People with strong legs are more likely to survive a heart attack, according to a new study. Researchers found that people with strong legs were less likely to develop heart failure after an attack.
They explained that a heart attack, known medically as myocardial infarction, is the most common cause of heart failure, with around 6% to 9% of heart attack patients going on to develop the condition. Previous research has shown that having strong quadriceps is associated with a lower risk of death in patients with coronary artery disease.
The new study tested the hypothesis that leg strength is associated with a lower risk of developing heart failure after acute myocardial infarction. A total of 932 patients hospitalised between 2007 to 2020 with acute myocardial infarction who did not have heart failure prior to their admission and did not develop heart failure complications during their hospital stay, with an average age of 66, took part.
Maximal quadriceps strength was measured as an indicator of leg strength. Patients sat on a chair and contracted the quadriceps muscles as hard as possible for five seconds.
A handheld dynamometer attached to the ankle recorded the maximum value in kilos. The measurement was performed on each leg and the researchers used the average of both values.
Strength was expressed relative to body weight, meaning that quadriceps strength in kilos was divided by body weight in kilos and multiplied by 100 for a percentage body weight value. Patients were classified as ‘high’ or ‘low’ strength according to whether their value was above or below the median for their sex.
The median value for women was 33% body weight and the median value for men was 52% body weight. A total of 451 patients had low quadriceps strength and 481 had high strength.
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During an average follow-up of four-and-a-half years, 67 patients (7.2%) developed heart failure. The incidence of heart failure was 10.2 per 1,000 person-years in patients with high quadriceps strength and 22.9 per 1,000 person-years in those with low strength.
The Japanese researchers analysed the association between quadriceps strength and the risk of developing heart failure. Compared with low quadriceps strength, a high strength level was associated with a 41% lower risk of developing heart failure. The research team also found that each 5% body weight increment in quadriceps strength was associated with an 11% lower likelihood of heart failure.
Study author 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."
He added: "The findings need to be replicated in other studies, but they do suggest that strength training involving the quadriceps muscles should be recommended for patients who have experienced a heart attack to prevent heart failure.”
The findings were presented at Heart Failure 2023, a scientific congress of the European Society of Cardiology in Prague, Czechia.
