Strength training may lower heart disease risk in women, study suggests

Women who do strength training may have a lower risk of major cardiovascular disease, particularly alongside aerobic activity, a study suggests.

Cardiovascular disease is the leading cause of death worldwide. Aerobic activities such as brisk walking, jogging, cycling and swimming are already established ways to help reduce the risk.

Strength or resistance training, also known as RT, is less established as a prevention strategy. It makes muscles work against a force and can involve body weight, free weights, resistance bands or machines.

Current US guidelines recommend at least two days of strength training and 150 minutes of moderate-to-vigorous aerobic activity each week.

They also recommend limiting sedentary behaviour, including prolonged television viewing, which is considered an independent risk factor for cardiovascular disease.

Dr Tianyue Zhang, lead study author and scientist in the department of nutrition at the Harvard T.H. Chan School of Public Health, said: “Despite its established health benefits, RT is often overlooked as a prevention strategy for CVD, and its impact on CVD risk, especially in middle-aged and older women, remains understudied.

“A key question is, how much does it add beyond aerobic activity alone?”

Researchers analysed data from 117,025 women participating in the Nurses’ Health Study and Nurses’ Health Study II.

The two groups had average starting ages of 66.8 and 48.1 years respectively.

The women reported their resistance training every four years, with exercises involving the arms and legs recorded separately.

Time spent watching television was used as the main measure of sedentary behaviour.

The researchers examined exercise and television-viewing habits alongside the incidence of major cardiovascular disease.

Major cardiovascular events included fatal or non-fatal heart attacks, strokes, coronary artery bypass surgery and percutaneous coronary intervention.

Coronary artery bypass surgery redirects blood around narrowed or blocked heart arteries. Percutaneous coronary intervention uses a small balloon, often followed by a stent, to open a narrowed artery.

Higher levels of strength training were associated with a lower risk of major cardiovascular disease, particularly heart attacks.

No statistically significant link with stroke was found when resistance exercise was considered separately.

Women completing at least two hours of strength training a week had a 20 per cent lower risk of major cardiovascular disease and a 44 per cent lower risk of heart attack than those doing none.

Each additional hour a week was associated with a five per cent lower risk of major cardiovascular disease and a 14 per cent lower risk of heart attack.

The associations weakened somewhat after researchers accounted for body mass index and conditions including diabetes, high blood pressure and high cholesterol, but remained clear.

Body mass index, or BMI, compares weight with height and is commonly used to assess whether someone is within a healthy weight range.

Strength training was also linked to additional benefits among women who did aerobic activity.

Women completing at least two hours of strength training and 150 minutes of aerobic activity each week had a 45 per cent lower risk of heart attack than those reporting no physical activity.

Women who met recommendations for strength training, aerobic activity and reduced television viewing had the lowest risks of major cardiovascular disease, heart attack and stroke compared with those who met some or none of the recommendations.

Zhang said: “These findings suggest that, within an already active population, RT is associated with additional reductions in CVD risk above and beyond overall aerobic activity.

“Alongside aerobic activity and reductions in sedentary behaviour, RT may be an important component of public health strategies for cardiovascular prevention in women.”

The study relied on participants reporting their own resistance training, meaning the data may not always have been precise.

Researchers also noted the possible influence of unmeasured factors and the limited diversity of participants.

They were unable to fully separate the effects of the type of resistance training performed from the overall amount completed.

Dr Harlan M. Krumholz, professor at Yale School of Medicine, said: “We have long encouraged resistance training, and this study provides strong evidence to reinforce that message.

“It should be included in a well-rounded health routine to support function and longevity.”