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If you are trying to cut back on added sugar — and you should, because excess sugar increases risks for obesity, diabetes, and heart disease — you might be tempted by products advertised as low sugar, no sugar, or sugar-free.

Many contain familiar low-calorie sugar substitutes like aspartame or sucralose instead of sugar. And as you’re reading labels, you also may run across another ingredient: sugar alcohol, which is used in products like sugar-free cookies, candies, ice cream, beverages, and chewing gums. Are any of these sweeteners a better choice nutritionally? Dr. Frank Hu, professor of nutrition and epidemiology with the Harvard T.H. Chan School of Public Health, weighs in below.

Are low-calorie or no-calorie sweeteners any healthier than natural sugar?

Also known as artificial sweeteners or sugar substitutes, the list of low-calorie and no-calorie sweeteners you may see on product nutrition labels includes acesulfame-K, saccharin, sucralose, neotame, and advantame. These have a higher sweetness intensity per gram than natural sugar.

So far research on them is mixed, although some observational studies have found that beverages containing low-calorie sweeteners are associated with a higher risk for diabetes and weight gain.

What exactly are sugar alcohols and how can you spot them?

Sugar alcohols may have the most misleading name, as they are neither sugar nor alcohol, according to Dr. Hu. “They are a type of carbohydrate derived from fruits and vegetables, although most commercial sugar alcohols are synthetically produced.”

You can usually spot many sugar alcohols on ingredient lists by “-ol” at the ends of their names. Examples include sorbitol, xylitol, lactitol, mannitol, erythritol, and maltitol.

Are sugar alcohols any healthier than other sugar substitutes or natural sugar?

Here is a look at the pros and cons.

The upside of sugar alcohols

Sugar alcohols reside in the sweet spot between natural sugar and low-calorie sweeteners. They are not as overly sweet as sweeteners and don’t add too many extra calories like sugar.

“Sugar alcohols are about 40% to 80% as sweet as natural sugar, whereas artificial sweeteners like aspartame are about 200 times sweeter,” says Dr. Hu. “And they have about 25% to 75% fewer calories per gram than sugar.”

Another upside of sugar alcohols is that they break down slowly in the gut. Hence, your body only absorbs part of their overall carbohydrates. “This keeps your blood sugar and insulin levels from spiking as they do with sugar,” says Dr. Hu. “That makes them a useful sugar substitute for people with diabetes.”

The downside of sugar alcohols

The main downside to sugar alcohols is this: when taken in high amounts they can cause gastrointestinal (GI) problems, such as abdominal pain, diarrhea, or loose stools.

Because sugar alcohols are slowly digested, they have more time to feed bacteria in the gut, which can lead to fermentation and produce excess gas. Their slow digestion also can pull extra water into the colon and cause a laxative effect.

People’s tolerance for sugar alcohols depends on many factors, including body weight, health conditions, and the amount and types of sugar alcohols. “Individual differences in digestion and metabolism, gut microbiome composition, and dietary habits can also make a difference,” says Dr. Hu. “For these reasons, we recommend introducing sugar alcohols into your diet gradually and observing how your body responds.”

For people who experience GI symptoms caused by sugar alcohols, Dr. Hu says cutting back on the amount of foods and drinks made with them often can correct the problem. “Sugar alcohols are commonly found in sugar-free or low-carb products, so pay attention to food labels” he says. “Because different sugar alcohols can have different effects, it might be useful to identify specific types of sugar alcohols that cause GI side effects.”

Do sugar alcohols have health risks?

Possible long-term health risks of sugar alcohol are still being explored. A 2023 observational study found a link between using erythritol as an added sweetener and cardiovascular disease events, such as stroke and heart attack, in people with heart disease or who had risk factors like diabetes and high blood pressure. However, these findings have not been confirmed in subsequent studies.

“Sugar alcohols offer a healthier alternative to sugar because of their lower calorie content and reduced glycemic response, which is the effect food has on blood sugar levels,” says Dr. Hu. “But they also have potential drawbacks, especially for those with sensitive digestive systems, so it’s best to consume them in moderation as part of an overall healthy eating pattern.”

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

If you spend time outdoors — which we all should do, for all sorts of reasons — you are likely to encounter biting bugs. Most of the time the bites are just a nuisance. But besides the fact that sometimes they can be painful or itchy, bug bites can lead to illness — like Lyme disease from ticks, or Zika, malaria, or West Nile disease from mosquitoes. So preventing bites is a good idea for all of us, and certainly for children.

