Remembering Dr. Walter Bortz, the Grandfather of Lifestyle Medicine

“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 Program now stands. After 93 years of 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.”

By Maya Shetty, BS

The Benefits of HIIT and Other Forms of Interval Training

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?


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

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

Practice of the Month: HIIT Workouts for All Levels

High-Intensity Interval Training (HIIT) is an intense workout that effectively boosts aerobic capacity and overall health in a shorter amount of time than traditional workouts. 

Former pro-athlete, celebrity trainer, and founder of Platinum Fitness, Peter Park, recommends HIIT workouts for his clients at every fitness level. He suggests one-to-two HIIT workouts per week, in addition to three-to-four days of low-intensity cardio exercise, such as walking or biking for 20 minutes to an hour. 

“Cardio workouts build endurance while HIIT builds muscle strength and higher-end aerobic capacity,” says Park, author of Foundation Training: Redefine Your Core, Conquer Back Pain, Move With Confidence and Rebound: Regain Strength, Move Effortlessly, Live Without Limits.

HIIT Routine

Park has 23 years of experience training elite athletes and has designed the following HIIT routine:

Warm up: Perform five reps of the exercises in the graphic at a slow and controlled pace, modifying as needed, and repeat.

Main set: Perform eight reps of the exercises at a faster pace with minimal rest between each exercise, then take a 45-second rest. Repeat with nine reps, then 10 reps for a total of three cycles.

Exercise Details:

  1. Body weight squats: Perform squats to parallel while extending your arms fully as you descend. Ensure you engage your core and maintain proper posture throughout the movement. Aim for a complete range of motion, focusing on squeezing your quads, core, and glutes at the top of each repetition. Maintain a steady tempo while staying in control.
    • Modification: Sit in a chair and stand back up.
  2. Push-ups: Keep your core engaged and maintain proper posture while performing push-ups. Maintain a controlled tempo and form.
    • Modification: Perform the push-ups on your knees, or against a wall or table.
  3. Jumping jacks: Stay smooth and controlled throughout the movement.
    • Modification: Stand with your feet hip-width apart and perform the jumping jack movement with your arms only.
  4. Stand-ups (aka Burpees): Begin by lying on your stomach on the floor with your hands at chest level. Jump your feet forward, contracting your abdominals, and stand up quickly. Return to the lying position and repeat the process.
    • Modification: Press hands into floor and step back into a high plank position, then step forward and return to a standing position.

Tips for HIIT at Every Fitness Level

Beginner: For individuals just starting out, focus on incorporating intense periods of exercise lasting at least one minute into one’s regular training routine. For example, one could speed up sections of a morning walk or finish a workout with a burst of all-out effort. Don’t worry if you become breathless and have trouble speaking – this is how you’re building your aerobic capacity!

Intermediate: Individuals who already participate in regular exercise but are relatively new to HIIT should focus on incorporating two-to-three HIIT workouts per week into their regular exercise regime. Any exercise modality can be turned into an IT protocol as long as one can push themselves into near maximal or maximal exertion. To optimize benefits, research suggests higher intensities and longer intervals are best. 

Advanced: In well-trained individuals, intense exercise is necessary to generate additional improvements in exercise performance and overall health. To achieve these benefits, extremely high-intensity sprint interval training (SIT) or long-interval HIIT at least three times per week may be necessary. 

Important Considerations

Prepare your body before engaging in HIIT: The intense nature of HIIT can be problematic for individuals with weaker musculoskeletal systems or chronic health issues. Additionally, healthy individuals unfamiliar with this workout type also risk injury. So, remember to build up your capacity for this workout by gradually incorporating periods of higher intensity into your regular exercise routine.

“Pushing your body to its physiological limits without proper training can lead to injuries, compromising your overall health and performance,” says Park. 

Don’t perform interval training every day: While it may be enticing to engage in HIIT daily due to its wide-ranging benefits, this workout can strain the body and hinder physical adaptations when performed too frequently. Instead, opt for one-to-two HIIT sessions per week and mix them with low-intensity activities such as walking or yoga for active recovery. 

