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Here’s a new fact about spring, summer, fall, and sometimes even winter, now that climate change has blurred seasonal boundaries: sizzling heat may be on the way, or currently blanketing your community.

High temperatures stress the body, leading to thousands of heat-related illnesses and deaths every year in the US. Creating a personal heat plan can help you stay safe when the heat index soars.

Caleb Dresser, MD, MPH, is the health care solutions lead for C-CHANGE, the Center for Climate Health and the Global Environment at the Harvard T.H. Chan School of Public Health, and an emergency medicine doctor at Harvard-affiliated Beth Israel Deaconess Medical Center. Below we interview him about who, how, and why heat harms. Then we’ll help you create your personal heat safety plan.

Interview edited for clarity

Who is especially vulnerable during hot weather?

High temperatures can affect anyone. But some people — children, outdoor workers, people who are pregnant or have health problems or disabilities, and older people — are more likely to experience harm when temperatures rise. For example:

• Young children, especially babies, have less physical capacity to deal with very high temperatures.
• People working outdoors may not have access to shade and could be performing physically intensive labor. They need adequate hydration, adequate breaks, and access to a cool space during break time, as OSHA guidelines spell out.
• People with chronic medical conditions, such as kidney disease or heart disease, may have difficulty adapting physiologically to hot weather, or may be more susceptible to its health impacts.
• And some people living with disabilities or certain neurological conditions may have difficulty with thermoregulation — that is, controlling the temperature of their bodies — or may not be able to take actions that keep them safe, such as taking off layers or moving to a cool area.

Which weather patterns create dangerous levels of heat?

Dangerous heat is the result of both high temperatures and high humidity, which interfere with our ability to cool off by sweating. In dry areas, extremely hot temperatures can be dangerous on their own.

Danger zones vary across the United States and around the world. But hospital use and deaths rise once we get above threshold temperatures. The threshold varies in different places depending on whether bodies, cultures, and architecture are adapted to heat.

For example, here in New England, where some people (particularly those of limited means) may not have access to air conditioning, we see increases in healthcare use and deaths at a lower temperature than in the American South, where people and organizations may be more used to dealing with hot weather.

When does hot weather become dangerous to our health?

Risk goes up the longer hot weather sticks around.

One hot day can put some people at risk. A stretch of several hot days in a row during a heat wave is particularly dangerous because it can overwhelm people’s ability to adapt. Eventually people run out of physiological reserves, leading to greater health harms and greater need for medical care.

Surprisingly, spring and early summer are particularly dangerous times because people and organizations aren’t as prepared for hot weather.

How to create your personal heat safety plan

Five key points to help you create a personal heat plan are below. Americares offers further information through heat tip sheets developed with the Harvard C-CHANGE team that are tailored to people in different health circumstances.

Planning is important because intense heat is occurring more often: a Climate Central analysis found 21 additional risky heat days, on average, for 232 out of 249 locations between 1970 and 2022.

• Stay ahead of hot weather. Check apps, websites, TV, or radio for updates on weather today and in coming days. If local weather alerts are available by phone or text, sign up.
• Have a cooling plan. When temperatures soar, you need to spend as much time as possible in cool spaces. Plan options if your home is likely to be too hot and unsafe to stay in. You may be able to stay with a neighbor or family member who has air conditioning until a heat wave passes. Many cities and towns have neighborhood splash pads for children, and open cooling centers or air-conditioned libraries, public buildings, or community centers to everyone — sometimes even overnight. Spending time in air-conditioned businesses or malls, or in a shady green space like a park, may help too.
• Sip plenty of fluids. Water is the best choice. Skip sugary drinks and avoid caffeine or alcohol.
• Use fans correctly. Fans help if surrounding air is relatively cool. If air temperatures are very high, it’s important to dampen your clothes or skin to help keep your body from overheating, and move to a cooler location, if possible.
• Know your personal risks and the signs of heat-related illness. If you have health problems or disabilities, or take certain medicines such as diuretics, talk to your doctor about the best ways for you to cope with heat. It’s also essential to know the signs of heat-related illnesses, which range from heat rash and sunburn to heat cramps, heat exhaustion, and heat stroke. This chart from the Centers for Disease Control and Prevention describes the signs to look for and what you can do, particularly when heat becomes an emergency.

