A recent study found that standing on one leg for 10 seconds was independently associated with survival and that those unable to perform this test had double the usual risk of premature death. This relationship is an association and not causal – meaning, the test cannot predict when someone will die. It does, however, highlight the importance of monitoring and maintaining balance as we age. Good balance later in life can lower fall risk and help maintain independence, mobility, functional abilities, and overall quality of life.

According to Corey Rovzar, an expert in balance a postdoctoral fellow at the Stanford Prevention Research Center in the School of Medicine, balance is often overlooked in most people’s exercise regimes and is not regularly included in routine health checks for middle-aged and older adults. This study highlights the importance of monitoring and maintaining balance as you age since balance tends to decline most rapidly beginning in your 60s – and this decline can lead to faulty biomechanics and/or falls. The good news is that you can improve your balance through training! This could be as simple as standing on one leg while you brush your teeth, performing single-leg exercises, or engaging in activities such as tai chi and yoga. Strength training is also important, especially for the lower body, because stronger muscles allow you to have greater stability as you move and to move at an ideal speed. The key to any exercise program is consistency – find something that you enjoy and stick with it!

By: Corey Rovzar, PhD & Maya Shetty, BS


Sources:

  1. Successful 10-second one-legged stance performance predicts survival in middle-aged and older individuals

Artwork

By: Sarita Khemani, MD

As a physician specializing in peri-operative medicine, I have witnessed firsthand the detrimental impact of muscle loss on patients. Whether it is individuals presenting with hip or spine fractures, or those who have suffered from bleeding in their brain following a fall, many of these acute conditions have a hidden underlying cause: the loss of muscle mass.

Although losing muscle may not seem like a significant concern, it can be a silent yet deadly issue that progressively drains our vitality and strength, leading us to become frail and dependent.

In this blog, we will explore the latest scientific research on the trajectory of muscle loss as we age and discuss practical steps that we can take to prevent or alleviate its effects.

Understanding Skeletal Muscle: Composition and Function

Skeletal muscle is the type of muscle tissue that we can control voluntarily, such as when we intentionally flex our biceps or perform other movements. It is composed of many smaller bundles of muscle fibers, each containing hundreds to thousands of individual fibers. These fibers are primarily made up of two proteins: myosin and actin, which work together to facilitate muscle contraction.

The muscle fibers themselves are arranged in a specific pattern, extending the muscle’s length between the tendinous ends, and are bundled together and wrapped in connective tissue. This arrangement allows the muscle to generate force and produce movement when it contracts.

In terms of composition, muscle tissue is approximately 70% water and 30% protein. The body synthesizes muscle protein from the amino acids that are present in the protein we consume through our diet.

Image credit: University of Miami: https://www.bio.miami.edu/dana/360/360F18_15.html

 

As we age, the gradual decline in muscle mass and strength worsens with each passing decade. This decline can be attributed to several factors, including reduced dietary protein intake, decreased physical activity, a decline in hormone levels, chronic inflammation, muscle denervation, mitochondrial dysfunction, infiltration of fat into muscle, and insulin resistance.

Research suggests that the rate of loss of muscle strength is greater than the loss of muscle mass and plays a crucial role in healthy aging. When low muscle mass and function, including strength and physical performance, occur with aging, it is known as sarcopenia. The term “sarcopenia” originates from the Greek words “sarx,” meaning flesh, and “penia,” meaning loss.

Sarcopenia can be classified into two categories: primary sarcopenia, which is the cumulative result of various factors leading to muscle loss with aging, and secondary sarcopenia, which is caused by a specific insult, such as surgery, hospitalization, or injury. By understanding these categories, we can better diagnose and manage sarcopenia in older adults.

The trajectory of age-related muscle loss

The loss of muscle strength with age can be surprising to many people, as it can start as early as age 30. As numerous research studies have shown, the rate of decline for muscle mass with age worsens with each decade.