Have fun: While incorporating HIIT into your exercise regimen, remember to prioritize your safety and comfort, but also do your best to make it enjoyable so that you stick with it. “HIIT workouts are much more fun with a training partner, says Park. “So, grab your spouse, friend, or co-worker and help each other get out of your comfort zone!”


By Peter Park, CSCS, BS & Maya Shetty, BS

5 Tips for a Successful Pickleball Experience

In the summer of 2023, pickleball was a popular sport for people of all ages. Pickleball is a paddle sport that combines elements of tennis, badminton, and ping-pong. Personally, I am a big pickleball enthusiast because it offers a perfect blend of competitiveness, social interaction, and physical activity. If you’re new to pickleball and want to join in the fun, here are a few valuable lessons that I wish I had known before first stepping onto the court:

Warm-Up: As a former collegiate athlete, you’d think I knew better, but I made the mistake of skipping the warm-up before my first pickleball session, and the consequences were immediate. Just an hour into the game, I pulled my quad and had to sit out the rest of the game. Warming up prepares your body for the physical demands of pickleball and significantly reduces the risk of injuries. Given that pickleball requires flexibility and a wide range of motion for success, a proper warm-up can give you that competitive edge you need on the court. Don’t repeat my mistake – prioritize warming up before your next pickleball game!

Hydration: Staying properly hydrated before playing pickleball is crucial. I’ve experienced firsthand how one hour on the pickleball court can quickly turn into four. So make sure to bring plenty of water and take water breaks between each match.

Footwork Matters: I initially underestimated the importance of footwork in pickleball. However, I soon discovered that the same quick positioning and agile footwork I honed on the tennis court were equally crucial in pickleball. Remember to wear shoes with good traction, support, and fit so you can move quickly without turning an ankle.

Communication is Key: Pickleball is often played in doubles, which requires excellent communication with your partner. If you have played pickleball, you know the irritation when the ball is hit right down the center and no one goes for it. Coordinate your moves, call out shots, and support each other on the court. Good teamwork can give you a significant advantage over your opponents.

Stay Patient: In the thrilling game of pickleball, it’s all too easy to get swept up in the excitement and rush your shots. But, I’ve learned that patience is a virtue during those long and intense rallies because (add the reason why). With experience, I’ve come to realize  that I can outplay most opponents through patience and consistency rather than power.


By Maya Shetty, BS

Is Running Bad for Your Knees? Research Says, “No”

Many people believe running is bad for your knees, but this commonly-held belief is not backed by solid evidence. Let’s take a closer look at the research and unravel the truth behind this myth.

A recent study explored the public’s perception of running and knee joint health–the findings were surprising. Around 29 percent of the general public believed that frequent running is harmful to the knees, and a significant 54 percent thought the same about running long distances. 

Interestingly, a different picture emerged when comparing these perceptions with those of healthcare providers. A greater proportion of healthcare providers actually viewed regular running as beneficial for knee health. 


“Despite the prevailing beliefs, current evidence finds that recreational running is not a risk factor for knee osteoarthritis. In fact, it has been found to be quite the opposite–running can be good for your knees.”  – Corey Rovzar, PhD, DPT, and postdoctoral fellow at the Stanford Prevention Research Center.


Studies have shown that recreational runners have a knee and hip osteoarthritis (OA) prevalence that is three times lower than that of sedentary non-runners. Competitive runners showed an even more impressive four-fold reduction in knee and hip OA prevalence. These results are due to the fact that regular running strengthens the muscles around the knee joint and supports overall joint health. Running also plays a vital role in maintaining healthy cartilage and bone density, which are crucial for knee function.

