The Unexpected Health Benefits of Forest Bathing

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By Vedika Patani and Carly Smith, BS, MPH(c)

This blog is part of the Stress Management newsletter. If you like this content, sign up here to receive our monthly newsletter!

Many people know that hiking in nature can help reduce stress and anxiety. But not everyone knows that forest bathing is a way to take the therapeutic effects of a scenic walk to the next level. While hiking is a great way to get outdoors and exercise, forest bathing is a practice of being calm and quiet among trees and being present with our natural surroundings.

“Both hiking and forest bathing harness the power of nature to offer a wide range of benefits for our physical and mental wellbeing,” says Rusly Harsono, MD, head of Stanford Lifestyle Medicine Social Engagement and Clinical Assistant Professor at the Stanford School of Medicine. “Hiking provides an outdoor activity that activates our nervous system for greater physical health, whereas forest bathing calms our nervous system and improves our emotional wellbeing, which is equally important to physical health.”

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What is Forest Bathing?

Forest bathing, or Shinrin Yoku, originated in Japan in the 1980s and involves taking deep breaths and experiencing the forest with full presence. Contrary to hiking, where the mind can still ruminate about work or challenging relationships, forest bathing is a mindfulness practice in that it brings the mind into the present moment by taking in the forest with all five senses. For example, a forest bather would visually observe the colors of the leaves and stop to notice the sun’s rays through the trees. They might close their eyes and take in a deep breath through the nose to capture the scent of pine. As they take a step, they may hear the crackling of a fallen leaf from under their shoe, and then pause to notice the sensation of the wind on their cheeks.

During the pandemic, forest bathing grew in popularity in the US as people searched for ways to calm their nervous system and connect outdoors while social distancing. But forest bathing is proving to be more than a lifestyle trend. Research is attributing this practice to numerous health benefits. 

Forest Bathing and Mental Health

While hiking focuses on the improvement of physical fitness, forest bathing fosters improved mental and emotional health. Some people who experience anxiety find that forest bathing calms their nervous system because their attention shifts from their worries to noticing the natural elements all around them—and these results are scientifically measurable.

Studies show that forest bathing can decrease the stress hormone cortisol. In one meta-analysis, researchers reviewed 971 articles and found that forest bathing effectively reduced serum and salivary cortisol levels, indicating its potential to reduce stress. 

Another meta-analysis reviewed studies where forest bathing was introduced to people living in urban environments, who generally have a higher risk of hypertension and psychological stress. Not only did the practice reduce their stress, but it also significantly lowered their blood pressure. 

“Forest bathing can be beneficial for everyone, but it is particularly advantageous for individuals living in urban environments,” says Dr. Harsono. “Urban dwellers typically experience higher stress levels, noise pollution, and reduced access to natural settings. Forest bathing provides them a valuable opportunity to escape these stressors and experience improved wellbeing through connection with nature.”

A Natural Immune Supporter

Forest bathing is not just important for improving wellbeing, but it may also improve one’s physical health. Studies have found that forest bathing could increase immune cell activity and aid in the expression of anti-cancer proteins. In one study, a group of 12 men aged 37-55 spent three days practicing forest bathing in three different forests. Afterward, the men showed a 50 percent increase in natural killer cells (which can kill tumor cells) and an increase in the anti-cancer proteins perforin, granzymes, and granulysin. 

Another research study showed that forest bathing improved immune function. When we inhale the oils released from trees (phytoncides), our cortisol levels decrease, and natural killer cell activity increases. These findings suggest forest bathing may have a preventive effect on cancer due to its ability to stimulate immune responses; however, more research needs to be conducted to better understand this phenomenon.

Forest Bathing Everywhere

One would think that forest bathing is only possible if you live in the country, however, this study showed that urban forest bathing (i.e. being mindful at a nearby park) still brought feelings of peacefulness to adolescents that live in metropolitan areas. This study observed the changes in the mental wellbeing of 44 adolescents before and after urban forest bathing. The results reported reduced anxiety, rumination, and skepticism, as well as increased feelings of social connectedness.

Lastly, landscape designers have taken note of the research supporting the healing effects of nature. At Stanford’s Lucile Packard Children’s Hospital in the heart of the San Francisco Bay Area, patients and their families have access to gardens and outdoor spaces to stroll and mindfully take in the natural beauty.

“Lucile Salter Packard’s vision for the hospital was to nurture the body and soul of every child by creating a restorative environment by integrating nature and art,” says Dr. Harsono, Pediatrician at Stanford Medicine Children’s Health. “We frequently bring children to the hospital garden during their recovery to help them manage their treatment and discomfort. Research supports this idea of incorporating forest bathing experiences into the care of sick children to improve their health outcomes and overall quality of life.”

 

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How to Be Mindful When You’re Stressed Out

By Carly Smith, BS, MPH(c)

This blog is part of the Stress Management newsletter. If you like this content, sign up here to receive our monthly newsletter!

I first began practicing mindfulness during my third year at Stanford University. I remember feeling overwhelmed by every aspect of my life – school, work, life, etc. Even the idea of being stressed would further stress me out. With the help of various mentors dedicated to student mental health and well-being though, I learned how I could best practice mindfulness and feel more in control of my mind.  

Mindfulness is an internal practice in which one shifts their focus to what and how they are feeling without much interpretation or judgment. If you’re reading this, perhaps you have already crossed off the first step in the process: name your feeling. 

What Am I Even Feeling?