About the Author

Francesca Coltrera, Editor, Harvard Health Blog

Francesca Coltrera is editor of the Harvard Health Blog, and a senior content writer and editor for Harvard Health Publishing. She is an award-winning medical writer and co-author of Living Through Breast Cancer and The Breast … See Full Bio View all posts by Francesca Coltrera

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Picture this: you’re with friends in an unfamiliar forest using only a map and a compass to guide you to an upcoming checkpoint. There are no cell phones or GPS gadgets to help, just good old brainpower fueled by a sense of adventure as you wind through leafy trees and dappled sunlight.

This is not an excursion to a campsite or a treasure hunt. It’s a navigation sport called orienteering — a fun way to get outside, exercise, and maybe even help fight cognitive decline, according to a 2023 study.

What is orienteering?

Orienteering combines map and compass reading with exercise. Competitors (“orienteers”) race against a clock to reach checkpoints in outdoor settings that can range from city parks to remote areas with mountains, lakes, rivers, or snowy fields.

“You can go out in a group or on your own. You get a very detailed map and navigate your way to checkpoints that record your time electronically,” says Clinton Morse, national communications manager with Orienteering USA, the national governing body for the sport in the United States.

Because orienteers are racing the clock, they might run on trails, hike up hills, or scramble around boulders. That’s for foot-orienteering events. There are also orienteering events with courses geared for mountain biking, cross-country skiing, or canoeing.

How might orienteering affect thinking skills?

A small 2023 study published online in PLoS One found a potential link between orienteering and sharp thinking skills.

Researchers asked 158 healthy people, ages 18 to 87, about their health, activities, navigation abilities, and memory. About half of the participants had varying levels of orienteering experience. The other participants were physically active but weren’t orienteers.

Compared with study participants who didn’t engage in orienteering, those who were orienteers reported

• having better navigational processing skills (recognizing where objects were, and where participants were in relation to the objects)
• having better navigational memory skills (recalling routes and landmarks).

The study was observational — that is, not a true experiment — and thus didn’t prove that orienteering boosted people’s thinking skills. But the link might be plausible.

“Aerobic exercise releases chemicals in the brain that foster the growth of new brain cells. And when you use a map and connect it to landmarks, you stimulate growth between brain cells,” says Dr. Andrew Budson, lecturer in neurology at Harvard Medical School and chief of cognitive and behavioral neurology at VA Boston Healthcare System.

Where can you find orienteering opportunities?

There are about 70 orienteering clubs across the United States, and many more around the world (the sport is extremely popular in Europe). To find an orienteering event in your area, use the club finder tool offered by Orienteering USA.

How can you get started with orienteering?

People of all ages and athletic levels can take part, because orienteering courses vary from local parks to wilderness experiences. Costs are about $7 to $10 per person for local events, or $25 to $40 per person for national events, plus any travel and lodging expenses.

To make orienteering easy at first, Morse suggests going with a group and taking things slowly on a short novice course. “You don’t have to race,” he says. “Some people do this recreationally to enjoy the challenge of completing a course at their own pace.”

The trickiest part is learning to read the map. Morse’s advice:

• Turn the map as you change directions. Hold the map so that the direction you’re heading in is at the top of the page. For example, if the compass indicates that you’re heading south, turn the map upside down, so the south part is on top and easier to follow.
• Create a mental image of what the map is telling you. If there’s a fence along a field on the map, build a picture of it in your mind so you can recognize it when you see it, even if you haven’t been there before.

Tips for safe and enjoyable orienteering events:

• Dress appropriately. Wear comfortable clothes including long pants, good walking shoes, and a hat.
• Lather up. You’ll be outside for at least an hour, and you’ll need sunblock and possibly tick and bug spray depending on the terrain. Preventing tick bites that can lead to Lyme disease and other tick-borne illnesses is important in many locations.
• Bring some essentials. Pack water, a snack, sunblock, bug spray, and your phone. (Keep the phone turned off unless you need to call for help.)
• Use good judgment. Know that the shortest route on the map won’t always be the best, since it might take you up a hill or through thick vegetation. It might be better to go around those areas.

Once you learn the basics of orienteering, you can make it more physically challenging (and a better workout) by going faster and trying to beat your previous times, or by signing up for a more advanced course that’s longer and requires more exertion and speed.