Age Percent loss of muscle mass/decade
50s 0.5-2%
60s 4-5%
70s 7-8%

The decline in muscle strength is more dramatic and can be 2-5 times greater than decline in muscle mass.

Age Percent loss of muscle strength/decade
50s 3-4%
60s 9-10%
70s 11-12%

A study found that there was muscle loss of between 35% and 40% occurring between the ages of 20 and 80. Additionally, studies of nursing home residents have found that sarcopenia, affects 30-40% of individuals. Mobility aids, such as canes, walkers, or wheelchairs, are commonly used by older adults, with 24% of those aged 65 years and older relying on such aids. Alarmingly, the death rate from falls is projected to rise sharply in the coming years, as shown in the graph below.

Image Credit: CDC:

Skeletal muscle mass is shown to be an independent predictor of death, highlighting its crucial effect on longevity.

These statistics don’t consider the sudden health events that can accelerate muscle loss. A rapid decline in muscle mass and health occurs with hospitalizations and illnesses. In addition to the lack of activity during hospital stays, other factors like increased levels of pro-inflammatory agents and cortisol can have a compounding effect. For older adults, this loss of muscle mass and function can lead to permanent disability or even death.

Connection between muscle health and dementia

Dementia affects more than 55 million people worldwide, and physical inactivity is one of the modifiable risk factors for the condition. There is a well-established link between low muscle mass, low physical activity, and cognitive impairment in old age.

Exercise releases myokines from the muscle, which crosses the blood-brain barrier and helps regulate BDNF, a protein that supports the survival and growth of neurons in the brain. Furthermore, the lower an individual’s muscle mass, the more significant their cognitive decline, suggesting a dose-dependent effect.

Steps to preserving muscle health and function.

Protecting your muscle mass is like increasing your savings: the greater the savings, the more comfortable you will be as you age.. While we might develop pharmacological treatments for muscle loss in the future, currently, the best way to preserve muscle function is to put in work upfront.

1. Strength training, “the medicine”

Resistance training activates our DNA to respond to stress, leading cells to produce increased muscle protein.

Initially, we may see an improvement in strength but not much muscle hypertrophy because of an increase in muscle protein breakdown. However, this slows down after about six weeks, and we start seeing an increase in muscle size.

Strength training can counteract the accumulation of fat in the muscle, improve the health of neuromuscular junctions, improve muscle quality, and reduce inflammatory markers.

People who do regular resistance training have a 20-year advantage. For example, 85-year-old weightlifters showed similar power and muscle features as 65-year-olds who did not engage in regular training in studies.

To achieve optimum improvement in muscle mass and strength, we should engage in resistance training 2-3 times per week per muscle group in addition to any aerobic exercises.

Resistance exercises that involve increasing load and speed should be done under supervision to ensure proper form and avoid injury.

2. Protein intake

Studies have shown that higher protein intake is associated with greater muscle mass and lower risk of developing frailty in older adults.

Protein intake should be individualized based on age, sex, activity level, and health status, but generally range from 1.6-2.2 grams per kilogram of body weight per day.

A systematic review and meta-analysis published in the British Journal of Nutrition in 2020 found that plant-based protein sources can be just as effective as animal-based sources for improving muscle health. It’s best to mix and match various plant-based sources of protein for optimum effect.

Consuming more than 35-50 grams of protein at one time does not provide any additional benefit for muscle growth, as excess protein is used for energy production. Therefore, it is best to spread protein intake out throughout the day rather than consuming the whole day’s amount in one sitting.

3. Supplements: Please see an excellent blog by Dr. Kaufman on this website to gain more knowledge about the safe use of supplements.

4. We all know to get good sleep and stay hydrated—more on these topics in future blog posts.

What Does Grip Strength Indicate About Your Health?

