We're all familiar with what to expect from a good workout- muscle ache, pounding heart, perhaps the pleasure of a runner's high if we're fortunate. But what about those odd, surprise sensations that creep upon you halfway through your sprint or in that final set of squats?We all have strapped on sneakers and hit the road for the first time in years with a humble expectations, perhaps burning lungs, a little jelly legs, and a good reminder that school cross country was a distant memory. What people weren't prepared for, 15 minutes into the run, was a sudden toothache—yes, tooth pain, in the middle of cardio.That run was the beginning of a closer investigation. Turns out, plenty of people have weird, even terrifying, physical symptoms while working out—and usually, it's your body just giving the whole system a check-up. Some of these symptoms are benign oddities, some may be indicators of issues that need to be taken more seriously. Here are five of the weirdest sensations people report when exercising—and what your body may be trying to communicate.1. Tooth Pain While RunningToothache during cardio could sound out of the ordinary, but it is quite more prevalent than you would imagine. Specialists have not identified a specific reason, but they provide some believable reasons.First, there's the issue of sinus pressure. Your sinus cavities sit right above your upper teeth, and during intense aerobic activity—when you’re breathing fast and hard—those sinuses can become inflamed or irritated, especially if you’re already fighting off a cold or allergies. This pressure can cause the sensation of toothache even when your teeth are perfectly healthy.Theory number two? You may be unconsciously clenching your jaw during hard work. As we grip the steering wheel harder when anxious, we can tense up the facial muscles and jaw during effort. As a result, we may get referred pain in our teeth. If this is an on-going problem, attempt to calm down while working and relax the jaw—alternatively, try a custom mouthguard on cardio days.2. Metallic Taste in the MouthIf you’ve ever been in the middle of a hard workout and suddenly noticed a weird metallic taste, you’re not alone—and no, it’s not your pre-workout supplement kicking in.That strange taste may be due to small amounts of blood from inflamed mucous membranes in the nose or throat, says sports medicine doctor Dr. Timothy Miller. Long runs or interval training at high intensities can inflame or even cause slight bleeding of the sensitive linings of these regions. And the end result? A mouth full of coppery strangeness.There is also the risk of lung capillary stress. On intense cardiovascular exertion, some red blood cells can leak into the lung air sacs, especially in top athletes or those going beyond their threshold. The taste is usually transient and benign—but it may also be your body shouting, "Hey, take it easy."3. Itchy Skin (Also Known as Runner's Itch)Few things derail a run faster than the urge to stop and scratch your legs mid-stride. If you’ve ever felt like your skin is crawling during a jog, you’ve likely encountered what’s commonly called runner’s itch.While not completely explained, professionals attribute this feeling to the increased blood supply during cardio. Because your heart is beating harder, capillaries dilate to send oxygenated blood to muscles. This dilation activates surrounding nerve endings, causing itching—particularly in areas such as the thighs, stomach, or arms.Runner's Question was generally harmless and transitory. It would be more pronounced among individuals resuming fitness, while the circulatory system was re-adapting to the pressure. If it hangs on or is joined by swelling and hives, see a doctor—it is likely an exercise-induced urticaria, an uncommon but real phenomenon. 4. Nose PainA drippy nose during exercise, particularly in cold air, is to be expected. But what about genuine nose pain or sinus pressure?This is due to a condition referred to as non-allergic rhinitis, most commonly caused by dry air, pollution, or changes in temperature. With exertion, speed of breathing forces air straight into your nasal passages. If the air is particularly cold or contains irritants such as smoke or pollen, it can provoke inflammation and pressure in the sinuses, leading to pain or discomfort in the face and upper nose.Although not harmful, this sensation is uncomfortable. Hydration, saline nasal spray, or masks in contaminated settings can all minimize the effect.5. Numb FingersNumbness or paresthesia in your fingers while exercising—particularly cardio or warm-ups involving arm use—can be unsettling. Oftentimes, the offender is not your hands but rather poor posture or compression of nerves further up the body.When your upper back, shoulders, or neck muscles are tight or weak—"tech neck" from hunching over a computer keyboard, for example—then it can pinches the nerves that run down into your arms. With increased blood flow, muscles start to contract and move, and these nerves become slightly pinched, leading to tingling or numbness.This feeling can also be caused by tension-related muscle imbalances, particularly if you are overcompensating on one side or neglecting upper-body stretching. If it lasts longer than the workout or happens often, it is probably time to go see a physical therapist or doc to eliminate more problematic conditions such as thoracic outlet syndrome or pinched cervical nerves.When to Pay Attention and When to See a DoctorFeeling odd during exercise can be disturbing. In most instances, they're benign and can be attributed to the body adjusting to stress, blood flow changes, or environmental factors. If these persist, increase in intensity, or are accompanied by extreme pain, dizziness, or shortness of breath, see a medical expert.Your body has a great way of providing you with feedback—if you pay attention. Tuning in to what these odd feelings may be trying to tell you can assist you in problem-solving smarter, remaining injury-free, and having fun along the route to fitness without unwarranted alarm.