The power of naming one’s feelings has been studied thoroughly in neuroscience. It is estimated that most people will spend nearly half their lives letting their mind wander. This mind wandering sensation is actually the heightening of our brain’s default mode network (DMN), an evolutionary adaptation that keeps us alert and is often overactive in individuals that suffer from anxiety. Consciously shifting one’s focus to perform a task – like labeling your feeling – centers brain activity to the prefrontal cortex, effectively inactivating the DMN. Another study conducted at UCLA found that the simple act of naming one’s emotion shifts brain activity from the amygdala (a structure that registers danger and fear) to the prefrontal cortex (the center of reason and logical thinking). Neurological studies show that when we are in the present moment, the prefrontal cortex is active and the amygdala and DMN are inactive.

“Mindfulness has been my go-to practice to reduce stress for many years now,” says Sharon Brock, Stanford Lifestyle Medicine Program Manager and UCLA-certified Mindfulness Facilitator. “Oftentimes, just labeling my emotions is enough to bring me back into balance.”

Whenever I practice mindfulness, sometimes all I need to do is call out my emotions. For me, this is often equivalent to calling out to a friend walking down the street or when Hogwarts students figure out what their patronus is. It is relieving to focus on what is right in front of me. The aforementioned switch from our brain’s DMN into the present moment keeps me grounded and helps repair my mental floodgates before becoming overwhelmed.

Listen to the Label Practice by mindfulness teacher and author, Sharon Brock.

Feel It to Heal It

Strong emotions like stress, anger, love, etc. all tend to really let us know they are with us by also manifesting themselves physically. Like many people, stress feels like a stiff neck and a tight chest for me. Once I have taken a moment to label my stress, I can turn my attention to how it is affecting me. Recognizing these emotions can give a quick explanation to why I feel off kilter, and allow me to become more aware of my physical self. My emotions become something more tangible for me to understand and experience.  

“If you can experience your emotions as a sensation in the body, it creates some space between you and the emotion,” says Brock. “By observing the sensations, you realize what emotions actually are: energies in motion. We don’t have to take our emotions so personally, they are just energies constantly coming and going in our experience.”

This act of feeling your feelings is a mindfulness tool offered as an alternative to other responses we can take when emotions are high. Observing before responding also helps to center one’s attention and direct brain activity to a calmer region, just like naming the feelings. Dr. Jon Kabat-Zinn developed a mindfulness-based stress reduction (MBSR) program as a non-pharmacological treatment for anxiety. This program heavily incorporates the mindfulness technique to observe our physical feelings with guided breathwork, body scans, and mindful movements. Body scanning, in particular, increases one’s bodily awareness by paying attention to how different body parts feel in the moment. 

Listen to the Observe Practice by mindfulness teacher and author, Sharon Brock.

Tips for Self Compassion

The most impactful thing I learned from my mindfulness course is that practicing mindfulness for stress reduction also requires practicing self compassion. Self compassion is the offering of love and kindness to ourselves and our emotions. Doing the opposite, criticizing oneself for feeling certain emotions, reactivates the amygdala and reintroduces stress to the body and mind. Recent research conducted at the Henry Wellcome Laboratories for Integrative Neuroscience & Endocrinology demonstrated that guided self-compassion exercises helped to significantly lower cortisol (the primary stress hormone) levels and increase heart rate variability. Participants with greater tendencies of self-criticism benefited greatly from learning to offer themselves gentleness when experiencing strong emotions. These findings indicate that practicing mindful self compassion has a physiological soothing effect on the body. 

“Many of us have a harsh inner critic, so it might feel strange at first to be nice to yourself, but the research shows that offering ourselves kindness reduces our stress,” says Brock, UC San Diego-certified Mindful Self-Compassion instructor. 

I used to believe that being my harshest critic was what guided my academic success. Not only was this method unsustainable, but it was often doing more harm than good. When we accept that emotions are transient and natural experiences, we do not need to judge ourselves for having them. In fact, we can offer ourselves compassion. For me, learning to offer myself self compassion was the mindfulness lesson that required the most practice. However, it has become a necessary aspect of my everyday life and has given me a reliable stress-management technique to keep in my mental toolbox forever.

Listen to the Self-Compassion Practice by mindfulness teacher and author, Sharon Brock.

 

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How Yoga Affects the Brain and Body to Reduce Stress

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By Vanika Chawla, MD, Stanford Psychiatrist

This blog is part of the Stress Management newsletter. If you like this content, sign up here to receive our monthly newsletter!

As a clinician at the Stanford Lifestyle Psychiatry clinic, I consider the impact of lifestyle factors such as sleep, nutrition, exercise, and mind-body practices such as yoga on my patients’ mental health and integrate these modalities into my treatment plans. I especially have a clinical and research interest in the therapeutic use of yoga as a lifestyle intervention. Yoga has been instrumental in my own wellbeing, therefore I am passionate about sharing the practice as a holistic intervention that promotes wellbeing in the body, mind, and spirit.

I was first immersed in yoga when I completed my 200-hour yoga teacher training in 2010, prior to medical school. I discovered that yoga was much more than physical postures – yoga is an integrative and holistic system of practices that aims to alleviate suffering. 

There are many different lineages and traditions of yoga, each emphasizing various components of the practice, including postures, breathwork, meditation, lifestyle, ethics and values, and recognizing our interconnectedness. There is a famous aphorism that captures the essence of yoga: yogas chitta vritti nirodhah. This Sanskrit phrase translates to, “Yoga is the calming of mental fluctuations or storms of the mind.” Thus, it was no surprise that on my journey to become a psychiatrist, I noticed parallels between yoga and psychiatry, including yoga’s therapeutic potential in addressing unmet needs in our current mental health care treatment models. 

