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.
Now, 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.
-Cardiovascular disease and hypertension
-Type 2 diabetes
-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 small proof-of-concept study found something for further exploration: the high dietary fiber vs low dietary fiber interaction with different prebiotic supplements. The study found that the supplements only affected those who weren’t taking in dietary fiber, thus taking prebiotic supplements may be ineffective if you already consume the recommended amounts of dietary fiber. The study included a very wide age range so the findings shouldn’t be printed on t-short quite yet, however it brings to light an interesting interaction. Ironically it’s often the people who already have a healthy diet that lean towards supplement intake even though they don’t need it!
By: Marily Oppezzo, PhD, MS, Head of Lifestyle Medicine Nutrition Pillar
- Holmes ZC, Villa MM, Durand HK, Jiang S, Dallow EP, Petrone BL, Silverman JD, Lin PH, David LA. Microbiota responses to different prebiotics are conserved within individuals and associated with habitual fiber intake. Microbiome. 2022 Jul 29;10(1):114. doi: 10.1186/s40168-022-01307-x. PMID: 35902900; PMCID: PMC9336045.
A great part of who were are is composed of the memories we have. With a growing interest in preventing the loss of memories, researchers have turned to preventative approaches – to address the lack of disease-modifying treatment for dementia.
A recent study found that lifestyle may be more important than age in determining the risk of dementia and cognitive health. The study included data from over 22,000 participants between the ages of 18 – 89 and found that, for all ages, lifestyle is a more important risk factor for cognitive decline than age. The risk factors that were examined range from early-life factors to late-life factors, including low education, traumatic brain injury, hypertension, smoking, diabetes, and depression.
In the study, participants with no risk factors for dementia had similar brain health to people 10-20 years younger than them! Additionally, the study found that each risk factor for dementia reduced cognitive abilities by the equivalent of 3 years of aging, and each additional risk factor added to this decline.
For the risk factors that are modifiable with nutrition, exercise, and stress management, this study suggests it is never too early to start caring for your brain health. Maintaining healthy lifestyle habits can prevent the loss of memory and shape the life you live.
By: Helena Zhang, BS
- LaPlume AA, McKetton L, Levine B, Troyer AK, Anderson ND. The adverse effect of modifiable dementia risk factors on cognition amplifies across the adult lifespan. Alzheimers Dement (Amst). 2022 Jul 13;14(1):e12337. doi: 10.1002/dad2.12337. PMID: 35845262; PMCID: PMC9277708.