Simple precautions will help

Before talking about insect repellents, it’s important to remember that there are simple and effective precautions, nearly all of which don’t involve any chemicals. For example:

• Empty out any standing water outside your home. That’s where mosquitoes breed.
• Wear long-sleeved shirts and long pants if you are going to be in areas with lots of biting insects. If you treat clothes (and shoes and gear) with 0.5% permethrin, it can be helpful.
• Be aware that mosquitoes are most likely to be out at dusk and dawn, and plan activities accordingly.
• To avoid tick bites, avoid wooded and brushy areas and keep to the center of paths when you hike. Be sure to do a tick check when you come home — not just of all the people in your group, but also any pets or gear that came along. Taking a shower soon after arriving home can help with both tick checks and washing off any unattached ticks.

Make choices about insect repellent

Insect repellents can be very useful. Some are more effective than others, and some can have side effects, so it’s important to do your homework. The Environmental Protection Agency has a great interactive tool that can help you choose the best repellent for your particular situation.

The most effective repellent is DEET (N, N-diethyl-meta-toluamide). It works against both mosquitoes and ticks, and is definitely the go-to repellent if you really want or need to prevent bites. The higher the concentration, the longer it lasts: 10% will give you about two hours of coverage, while 30% can protect you for about five hours. The American Academy of Pediatrics (AAP) recommends not using more than 30% on kids, and not using any repellents on infants less than 2 months old.

The most common side effect is skin irritation, and if you ingest it (you never know with little kids) it can lead to nausea and vomiting. Eye irritation is possible, which is why you should never spray any repellent directly to the face, but rather put it on your hands and then carefully apply to the face. In very rare cases, like one in every 100 million users, DEET can lead to brain problems such as seizures if used in high doses. This is an incredibly rare side effect, and not something that should stop you from using it, especially if you are in an area with a lot of ticks, or an area with lots of disease-carrying mosquitoes.

Here are some alternatives with minimal to no side effects (eye irritation most common; avoid as noted above):

• oil of lemon eucalyptus, or PMD (the manmade alternative). This works nearly as well as DEET.
• picaridin, which works better against mosquitoes than ticks
• 2-undecanone
• IR-3535, the active ingredient in Avon products, although it is not very effective
• citronella, although it is even less effective.

Applying insect repellent — and sunscreen

Whatever you use, follow label directions and be sure that you are careful as you apply it to all exposed skin. It’s best to spray in an open area — and spray clothing too. Pump bottles and wipes with insect repellent may help you apply products carefully. Try to choose the best product for your situation so that you can apply it just once; the EPA tool is great for that. Don’t forget sunscreen; apply that first so your skin can absorb it.

The Centers for Disease Control and Prevention (CDC) has more information about applying insect repellent on children and preventing bites from mosquitoes and ticks.

Also visit the Harvard Health Publishing Lyme Wellness Initiative to learn about preventing –– or living with –– Lyme disease and other tick-borne illnesses.

About the Author

Claire McCarthy, MD, Senior Faculty Editor, Harvard Health Publishing

Claire McCarthy, MD, is a primary care pediatrician at Boston Children’s Hospital, and an assistant professor of pediatrics at Harvard Medical School. In addition to being a senior faculty editor for Harvard Health Publishing, Dr. McCarthy … See Full Bio View all posts by Claire McCarthy, MD

Over the course of a lifetime, as many as seven in 10 adults in the United States will directly experience or witness harrowing events. These include gun violence, car accidents, and other personal trauma; natural or human-made disasters, such as Hurricane Katrina and the 9/11 terrorist attacks; and military combat. And some — though not all — will experience post-traumatic stress disorder, or PTSD.

New guidelines released in 2024 can help guide effective treatment.

What is PTSD?

PTSD is a potentially debilitating mental health condition. It’s marked by recurrent, frightening episodes during which a person relives a traumatic event.

After a disturbing event, it’s normal to have upsetting memories, feel on edge, and have trouble sleeping. For most people, these symptoms fade over time. But when certain symptoms persist for more than a month, a person may be experiencing PTSD.

These symptoms include

• recurring nightmares or intrusive thoughts about the event
• feeling emotionally numb and disconnected
• withdrawing from people and certain situations
• being jumpy and on guard.

The National Center for PTSD offers a brief self-screening test online, which can help you decide whether to seek more information and help.

Who is more likely to experience PTSD?

Not everyone who experiences violence, disasters, and other upsetting events goes on to develop PTSD. However, military personnel exposed to combat in a war zone are especially vulnerable. About 11% to 20% of veterans who served in Iraq or Afghanistan have PTSD, according to the National Center for PTSD.