Considerations for Individuals With Pre-Existing Knee Conditions

If you have a pre-existing knee condition, such as knee OA, running may exacerbate symptoms because the cartilage in the knee has broken down, leaving less cushioning around the joint. Cartilage does not have the ability to regenerate and while running can maintain cartilage health, it can not bring it back once it’s gone. If you struggle with knee OA, opting for lower-impact exercises, such as walking, cycling, or swimming, is advisable. Consulting with a healthcare provider or a physical therapist can help you develop a safe and effective exercise routine that works specifically for you. 

Guidance For Inexperienced Individuals

Michael Fredericson, MD, the Director of the Lifestyle Medicine Program and PM&R Sports Medicine at Stanford, cautions against taking up running after the age of fifty without prior experience. According to Dr. Fredericson, “You need to get fit to run, rather than run to get fit, and this becomes even more important after the age of 50. If you’re just starting out, begin with general conditioning that targets hip and core muscles and slowly build up your running.”

It’s time to put this myth to rest. Running is not bad for your knees; in fact, it can be healthy for them! If you do not suffer from a pre-existing knee condition and are generally fit, let’s embrace the evidence and remember that running, when done responsibly, can contribute to healthier and happier knees. So, lace up those running shoes and hit the pavement with confidence, knowing that you’re taking strides toward a stronger and more resilient you!


By: Corey Rovzar, PhD, DPT, Maya Shetty, BS, & Michael Fredericson, MD


  1. Esculier J-F, Besomi M, Silva D de O, et al. Do the General Public and Health Care Professionals Think That Running Is Bad for the Knees? A Cross-sectional International Multilanguage Online Survey. Orthopaedic Journal of Sports Medicine. 2022.
  2. Alentorn-Geli E, Samuelsson K, Musahl V, Green CL, Bhandari M, Karlsson J. The Association of Recreational and Competitive Running With Hip and Knee Osteoarthritis: A Systematic Review and Meta-analysis. J Orthop Sports Phys Ther. 2017 Jun

Enhancing Memory Through the Power of Aerobic Exercise

It is generally understood that exercise is good for our physical bodies, but did you know that exercise can also improve cognitive performance? One such benefit of aerobic exercise specifically is its ability to enhance our memory. There have been a multitude of studies designed to investigate the nuances of this exact phenomenon, including a recent systematic review and meta-analysis.

Aerobic Exercise Improved Performance on Memory Tests

The analysis reviewed nine different studies with patients aged 50 years old and older. Six of the studies used exercise regimens that follow the U.S. Department of Health & Human Services recommendations for aerobic physical activity. These guidelines suggest that all adults should engage in at least 150 minutes of moderate aerobic exercise (like brisk walking or cycling) or 75 minutes of vigorous aerobic exercise (like jogging or dancing) on a weekly basis. In the studies, the type of exercises varied from brisk walking to swimming, but all that met the U.S. guidelines reported “significant and large” effects. It is important to note that the duration of the studies ranged from three months to one year, each with its own unique breakdown of how to meet these total weekly minutes. 

In order to study the link between exercise and memory, there are several  memory tests that scientists can use to test the different aspects of our memory. While most of the included studies chose to observe changes in working and logical memory (important for reasoning and decision-making), some used tests to observe the changes in spatial and episodic memory (remembering information like names, places, and colors). The results of the overall meta-analysis concluded that there was a strong relationship between undergoing aerobic exercise and improvements in memory. 

What is BDNF?

Dr. Doug Noordsy, Head of Cognitive Enhancement at Stanford Lifestyle Medicine, hypothesizes that aerobic exercise improves memory by releasing Brain-Derived Neurotrophic Factor (BDNF), which was discussed in the analysis. BDNF is a protein that is released due to the widening of the blood vessels (systemic vasodilation) that occurs during physical activity. Once this protein reaches our brain through the bloodstream, it aids the longevity and growth of healthy neurons, which are vital for learning and memory processes. Also, exercise turns on specific genes that activate neurotrophic factors like BDNF, allowing us to create additional BDNF as we exercise throughout life. 

