New research highlights the role of leg strength in reducing the risk of heart failure following a heart attack. Findings from a study involving 932 patients shed light on the significance of quadriceps muscles and the potential for strength training as a preventive measure.
New research presented at Heart Failure 2023, a scientific congress of the European Society of Cardiology (ESC), suggests that individuals with strong leg muscles are less likely to experience heart failure following a heart attack.
The study, which aimed to investigate the association between leg strength and the risk of developing heart failure after an acute myocardial infarction, involved 932 patients who were hospitalized between 2007 and 2020 for a heart attack. Notably, these patients had no history of heart failure before admission and did not experience heart failure complications during their hospital stay.
The participants had a median age of 66 years, and 81% of them were men. This study adds to previous research indicating that strong quadriceps muscles are linked to a lower risk of mortality in individuals with coronary artery disease, further highlighting the potential benefits of leg strength in cardiovascular health.
Maximal quadriceps strength was assessed as a measure of leg strength in this study. To evaluate this, patients were seated on a chair and instructed to contract their quadriceps muscles with maximum effort for a duration of five seconds.
Using a handheld dynamometer attached to the ankle, the highest recorded value in kilograms (kg) was captured. This measurement was conducted for each leg, and the average of the two values was calculated.
To account for body weight variations, the strength values were expressed relative to body weight. Specifically, the quadriceps strength in kilograms was divided by the patient’s body weight in kilograms and then multiplied by 100 to obtain a percentage value relative to body weight.
To determine the strength classification of patients, the researchers used the median value for each sex as a reference point. Women with a quadriceps strength value above 33% of body weight were classified as having high strength, while those below this threshold were considered to have low strength.
For men, the corresponding cutoffs were above 52% body weight for high strength and below for low strength. Among the participants, 481 individuals were classified as having high strength, while 451 had low strength.
Over the course of an average follow-up period of 4.5 years, the researchers observed that 67 patients, equivalent to 7.2% of the sample, developed heart failure. The incidence rate of heart failure was calculated as the number of cases per 1,000 person-years. In patients with high quadriceps strength, the incidence rate was 10.2 cases per 1,000 person-years. In contrast, those with low quadriceps strength had a higher incidence rate of 22.9 cases per 1,000 person-years.
Health researchers conducted a comprehensive analysis to examine the link between the strength of the quadriceps muscles (categorized as low or high) and the risk of developing heart failure.
In order to provide accurate results, the analysis took into account various factors known to be associated with the development of heart failure following a heart attack, such as age, sex, body mass index, history of myocardial infarction or angina pectoris, diabetes, atrial fibrillation, chronic obstructive pulmonary disease, peripheral arterial disease, and kidney function.
The findings revealed that individuals with high quadriceps strength had a significantly lower risk of developing heart failure compared to those with low strength. Specifically, the high strength level was associated with a 41% reduced risk of heart failure (hazard ratio [HR]: 0.59; 95% confidence interval [CI] 0.35–1.00; p=0.048), after adjusting for the aforementioned factors.
Moreover, the researchers examined the relationship between quadriceps strength as a continuous variable and the risk of heart failure. They found that for every 5% increase in quadriceps strength, there was an 11% decrease in the likelihood of developing heart failure (HR 0.89; 95% CI 0.81–0.98; p=0.014).
According to Mr. Kensuke Ueno, a physical therapist at Sagamihara’s Kitasato University Graduate School of Medical Sciences in Japan and the author of the study, quadriceps strength can be easily and accurately measured in clinical practice.
The study suggests that assessing quadriceps strength could assist in identifying patients who are at a higher risk of developing heart failure following a myocardial infarction, enabling them to receive more intensive surveillance.
While further research is required to validate these findings, they do propose that patients who have suffered a heart attack should consider incorporating strength training exercises that target the quadriceps muscles as part of their preventive measures against heart failure.
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