Your future lies in the palm of your hand… kind of. A popular topic in longevity and exercise science involves the association between grip strength and life span, but what exactly are people talking about? Two recent studies describing the relevance of grip strength in the field have started to analyze what information one’s grip strength actually provides. “Grip strength is inversely associates with DNA methylation age acceleration” covers cross-sectional and longitudinal associations between hand grip strength and three different clock models to describe the pace of one’s aging in American adults over the age of 50 years old. Essentially, these three different clocks take in information from a DNA methylation sample, and output a relative estimate of how quickly someone is aging based on the different health outcome risk biomarkers they are entrained on. As it pertains to grip strength, the three age-acceleration clocks looked at in the study found significant associations to suggest that greater grip strength can help one protect their body from physically aging faster. These clocks could be useful tools in future clinical applications to begin to better understand the needs of different patients later in life. However, there is still work left to be done as the sample of this study may not be representative of the diverse middle and older aged populations in the larger United States or on a global scale. When reading information from the study above, it can also be easy to believe that increasing the amount of grip-strength exercises you’re doing will help you slow down how fast you’re aging and live longer, which is not exactly the case. Another study from the Journal for Clinical Interventions in Aging, reviews the literature to suggest how grip strength’s relevance to aging science may be due to its associations with total body strength, bone density, reduced risk of falls and fractures, etc. Knowing that there is ample research on the protective effects of these measurements on later-in-life life expectancy, grip strength may be a starting place to begin to clinically understand risks the potential mobility and functionality risks for some patients.

 

To read the full article from the Journal of Cachexia, Sarcopenia, and Muscle, follow this link: https://doi.org/10.1002/jcsm.13110

To read the full article from the Journal for Clinical Interventions in Aging, follow this link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6778477/.

 

By: Carly Mae Smith

By Maya Shetty

By now, we have all heard that exercise is good for us. But why is this? And if it’s so beneficial, why is it so hard to get up and do it? Nearly 80% of US adults are not meeting The Center for Disease Control(CDC) exercise guidelines, which call for a minimum of 150 minutes a week, or 21 minutes a day. To understand the disconnect between exercises’ necessity and our difficulty doing it, we can refer to evolution and why humans evolved to do it in the first place.

The first humans emerged around 200,000 years ago and, unsurprisingly, their lives looked very different from our lives today. While we complain about having to take the escalators instead of the stairs or when Uber Eats takes too long, our ancestors were running from predators and hunting for prey. In fact, humans survived through hunting and gathering practices for 95% of human history. This means the majority of our evolution was spent living as nomadic hunter-gatherers. Therefore, our bodies and behaviors are adapted to this lifestyle.

An Evolutionary PerspectiveNow, you may be wondering how this translates to exercise in today’s society. Well, as hunter-gatherers, our ancestors’ main advantage was endurance. We are not the strongest or fastest animals out there, so survival was dependent on our ability to outrun our predators and prey. Evolutionarily, we are endurance athletes adapted for consistent, long bouts of physical activity. If this is the case, then why does the average American spend most of their time relatively immobile? This is because we are also adapted for inactivity and energy conservation whenever possible. Thinking again about the hunter-gatherer lifestyle, our ancestors were constantly trying to maintain their energy balance – food intake vs. energy expenditure. It made sense to exercise only when necessary for survival, and conserve energy whenever possible. In today’s society, however, this biological tendency no longer serves us, as our environment has been engineered for an extremely positive energy balance: excess food with little energy expenditure. Now we must go against our biological tendencies and make the decision to exercise, even when our body is telling us not to, in order to maintain good health. 