On a personal note, my yoga practice provided me with a set of tools to manage the stresses and rigors of medical training, whether it was cultivating new perspectives when faced with challenges or practicing breathwork before a big exam to help with stress. 

How Yoga Improves Mental Health

While yoga is an ancient practice originating in India, it has only recently been applied for therapeutic purposes, and thus, the clinical evidence is in its early stages. There are many possible mechanisms for how yoga may improve mental health and counteract stress. One well-accepted mechanism is that yoga helps regulate the autonomic nervous system (ANS) and hypothalamic-pituitary axis (HPA), both of which are stress response systems. While stress is an inevitable and necessary part of life, prolonged and chronic stress can lead to dysfunction in these systems, potential negative physiological and physical consequences, and can even contribute to the development of mental health disorders. 

Yoga is proposed to exert its benefits through top-down and bottom-up processes facilitating bi-directional communication between the brain and body. Top-down mechanisms are conscious and intentional inputs from the brain to the body, such as setting an intention to relax. Bottom-up processes are inputs from the body to the brain, where signals travel from the muscles, heart, lungs, and other systems to different parts of the brain. Practices like yoga postures and breathing can change the signals that are carried to our brain, such as assessments of our sense of safety and wellbeing. Through top-down and bottom-up pathways, yoga can counteract the “fight, flight, or freeze” responses that may persistently arise in the face of stress. Accordingly, yoga has been shown to confer several changes in physiological markers implicated in stress, including cortisol, inflammatory cytokines, heart rate variability, as well as the release of neurotransmitters, such as GABA. 

The Neuroscience of Yoga

In addition, there is evidence of changes in both brain structure and function related to the practice of yoga. These include changes in the prefrontal cortex (PFC), amygdala, hippocampus, and default mode network (DMN). The PFC manages our highest-order cognitive abilities, such as decision-making and goal-setting. Stress and other strong emotions can negatively impact the abilities of the PFC. 

Research shows that regular yoga practice leads to increased activation of the PFC and thus may counteract deleterious effects of stress on the brain. Further, yoga impacts the activity of the amygdala, which is involved in processing emotions. Yoga may also increase the volume of the hippocampus, which is involved with memory and learning and is known to decrease in size with age. Finally, the DMN is involved in rumination and mind wandering, which may interfere with cognitive function and lead to decreased wellbeing. The DMN is implicated in many psychiatric disorders, such as depression and ADHD, and yoga has been shown to modulate the activity of the DMN. 

While yoga cannot change our external stressors, it can allow us to respond rather than react to stress. Yoga can counteract the harmful physical effects of stress and lead to changes in the body, brain, and mind that increase resilience and adaptability. 

Tips for People New to Yoga

From Kundalini to Vinyasa flow, there are many different types of yoga, so I recommend those new to yoga try different styles and see which practice aligns with their needs and feels safe and supportive. I suggest taking classes from credentialed teachers (with a minimum of RYT-200 hr training) who offer modifications and adaptations. There are resources like Yoga-X online classes, which provide holistic yoga practices at no cost. If you are seeking yoga for a specific health or therapeutic purpose, then community classes may have limitations. You may instead look for therapeutic yoga classes or yoga therapy in conjunction with support and consultation from your healthcare provider.

 

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Dr. Vanika Chawla’s Journey to Enhancing Mental Health with Yoga

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By Maya Shetty, BS

This blog is part of the Stress Management newsletter. If you like this content, sign up here to receive our monthly newsletter!

Vanika Chawla, MD, FRCPC, a psychiatrist, registered yoga teacher, and member of the Stanford Lifestyle Medicine Cognitive Enhancement pillar, has dedicated her career to improving mental health treatment through innovative and holistic approaches. Her distinctive background, combining both yoga and Psychiatry, offers a unique perspective on the potential of accessible stress management interventions.

“I view yoga as a novel lens for approaching mental health – one that can concurrently complement our existing treatment models and empower providers and patients to expand their therapeutic toolbox,” says Dr. Chawla.

Dr. Chawla works alongside Douglas Noordsy, MD, Assistant Director of Stanford Lifestyle Medicine, at Stanford Medicine’s Lifestyle Psychiatry Clinic. Leveraging her unique blend of medical and yoga expertise, she focuses on innovative approaches to psychiatric care that incorporate lifestyle changes and holistic interventions into her patients’ treatment plans. In addition to her clinical work, she is actively engaged in a 300-hour Yoga Teacher Training program offered through Stanford Yoga-X, which focuses on integrating yoga into health care in an evidence-based yet holistic manner.

“I am so happy to be at Stanford because they are thinking outside the box in terms of how we can support people and enhance their mental health,” says Dr. Chawla. “It’s really cool that I found a place to work that allows me to integrate my lifelong interests in yoga and healthcare.”

Dr. Chawla’s research interests are also centered around yoga as an intervention in mental health. “Yoga is definitely a big research area that has made a lot of progress in recent years, however, significant gaps remain in the current literature,” she says. “Future research is needed to deepen our comprehension of the intricate mechanisms of how yoga affects the brain and body.”

