Skip Leg Day at the Gym? New Study Shows Why It May be Essential to Heart Health | Explained

Hate leg day at the gym? Or worse, do you skip it? Now, you have a scientific reason not to do so.

Exciting findings presented at the Heart Failure 2023, a prestigious scientific congress hosted by the European Society of Cardiology (ESC), reveal a compelling connection between leg strength and the risk of developing heart failure following a heart attack.

According to the researchers, a heart attack, scientifically referred to as a myocardial infarction, stands as the leading trigger for heart failure, with approximately six to nine percent of heart attack survivors subsequently experiencing this condition.

The researchers delved into the hypothesis that leg strength might play a pivotal role in reducing the risk of developing heart failure after experiencing a heart attack. To put their theory to the test, they meticulously examined a group of 932 patients who had been hospitalized for acute myocardial infarction (heart attack) between 2007 and 2020. These patients, with a median age of 66, had not previously been diagnosed with heart failure.

What they discovered was truly astounding. Among the patients with lower quadriceps (leg muscle) strength, the incidence rate of subsequent heart failure was alarmingly high, standing at 22.9 cases per 1,000 person-years. In stark contrast, those with higher quadriceps strength exhibited a significantly lower incidence rate of 10.2 cases per 1,000 person-years. Just to clarify, person-years is a unit of measurement that considers the number of individuals in a study multiplied by the duration of the study.

The researchers didn’t stop there; they diligently followed up with the same group of participants after four-and-a-half years. To their great interest, they found that 67 individuals had developed heart failure during this period. The most fascinating revelation was that those with “high” quadriceps strength boasted a staggering 41 percent lower risk of developing heart failure compared to their counterparts with “low” quadriceps strength.

But that’s not all! The study also highlighted another intriguing observation. For each five percent increase in body weight attributed to enhanced quadriceps strength, the likelihood of experiencing heart failure dropped by an impressive 11 percent.

These groundbreaking findings shed new light on the importance of leg strength in the prevention of heart failure. It emphasizes the potential impact of maintaining strong leg muscles, not only for overall physical fitness but also for safeguarding against the debilitating effects of heart-related conditions.

The author of the study, Kensuke Ueno – a physical therapist at Kitasato University Graduate School of Medical Sciences – said: “Quadriceps strength is easy and simple to measure accurately in clinical practice. Our study indicates that quadriceps strength could help to identify patients at a higher risk of developing heart failure after myocardial infarction who could then receive more intense surveillance.”

But Why Does This Happen?

Kensuke Ueno and Dr. Kentaro Kamiya are researchers in the Department of Rehabilitation at Kitasato University School of Allied Health Sciences in Japan and authors of the new research.

According to Kamiya, a process known as myocardial remodeling or cardiac remodeling can occur in the heart following a heart attack (medically termed myocardial infarction). This process involves the accumulation of fibrous tissue, leading to the enlargement of the heart. However, emerging evidence suggests that exercise-based cardiac rehabilitation has the potential to alter this remodeling process, ultimately improving heart function.

Kamiya emphasizes that cardiac remodeling is the primary factor contributing to the development of heart failure following a heart attack. Interestingly, myokines, which are peptides or amino acid chains released by muscle fibers, may play a crucial role in this context, as per a report by CNN.

Kamiya explains, “Exercise has the potential to mitigate cardiac remodeling. Furthermore, recent studies have revealed that skeletal muscle itself releases myokines, which are cytokines with diverse effects, including the prevention of atherosclerosis progression, stabilization of blood pressure, and protection against age-related diseases. Maintaining skeletal muscle mass might be associated with a reduced risk of heart failure through the action of these myokines, although the precise mechanism remains unclear.”

Strength Training or Cardio for Heart Health?

Recent research published in the Journal of Medicine & Science in Sports & Exercise in 2019 has shed light on the significant benefits of strength training exercises for heart health, comparable to those of cardiovascular exercises. The study, conducted on nearly 13,000 adults with an average age of 47, discovered that individuals who engaged in strength training exercises for at least one hour per week had a remarkable 40 to 70 percent lower risk of experiencing a heart attack or stroke, in comparison to those who did not exercise at all. Notably, all the participants in the study were free from any pre-existing cardiovascular conditions.

Interestingly, the researchers found that the frequency of workouts, whether once, twice, or thrice a day, did not significantly affect the results. What truly mattered was achieving the target of 150 minutes of exercise per week. Moreover, the study concluded that exercising for more than an hour per week did not provide additional benefits to an individual’s heart health. These findings highlight the importance of incorporating strength training into one’s exercise routine for a healthy heart, while also emphasizing the significance of meeting the recommended exercise duration rather than exceeding it.