What about people who were not in the military? Within the general population, estimates suggest PTSD occurs in 4% of men and 8% of women — a difference at least partly related to the fact that women are more likely to experience sexual assault.

What are the new guidelines for PTSD treatment?

Experts from the U.S. Department of Veterans Affairs and Department of Defense collaborated on new guidelines for treating PTSD. They detailed the evidence both for and against specific therapies for PTSD.

Their findings apply to civilian and military personnel alike, says Dr. Sofia Matta, a psychiatrist at Harvard-affiliated Massachusetts General Hospital and senior director of medical services at Home Base, a nonprofit organization that provides care for veterans, service members, and their families.

The circle of care is widely drawn for good reason. “It’s important to recognize that PTSD doesn’t just affect the person who is suffering but also their families and sometimes, their entire community,” Dr. Matta says. The rise in mass shootings in public places and the aftermath of these events are a grim reminder of this reality, she adds.

Which treatment approaches are most effective for PTSD?

The new guidelines looked at psychotherapy, medications, nondrug therapies. Psychotherapy, sometimes paired with certain medicines, emerged as the most effective approach.

The experts also recommended not taking certain drugs due to lack of evidence or possible harm.

Which psychotherapies are recommended for PTSD?

The recommended treatment for PTSD, psychotherapy, is more effective than medication. It also has fewer adverse side effects and people prefer it, according to the guidelines.

Which type of psychotherapy can help? Importantly, the most effective therapies for people with PTSD differ from those for people with other mental health issues, says Dr. Matta.

Both cognitive processing therapy and prolonged exposure therapy were effective. These two therapies teach people how to evaluate and reframe the upsetting thoughts stemming from the traumatic experience. The guidelines also recommend mindfulness-based stress reduction, an eight-week program that includes meditation, body scanning, and simple yoga stretches.

Which medications are recommended for PTSD?

Some people with severe symptoms need medication to feel well enough to participate in therapy. “People with PTSD often don’t sleep well due to insomnia and nightmares, and the resulting fatigue makes it hard to pay attention and concentrate,” says Dr. Matta.

Three medicines commonly prescribed for depression and anxiety — paroxetine (Paxil), sertraline (Zoloft), and venlafaxine (Effexor) — are recommended. Prazosin (Minipress) may help people with nightmares, but the evidence is weak.

Which medications are not recommended for PTSD?

The guidelines strongly recommended not taking benzodiazepines (anti-anxiety drugs often taken for sleep). Benzodiazepines such as alprazolam (Xanax) and clonazepam (Klonopin) offer no proven benefits for people with PTSD. They have several potential harms, including negative cognitive changes and decreased effectiveness of PTSD psychotherapies.

What about cannabis, psychedelics, and brain stimulation therapies?

Right now, evidence doesn’t support the idea that cannabis helps ease PTSD symptoms. And there are possible serious side effects from the drug, such as cannabis hyperemesis syndrome (severe vomiting related to long-term cannabis use).

There isn’t enough evidence to recommend for or against psychedelic-assisted therapies such as psilocybin (magic mushrooms) and MDMA (ecstasy). “Because these potential therapies are illegal under federal law, the barriers for conducting research on them are very high,” says Dr. Matta. However, recent legislative reforms may make such studies more feasible.

Likewise, the evidence is mixed for a wide range of other nondrug therapies, such as brain stimulation therapies like repetitive transcranial magnetic stimulation or transcranial direct current stimulation.

About the Author

Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

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

When a prostate-specific antigen (PSA) blood test produces an abnormal result, the next step is usually a prostate biopsy. A biopsy can confirm or rule out a cancer diagnosis, but it also has certain drawbacks. Prostate biopsies are invasive procedures with potential side effects, and they often detect low-grade, slow-growing tumors that may not need immediate treatment — or any treatment at all.

Researchers are exploring various strategies for avoiding unnecessary biopsies. Specialized magnetic resonance imaging (MRI) scans, for instance, can be useful for predicting if a man’s tumor is likely to spread. A blood test called the Prostate Health Index (PHI) measures various forms of PSA, and can help doctors determine if a biopsy is needed.

In April, researchers at the University of Michigan published results with a test that screens for prostate cancer in urine samples. Called the MyProstateScore 2.0 (MPS2) test, it looks for 18 different genes associated with high-grade tumors. “If you’re negative on this test, it’s almost certain that you don’t have aggressive prostate cancer,” said Dr. Arul Chinnaiyan, a professor of pathology and urology at the University, in a press release.

