Everybody knows exercise is good for you. So the more you do it, the better you should feel, right?
All that lifting, lunging and long-arm crunching can trigger some unusual side effects -- from a pounding headache to an unexpected orgasm to a runny nose.
"People put a lot of stress on their body they're not used to," said Steven Page, a sports medicine specialist at Brandon Orthopedic Associates. "They start a new routine, or increase the intensity, or they don't work out regularly and do a heavy workout; they can all be triggers."
Some problems are the result of inadequate nutrition or hydration, said fitness expert Jennifer Cassetty.
"What you put in your body is what you're going to get out of it," Cassetty said. "Good hydration ensures you can sustain physical activity. If you don't have the proper foundation, it's going to throw everything out of whack -- which can cause the body to experience some problems."
Experts say when you start a workout program, build the intensity slowly, exercise regularly and maintain proper nutrition.
"Even if you're predisposed to certain illnesses, exercising regularly can prevent them," Cassetty said. "But before you start an exercise regimen, you need to make sure there are no underlying health issues that could cause problems."
For some exercise enthusiasts, workouts bring on more than aching muscles, they can trigger an aching head. Primary exercise or exertion headaches are usually harmless. But a first-time sudden-onset headache is something your doctor should know about.
"Exercise-induced headaches are common because of the sudden stress on the body," Page said. "But if you haven't had headaches all your life and during exercise you start getting them -- and you have high blood pressure -- that can be the only sign you have of heart disease."
Pulled or strained muscles in your neck, back and shoulders also can cause major headaches. And so can dehydration.
Migraine sufferers don't have to give up exercising, Page said. Just start slowly, and don't overdo it. "Make sure you include a warm-up period and increase your time gradually."
There are also medications that can be prescribed by your doctor to help your headaches, he said.
If your workout includes lots of jumping or jogging and suddenly your shorts feel damp, it might not be sweat.
Stress incontinence occurs when the pelvic muscles that support your bladder become weak, Cassetty said. It can develop after pregnancy, and men who have had prostrate surgery also can suffer from it. But there are exercises that may help, she said.
Kegel exercises (where you repeatedly contract and relax the pelvic-floor muscles as though you're stopping and starting the flow of urine) are helpful. Twice a day, do a series of 10 contractions while standing, sitting and lying down.
Losing weight also can also help relieve extra pressure. Severe cases of incontinence may need surgery, Cassetty said.
"Unfortunately, this is one of those conditions that becomes more common as we age," she said. But it's not uncommon for young men and women to experience problems, as well, if they have an intense workout.
Exercise-Induced Anaphylaxis (EIA)
Eating a meal before a workout can leave you feeling sluggish. Eating the wrong foods before exercising can be downright lethal.
Exercise-induced anaphylaxis is similar to the reaction caused by foods, drugs and insect stings, Page said.
In some people with food allergies, the food alone isn't enough to trigger an allergic response, he said. "But when coupled with exercise, it can bring about this condition."
EIA can be triggered by foods such as wheat, nuts or shellfish. When eaten before a workout, they can cause allergic reactions such as hives, nausea, wheezing and trouble breathing.
If you aren't sure if that's the problem, or you don't know what your food allergies are, see an allergist.
Stop exercising at the first sign of symptoms and until they completely disappear. If your symptoms don't improve after you stop exercising, get to a doctor.
People who have suffered an EIA attack can still exercise, but they need to take precautions, Page said. Use the buddy system, and make sure your buddy knows how to administer adrenalin. And keep an antihistamine with you when you exercise.
People with or without chronic asthma can find themselves gasping for air during a workout.
Exercise-induced asthma is a narrowing of the airways in response to exertion, which causes coughing, wheezing, shortness of breath, tightness in the chest and fatigue, Page said. Typically, symptoms of exercise-induced asthma start after five to 15 minutes of working out.
Using a short-acting bronchodilator (rescue inhaler) before -- or during -- exercise can help you keep moving without the asthma slowing you down.
If your nose is running as fast as you're moving, you're not alone.
Rhinitis is an inflammation of the nasal mucous membranes. Symptoms include excessive mucus production, congestion, sneezing and itchy, watery eyes.
It can happen whether or not you have allergies. And it doesn't matter whether you are exercising inside or outside, or if the air is cold or warm. It usually happens with vigorous exercise such as running, cycling or skiing.
If you don't mind a drippy nose, keep a generous supply of tissues stuffed in your workout pants or jacket. If your nose is ruining your workout, see an allergist for a prescription.
Orgasms or "Coregasms"
Exercise can make you feel good about yourself in more ways than one. Many ladies become sexually aroused from a workout that involves the deep core, quads and inner thighs.
"It's basically exercises like crunches, leg raises or exercises where you tend to relax the pelvis muscles, tense them, and relax them again that can create stimulation," Page said.
Feel-good endorphins released during exercise also can play a role.
Unless you're bothered by having a "coregasm" right in the middle of the gym, there doesn't seem to be anything to worry about, he said.
If your feet are losing feeling in the middle of your workout, check the fit of your sneakers and make sure your laces aren't tied too tight. Restrictive shoes can pinch a nerve.
If that's not the answer, it might be "exercise-induced compartment syndrome." That's what happens when muscles increase in size during exercise, putting pressure on blood vessels and nerves and causing numbness, pain and poor circulation. Switch activities and see if it helps. If symptoms persist, follow up with a doctor for diagnosis.
Sweat may not be the only thing you're working up during that exercise class. Consider that most people pass gas at least 14 times a day, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
"People get moving, and things move around and start the digestive process," Cassetty said. Gases can build up because you're moving and swallowing air; and that starchy meal could work its way through your digestive system.
High-fiber foods, dairy and carbonated beverages also can induce gas. But some exercises, such as walking and jogging after a meal, actually can help relieve gas. Exercise also can improve your digestion. If the gas is excessive and causes abdominal pain and discomfort, have it checked, she said.