In residency, she was involved in research projects focused on using yoga to address anxiety in children. In 2022, she was one of two recipients of the inaugural Stanford Lifestyle Medicine Seed Grants, securing a $10,000 grant to further her research in the field of Lifestyle Medicine. The project, titled ACTIVATE, seeks to create a digital tool that helps individuals with mental health disorders and make positive lifestyle changes to enhance their psychological and physical well-being.

Originally from Peterborough, Canada, Dr. Chawla completed her undergraduate studies in health sciences at McMaster University in Ontario. Here, she began exploring her interests in the mental health field. Her journey took a pivotal turn during a volunteer trip to India that exposed her to yoga as a cultural practice. This encounter sparked her fascination with the practice, leading Dr. Chawla to complete her 200-hour registered yoga teacher training the following year.

“There is so much more to yoga practice than most people realize. There is such a big psychological and social component,” says Dr. Chawla. “It’s not just the postures. There’s breathing, meditation, ethics, values, connection, and community. It’s such a broad, diverse practice and I was really blown away by that.”

She pursued her medical degree at the University of Calgary and her psychiatry residency at the University of Toronto. During her residency training, she observed parallels between psychiatry, psychology, and yoga. “I began to see how yoga could address many unmet needs in our current mental health care models, bridging gaps where medications and psychotherapy may fall short,” says Dr. Chawla. 

These interests led her to Stanford University, where she found many opportunities in the realm of lifestyle medicine and mental health. 

Looking ahead, Dr. Chawla plans to continue exploring innovative ways to improve mental health interventions through research and medical practice, including best practices for incorporating yoga into clinical care. Her vision includes working with marginalized populations, delivering culturally-informed and trauma-informed care, and ensuring that these interventions are accessible to all. To reach these goals, she plans to continue the development of digital applications like ACTIVATE to reach a broader audience.

“Yoga is a comprehensive system that includes a lot of different practices: movement, breathwork, meditation, community, and more,” says Dr. Chawla. “Because of this, it can be tailored and adapted to what people need, to help people of all backgrounds manage their stress through avenues that work best for them.”

 

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Practice of the Month: 100-Breath Mindfulness Practice to Reduce Stress

By Carly Smith, BS, MPH(c)

This blog is part of the Stress Management newsletter. If you like this content, sign up here to receive our monthly newsletter!

This month, Stanford Lifestyle Medicine Assistant Director Douglas Noordsy, MD, recommends a breathwork practice called the 100-Breath Mindfulness Practice. Breathwork refers to the practice of controlling the pace of one’s breathing with the intention of steadying one’s mental, emotional, and physical condition. Mindfulness entails anchoring the mind in the present moment. Therefore, a mindful breathwork practice brings the mind into the present moment by focusing on the breath. 

Dr. Noordsy recognizes that mindfulness meditation might be intimidating for some, so he offers this breathing practice as a quick-and-easy mindfulness exercise that one can do anytime, anywhere. 

“The 100-breath practice is an excellent, portable technique for letting go of overthinking and reducing stress,” says Dr. Noordsy, head of Lifestyle Medicine Cognitive Enhancement and Professor of Psychiatry at the Stanford School of Medicine. 

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100-Breath Mindfulness Practice

1. Get in a comfortable position and start taking long, slow, deep breaths.

  • You can do this sitting cross-legged on the floor or on a meditation cushion, sitting at your desk at the office, or even while taking a walk. If it helps you focus and it’s safe to do so, you can close your eyes during the practice.

2. Breathe in through your nose and out either your nose or mouth, whichever is more comfortable. 

3. Focus all of your attention on your breath and count them from 1 to 100.

  • Inhale, “one.” Exhale, “two.” Inhale, “three.” Exhale, “four”…
  • The counting anchors your attention on your breath and in the present moment. It also curbs distraction and enhances your ability to focus. And since you are counting to 100, you can do the practice anywhere without watching the clock.

4. When you notice a thought enter your mind, bring your focus back to the practice, and count the next breath where you left off. 

  • It’s important not to judge yourself when your mind is racing. Having a busy mind is completely natural. Be gentle with yourself when thoughts arise, simply let the thoughts come and go, and return your focus back to the breath.

5. Continue this process until you reach 100 breaths.

  • The average person takes 100 breaths in about 5 minutes. 
  • If 100 breaths is too much to start with, try 25 or 50 breaths first and gradually work your way up. Remember, this is a practice, so it’s okay to start small.

6. Celebrate your body and mind for taking a moment to slow down and practice. 

How Does Breathwork Affect the Body?

The 100-Breath Mindfulness Practice, like other breathwork exercises, works to calm both the body and mind by bringing the nervous system back into a state of peace. When the body is under stress, either physical or emotional, the sympathetic nervous system takes control, which increases heart rate, hastens respiration, and floods the body with adrenaline to either fight or flee from the source of stress. This is the body’s natural response to danger, which would be helpful if being attacked by a saber-toothed tiger but not so beneficial when feeling stressed about cooking a big holiday dinner or while parsing through work emails. 

Instead, breathing exercises like the 100-Breath Mindfulness Practice, box breathing, or cyclic sighing can help shift our nervous system from the sympathetic (stressful) to the parasympathetic (peaceful) nervous system. Different organs, like the heart, lungs, and brain, constantly send each other “biofeedback” or signals that keep them operating in harmony. By slowing down breathing and directing one’s attention inwards, the diaphragm stimulates the vagus nerve, which then tells the rest of the body to relax. The breathing exercise helps to slow our heart rate down to match our relaxed breathing, leading to cardiac coherence and a tranquil state for the body and mind.