Gathering data and further testing

To create the test, Dr. Chinnaiyan and his colleagues first turned to publicly-available databases containing over 58,000 prostate cancer-associated genes. From that initial pool, they narrowed down to 54 genes that are uniquely overexpressed in cancers classified as Grade Group 2 (GG2) or higher. The Grade Group system ranks prostate cancers from GG1 (the least dangerous) to GG5 (the most dangerous).

The team tested those 54 genes against archived urine samples from 761 men with elevated PSA who were scheduled for biopsy. This effort yielded 18 genes that consistently correlated with high-grade cancer in the biopsy specimens. These genes now make up MPS2.

Then the team validated the test by performing MPS2 testing on over 800 archived urine samples collected by a national prostate cancer research consortium. Other researchers affiliated with that consortium assessed the new urine test’s results against patient records.

Interpreting the results

Study findings showed that MPS2 correctly identified 95% of the GG2 prostate cancers and 99% of cancers that were GG3 or higher. Test accuracy was further improved by incorporating estimates of the prostate’s size (or volume, as it’s also called).

According to the team’s calculations, use of the MPS2 would have reduced unnecessary biopsies by 37%. If volume was included in the measure, then 41% of biopsies would have been avoided. By comparison, just 26% of biopsies would have been avoided with the PHI.

Dr. Chinnaiyan and his co-authors emphasize that ruling out high-grade cancer with a urine test offers some advantages over MRI. The specialized multi-parametric MRI scans needed to assess high-grade cancer in men with elevated PSA aren’t always available in community settings, for instance. Moreover, the interpretation of mpMRI results can vary from one radiologist to another. Importantly, the MPS2 can be updated over time as new prostate-cancer genes are identified.

Commentary

Dr. Boris Gershman, a urologist at Harvard-affiliated Beth Israel Deaconess Medical Center in Boston, and a member of the advisory and editorial board for the Harvard Medical School Guide to Prostate Diseases, described the new study results as promising. “It does appear that the performance of the 18-gene urine test is better than PSA alone,” he says.

But Dr. Gershman adds that it will be important to consider how such a test will fit into the current two-stage approach for PSA screening, which entails prostate MRI when the PSA is abnormal. Where MRI delivers a yes/no result (meaning lesions that look suspicious for cancer are either present or not), the MPS2 provides numerical risk estimates ranging between 0% and 100%. “The challenge with clinical implementation of a continuous risk score is where to draw the line for biopsy,” Dr. Gershman says.

“This research is very encouraging, since many men in rural areas may not have access to prostate MRI machines or the added sophistication that is needed in interpreting these MRI scans,” says Dr. Marc Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center. “A widely available urine test may eventually help provide more precision in determining who should undergo a prostate biopsy, and may also help to assess the probability that a cancer is clinically significant and in need of treatment.”

About the Author

Charlie Schmidt, Editor, Harvard Medical School Annual Report on Prostate Diseases

Charlie Schmidt is an award-winning freelance science writer based in Portland, Maine. In addition to writing for Harvard Health Publishing, Charlie has written for Science magazine, the Journal of the National Cancer Institute, Environmental Health Perspectives, … See Full Bio View all posts by Charlie Schmidt

About the Reviewer

Marc B. Garnick, MD, Editor in Chief, Harvard Medical School Annual Report on Prostate Diseases; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Marc B. Garnick is an internationally renowned expert in medical oncology and urologic cancer. A clinical professor of medicine at Harvard Medical School, he also maintains an active clinical practice at Beth Israel Deaconess Medical … See Full Bio View all posts by Marc B. Garnick, MD

Cognitive behavioral therapy (CBT) teaches people to challenge negative thought patterns and turn less often to unhelpful behaviors. These strategies can improve your mood and the way you respond to challenging situations: a flat tire, looming deadlines, family life ups and downs.

Yet there’s much more depth and nuance to this well-researched form of psychotherapy. It has proven effective for treating anxiety, depression, and other mental health conditions. Tailored versions of CBT can also help people cope with insomnia, chronic pain, and other nonpsychiatric conditions. And it can help in managing difficult life experiences, such as divorce or relationship problems.

What are the key components of CBT?

One important aspect of CBT relates to perspective, says psychologist Jennifer Burbridge, assistant director of the Cognitive Behavioral Therapy Program at Harvard-affiliated Massachusetts General Hospital.