We can see just how much our physical activity differs from our hunter-gatherer ancestors by studying the few modern day hunter-gatherer communities. These populations are often used as models in public health due to their remarkably low rates of chronic disease and disability with age, a stark difference from modern day America. Researchers analyze the behaviors of these populations to have a better understanding of the evolutionary causes of chronic diseases – Why are they so common now vs. then? The most commonly studied population is the Hadza, a hunter-gatherer population in Tanzania. Decades of research has quantified their daily physical activity and how it changes throughout the lifetime. Most notably, the Hadza people average 15,800 steps, about 6 to 9 miles, per day. Meanwhile, Americans average less than 4,800 steps, about 2 miles, per day – about ⅓ the steps of modern hunter-gatherers. On top of this, the average American reduces the amount of steps they take per day by about half between the ages of 40 to 70. The Hadza people, on the other hand, barely change their physical activity levels with age. These behaviors have measurable effects on our physiology. In hunter-gatherer populations, the functional losses of aging, such as declining muscle mass and cardiovascular function, are seen at a significantly lesser rate, if at all, when compare to the American population. This aligns with the theory of disuse and aging brought forth by Walter Bortz II, a former Stanford professor of Medicine and one of America’s most distinguished scientific experts on aging and longevity. Dr. Bortz theorizes the changes commonly associated with aging, such as loss of muscle mass and decreased VO2max, are due to disuse with age, rather than aging itself. The differences in physical capabilities with age seen between the modern American and the Hadza people suggest our sedentary lifestyle may contribute to accelerated aging. By being sedentary, we oppose the evolutionary history encoded in our genes for periodic activity, leading to accelerated physiologic loss with age due to disuse. 

 Regular physical activity stimulates our body to allocate energy toward repair and maintenance, slowing cellular senescence and aging. It has also been seen to have dose dependent effects on the risk of several chronic conditions and other health problems. 

These include:

-Cardiovascular disease and hypertension

-Type 2 diabetes

-Arthritis 

-Osteoporosis

-Stroke

-Lung disease

-Many cancers

-Alzheimer’s disease and dementia of any type

We as humans are adapted for lifelong physical activity. However, the necessity of exercise is as encoded into our genes as the drive to not exercise. The world around us was built for convenience rather than health. And for this reason, it is understandable that the majority of people live a predominately sedentary life. For better lifelong health, we need to make the purposeful decision every day to walk more, sit less, and be physically active. Remember, something is better than nothing, so find something that brings you enjoyment and is able to make a habit of it! Whether it be running, dancing, boxing, walking, or just taking the stairs at work, be proud of yourself for putting in the effort. Your health will thank you later.

This study examined whether progressive overload via increasing weight or increasing repetitions elicited similar muscular adaptations. Progressive overload is the continual increase of workload over time throughout a training regimen, which is necessary to stimulate ongoing muscular adaptation and is traditionally accomplished through increases in load (weight). This study investigated using continual increases in repetitions as compared to weight to progressively increase workload and the resulting outcomes for muscular strength, hypertrophy, and endurance.

Overall, there were improvements in all three variables in both groups that were similar between the groups. Strength (measured by 1RM back squat) increased in both groups and slightly favored the load group with an effect size of 2kg but a wide confidence interval. Muscle endurance increased in both groups and slightly favored the reps group by 2%. Hypertrophy improved similarly in both groups with the exception of one muscle (of 4 tested), the rectus femoris, which slightly favored the reps group.

 A few caveats to note: this study started with quite a high rep range for both groups (8-12 reps as a starting point), and the reps group increased from there. This is quite a high rep range even at the starting point, and the practicality of implementing an increasing rep scheme from that baseline and maintaining good adherence to training might be difficult. Along these lines, the authors noted that the reps group seemed to have a harder time training to actual failure likely due to “greater metabolic acidosis and discomfort” (translation: it was difficult and painful). In addition, this study population was young people with prior weight training experience, and the results may not be generalizable to other groups. The authors attempted to control for dietary factors with self-reported food diaries, but the accuracy of this is questionable and there could be dietary related differences between the groups. Finally, this protocol included training to failure, which when implemented in the real world may increase risks (greater fatigue, injury) and may not be necessary to achieve substantial improvements in the desired outcomes.

Overall, this study suggests that progressive overload in strength training can likely be achieved with either increases in load or reps assuming sufficient training stimulus (effort). Further research is needed to determine if there are benefits for one protocol or the other for relative improvements in strength, hypertrophy, or endurance. Future study should also evaluate practicality/adherence and generalizability to other groups.