And no matter which event you take part in, enjoy the adventure. “You’re not just following a path, you’re solving puzzles while being immersed in nature,” Morse says. “It’s a great way to experience the outdoors.”

About the Author

Heidi Godman, Executive Editor, Harvard Health Letter

Heidi Godman is the executive editor of the Harvard Health Letter. Before coming to the Health Letter, she was an award-winning television news anchor and medical reporter for 25 years. Heidi was named a journalism fellow … See Full Bio View all posts by Heidi Godman

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

We’re bombarded with advertisements that tout all sorts of health benefits for vitamins and supplements, including improved memory. A May 2023 study of older adults suggests that a daily multivitamin can do just that — improve your memory enough such that it can function as if you were three years younger.

So, should you take that daily multivitamin? Let’s take a close look at the study.

Who took part in this multivitamin study?

This research is part of a larger study examining the effects of a multivitamin and/or cocoa (the main ingredient in chocolate) on cardiovascular and cancer outcomes. A prior sub-study found that a daily multivitamin improved thinking and memory — at least when evaluated with cognitive testing completed by phone.

For this study, 3,562 participants were willing and able to perform some tests of thinking and memory on a home computer. Half received a multivitamin; the other half received a placebo.

The participants identified as 93% white, 2.5% African American, and 1.4% Hispanic, so the results may not be generalizable. They were also well educated: more than half had completed college. In both groups, the average age was 71.

How did the researchers test memory?

The investigators evaluated the participants’ thinking and memory at baseline and after one, two, and three years.

For the memory test, participants were asked to memorize 20 words shown consecutively on a computer screen. Immediately after viewing these words, they had to type in as many words as they could remember (this was the primary measure of memory). Fifteen minutes later, they also typed in all the words they recalled (a secondary measure of memory).

Other secondary measures included:

• a novel object discrimination test (is this object the same or different from one recently shown?)
• an executive control test (in an array of nine arrows, is the central arrow red or blue?).

The participants repeated all of the tests one, two, and three years later.

What were the results of this study?

The two groups differed in immediate recall at year one:

• Those who took a placebo went from immediately recalling an average of 7.21 words at baseline to 7.65 words (a difference of 0.43 words)
• Those who took a daily multivitamin group went from 7.10 words at baseline to 7.81 words (a difference of 0.70 words).

This result was statistically significant. Additionally, these small effects held up at years two and three. By year three, the placebo group immediately recalled an average of 8.17 words and the multivitamin group immediately recalled 8.28 words.

No differences occurred between the two groups on secondary memory and executive function tests.

How can a multivitamin improve memory?

The authors note that low levels of vitamins B12 and D have been linked to cognitive decline and dementia. In a subset of participants who had their blood drawn, the levels of these vitamins did rise in the multivitamin group.

It seems plausible that a few of the 3,562 participants had low levels of these or other vitamins that are important for thinking and memory. In the placebo group, the few who had vitamin deficiencies would likely show less improvement in memory after their baseline tests, or a small decline. By contrast, those few participants in the multivitamin group with deficiencies would have them corrected by the supplements and, therefore, would perform relatively better.

Although this is just speculation, it would explain the small but seemingly real results — results that replicate the researchers' prior study, which used a telephone cognitive test to show thinking and memory benefit from a daily multivitamin.

It’s also worth noting that practice on memory tasks — the so-called practice effect — could contribute to small improvements shown from baseline to year one and year three.

Should you take a multivitamin to improve your memory?

The authors admitted that the effect of the multivitamin on immediate memory was small and may not be noticeable. However, they pointed out that this small effect could be important at the level of an entire population.

My opinion? You shouldn’t bother taking a multivitamin to try to improve your immediate recall of 20 words from 8.17 to 8.28 words. But it is worth speaking with your doctor about whether you could have a vitamin deficiency in B1, B6, B12, D, or any other important vitamins. I see several patients in my clinic every week who have startlingly low levels of vitamin D and B12. Your doctor may want to measure these levels. Or they may suggest simply taking a multivitamin daily.

If, after reading this article, you’ve decided to take a multivitamin, please check with your doctor or pharmacist about which one would be best for you. Make sure that they review any other vitamins, supplements, and medications you take to avoid rare but serious interactions.