“Therapists who practice CBT don’t see the problems or symptoms people describe as having one single cause, but rather as a combination of underlying causes,” she says. These include

• biological or genetic factors
• psychological issues (your thoughts, physical sensations, and behaviors)
• social factors (your environment and relationships).

Each of these factors contributes to — and helps maintain — the troublesome issues that might prompt you to seek therapy, she explains.

How does CBT describe our emotions?

Our emotions have three components: thoughts, physical sensations, and behaviors.

“Thoughts are what we say to ourselves, or 'self-talk,'” says Burbridge. Physical sensations are what we observe in our bodies when we experience an emotional situation: for example, when your heart rate rises in stressful circumstances. Behaviors are simply the things you do — or do not do. For instance, anxiety might prevent you from attending a social event.

All three components are interrelated and influence one another. That’s why CBT helps people to develop skills in each of them. “Think of it as a wellness class for your emotional health,” says Burbridge.

How long does CBT last?

CBT is a goal-oriented, short-term therapy. Typically it involves weekly, 50-minute sessions over 12 to 16 weeks. Intensive CBT may condense this schedule into sessions every weekday over one to three weeks.

Is CBT collaborative?

“When I first meet with someone, I’ll listen to what’s going on with them and start thinking about different strategies they might try,” Burbridge says. But CBT is a collaborative process that involves homework on the patient’s part.

What might that mean for you? Often, a first assignment involves self-monitoring, noting whether there are certain things, events, or times of day that trigger your symptoms. Future sessions focus on fine-tuning approaches to elicit helpful, adaptive self-talk, and problem-solving any obstacles that might prevent progress.

Certain thinking patterns are often associated with anxiety or depression, says Burbridge. Therapists help people recognize these patterns and then work with patients to find broader, more flexible ways to cope with difficult situations.

“We’re cognitive creatures with big frontal lobes that help us analyze situations and solve problems. That’s useful in some situations. But at other times, when you’re trying to manage your emotions, it may be better to pause and acknowledge and accept your discomfort,” says Burbridge.

Which CBT tools and strategies can help?

That particular skill — paying attention in the present moment without judgement, or mindfulness — is a common CBT tool. Another strategy that’s helpful for anxiety, known as exposure or desensitization, involves facing your fears directly.

“People avoid things that make them nervous or scared, which reinforces the fear,” says Burbridge. With small steps, you gradually expose yourself to the scary situation. Each step provides learning opportunities — for example, maybe you realize that the situation wasn’t as scary as you though it would be.

By trying new things instead of avoiding them, you begin to change your thought patterns. These more adaptive thinking patterns then make it more likely you will try new or challenging experiences in the future, thereby increasing your self-confidence.

How does CBT work?

Brain imaging research suggests conditions like depression or anxiety change patterns of activity in certain parts of the brain. One way CBT may help address this is by modifying nerve pathways involved in fear responses, or by establishing new connections between key parts of the brain.

A 2022 review focused on 13 brain imaging studies of people treated with CBT. The analysis suggested CBT may alter activity in the prefrontal cortex (often called the “personality center”) and the precuneus (which is involved in memory, integrating perceptions of the environment, mental imagery, and pain response).

Who might benefit from CBT?

CBT is appropriate for people of all different ages. This can range from children as young as 3 years — in tandem with parents or caregivers — to octogenarians. In addition to treating anxiety and depression, CBT is also effective for

• eating disorders
• substance abuse
• personality disorders
• attention deficit hyperactivity disorder (ADHD)
• obsessive compulsive disorder (OCD).

Additional evidence shows CBT may help people with different health issues, including irritable bowel syndrome, chronic fatigue syndrome, fibromyalgia, insomnia, migraines, and other chronic pain conditions. The therapy may also benefit people with cancer, epilepsy, HIV, diabetes, and heart disease.

“Many medical conditions can limit your activities. CBT can help you adjust to your diagnosis, cope with the new challenges, and still live a meaningful life, despite the limitations,” says Burbridge.

About the Author

Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

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

On the Gulf Coast of Florida where I live, the telltale sign of summer is not an influx of beachcombers, afternoon storms that arrive exactly at 2 p.m., or the first hurricane warning, but the appearance of hundreds of paddleboarders dotting the inlet waters.

From afar, paddleboarding looks almost spiritual — people standing on nearly invisible boards and gliding across the surface as if walking on water.

But this popular water sport offers a serious workout, just as kayaking and canoeing do. While floating along and casually dipping a paddle in the water may look effortless, much goes on beneath the surface, so to speak.

