Protecting the health of your heart to the greatest extent possible may require far more exercise than current guidelines recommend.Today, health experts generally advise 150 minutes of moderate-to-vigorous physical activity (MVPA) a week.But what happens if you work out more than that?A study of health data from the United Kingdom suggests that the more physical activity you do, the better for your cardiovascular system.The long-term data analysis was conducted by researchers in China and included 17,088 people in the UK Biobank, whose health was tracked for roughly eight years.Participants who met current exercise guidelines showed an 8 to 9 percent lower risk of experiencing a serious cardiovascular event, like a heart attack or stroke.Those who exercised three to four times that amount, however, showed a risk reduction of more than 30 percent.That's roughly 9 to 10 hours of exercise a week, which is an intimidatingly large number for our busy modern lives. But the associated health outcomes are also much greater, especially for those with a lower level of fitness to start.The study's press release at the British Medical Journal argues that "current exercise guidelines are too low" and that "less fit individuals need to do more exercise to get the same benefits."But Aiden Doherty, a biomedical informatician at the University of Oxford who was not involved in the current study, argues that is "misleading".What the study essentially found, Doherty explains, is that every step counts, especially for people with low levels of fitness."We can't give much weight to the figure of 560 to 610 minutes of exercise a week," Doherty writes in an independent perspective for Science Media Centre."Clearly, there will be cardiovascular benefit for people who are able to do more than 1 hour 20 minutes of moderate-to-vigorous intensity physical activity per day, but this is not a sensible public health message."More exercise may be better, but it's important that public health recommendations remain realistic. (BGStock72/Canva)Whatever the press release might say, the study authors, led by Zhide Liang at Macao Polytechnic University in China, agree with Doherty that current guidelines should stay.Even now, large proportions of the population do not meet current guidelines, the authors conclude, which means "the primary public health message remains straightforward: achieving 150 min/week of MVPA delivers meaningful cardiovascular protection regardless of fitness level."Readers should take comfort in knowing they don't necessarily need to spend all day in the gym for their hearts to reap the benefits of exercise.The UK Biobank sample included 1,233 serious cardiovascular events over the course of nearly eight years, including atrial fibrillation, heart attacks, heart failure, and stroke.Cardiologist Steffen Petersen from Queen Mary University of London writes in an independent perspective that this is a "large, well‑conducted observational study".Even though the research can only reveal associations between exercise and cardiovascular outcomes, the study authors used an inference method called Mendelian Randomization to get closer to causality."A major strength of this work is the use of device‑measured activity and fitness rather than self‑report, which increases confidence in the observed dose–response relationships," adds Petersen.The study reveals a steep escalation in cardiovascular outcomes based on the 'dose' of weekly exercise. A 20 percent risk reduction, for instance, required participants to undertake roughly 340 to 370 minutes of exercise per week (more than double current guidelines).Related: Scientists Revealed How Much Exercise You Need to 'Offset' Sitting All DayIndividuals with the lowest fitness, however, had to put in more time to achieve the same benefits. For them to achieve the same 20 percent risk reduction, the analysis suggests that they need about 30 to 50 additional minutes of MVPA per week, compared to someone with a higher fitness level."Importantly, these findings simultaneously reinforce the public health value of the current 150 min/week guideline," the study authors conclude."This threshold functions as a robust universal minimum… "To achieve even more protection for the heart, however, physical activity probably needs to increase even more. But it's important to be realistic.Only 12 percent of participants in the BioBank sample achieved at least 560 minutes of exercise per week, "indicating that although such volumes are attainable, they represent a high behavioral threshold for most individuals."Public health messaging needs to take this into account, which is why it usually provides a minimum recommendation.At the same time, however, it's also important to determine exactly how much exercise an individual needs to achieve maximum health benefits.Randomized controlled trials are now needed to see if these higher exercise thresholds really do result in better heart health.The study was published in the British Journal of Sports Medicine.