 

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Remembering Dr. Walter Bortz, the Grandfather of Lifestyle Medicine

By Maya Shetty, BS

“Living longer is active, not passive. You create your own destiny.”

These are the wise words of Dr. Walter Bortz II, the former Stanford professor and physician whose pioneering work laid the foundation upon which our Lifestyle Medicine Program now stands. After 93 years, filled with groundbreaking research, influential books, and inspiring athletic achievements, Dr. Bortz peacefully passed away on August 5th.

 “Dr. Bortz is considered the grandfather of lifestyle medicine and was a great mentor for me,” says Michael Fredericson, MD, Director of Stanford Lifestyle Medicine. “He was way before his time and was promoting lifestyle medicine principles to his patients and the greater community before anyone else.”

As one of America’s most distinguished scientific experts on aging and longevity, Dr. Bortz devoted his life to reshaping our perspective on aging and health. He boldly challenged the conventional belief that growing older inevitably leads to frailty and decline, asserting that aging should be regarded as a treatable condition largely caused by disuse. By understanding aging in this way, he advocates for a more proactive approach to maintaining lifelong health and vitality through regular exercise. Practicing what he preached, Dr. Bortz was an avid runner who completed 45 marathons across the world, including the 2013 Boston Marathon at the age of 83. 

His work continues to inspire countless individuals to take charge of their well-being and recognize that they have the power to shape both the quality and duration of their lives. Dr. Bortz wrote several books on this topic, including We Live Too Short and Die Too Long, Dare to be 100, The Roadmap to 100, Living Longer for Dummies, Next Medicine, and Occupy Medicine.

“He was my best friend, best man and best expert on how quality of life trumps quantity of life, and health span is far more important than life span,” said attorney Jack Russo, who was Dr. Bortz’s next-door neighbor, running buddy, and co-advisor to the Stanford Lifestyle Medicine program. “If his philosophy is adopted worldwide, the medical profession will be transformed, as will all of us.”

Click to read more about the life chronology of Dr. Walter Bortz II

 

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What Should Athletes Eat to Fuel Peak Performance?

Athletes, driven by the pursuit of peak performance, have been in the spotlight for numerous studies exploring how various dietary patterns optimize performance. Due to the breadth of research and recommendations available, athletes are at a crossroads when determining the best way to fuel their goals. For this reason, our Stanford Lifestyle Medicine team members (Matt Kaufman, MD, Maya Shetty, BS, Michael Fredericson, MD, and Marily Oppezzo, PhD) reviewed the research regarding how popular diets impact athletic performance and well-being. They summarized their findings in a comprehensive research article titled Popular Dietary Trends’ Impact on Athletic Performance: A Critical Analysis Review, which was recently published in the journal Nutrients. Their research focused on six dietary patterns: Mediterranean diet, ketogenic diet, low-carbohydrate diet, plant-based diet, intermittent fasting, and disordered eating. Whether you are an elite athlete or an enthusiastic beginner, keep reading to learn more.

Mediterranean Diet

The Mediterranean diet, rich in whole grains, unsaturated fats, lean proteins, fruits, and vegetables, is consistently associated with improved health and performance for athletes. Research on athletes finds this diet is linked to improved muscle power and endurance, as well as body composition. The low inflammatory index of this diet is also associated with enhanced recovery time.

Ketogenic Diet

The ketogenic diet restricts the consumption of carbohydrates and protein to boost the use of fat as an energy source, thus improving weight loss and potentially athletic performance. While this may help athletes, such as wrestlers, who need to stay within specific weight requirements, the prolonged carbohydrate restriction can negatively affect training performance. Research has shown this restriction can increase baseline heart rates, perceived exertion, and rate of bone loss, harming short and long-term performance. However, research has not found significant decrements in performance for athletes following this diet.

Low-Carbohydrate Diet

People often think that Ketogenic and Low-Carbohydrate diets are the same. A low-carbohydrate diet is less restrictive and does not restrict protein intake in the same way that Ketogenic diets would. Research has found that athletes on this diet have no differences in muscle strength and power compared to athletes following a regular diet. However, notable improvements in sprint times and exhaustion perceptions have been observed. As carbohydrates are restricted, the same detriments on performance found in ketogenic diet research may occur. Studies examining low-carbohydrate diets use extremely variable interventions that are difficult to compare. Thus, more research is needed to determine its specific impact on performance.

Plant-Based Diet

Plant-based diets are also adopted by many athletes due to ethical or health-conscious reasons. This choice is supported by the literature, which suggests that vegetarian and vegan athletes perform just as well in terms of endurance and strength as their omnivorous counterparts. Following a plant-based diet can have numerous health benefits. Plant-based protein sources, such as tofu, lentils, and beans, have been found to improve circulation, reduce inflammation, lower oxidative stress, promote a healthy gut microbiome, enhance glycogen stores, and support leaner body weights.

However, due to the restrictions of these dietary patterns, following them without proper planning may lead to nutritional deficiencies, such as protein, vitamins B12 and D, iron, zinc, calcium, total calories, and iodine. These deficiencies may affect performance, recovery, and bone health. Despite the risk of these deficiencies, staying attentive to one’s nutritional needs and working with a sports dietician can help you to either take the right supplements or plan a plant-based diet that meets all your needs.