As warm weather beckons and paddle season arrives, it pays to get key muscles in shape before heading out on the water.

Tuning up muscles: Focus on core, back, arms, and shoulders

“Paddling a kayak, canoe, or paddleboard relies on muscles that we likely haven’t used much during winter,” says Kathleen Salas, a physical therapist with Spaulding Adaptive Sports Centers at Harvard-affiliated Spaulding Rehabilitation Network. “Even if you regularly weight train, the continuous and repetitive motions involved in paddling require endurance and control of specific muscles that need to be properly stretched and strengthened.”

While paddling can be a whole-body effort (even your legs contribute), three areas do the most work and thus need the most conditioning: the core, back, and arms and shoulders.

• Core. Your core comprises several muscles, but the main ones for paddling include the rectus abdominis (that famed “six-pack”) and the obliques, located on the side and front of your abdomen. The core acts as the epicenter around which every movement revolves — from twisting to bending to stabilizing your trunk to generate power.
• Back: Paddling engages most of the back muscles, but the ones that carry the most load are the latissimus dorsi muscles, also known as the lats, and the erector spinae. The lats are the large V-shaped muscles that connect your arms to your vertebral column. They help protect and stabilize your spine while providing shoulder and back strength. The erector spinae, a group of muscles that runs the length of the spine on the left and right, helps with rotation.
• Arms and shoulders: Every paddle stroke engages the muscles in your arms (biceps) and the top of your shoulder (deltoids).

Many exercises specifically target these muscles, but here are three that can work multiple paddling muscles in one move. Add them to your workouts to help you get ready for paddling season. If you haven’t done these exercises before, try the first two without weights until you can do the movement smoothly and with good form.

Three great exercises to prep for paddling

Wood chop

Muscles worked: Deltoids, obliques, rectus abdominis, erector spinae
Reps: 8–12 on each side
Sets: 1–3
Rest: 30–90 seconds between sets

Starting position: Stand with your feet about shoulder-width apart and hold a dumbbell with both hands. Hinge forward at your hips and bend your knees to sit back into a slight squat. Rotate your torso to the right and extend your arms to hold the dumbbell on the outside of your right knee.

Movement: Straighten your legs to stand up as you rotate your torso to the left and raise the weight diagonally across your body and up to the left, above your shoulder, while keeping your arms extended. In a chopping motion, slowly bring the dumbbell down and across your body toward the outside of your right knee. This is one rep. Finish all reps, then repeat on the other side. This completes one set.

Tips and techniques:

• Keep your spine neutral and your shoulders down and back
• Reach only as far as is comfortable.
• Keep your knees no farther forward than your toes when you squat.

Make it easier: Do the exercise without a dumbbell.

Make it harder: Use a heavier dumbbell.

Bent-over row

Muscles worked: Latissimus dorsi, deltoids, biceps
Reps: 8–12
Sets: 1–3
Rest: 30–90 seconds between sets

Starting position: Stand with a weight in your left hand and a bench or sturdy chair on your right side. Place your right hand and knee on the bench or chair seat. Let your left arm hang directly under your left shoulder, fully extended toward the floor. Your spine should be neutral, and your shoulders and hips squared.

Movement: Squeeze your shoulder blades together, then bend your elbow to slowly lift the weight toward your ribs. Return to the starting position. Finish all reps, then repeat with the opposite arm. This completes one set.

Tips and techniques:

• Keep your shoulders squared throughout.
• Keep your elbow close to your side as you lift the weight.
• Keep your head in line with your spine.

Make it easier: Use a lighter weight.

Make it harder: Use a heavier weight.

Superman

Muscles worked: Deltoids, latissimus dorsi, erector spinae
Reps: 8–12
Sets: 1–3
Rest: 30–90 seconds between sets

Starting position: Lie face down on the floor with your arms extended, palms down, and legs extended.

Movement: Simultaneously lift your arms, head, chest, and legs off the floor as high as is comfortable. Hold. Return to the starting position.

Tips and techniques:

• Tighten your buttocks before lifting.
• Don’t look up.
• Keep your shoulders down, away from your ears.

Make it easier: Lift your right arm and left leg while keeping the opposite arm and leg on the floor. Switch sides with each rep.

Make it harder: Hold in the “up” position for three to five seconds before lowering.

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

My favorite summer activities officially kick in when the calendar flips to May. It's prime time for open water swimming, running, cycling, hiking, and anything else that gets me outside and moving. Yet, my first step is to get my legs in shape.