About the Author

Andrew E. Budson, MD, Contributor; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Andrew E. Budson is chief of cognitive & behavioral neurology at the Veterans Affairs Boston Healthcare System, lecturer in neurology at Harvard Medical School, and chair of the Science of Learning Innovation Group at the … See Full Bio View all posts by Andrew E. Budson, MD

Trauma can register within our bodies on a cellular level. What that means to an individual — and how best to heal from serious traumas encountered in life — is the focus of a newer form of mental health counseling known as somatic therapy.

The resounding success of The Body Keeps the Score — a fixture on the New York Times bestseller list for more than four years running — testifies to mounting public awareness that trauma affects people deeply. Thus far, though, somatic therapy hasn’t caught up to cognitive behavioral therapy (CBT) and related techniques in understanding, use, or research proving its worth, a Harvard expert says.

What is somatic therapy?

Most people likely haven’t heard of somatic therapy, says Amanda Baker, director of the Center for Anxiety and Traumatic Stress Disorders and a clinical psychologist in the department of psychiatry at Massachusetts General Hospital. Unlike other mind-body approaches such as mindfulness meditation, mind-body stress reduction (MBSR), and mindfulness and self-compassion (MSC) — which are steadily growing in use — somatic therapy hasn’t hit the mainstream.

What’s the fundamental concept? “It’s a treatment focusing on the body and how emotions appear within the body,” Baker explains. “Somatic therapies posit that our body holds and expresses experiences and emotions, and traumatic events or unresolved emotional issues can become ‘trapped’ inside.”

Who might benefit from somatic therapy?

Since disturbing feelings often show up in the body in debilitating ways, somatic therapy aims to drain those emotions of their power, relieving pain and other manifestations of stress, such as disrupted sleep or an inability to concentrate.

These types of emotions can stem from a variety of conditions and circumstances that somatic therapy may potentially help alleviate. They include

• post-traumatic stress disorder (PTSD)
• complicated grief
• depression
• anxiety
• trust and intimacy issues
• self-esteem problems.

“Anxiety can lead to muscle tension, particularly in the neck, shoulders, jaw, and back,” Baker says. “It can cause a lot of discomfort, pain, stiffness, and trouble with daily activities. If we’re experiencing chronic anxiety or distress, it’s almost like we have our foot on a gas pedal. It’s not a panic attack, but we’re never feeling a reprieve and there’s a constant wear and tear on the body.”

How does somatic therapy differ from talk therapies?

Typical talk therapies such as CBT engage only the mind, not the body, encouraging people to become aware of disturbing thoughts and behavior patterns and work to change them.

But in somatic therapy, the body is the starting point to achieve healing. This form of therapy cultivates an awareness of bodily sensations, and teaches people to feel safe in their bodies while exploring thoughts, emotions, and memories.

“Cognitive behavioral therapies focus on conscious thought and work on challenging thoughts in relation to anxiety and behaviors, helping desensitize people to uncomfortable sensations,” Baker says. “But somatic therapy is more about relieving the tension, as opposed to desensitizing people to it.”

Even mindfulness meditation, which some experts consider somatic in nature, differs in one key way from somatic therapy, Baker says. “Mindfulness meditation lets any feeling or emotion come into our minds without judgment, as opposed to homing in specifically on bodily sensations that are happening,” she says.

How is somatic therapy carried out?

A somatic therapist helps people release damaging, pent-up emotions in their body by using various mind-body techniques. These can vary widely, ranging from acupressure and hypnosis to breathwork and dance.

Other techniques are just as integral but aren’t household terms. Some on this list include:

• body awareness, which helps people recognize tension spots in the body as well as conjure calming thoughts
• pendulation, which guides people from a relaxed state to emotions similar to their traumatic experiences and then back to a relaxed state
• titration, which guides people through a traumatic memory while noting any accompanying physical sensations and addressing them in real time
• resourcing, which helps people recall resources in their lives that promote feelings of calm and safety, such as special people and places.

What to know if you’re considering somatic therapy

Scant scientific research has focused on somatic therapy and its benefits, Baker notes. That’s one reason why she always recommends cognitive behavioral therapy, which has proven benefits, as at least a starting point.

“Anecdotally, I’ve heard people do find tremendous benefit from somatic therapy, but it doesn’t have the same research backing yet as CBT and some other forms of therapy,” she says.

