Month: August 2021

Polio is a potentially life-threatening or disabling illness that spreads from person to person. Thanks to vaccination, the United States has been polio-free since 1979, and the spread of this highly contagious disease has been interrupted in most countries. Yet on June 22, the United Kingdom Health Security Agency announced that it had detected poliovirus in a most unexpected place: the sewers of London.

Over the past several months, scientists at the agency repeatedly found poliovirus in London sewer water. The viruses were genetically similar, suggesting that they were the result of limited spread within a family or close-knit community. Just how concerned should all of us be about this news?

Health clues found in wastewater

Sampling of wastewater for genetic material from viruses is a powerful tool used by epidemiologists to track outbreaks of polio and other diseases. Surges in the amount of SARS-CoV-2 RNA in Boston wastewater have been highly predictive of COVID outbreaks. Wastewater may also help to detect the spread of influenza and antibiotic-resistant bacteria.

Poliovirus infection was once a common and dreaded disease. Most people with poliovirus either had no symptoms or mild gastroenteritis (stomach flu). But one in 100 people developed paralysis, or poliomyelitis. In half of the affected patients, this paralysis was permanent.

In the UK, wild poliovirus has been eliminated since 1984. Although great progress has been made in many parts of the world, complete eradication of polio has been elusive. Pakistan and Afghanistan have never been free from wild-type polio, and outbreaks have recently taken place in Malawi and Mozambique, countries which had previously eliminated polio.

The reasons for this backsliding are complex. Some contributing factors are diversion of scarce resources toward the COVID-19 pandemic, backlogs in vaccine manufacturing, anti-vaccine agitation, and violence directed at vaccine workers.

Another problem is vaccine-derived poliovirus. In the United States and most other countries, injections containing killed viruses are used. While these vaccines are safe, they are less effective than oral vaccines at breaking the chain of polio transmission. Oral vaccines stimulate long-lived immune responses in the lining of the intestines, where polioviruses replicate. Unfortunately, oral vaccines contain weakened but live viruses, which occasionally revert to a more dangerous form. In fact, the poliovirus found in London was a vaccine-derived strain that the infected individual had likely acquired from travel abroad.

Who is at risk for poliovirus stemming from this source?

Vaccine-derived viruses pose little risk to highly vaccinated populations, but they are able to spread in communities with low polio vaccination rates. In some cases, this can even cause paralytic disease. Because of these risks, steps are being taken to gradually phase out the use of oral polio vaccines.

If you’re concerned about polio, the best protection against this disease is vaccination. Children should receive a full series of four shots of inactivated polio vaccine, given at specific intervals, that helps with developing immunity.

Nationwide, rates of childhood polio vaccination in the United States are still high (nearly 93%). However, some infectious disease experts worry that the weakening of vaccine mandates in some areas has created islands of vulnerability in this sea of immunity. Communities in the US with low childhood vaccination rates have been vulnerable to large measles outbreaks in recent years, and might also be vulnerable to polio outbreaks.

With few exceptions, adults who were fully vaccinated as kids do not need booster shots. These exceptions include travel to a country with active polio transmission, laboratory work with poliovirus, or providing health care to polio patients and their close contacts. A single lifetime booster dose of inactivated polio vaccine is adequate for these high-risk scenarios.

About the Author

John Ross, MD, FIDSA, Contributor

Dr. John Ross is an assistant professor of medicine at Harvard Medical School. He is board certified in internal medicine and infectious diseases, and practices hospital medicine at Brigham and Women’s Hospital. He is the author … See Full Bio View all posts by John Ross, MD, FIDSA

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

When trying intermittent fasting, both the quantity and quality of what you eat during your eating window matter.

Intermittent fasting is a trendy topic that arises repeatedly in my clinic these days. I get it: restrict the time period when you eat, but within that time window eat as you normally would. No calorie counting. No food restrictions. Simple and flexible. In an on-the-go world, intermittent fasting has come into vogue as a potential pathway toward sustainable weight loss.

What is Intermittent fasting?

Intermittent fasting (IF) has become a catch-all term for one of the key levers in our dietary pattern: timing. More accurately, intermittent fasting refers to an eating schedule that is designed to expand the amount of time your body experiences a fasted state. You achieve this by reducing the so-called eating window. The most popular time-restricted eating protocols (typically based on study designs) are explained in these previously published articles:

• Time to try intermittent fasting?
• Intermittent fasting: The positive news continues
• Not so fast: Pros and cons of the newest diet trend

How might time-restricted eating help with weight loss?

To start, consider a fed state that promotes cellular growth versus a fasted state that stimulates cellular breakdown and repair. Both can be beneficial or harmful, depending on the context (consider how cellular growth builds lean muscle mass and also spawns cancer). Many of our genes, particularly those that regulate our metabolism (how we digest and utilize the energy from food), are turned on and off each day in accordance with our innate circadian rhythms (our sleep/wake cycle).

We transition from a fed to an early fasted state several hours — five to six, on average — after our last meal. This often aligns with the time when the sun has set, our metabolism slows, and we sleep. However, in our modern environment with artificial lights, 24-hour convenience stores, and DoorDash, we are persistently primed to eat. Rather than obeying our circadian cues, we are eating at all times of day.