“Legs are the foundation for most activities,” says Vijay Daryanani, a physical therapist at Harvard-affiliated Spaulding Rehabilitation Hospital. “They're home to some of the body’s largest muscles, and building healthy legs can improve one’s performance, reduce injury, and increase endurance.”

Four leg muscle groups to build for summer activities

Four muscles do the most leg work: quadriceps, gluteus maximus (glutes), hamstrings, and calves. Here is a look at each.

Quadriceps (quads). Also known as the thigh muscles, the quads are a group of four muscles (hence the prefix "quad'). They extend your leg at the knee and power every leg action: stand, walk, run, kick, and climb.

Glutes. The body’s largest muscles, the glutes (your buttock muscles) keep you upright and help the hips and thighs propel your body forward.

Hamstrings. The hamstrings are a group of three muscles that run along the back of your thighs from the hip to just below the knee. They allow you to extend your leg straight behind your body and support hip and knee movements.

Calves. Three muscles make up the calf, which sits in the back of the lower leg, beginning below the knee and extending to the ankle. They work together to move your foot and lower leg and push you forward when you walk or run.

Spotlight muscle strength and length

Strength and length are the most important focus for building summer-ready legs, says Daryanani. “Strengthening leg muscles increases power and endurance, and lengthening them improves flexibility to protect against injury.”

If you are new to exercise or returning to it after time off, first get your legs accustomed to daily movement. “Start simply by walking around your home nonstop for several minutes each day, or climbing up and down stairs,” says Daryanani.

After that, adopt a walking routine. Every day, walk at a moderate pace for 20 to 30 minutes. You can focus on covering a specific distance (like one or two miles) or taking a certain number of steps by tracking them on your smartphone or fitness tracker. You won’t just build leg strength — you’ll reap a wide range of health benefits.

There are many different leg muscle-building exercises, some focused on specific activities or sports. Below is a three-move routine that targets the four key leg muscles. Add them to your regular workout or do them as a leg-only routine several times a week. (If you have any mobility issues, especially knee or ankle problems, check with your doctor before starting.)

To help lengthen your leg muscles and increase flexibility, try this daily stretching routine that includes several lower-body stretches.

Dumbbell squats

Muscles worked: glutes and quads

Reps: 8-12

Sets: 1-2

Rest: 30-90 seconds between sets

Starting position: Stand with your feet apart. Hold a weight in each hand with your arms at your sides and palms facing inward.

Movement: Slowly bend your hips and knees, leaning forward no more than 45 degrees and lowering your buttocks down and back about eight inches. Pause. Slowly rise to an upright position.

Tips and techniques:

• Don’t round or excessively arch your back

Make it easier: Do the move without holding weights.

Make it harder: Lower yourself at a normal pace. Hold briefly. Stand up quickly.

Reverse lunge

Muscles worked: quads, glutes, hamstrings

Reps: 8-12

Sets: 1-3

Rest: 30-90 seconds between sets

Starting position: Stand straight with your feet together and your arms at your sides, holding dumbbells.

Movement: Step back onto the ball of your left foot, bend your knees, and lower into a lunge. Your right knee should align over your right ankle, and your left knee should point toward (but not touch) the floor. Push off your left foot to stand and return to the starting position. Repeat, stepping back with your right foot to do the lunge on the opposite side. This is one rep.

Tips and techniques:

• Keep your spine neutral when lowering into the lunge.
• Don't lean forward or back.
• As you bend your knees, lower the back knee directly down toward the floor with the thigh perpendicular to the floor.

Make it easier: Do lunges without weights.

Make it harder: Step forward into the lunges, or use heavier weights.

Calf raises

Muscles worked: calves

Reps: 8-12

Sets: 1-2

Rest: 30 seconds between sets

Starting position: Stand with your feet flat on the floor. Hold on to the back of a chair for balance.

Movement: Raise yourself up on the balls of your feet as high as possible. Hold briefly, then lower yourself.

Make it easier: Lift your heels less high off the floor.

Make it harder: Do one-leg calf raises. Tuck one foot behind the other calf before rising on the ball of your foot; do sets for each leg. Or try doing calf raises without holding on to a chair.

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

It’s never easy for parents to talk to their teens about having sex. Many parents feel that talking about it is the same as condoning it, so they are hesitant to do so. But according to the most recent Youth Risk Behavior Survey (YRBS), a national survey of high school students, by the end of high school 30% have had sex.

It can be impossible to know for sure if your teen has had sex. Even if they haven’t, it’s likely that at some point they will — and they need to have information to help keep themselves safe and healthy.