Dr. Matthew Kaufman, the lead author of the review paper, states, “Because plant-based diets are high in carbohydrates, low in fat, and rich in vitamins, minerals, and antioxidants, they can provide important nutrients an athlete needs for performance. In order to maximize a plant-based diet for training and competition, athletes may want to consult with a sports dietitian to ensure adequate nutrient intake and to get well-balanced examples of nutritionally fulfilling meals.”

Intermittent Fasting

Intermittent fasting, with its varying protocols, involves limiting the time window for eating during the day. This dietary pattern might not be suitable for athletes given their training schedules or the nutrition to fuel performance. As a result, the potential risks may outweigh the benefits. Limited eating windows may be helpful for weight loss or maintaining a strict weight class, but it can also lead to low energy availability and actually harm performance and overall health. Research studies have found that intermittent fasting impaired athletes’ sprint speed and endurance.

Disordered Eating

The pressure to maintain a low body weight for athletics can lead to restrictive diets or even clinical eating disorders, affecting both physical and mental health. These include anorexia nervosa, bulimia nervosa, binge eating disorder, and orthorexia. Athletes, especially those in aesthetics-focused sports such as gymnastics, dance, and ice skating, have the highest rates of disordered eating and eating disorders. These eating patterns can weaken muscles, cause fatigue, and lead to injuries and complications like anemia and osteoporosis. Restrictive diets like ketogenic, plant-based, or intermittent fasting might appeal to athletes with disordered eating tendencies. Thus, athletes should carefully assess their motivations for diet changes and consult professionals to ensure their nutritional needs are met.

 

To summarize, the researchers found that the Mediterranean diet has the most benefits for athletes regarding recovery and performance. Low-carbohydrate and ketogenic diets show no harm to athletic performance; however, the non-ketogenic low-carbohydrate diets that emphasize protein intake might be more sustainable for the energy demands of athletics. Vegans and vegetarians are at high risk for nutrient deficiencies, especially in nutrients essential for athletic recovery and muscle maintenance. Intermittent fasting may aid weight loss but could hamper athletic performance in endurance and aerobic sports.  For any dietary intervention, the reasoning for the change should be closely monitored by the athlete and their healthcare team to ensure disordered eating is not a risk. Restricting the type and amount of food an athlete consumes can severely impact performance and overall well-being.

Dr. Matthew Kaufman, the lead author of this review article, emphasizes, “Nutrition and athletic performance are inextricably linked. The Mediterranean diet is abundant in foods that support the high energy demands of athletes and promote recovery. However, no one diet is universally recommended for athletes, and any dietary changes should be done in collaboration with healthcare professionals to ensure maintenance of overall health.”

 

By Maya Shetty, BS

Source:

  1. Kaufman M, Nguyen C, Shetty M, Oppezzo M, Barrack M, Fredericson M. Popular Dietary Trends’ Impact on Athletic Performance: A Critical Analysis Review. Nutrients. 2023 Aug 9;15(16):3511. doi: 10.3390/nu15163511. PMID: 37630702; PMCID: PMC10460072.
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The Benefits of HIIT and Other Forms of Interval Training

By Maya Shetty, BS

In an era where time is a precious commodity, individuals are constantly seeking efficient ways to achieve their fitness goals. Amidst this quest, high-intensity interval training (HIIT), which is a type of interval training (IT), has gained popularity among fitness enthusiasts due to its ability to yield significant health benefits in a short amount of time.

“I recommend interval training for people who are busy but still want to get fit, because it gets great results in a fraction of the amount of time compared to more traditional cardio workouts. Interval training can be a powerful tool in a well-rounded fitness plan,” says Anne Friedlander, PhD, exercise physiologist and assistant director of Stanford Lifestyle Medicine.

What is Interval Training?

Interval training (IT) was originally defined in 1973 as “intermittent periods of intense exercise separated by periods of recovery.” HIIT stands for high-intensity interval training, which has become the most popular form of IT in recent years. This back-and-forth between physical effort and rest is effective because it challenges the body without causing total exhaustion. IT can encompass various exercise modalities, including cardio, explosive movements with weights, and bodyweight exercises, as long as the period of intense exercise strenuously stimulates the body.

Despite IT’s recent surge in popularity in the US, European runners in the 1950s commonly used this training method, including long-distance runner Emil Zatopekl from the Czech Republic. Zatopekl’s success in the 1952 Olympics is believed to have ignited the widespread adoption of IT across various sports disciplines.

In 2006, a study conducted by Canadian researcher Martin Gibala sparked enthusiasm for IT to improve fitness, not only among athletes, but for the general population as well. The Gibala paper found that even though study participants trained eight hours less over a two-week period, their IT protocol (four to six, 30-second cycling intervals at supramaximal effort with a four-minute recovery) yielded similar fitness and muscle improvements compared to their moderate intensity continuous training (MICT) protocol (90 to 120 minutes of continuous cycling). Adaptations included better time-trial performance (time to complete a set amount of work on a bike), increased oxidative capacity (ability of muscles to use oxygen), buffering capacity (ability to handle acidity during exercise), and glycogen content (more energy stores in the muscles).

Since this pivotal 2006 study, researchers have studied IT protocols extensively and found, when compared to MICT, participants can elicit the same or greater benefits in mitochondrial density, aerobic capacity, metabolic health, insulin sensitivity, body composition, heart disease progression, and markers of genetic age.