So, next time you catch yourself recalling an old story or trying to match a name to a face, remember to move your body and get your heart rate up!


By: Carly Smith, BS, MPH(c)


  1. Hoffmann et al. Aerobic Physical Activity to Improve Memory and Executive Function in Sedentary Adults without Cognitive Impairment: A Systematic Review and Meta-analysis“. Journal of Preventative Medicine Reports. Sep. 2021.

Exercise is Medicine: The Benefits of Exerkines

The health benefits of regular exercise have long been established, extending across multiple organ systems and contributing to longevity, resilience, and an enhanced health span.

In 2000, researchers discovered that muscle contraction can lead to the release of a molecule known as Interleukin-6 (IL-6). With the discovery shedding light on a previously unexplored arena of exercise science, researchers began to explore the concept of ‘exerkines’.

What Are Exerkines?

Exerkines are hormones, metabolites, proteins, and nucleic acids that are are secreted in response to acute and chronic exercise. While acute exercise is usually a single episode of either aerobic or resistance exercise, chronic exercise is described as multiple exercise episodes that are performed over the course of weeks to months.

Through endocrine, paracrine and/or autocrine pathways, exerkines may be responsible for many of the established benefits of exercise, such as preventing and mitigating disease. Moreover, these signaling molecules may be capable of promoting healthy aging and increasing resilience, which is the ability of the body to resist, adapt to, recover or grow in response to stressors.

How Do Exerkines Affect Our Organ Systems?

While the initial focus of exerkine research was primarily on skeletal muscles, recent exploration of these molecules has demonstrated that they are released by and influence multiple tissues and organs within the body. A few illustrations of their their wide-ranging and systemic effects include:

  • In the cardiovascular system, exerkines lead to cardioprotection by enhancing vascularization and angiogenesis, and improving blood pressure, endothelial function, and overall fitness.

  • In adipose tissue, exerkines increase fatty acid uptake, the breakdown of fats and other lipids, energy expenditure, and glucose metabolism.

  • In the liver, exerkines also increase fatty acid uptake and glucose metabolism.

  • In skeletal muscle, exerkines enhance mitochondrial biogenesis, protein synthesis, stem cells, and capillarization to stimulate muscle regeneration.

In the quest to demystify the health benefits of exercise, our understanding of exerkines is emerging as a hopeful frontier. Alongside the potential to improve cardiovascular, metabolic, immune, and neurological health, new targets for treating cardiovascular disease, type 2 diabetes, and obesity may be found through exerkine research.

With every step, jump, and lift, we are not just strengthening muscles and burning calories – we are releasing a team of powerful signaling molecules that are a testament to the enduring truth: exercise is medicine.


By: Helena Zhang, BS & Jonathan Bonnet, MD


  1. Chow, L.S., Gerszten, R.E., Taylor, J.M. et al. Exerkines in health, resilience and diseaseNat Rev Endocrinol 18, 273–289 (2022).
Aerobic & Resistance

Aerobic & Resistance Exercise Improves Sleep

Sleep, a fundamental element of human biology, plays a crucial role in various physiological processes. A good night’s sleep is essential for immune function, cognitive performance, emotional well-being, and overall physical health. Exercise is another critical lifestyle factor with tremendous potential to improve your health. Regular physical activity has numerous benefits, from reducing the risk of chronic diseases to improving mental health. However, could exercise improve your sleep?

Impact of Resistance Exercise on Sleep

A 2017 review found that “chronic resistance exercise improves all aspects of sleep, with the greatest benefit for sleep quality” in individuals with sleep problems. In this study, Kovacevic et al. employed a systematic review methodology by conducting an electronic database search of randomized controlled trials. Many studies fit the criteria, but three acute resistance exercise studies, seven chronic resistance exercise studies, and three combined aerobic and resistance exercise studies met the researcher’s inclusion criteria and were analyzed for sleep outcomes. The primary finding from this review was improvements in sleep from chronic exercise; these improvements were “moderate-to-large, and commonly affected overall sleep quality, sleep latency, sleep efficiency, mid-sleep disturbance, and daytime dysfunction”. In comparison, the primary medications prescribed to improve sleep quality had “only small-to-moderate effects on sleep quality” and instead have “adverse effects such as rebound insomnia, depression and anxiety, cognitive impairment, and an increased risk of falls, cancer, and overall mortality” if used in the long-term. Kovacevic et al. call for further research and more data on aerobic exercise but cites an earlier paper that noted how aerobic exercise could improve sleep quality.