Plenty of research, mainly in animal models but also some human trials, indicates that your body experiences numerous benefits from being in a fasted state, given its impact on cellular processes and function. In a fully fasted state, your metabolism switches its primary source of fuel from glucose to ketones, which triggers a host of cellular signaling to dampen cellular growth pathways and increase cellular repair and recycling mechanisms. Repeated exposure to a fasted state induces cellular adaptations that include increased insulin sensitivity, antioxidant defenses, and mitochondrial function.

Given how much of chronic disease is driven by underlying insulin resistance and inflammation, it’s plausible that fasting may help reduce diabetes, high cholesterol, hypertension, and obesity. And multiple short-term clinical studies provide evidence that intermittent fasting — specifically, time-restricted feeding — can improve markers of cardiometabolic health.

Is intermittent fasting a reliable strategy to achieve weight loss?

To date, the answer has remained murky due to the quality of the evidence, which often involves very small sample sizes, short intervention periods, varied study designs (often lacking control groups), different fasting protocols, and participants of varying shapes and sizes. The data on intermittent fasting and its impact on weight loss largely involves studies that employ the time-restricted eating methodology of intermittent fasting. A recent compilation of the evidence suggests that limiting your eating window might indeed help you shed a few pounds.

New research on IF as a tool for weight loss

To tease out the independent impact of time restriction on weight loss, we need to evaluate a calorie-restricted diet combined with time-restricted eating, compared to time-restricted eating alone. The recent results of a yearlong study assessed this exact question: does time-restricted eating with calorie restriction produce greater effects on weight loss and metabolic risk factors in obese patients, as compared with daily calorie restriction alone?

To answer this question, the trial involved people ages 18 to 75 with BMIs between 28 and 45, notably excluding those who were actively participating in a weight-loss program or using medications that affect weight or calorie intake. Participants were instructed to follow a 25% calorie-reduced diet (1,500 to 1,800 calories per day for men and 1,200 to 1,500 calories per day for women) with a set ratio of calories from protein, carbs, and fats. In order to confirm adherence to the diet (a notorious challenge in diet studies), participants were encouraged to weigh foods and were required to keep a daily dietary log, photograph the food they ate, and note the times at which they ate with the use of a custom mobile app.

Half of the participants (those in the time-restricted eating group) were instructed to consume the prescribed calories within an eight-hour period, whereas the other half in the daily-calorie-restriction group consumed the prescribed calories without time restriction. All participants were also instructed to maintain their usual daily physical activity throughout the trial, to remove this variable and to isolate the timing of food intake as the only difference between the two groups.

After a full year, 118 patients successfully completed the study, with similar rates of adherence to the diet and composition of the diet between the two groups. Both groups lost a significant amount of weight: an average of about 18 pounds for the time-restricted eating group and 14 pounds for the daily-calorie-restriction group. The difference in weight loss between the two groups was not statistically significant, nor was there a significant difference in weight loss among subgroups when sorted by sex, BMI at baseline, or insulin sensitivity. The resulting improvements in blood pressure, lipids, glucose, and cardiometabolic risk factors were also similar between the two groups. This trial provides strong evidence that, all else being equal, restricting the eating window alone does not have a substantive impact on weight loss.

What does the new research on IF mean for you?

For most people (with notable exclusions of those who have diabetes, eating disorders, are pregnant or breastfeeding, or require food with their meds), a time-restricted eating approach appears to be a safe strategy that is likely to produce some weight loss, assuming you are not changing your current dietary pattern (eating more calories).

The weight loss effects of time-restricted eating derive primarily from achieving a negative energy balance. If you maintain your regular diet and then limit the time window during which you eat, it is likely that you will eat a few hundred fewer calories per day. If this is sustainable as a lifestyle, it could add up to modest weight loss (3% to 8% on average, based on current data) that can produce beneficial improvements in cardiometabolic markers such as blood pressure, LDL cholesterol and triglyceride levels, and average blood sugar.

But — and this is a big but — if you are overcompensating for the time restriction by gorging yourself during your eating window, it will not work as a weight loss strategy. And it may indeed backfire. The other two levers in your dietary pattern — the quantity and quality of what you eat during your eating window — still matter immensely!

One downside of IF: Loss of lean muscle mass

While weight loss for cardiometabolic health is a sensible goal, weight loss from any intervention (including intermittent fasting) often entails a concurrent loss of lean muscle mass. This has been a notable finding — what I might even call an adverse side effect — of intermittent fasting protocols. Given the importance of lean muscle mass for revving your metabolic rate, regulating your blood sugar, and keeping you physically able overall, pairing resistance training with an intermittent fasting protocol is strongly advised.

Finally, the weight loss achieved through time-restricted eating (which we often refer to interchangeably with intermittent fasting) is likely different than the cellular adaptations that happen with more prolonged fully fasted states. At this time, it is hard to determine the degree to which the cardiometabolic benefits of fasting derive from weight loss or from underlying cellular adaptations; it is likely an interrelated combination of both.

Nevertheless, it seems clear that in a 24/7 world of around-the-clock eating opportunities, all of us could benefit from aligning with our circadian biology, and spend a bit less time in a fed state and more time in a fasted state each day.

About the Author

Richard Joseph, MD, Contributor

Dr. Richard Joseph is the founder of VIM Medicine, cofounder of Vital CxNs, a practicing clinician in the Center for Weight Management and Wellness at Brigham and Women’s Hospital in Boston, MA, and a faculty member at Harvard … See Full Bio View all posts by Richard Joseph, MD