Based on studies by the state health department, the Surgeon General has formulated tables that list standard exercise requirements for various age groups  People whose activity level falls within the range given for their age experience fewer cardiovascular problems than those whose activity level falls below the given range
Ttherefore, if people whose activity level falls below their given range increased their time exercising to fall within that range, their cardiovascular health would improve
Increasing the activity level would not itself cause cardiovascular health problems for people.