Health insurance may be more likely to cover somatic therapy, she says, when a person is dealing with extreme symptoms of mental trauma, such as seizures. Otherwise, insurers are more apt to cover established therapies such as CBT.

Additionally, finding an experienced somatic therapist can be challenging. “I think fewer folks are going to be trained in somatic therapies than CBT, so finding an experienced practitioner is definitely a tricky process,” Baker says. One useful resource is the US Association for Body Psychotherapy, which offers a Find a Therapist search tool online.

About the Author

Maureen Salamon, Executive Editor, Harvard Women's Health Watch

Maureen Salamon is executive editor of Harvard Women’s Health Watch. She began her career as a newspaper reporter and later covered health and medicine for a wide variety of websites, magazines, and hospitals. Her work has … See Full Bio View all posts by Maureen Salamon

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

There are warnings just about everywhere you look: The coffee you're about to drink is hot! Construction ahead! This product may contain peanuts!

In many cases, the reasons for these warnings are clear. But sometimes warnings raise more questions than they answer. When I was at the gym recently, these warnings on the exercise bike and treadmill were hard to miss in a bright red font:

• Obtain a medical exam before beginning any exercise program.
• Overexercise may result in serious injury or death.
• If you feel faint, dizzy, or have pain stop exercising immediately.

What exactly did the warning writers mean by "any exercise program"? What constitutes overexercise? Does having any pain anywhere mean you should stop working out?

Finally, I wonder: might these warnings cause unnecessary worry that actually discourages people from exercising?

Is it safe to start exercising without checking with a doctor?

A doctor's approval isn't necessary for most of us. Most people can safely begin a low-intensity exercise program and slowly increase their efforts over time. Choose activities that would allow you to carry on a conversation, such as:

• using light weights that are easy for you to lift
• walking at a leisurely pace
• biking at a leisurely pace (less than 5 mph)
• stretching and balancing activities
• light housework or yard work.

If you're starting at a low fitness level, make small increases in your workout over time. For example, if you start out walking 10 minutes a day, add one minute to your walk every week or two. Once you're walking 20 minutes a day, try picking up the pace a bit.

Who should be careful about exercising?

Of course, exercise is riskier if you have certain health conditions. It makes sense to ask a health care professional to make exercise recommendations if you're concerned about your health or have any of these conditions:

• Coronary artery disease, including symptoms of angina or a previous heart attack. Exercise that's too much too soon could stress the heart and trigger a heart attack or dangerous heart rhythm. Lower-intensity workouts (such as short walks at a comfortable pace) may be preferable, at least until it's clear that you can tolerate more.
• Exercise-induced asthma. Your doctor may recommend inhaled treatment to open up airways in your lungs just before or during exercise.
• Muscle disease, such as a metabolic myopathy. Your doctor may discourage you from engaging in certain exercises, such as sprinting or long-distance running.
• Back pain. Low impact exercise, such as biking or swimming, may be a better choice for people with back pain than higher-impact options, such as jogging or basketball.

If exercise is so good for you, why the warnings?

Let's review possible reasons for certain warnings:

• Having a medical examination before starting an exercise program might uncover a condition that makes exercise risky. The best example is probably coronary artery disease, which could trigger a heart attack during intense exercise. Fortunately, sudden heart problems during exercise are relatively rare (though you might think otherwise based on TV and movies, including an episode from the Sex and the City reboot).
• Overexercise is not a well-defined medical term. But it's true that suddenly exercising at high intensity when you're not used to it might be hazardous.
• Stopping exercise if you're feeling faint or dizzy presumably refers to concerns about severe dehydration or other causes of low blood pressure.
• Warnings about pain could refer to chest pain that might be a sign of heart trouble. Or it could be a warning about a type of severe muscle damage called rhabdomyolysis (which may complicate prolonged or intense exercise).

Of course, it's also possible these warnings have little to do with your health and everything to do with lawyers! That is, the equipment manufacturers might hope these warnings will ward off lawsuits from people who suffer a medical problem while using their equipment.

Are these warnings helpful?

Probably not.

All the warnings, alerts, and cautions in our everyday lives can become background noise. Despite red letters and bold fonts, warnings like these are easily overlooked.

Nor do they add much. My guess is that most people experiencing significant dizziness or pain during a workout will stop what they're doing even without reading a warning label. And serious medical conditions arising during exercise are rather rare, so the impact of warning everyone about them is likely small.

