A new study in the British Journal of Sports Medicine shows that people with very low fitness levels may need more exercise to get the same heart health benefits as fitter people. The research found that these individuals should do an extra 30 to 50 minutes of moderate or vigorous activity each week.

Current health recommendations, such as from the World Health Organization, suggest at least 150 minutes of exercise per week for adults. However, this study suggests that amount may not be enough for those who are less fit, because their bodies respond differently.

Experts say these results are important for making better public health advice. They suggest exercise plans should depend on a person’s own fitness level to help reduce the risk of heart disease.