In the U.S., one person dies of heart disease every 36 seconds, making it the leading cause of death for both men and women, according to the Centers for Disease Control and Prevention (CDC). That’s exactly why heart symptoms—however subtle—should always be taken seriously.However, heart conditions aren’t always signaled by a telltale pain in the chest or arm: there are other red flags that may tip you off to a coronary condition. David Newby, MD, PhD, a professor of cardiology at the BHF Centre of Research Excellence at the University of Edinburgh, recently alerted the public to one such symptom. He warned that this seemingly unrelated sensation, which can occur when you walk or exercise, could be a sign of a serious heart problem. Read on to find out which surprising symptom to look out for on your next stroll.RELATED: If You Have Swelling in 1 of These 3 Areas, It Could Be Heart Disease. The subtle symptom could tip you off to Peripheral Arterial Disease. In his warning, Newby sounded the alarm against a condition called Peripheral Arterial Disease (PAD), which affects an estimated 8.5 million Americans—in many cases, without their knowledge.According to the American Podiatric Medical Association (APMA), PAD is caused when a buildup of plaque from fatty deposits or excess calcium causes one’s arteries to harden, narrow, or become blocked. This leads to a reduction of blood flow to the legs and feet, and can increase your risk of heart attack or stroke.And for more health news sent directly to your inbox, sign up for our daily newsletter. Cramping in your calves can be a sign of PAD. Newby says that this reduced blood flow to the legs can trigger PAD symptoms when you walk or exercise. “If you get a gripping, cramping sensation in your calves when you are walking, it might be worth seeing your doctor, as that can be a marker of PAD,” he wrote for BHF’s Heart Matters Magazine. He suggested making an appointment with your medical provider if you happen to notice this type of cramping.The APMA seconds his recommendation, adding that you should never ignore leg pain without a known cause. “It is important to discuss any leg or thigh pain that you are having with your podiatric physician since it could be a warning sign of a serious disease such as PAD,” the organization says, noting that early intervention can reduce the likelihood of heart attack and stroke.RELATED: If You Skip This Meal, Your Heart May Be in Danger, Studies Say. Changing your health habits can help. According to the American Heart Association, there is no silver bullet solution for curing PAD, but there are several ways to reduce or even reverse your symptoms. These lifestyle changes most commonly include a healthy diet, increased exercise, and quitting tobacco. Additionally, some doctors may prescribe claudication medication or surgery in more severe cases.As with many heart conditions, early detection of PAD is key. Thankfully, your podiatric physician can perform a simple test called an ankle-brachial index (ABI) to determine if you have this condition. By comparing the blood pressure in your ankles with the blood pressure in your arm, an ABI should alert your doctor to the problem if one exists. Look out for these other leg symptoms, too. As the APMA points out, your leg symptoms resulting from PAD may go beyond simple cramping. The organization says that you may also experience the symptom as “fatigue, tiredness, or pain in your legs, thighs, or buttocks that always happens when you walk but goes away when you rest,” or “foot or toe pain…that often disturbs your sleep.”Those with PAD may also develop skin wounds or ulcers on the feet or toes that do not heal for eight to 12 weeks. For this reason, the American Heart Association suggests always taking off your socks for routine check ups.RELATED: If You Take This Popular Supplement, Your Heart May Be Risk, Study Says.