The bottom line

Don't be overly alarmed by alerts slapped on exercise equipment. True, it's best not to drop weights on your foot or exercise way too hard or long. If you are worried about workout risks or have been advised to be especially careful about exercising, it's reasonable to talk about it with your doctor.

But that conversation isn't necessary for most people, including those with well-controlled chronic illness such as high blood pressure, diabetes, or coronary artery disease. In fact, regular exercise helps treat many illnesses.

Exercise is among the most important things you can do to improve your health. And inactivity is a generally a much bigger risk than exercising.

So, if you see warnings on the gym equipment at your next workout, keep this in mind: there are much riskier things to worry about. Like hot coffee.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD

Remember childhood summers when you climbed monkey bars, swung from ropes, and jumped over streams? Rain just added to the fun, leaving you soaked and muddy.

You can relive those adventures by signing up for a mud run. These outdoor team events focus on navigating through military-inspired obstacle courses and getting good and dirty in the process.

Tough Mudder and Spartan races are the most well-known mud races. But similar mud runs are available in most states. Some offer shorter distances and levels of difficulty. Others are designed just for women, kids, or families.

How do mud runs work?

Usually these events follow the same basic concept: participants traverse a course that covers anywhere from three to 10 miles (or longer), and tackle 10 to 25 obstacles.

While some mud races can be done solo, most are designed as team-oriented events. Teams are often coed and consist of five to 10 people. There is no time limit, but depending on the distance and number of obstacles, most teams complete the course in anywhere from less than an hour to three-plus hours.

The obstacles are challenging enough that most people need help — physically and emotionally — to navigate over, under, and across them. This is where a “we’re-all-in-this-together” comradery comes into play.

What sort of obstacles are featured in mud runs?

Common obstacles include

• climbing over spider web-like cargo nets
• scaling walls of various heights
• swinging from ropes with handles
• keeping your balance while walking across beams or logs
• carrying logs or sandbags
• slithering under barbed wire.

And then there’s all the mud. Be prepared to trudge through sticky mud pits, crawl through muddy tunnels, and shoot down mud-slick slides.

What are the health benefits of a mud run?

According to Dr. Aaron Baggish, founder of the Cardiovascular Performance Center at Harvard-affiliated Massachusetts General Hospital, the benefits of these events come from how they are constructed.

“Obstacle racing combines large-muscle, whole-body resistance exercises superimposed on a long-distance endurance race,” he says. “They are a snapshot of all-around conditioning, as you need strength, stamina, and mobility.”

Besides the physical benefits, mud races offer psychological challenges, and the emotional rewards, of conquering tasks that require planning, coordination, and strategy.

How can you prepare for a mud run?

Mud races require strenuous exercise, so discuss your safety and capabilities with your doctor before signing up for an event. While almost anyone of any age can participate in these events, they require a certain level of conditioning to complete and to reduce the risk of experiencing injury.

“Training for obstacle races incorporates many aspects of fitness and performance,” says Dr. Baggish. “So it’s best to prepare with a coach or trainer who understands the fundamental skills needed to complete these races.”

Whether or not you work with a trainer, you’ll want to focus on:

• Aerobic fitness. While you won’t consistently run as you do in a traditional road race, such as a 5K or a half marathon, you do have to hustle from obstacle to obstacle. “Optimal training for such obstacle races involves a combination of steady-state aerobic base training like jogging or cycling, coupled with interval work that simulates the start-and-stop nature of competition,” says Dr. Baggish.
• Grip strength. You will have to grab, hold, and pull yourself against gravity. Exercises that can help include pull-ups and farmer carries (where you hold dumbbells or kettlebells in each hand while you walk back and forth). Good form is essential during these exercises to help you avoid injury. Remember to start low when working with weights and go slow.
• Plyometrics. Many obstacles require explosive jumps and quick movements. Exercises like box jumps, burpees, and jump squats can help replicate these moves.

