Scientists reveal how much exercise you really need to protect your heart

Adults may need far more weekly exercise than current guidelines recommend to achieve a major reduction in the risk of heart attack and stroke, according to findings from an observational study published online in the British Journal of Sports Medicine.

The researchers found that substantial cardiovascular protection was associated with 560 to 610 minutes of moderate-to-vigorous physical activity each week. That amount is roughly 3 to 4 times higher than the current public health recommendation of at least 150 minutes per week.

Moderate-to-vigorous activities include brisk walking, running, and cycling.

Fitness Level May Change Exercise Needs

The study also suggests that people with lower fitness levels may need slightly more exercise than highly fit individuals to receive similar cardiovascular benefits.

Based on the findings, the researchers argue that the current one-size-fits-all approach to exercise recommendations may need to be reconsidered. Instead, future guidance could include personalized activity targets based on a person's fitness level.

Cardiorespiratory fitness varies widely from one person to another and is considered a strong indicator of cardiovascular health. Poor cardiorespiratory fitness has been closely linked to a greater risk of heart attack, stroke, and early death.

One common way to measure cardiorespiratory fitness is through VO2 max, which refers to the highest rate at which the body can take in and use oxygen during intense exercise. The measurement reflects how efficiently the heart, lungs, and muscles work together to deliver and use oxygen.

Researchers Examined Exercise and VO2 Max

Researchers at Macao Polytechnic University in China investigated how physical activity and cardiorespiratory fitness, measured through estimated VO2 max, were associated with cardiovascular disease risk.

Their analysis included 17,088 people enrolled in a UK Biobank study between 2013 and 2015. Participants had an average age of 57. Of the group, 56% were female, and 96% were white.

Each participant wore a wrist device for seven consecutive days to record typical physical activity. They also completed a cycling test that was used to estimate VO2 max.

The researchers also considered smoking, alcohol use, self-rated health, diet, body mass index, resting heart rate, and blood pressure.

More Than 1,200 Cardiovascular Events Recorded

Over an average follow-up period of 7.8 years, the researchers recorded 1,233 cardiovascular events. These included 874 cases of atrial fibrillation, 156 myocardial infarctions, 111 cases of heart failure, and 92 strokes.

Adults who met the guideline of 150 minutes of exercise per week had a modest 8 to 9% lower cardiovascular risk. This association was similar across all fitness levels.

However, achieving what the researchers defined as substantial protection, meaning a reduction in risk of more than 30%, was associated with 560 to 610 minutes of moderate to vigorous activity per week.

Only 12% of participants reached that level of exercise.

Lower Fitness Was Linked to a Higher Exercise Target

People with the lowest fitness levels needed about 30 to 50 additional minutes of exercise per week compared with highly fit participants to obtain similar benefits.

For example, a 20% reduction in the risk of cardiovascular events was associated with 370 minutes of moderate to vigorous exercise per week among those with the lowest fitness. People with the highest fitness levels needed about 340 minutes per week to reach the same reduction in risk.

The researchers say, "This finding highlights the steeper challenge faced by deconditioned populations."

Study Cannot Prove Cause and Effect

Because the research was observational, it cannot establish that higher levels of exercise directly caused the lower cardiovascular risk.

The researchers also noted several limitations. The people included in the study may have been healthier and fitter than the general population. Cardiorespiratory fitness was estimated rather than measured directly, and the analysis did not assess sedentary time or lower-intensity exercise.

Even with those limitations, the researchers said the findings support current exercise guidelines as a reliable minimum level for cardiovascular protection.

At the same time, they suggested that more detailed recommendations could help motivated patients increase their activity and gain greater heart health benefits.

"Future guidelines may need to differentiate between the minimal moderate to vigorous exercise volume required for a basic safety margin and the substantially higher volumes necessary for optimal cardiovascular risk reduction," they conclude.

Reporting from ScienceDaily contributed to this story.