What parents should know about sexually transmitted infections

Sexually transmitted infections, or STIs, are very common. They may be caused by bacteria, viruses, or other microorganisms, and spread through all kinds of sex. While most STIs are treatable, they can affect fertility in both women and men, can cause health problems for a baby during pregnancy, and can sometimes lead to lifelong infection or serious complications. That’s why teens need to know about them.

Below are the high-level facts about some of the most common infections: what causes them, what symptoms may occur, and how they are treated.

Chlamydia

Chlamydia is the most frequently reported bacterial STI in the United States — but just as many cases are asymptomatic, so the numbers may be higher than we realize.

Symptoms, if they are present, can include discharge from the vagina or penis, pain with urination, or pain and swelling of the testicles (this is rare). A test of the urine (or a swab from the affected area) can diagnose it, and it is curable with antibiotics. If left untreated it can lead to infertility, more commonly in women than men.

Gonorrhea

Gonorrhea is another STI caused by a bacteria, and it can also be asymptomatic. When symptoms occur, they are very similar to chlamydia. Gonorrhea also can cause infertility in both women and men. While it is treatable, some infections have been resistant to the usual antibiotics used, so additional testing and treatment is sometimes needed.

Trichomoniasis

Trichomoniasis is caused by a protozoa. It is another STI that can be asymptomatic. When there are symptoms, they are usually itch, irritation, and discharge. It is curable with medication.

Syphilis

Syphilis has been on the rise. In the first stage of infection there is usually a firm, round, painless sore where the infection entered the body. The sore is generally there for three to six weeks, but as it is painless it may go unnoticed.

In the second stage there is a more extensive rash, though it can be faint and go unnoticed, along with general feelings of illness such as fever, sore throat, fatigue, swollen lymph nodes, or weight loss.

If syphilis still goes unnoticed it can linger in the body for years, sometimes affecting organ systems, including the brain. It is curable with antibiotics, but if found late the damage it can do may be permanent. This infection can be very serious during pregnancy.

HSV

HSV (herpes simplex virus) causes blistering sores. There is both oral herpes (mouth sores) and genital herpes. Oral herpes, caused by HSV1, is not usually caused by sex — but it can lead to genital herpes through oral sex. Genital herpes is more commonly caused by HSV2.

The sores of herpes can recur throughout life. There is no cure for herpes, but there are medications that can shorten or prevent outbreaks. This infection can be particularly dangerous during pregnancy, although the risks can be managed with good prenatal care.

HPV

HPV (human papilloma virus) is the most common sexually transmitted infection. It can be transmitted even by close skin-to-skin touch, and infections are generally asymptomatic.

Most cases of HPV (90%) get better by themselves — but if they don’t, over time the virus can cause genital warts or certain cancers. Luckily, there is an effective vaccine to prevent HPV that can be given starting at age 9.

HIV

HIV (human immunodeficiency virus) is more common among people who have other STIs — mostly because having STIs is a sign of risky sexual behavior. It can be very hard to know if a person has it, because the early symptoms can feel like having the flu, and then people can move into a long period of time of having no symptoms at all.

While there is no cure for HIV, there are medications to control it, as well as medications that can prevent it.

Talking to teens about preventing STIs

All of this sounds scary. But there are actually some simple things teens can do to prevent infections or minimize complications, which is why parents need to talk with them.

Teens can:

• Use condoms every single time they have sex — and use them properly. According to the report mentioned above, about half of sexually active high schoolers don’t use condoms regularly.
• Limit their number of sexual partners — and have frank conversations with those partners before having sex. Asking about sexual history, and getting testing before starting a sexual relationship, can make a difference.
• Get tested regularly. Sexually active teens should be tested for gonorrhea and chlamydia every year, or more frequently based on their sexual history or symptoms. Testing for other infections may be a good idea too. In the YRBS, 95% of high schoolers had not been tested for STIs in the past year, which is frightening given that nearly a third report being sexually active.

Make sure your teen sees their doctor regularly. And encourage them to be honest with their doctor during their visits. As a parent, you can help by giving your teen confidential time alone with the doctor.

About the Author

Claire McCarthy, MD, Senior Faculty Editor, Harvard Health Publishing

Claire McCarthy, MD, is a primary care pediatrician at Boston Children’s Hospital, and an assistant professor of pediatrics at Harvard Medical School. In addition to being a senior faculty editor for Harvard Health Publishing, Dr. McCarthy … See Full Bio View all posts by Claire McCarthy, MD