In the last two decades, IT has evolved into various types, such as HIIT and sprint interval training (SIT), which have differences in physiological and psychological responses depending on the duration and intensity of the exercise protocol. Many use the classifications outlined in a 2014 review paper, which defines HIIT as a training protocol that requires “near maximal” effort, eliciting 80 to 100 percent of maximal heart rate (HRmax) or aerobic capacity (VO2max). (A very rough estimate of your max heart rate can be obtained using the formula: 220 – your age.) SIT, on the other hand, is classified as a training protocol that requires “supramaximal” or all-out effort, using at least 100 percent of one’s maximal aerobic capacity.

“No matter what your starting fitness level, adding intensity to your workouts can help you achieve your health and fitness goals,” says Dr. Friedlander, adjunct professor in the Stanford Program in Human Biology. “There are many different protocols out there, but the key element is pushing yourself hard for short bursts of time separated by recovery periods. Those bursts of hard work will jump start beneficial adaptations in your physiology and metabolism.”

What are the Benefits of Interval Training?

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Muscle Health

The 2006 Gibala paper was the first to reveal how SIT has nearly the same effects on skeletal muscle adaptations as MICT despite significantly less training time and workload. Additional research has shown that a single session of HIIT or SIT increases mitochondrial biogenesis (the process through which muscle cells increase the number and functional capacity of mitochondria), and repeated sessions lead to overall increases in mitochondrial density. Mitochondrial biogenesis plays a crucial role in energy production, metabolic regulation, and overall cellular health. It is important to have healthy and functioning mitochondria to maintain muscle health and decrease the risk of sarcopenia (age-related muscle loss).

Research suggests, in the short-term, that the intensity and interval nature of HIIT and SIT increases mitochondrial biogenesis more than MICT, even when performed for less time and at an equal or less total amount of work. Therefore, incorporating interval training into your lifelong exercise routine (such as adding short bouts of running to your daily walks) will help improve your short-term, and possibly long-term, muscle function.

Body Composition

A meta-analysis that included individuals of all ages and health statuses found SIT protocols were more time efficient than MICT and HIIT in decreasing body fat.

Another meta-analysis, looking at studies including only overweight individuals, found HIIT protocols were more time efficient than MICT in reducing whole-body fat mass and waist circumference. Here, the researchers found that running protocols were more effective than cycling protocols for decreasing body fat, potentially because running uses more muscles throughout the body, which leads to greater energy expenditure.

Cardiovascular Health

A wealth of research since 2006 has consistently demonstrated that IT provides superior improvements in markers of cardiovascular health, cardiometabolic health, and mitigates the risk of heart disease progression more efficiently compared to MICT.

Cardiorespiratory health: VO2max (the body’s maximum rate of oxygen consumption) is a common indicator of cardiorespiratory health. Individuals with a higher VO2max tend to have better overall physical fitness, improved lung function, stronger heart muscles, and enhanced oxygen delivery to the body’s tissues.

A meta-analysis determined that both HIIT and SIT protocols are more efficient than MICT regarding the improvement of VO2max (cardiorespiratory fitness). One study found that SIT increased VO2max to the same extent as MICT, but in one-fifth of the time.

The duration of intervals may also have an impact on VO2max. A comprehensive meta-analysis revealed that IT protocols with longer intervals of intensity (three-to-five minutes) yielded greater improvements in VO2max compared to shorter interval protocols performed for the same total amount of time.

Cardiometabolic health: Interval training is also a powerful tool for improving markers of cardiometabolic health, such as insulin sensitivity and insulin resistance.

A meta-analysis found a variety of IT protocols were superior to MICT in improving insulin resistance, lowering blood glucose levels, and decreasing body weight. The analysis examined various IT protocols, including HIIT and SIT, with a range of two-to-sixty intervals, durations from four seconds to five minutes, and both maximal and supramaximal intensities. Some studies were conducted in lab settings with stationary bikes or treadmills, while others were outdoors on tracks or trails.

“Although research has confirmed that IT is a more time-efficient method than MICT for improved muscle, cardiorespiratory, and cardiometabolic health in the short-term, more research is needed to confirm that those superior benefits continue in the long-term,” says Dr. Friedlander. “As with many aspects of life, balance is key.  Therefore, integrating IT into a well-rounded fitness plan is probably healthier and more advantageous in the long-term than doing IT as your only training method.”

Brain Health

Research suggests that regular physical activity can mitigate age-related volume loss in brain regions associated with memory by improving blood flow to the brain and increasing the maintenance and production of neurons.

One study suggests that intense exercise, like HIIT and SIT, can enhance memory in older adults more effectively than MICT protocols. Participants in this study underwent a HIIT protocol, which included four-minute intervals of running on a five percent incline, interspersed with three-minute recovery periods of walking. They performed this protocol three times per week for a total of 12 weeks, resulting in improved memory performance significantly more than MICT or stretching protocols.

Another study found that young adults had more memory improvements following HIIT sessions (two-minute intense intervals interspersed with two-minute recovery periods) than MICT training sessions. The underlying mechanisms behind these improvements in memory are unknown, but the study did find a correlation between memory improvements and the release of blood lactate following exercise.

During exercise, the chemical lactate travels via the bloodstream to the brain and it is hypothesized that lactate promotes the creation of new cells and blood vessels, thus improving brain function. Higher exercise intensity leads to higher lactate production, resulting in increased levels of lactate in the bloodstream.

It has also been hypothesized that exercise induces the release of brain derived neurotrophic factor (BDNF), a protein that plays an essential role in the health and function of our brain cells. BDNF can be thought of as a “brain fertilizer” that helps neurons grow, survive, and communicate with each other.