By: Sarah DeParis, MD


Journal Reference:

  1. Plotkin D, Coleman M, Van Every D, Maldonado J, Oberlin D, Israetel M, Feather J, Alto A, Vigotsky AD, Schoenfeld BJ. Progressive overload without progressing load? The effects of load or repetition progression on muscular adaptations. PeerJ. 2022 Sep 30;10:e14142. doi: 10.7717/peerj.14142. PMID: 36199287; PMCID: PMC9528903.

During periods of stress, many of us forgo exercising and indulge in unhealthy eating. This study provides insight into how physical acitivty can lead to stress reduction and enhance positive feelings if we are able to include exercise into our daily schedule during difficult times. The effect of physical activity lasts for hours after the session and has prolonged positive effect.

By: Sarita Khemani, MD, Head, Lifestyle Medicine Stress Pillar


Journal Reference:

  1. Schultchen D, Reichenberger J, Mittl T, Weh TRM, Smyth JM, Blechert J, Pollatos O. Bidirectional relationship of stress and affect with physical activity and healthy eating. Br J Health Psychol. 2019 May;24(2):315-333. doi: 10.1111/bjhp.12355. Epub 2019 Jan 22. PMID: 30672069; PMCID: PMC6767465.

This review article clearly highlights the importance of healthy lifestyle choices on mental health. Whole plant based diet and daily exercise have remarkable effects on our mood. In many studies, the effect has been described as equivalent to taking antidepressant medications. In addition, good sleep, daily gratitude, positive thoughts about the future, and being of service to others has also been shown to have lasting positive effects on our mental health.

By: Sarita Khemani, MD, Head, Lifestyle Medicine Stress Pillar


Journal Reference:

  1. Morton DP. Combining Lifestyle Medicine and Positive Psychology to Improve Mental Health and Emotional Well-being. Am J Lifestyle Med. 2018 Apr 18;12(5):370-374. doi: 10.1177/1559827618766482. PMID: 30283261; PMCID: PMC6146362.

A recently published study compared the effects walking in different environments has on the brain. Study participants were randomly assigned to go on a 60-minute walk in a natural or urban environment, and questionnaires and fMRI scans were administered before and after the walk. fMRI scans were used to measure the activation of different brain regions, while questionnaires were used to gauge participant’s perceived mood and stress levels. The study found that a one-hour walk in nature decreased activity in the amygdala, while no change was seen after a one-hour walk in an urban-environment. The amygdala is the part of our brain primarily associated with regulating emotions and processing stressful events. An overactive amygdala is associated with anxiety, while, decreased activity has an anxiolytic effect. Therefore, the findings of thisstudy suggest a walk in nature may be more beneficial for managing stress than a walk in the city. Additionally, our environment plays an important role in the cognitive benefits of walking. This study is a great example of how multiple components of lifestyle medicine can come together. Exercise and being in nature are both powerful tools for managing stress and improving mental health; however, their effect is even more potent when combined.

By: Maya Shetty, BS, Lifestyle Medicine Fellow

 


Journal Reference:

  1. Sudimac S, Sale V, Kühn S. How nature nurtures: Amygdala activity decreases as the result of a one-hour walk in nature. Mol Psychiatry. 2022 Sep 5. doi: 10.1038/s41380-022-01720-6. Epub ahead of print. PMID: 36059042.

This study found that high-intensity progressive resistance training improves lean mass and function in rheumatoid arthritis patients.

By: Sarah DeParis, MD

 


Journal Reference:

  1. Lemmey AB, Marcora SM, Chester K, Wilson S, Casanova F, Maddison PJ. Effects of high-intensity resistance training in patients with rheumatoid arthritis: a randomized controlled trial. Arthritis Rheum. 2009 Dec 15;61(12):1726-34. doi: 10.1002/art.24891. PMID: 19950325.