Furthermore, their work highlighted how “higher intensity and greater frequency of training offer greater sleep benefits”. More specifically, the chronic resistance exercises studied that had the most benefits included machine-based resistance exercise, circuit training, and resistance bands for an average duration of 14 weeks total with approximately 60 minutes per session. Studies with high exercise intensity as compared to low-to-moderate intensity, and with a frequency of 3 days/week as compared to 1-2 days/week, had a larger beneficial effect on sleep quality.

The review presented another pathway by which exercise could improve sleep; exercise improves levels of anxiety and depression, both of which deeply affect sleep — “notably, exercise has been shown to be an effective treatment for major depression and sleep disturbance is one of the core symptoms of depressive illness” and “the majority of chronic studies included in this review reported significant improvements in neuropsychological outcomes”.

Impact of Aerobic Exercise on Sleep

Additional research has also shown the further benefits of aerobic exercise for people with established sleep disorders. One study showcased how “4 months of aerobic exercise training in a sample of older adults with insomnia significantly improved sleep quality while also reducing daytime sleepiness and depressive symptoms”. Another study found that “12 weeks of moderate-intensity aerobic and resistance exercise resulted in a 25% reduction in OSA [obstructive sleep apnea] severity”. Lastly, studies have even shown that the circadian rhythms disrupted in neurodegenerative disease can be improved with exercise — “exercise has proven to be a low risk and beneficial intervention to improve overall health and sleep disorders in AD [Alzheimer’s disease] and PD [Parkinson’s Disease]”. In particular, “physical activity, even at low intensities, has been reported to improve sleep quality, reduce time to fall asleep, and increase the duration of sleep in the elderly… evidence indicates that exercise increases total sleep time and slow-wave sleep”.

We all strive for better sleep even if we do not have a known sleep disorder, and it could be within our grasp through a novel route. Exercising for an hour three times a week at high intensity with machine-based resistance exercise, circuit training, or resistance bands can improve your sleep quality and decrease issues in the day. Even once a week at a lesser intensity for 40 minutes showed beneficial effects! Sleep and exercise are significant pillars in lifestyle medicine, and it is fascinating how one affects the other. Rather than relying on medications that can have adverse effects, research suggest exercise is a natural way we can improve our sleep. While further research is needed, recognizing the interconnectedness of exercise and sleep as critical components of a healthy lifestyle is crucial.

By: Keshav Saigal, BS(c)


  1. Kline, Christopher E. The bidirectional relationship between exercise and sleep: Implications for exercise adherence and sleep improvement.” American Journal of Lifestyle Medicine. 2014 August
  2. Kline, Christopher E et al. “The effect of exercise training on obstructive sleep apnea and sleep quality: a randomized controlled trial.” Sleep. 2011 December
  3. Kovacevic, Ana et al. “The effect of resistance exercise on sleep: A systematic review of randomized controlled trials.” Sleep Medicine Reviews. 2018 June
  4. Memon, Adeel A et al. “Effects of exercise on sleep in neurodegenerative disease.” Neurobiology of Disease. 2020 July
  5. Reid, Kathryn J et al. “Aerobic exercise improves self-reported sleep and quality of life in older adults with insomnia.” Sleep Medicine. 2010 October
  6. Yang, Pei-Yu et al. “Exercise training improves sleep quality in middle-aged and older adults with sleep problems: a systematic review.” Journal of physiotherapy. 2012 September