Research studies have determined the majority of BDNF is produced in the brain, but other parts of the body, such as skeletal muscle and blood vessels, can also produce BDNF when stimulated by exercise. The previous studies in older and younger adults found that both HIIT and MICT protocols increased BDNF in the bloodstream immediately following exercise.

“Whether your goals relate to health, performance, or body composition changes, research has shown time and time again that IT protocols provide a time efficient way to target those goals,” says Dr. Friedlander. “However, you shouldn’t do IT every day as the intense nature of the activity requires sufficient recovery time, so as not to wear yourself down.”

Types of Interval Training Workouts

Since it is not recommended to do IT every day, one can integrate one of the following IT workouts a couple of times into their weekly exercise regimen.

Here are a few IT training methods that can be modified to any fitness level:

Martin Gibala General Recommendations: Gibala, one of the most notable IT researchers, recommends three sessions of HIIT or SIT exercise per week. Intervals should be between one and four minutes and the entire workout, including rest, should be between 20 to 30 minutes.

Fartlek: Fartlek is a running training method that involves alternating between faster-paced running and slower recovery periods, which can be at an easy or moderate pace. Fartlek training is flexible and can be adjusted based on the terrain, fitness level, and desired outcomes.

Tabata: Tabata involves 20 seconds of all-out intense exercise followed by 10 seconds of rest, repeated for a total of eight rounds (four minutes total). Tabata workouts can be customized for various training modalities that include stationary bikes, sprints, or body weight exercises.

4×4 Interval Training: In 4×4 IT, one performs four sets of intense intervals, with each set consisting of a four-minute, high-intensity exercise followed by a three-minute recovery period. This protocol should last a total of 28 minutes with each set lasting seven minutes (four minutes of activity and three minutes of recovery).

10-20-30: 10-20-30 training involves intervals of an aerobic exercise that alternates interval times. The workout consists of repeating cycles of 30 seconds of low-intensity exercise, followed by 20 seconds of moderate-intensity exercise, and finally, 10 seconds of high-intensity exercise. This pattern is repeated for several intervals, typically for a total of four to five minutes. 

“Whatever your fitness level, incorporating safe and balanced interval training into your exercise routine can improve several aspects of your health and fitness.  This is even true as we get older,” says Dr. Friedlander. “As we age, we tend to stay in our comfort zones, but sometimes it is good to push ourselves to keep our maximum capacity higher. This allows all of our other activities of daily life to feel easier. It can help us live life to the fullest into our later years.”

 

“If you’re new to interval training, start by adding a few bursts of running or hill climbing into your daily walk or find the stairs in your building at work and do three rounds of vigorously climbing while slowing descending them,” says Dr. Friedlander. “Regardless of your age or fitness level, we encourage you to embrace the challenge of IT and experience its whole-body health benefits!”

 

By Maya Shetty, BS

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Enhancing Health and Speed in Female Distance Runners Through Improved Diet

A groundbreaking nutrition study for female collegiate runners was recently published by Professor  Michael Fredericson, MD, Stanford Lifestyle Medicine (SLM) Director, and Megan Roche, MD, member of the SLM Movement & Exercise pillar. The study’s goals were to improve the health of these runners through a diet intervention, decrease the incidence of bone stress injuries (aka stress fractures), and ultimately improve their performance.

“A runner’s diet is extremely important for maintaining overall health,” says Dr. Fredericson, who has served as the Stanford University track team head physician for decades. “Runners who are excessively lean are prone to injuries, infectious diseases, mental health problems, and loss in bone density.”

The study followed 78 female long-distance runners at both Stanford and UCLA. Over a four year period, the athletes were educated on caloric and balanced nutrient intake, with regular presentations by dieticians and individualized consultations. Athletes with nutrition deficiencies, irregular menstruation, or injuries had more frequent meetings with dieticians. Throughout the study, incidence of bone stress injuries were tracked in the participating athletes.

The nutrition counseling resulted in a remarkable 50 percent reduction in bone stress injuries and doubled the occurrence of regular menstruation among athletes, indicating improved overall health. Even though bone stress injuries affect runners of both genders, there is a higher prevalence among females, which is why the study focused specifically on female distance runners. While the reasons for these findings remain unclear, factors such as male bone density and potential protective effects of testosterone might contribute to the observed gender discrepancy.

In addition to these improvements in health, the nutrition counseling intervention also enhanced athletic performance. Athletes who regained their menstrual cycles and achieved higher bone density also demonstrated enhanced athletic capabilities.

“Your strongest self is your fastest self,” says the second researcher of the study, Dr. Roche, who is an ultrarunner and running coach. “The idea that a leaner body makes for a faster stride is common among distance runners. But it’s inaccurate and sets a dangerous ideal.”

Crucial to the success of the study was shifting the team’s mindset on nutrition and weight. At Stanford University, the coaches and dieticians for the  women’s track and cross-country teams, who were actively involved in the study, played a significant role in fostering a positive perspective on nutrition among the athletes.

Dr. Fredericson and Dr. Roche hope that athletes from every sport, age, and gender can learn from this study. Here is their advice for all athletes:

  1. Eat enough to maintain a healthy weight, which varies from athlete to athlete.
  2. Replenish within 30 minutes after a workout, ideally with carbohydrates and protein.
  3. Consume four to five frequent smaller meals throughout day, rather than three larger meals.
  4. Don’t shy away from healthy, plant-derived fats, like nuts and avocados.
  5. Remember to get enough calcium and Vitamin D for bone strength.

 

By Maya Shetty, BS

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