How to stay safe in the mud

While being physically prepared can help reduce the risk of injury, you should take other precautions to stay safe. For instance:

• Choose your race depending on level of fitness. Be sure you know what you’re getting into before you go.
• Wear lightweight, moisture-wicking clothing. Avoid cotton, which gets heavy with mud and sweat.
• Wear a headband, protective eyewear, or visor to keep mud out of the eyes.
• Wear long shorts or pants that cover your knees to prevent scraping, or opt for knee pads.
• Consider gloves to protect your hands and provide extra grip.
• Cover your feet with petroleum jelly or an anti-chafing cream before putting on socks to protect wet feet from chafing and blisters.
• Tie shoelaces tightly (but not so tight that they cut off circulation). Mud creates suction and you can quickly lose a shoe.
• Pace yourself. Walk or take a break when needed.

Where can you find a mud run?

It depends on the level of challenge that you seek. Are you ready for a Tough Mudder or Spartan race? Looking for a family first mud run, or a Muddy Princess or Muddy Kids event?

These additional sites also can help you find mud races in your area:

• Mud Run Finder (US)
• Run Guides (Canada and the US)
• Savage Race (US)

About the Author

Matthew Solan, Executive Editor, Harvard Men's Health Watch

Matthew Solan is the executive editor of Harvard Men’s Health Watch. He previously served as executive editor for UCLA Health’s Healthy Years and as a contributor to Duke Medicine’s Health News and Weill Cornell Medical College’s … See Full Bio View all posts by Matthew Solan

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

There are certain things our bodies do so often and so automatically that we barely notice them. Yawning, growling stomachs, and runny noses are good examples. Each is a universal part of our daily human experience.

But did you ever wonder why? Below are a few things we know and a few we suspect.

Why do you yawn?

Perhaps you associate yawning only with being tired or bored. While we don’t know exactly why people yawn, there’s no shortage of theories. Yawning may

• stretch out our lungs and nearby tissues, preventing tiny airways in the lungs from collapsing
• distribute a chemical called surfactant, a gooey liquid that coats the tiny air pockets in the lungs and helps keep them open
• help prepare our bodies for transitions between wakefulness and rest: For example, yawning often occurs after a period of relaxation and when awakening from sleep. And it may serve as an internal signal that it’s time to sleep, or time to take a break from activities (such as driving).
• play a role in maintaining proper brain temperature: Our brain functions best within a narrow range of temperatures. Some experts believe yawning can help cool the brain through complex effects on nearby circulation and the sinuses.

It’s also unclear why yawning is contagious. In the animal kingdom, it’s common to see contagious yawning among members of a group, perhaps as a signal for collective behavior (such as moving from activity to rest).

Why does your stomach growl?

That rumbling in your stomach is known medically as borborygmi — an excellent Scrabble word if you have the right letters. We usually assume it reflects hunger. And it’s true that the experience of hunger can make itself heard in anticipation of a meal.

But your stomach may also growl after a meal, when the stomach and intestines propel liquids and food through the digestive tract. Stress can also trigger stomach rumbling.

What’s causing all that noise — and is it ever a problem? It may be due to gas moving around in response to muscular contractions of the intestinal walls. Occasionally, noises from the abdomen may be a sign of an intestinal infection or other trouble. If you’re experiencing other symptoms, such as pain or fever, check in with your doctor. But the vast majority of noises are harmless and a sign that your gut is working normally.

Why does your nose run?

Sometimes it can seem like your nose is running for no reason. But there are some well-known triggers, such as:

• Infection. When you have a cold, mucous membranes produce more mucus as part of your defense system: more mucous flowing out means fewer germs getting in.
• Allergies. Pollen, ragweed, or other triggers stimulate immune cells that produce histamine. Histamine opens up blood vessels just beneath the mucous membranes, and that leads to increased production and release of fluid and mucus. As with infection, this response may be helpful to dilute the offending trigger and rid it from the area.
• Cold, dry air. The inside surface of the nose is covered with mucous membranes that warm and humidify air well before it reaches the lungs. When you inhale dry, cold air through your nose, these membranes humidify the air by secreting water and mucus.
• Spicy foods. Spices like capsaicin act as an irritant to the sinuses and mucous membranes, which release fluid in response.

The bottom line

Some of the most common everyday human experiences are also some of the least understood. There are many other examples, of course: Why are we ticklish? What purpose do hiccups serve? What’s the deal with brain freeze? Perhaps topics for another day.

It may seem like a leap of faith, but it’s likely there are very good reasons for the way our bodies work — even when we don’t know what those reasons are.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD