femoris muscle plays a role in improving blood circulation to the heart, acting as a secondary “heart” by compressing the blood vessels in the lower extremities, thus positively impacting heart failure prevention.
Dr. Kensuke Ueno, the lead author of the study, emphasized the importance of leg muscle training related to the quadriceps femoris muscle for preventing heart failure, particularly in patients who have experienced myocardial infarction.
To strengthen the quadriceps femoris muscle, activities such as squats and indoor cycling are recommended. During squats, it is important to maintain a C-shaped curve in the lower back and avoid allowing the knees to extend past the toes. Adjusting the saddle height on an indoor bicycle to ensure a slight bend of 10-15 degrees in the knees when the feet are placed at the lowest position can help reduce stress on the kneecap. If muscle weakness makes resistance training difficult, consistently climbing apartment stairs can be beneficial. When ascending stairs, pushing off with the entire sole of the foot and climbing two steps at a time is recommended. Another effective exercise for strengthening the quadriceps femoris muscle involves lying on the floor, extending the knees, and pulling the toes toward the body at a 45-degree angle for a 3-second hold.
These research findings were recently presented at the “Heart Failure 2023” conference organized by the European Society of Cardiology.
