Fight Aging!

It is no big secret that regular exercise and greater fitness leads to better health and a longer life expectancy, though it remains uncertain as to where the point of greatest benefit lies. What is the dose-response curve for exercise? How does it vary by circumstances and type of exercise? Given the glacial pace of demographic studies, I fully expect good answers to those questions, with robust data behind them, to arrive only decades from now, after the point at which the first rejuvenation therapies exist. What we know today about exercise and aging, gathered from large long-running studies of past decades, is but an outline of the full picture. Athletes at the top of their profession go on to live from a few years to a decade longer on average than the rest of the population, but the data doesn't tell us whether that is because of exercise and fitness, or because only more robust people tend to succeed at becoming professional athletes. At the other end of the scale, there is a few year difference in life expectancy and sizable health difference in the outcomes resulting from being sedentary versus undertaking regular moderate exercise. It is much more certain that this is an effect of the choice to work on fitness versus the case that more resilient people tending to exercise more frequently.

When it comes to a high expectation of positive results for the future of your health, there really are only three options at the present time: regular moderate exercise, some form of calorie restriction or equivalent intermittent fasting, and working to accelerate the right research programs, such as through philanthropic donations. In my eyes that means SENS and SENS-like work focused on the repair of the cell and tissue damage that causes aging, but other people will have other opinions. As for any of the other stuff that the supplement and anti-aging industry will try to sell you on, it is either the case that the scientific evidence is sparse, sketchy, and changeable, the benefits are small and uncertain in comparison to exercise or calorie restriction, or the solid scientific consensus is that there is no benefit.

In an age of rapidly progress in biotechnology, and thus the potential for radical advances in medicine from decade to decade, it makes sense to keep yourself fit. Quite aside from better long-term health being a more pleasant and less expensive experience than worse long-term health, unlike our ancestors we now find ourselves in a situation in which every extra year counts. Will we live to enjoy the first therapies capable of repairing the causes of aging and thus producing at least partial rejuvenation, or will we miss out? That's up to us, not just by staying fit, but more importantly by helping to speed progress towards the development of these therapies. On this topic, here are a couple of recent research publications that, like many others of a similar nature, are an incentive to stay fit and avoid more of the consequences of aging:

Can physical exercise enhance long-term memory?

Exercise can enhance the development of new brain cells in the adult brain, a process called adult neurogenesis. These newborn brain cells play an important role in learning and memory. A new study has determined that mice that spent time running on wheels not only developed twice the normal number of new neurons, but also showed an increased ability to distinguish new objects from familiar objects.

As rodents prefer to spend more time with novel objects than familiar ones, the researchers first exposed the mice to two identical objects (cones or pyramids, in either black or white). After 1.5 hours, one of the objects was replaced with a new object (cone for pyramid or vice versa) and the mice were observed. After 24 hours elapsed, the new object was again swapped, either with a similar object (same color but different shape) or a distinct object (different color and shape). After the short 1.5-hour interval, both running and sedentary mice were able to distinguish similar and distinct objects. However, after 24 hours, a difference was observed. Whereas distinct objects were remembered and recognized by both cohorts of mice, only the running mice could faithfully distinguish similar looking objects. Investigators determined therefore that the running mice had developed better pattern separation capabilities than sedentary mice.

To investigate further, the researchers looked for changes in the brains of the mice. By using markers that could identify newly-formed brain cells, they found that running mice developed about twice as many new cells, and those cells had longer dendrites, compared to the sedentary mice, which facilitates the formation of new synaptic contacts between the nerve cells.

Walking faster or longer linked to significant cardiovascular benefits in older adults

In a large prospective community-based study of older Americans, modest physical activity was associated with a lower risk of cardiovascular disease (CVD). This was true even among men and women older than age 75 at baseline - a rapidly growing population for whom regular activity has been advised, but with little supportive empirical evidence. The researchers studied 4,207 men and women who had been enrolled in the Cardiovascular Health Study (CHS) and who were then followed for 10 years. After adjustment for other risk factors and lifestyle behaviors, those who were more active had significantly lower risk of future heart attacks and stroke. Adults who walked at a pace faster than three miles per hour (mph) had a 50%, 53%, 50% lower risk of coronary heart disease (CHD), stroke and total CVD, respectively, compared to those who walked at a pace of less than two mph. Those who walked an average of seven blocks per day or more had a 36%, 54% and 47% lower risk of CHD, stroke and total CVD, respectively, compared to those who walked up to five blocks per week. Those who engaged in leisure activities such as lawn-mowing, raking, gardening, swimming, biking and hiking, also had a lower risk of CHD, stroke and total CVD, compared to those who did not engage in leisure-time activities.

Higher resting heart rate linked to increased risk of death from all causes

A higher resting heart rate is associated with an increased risk of death from all causes in the general population, even in people without the usual risk factors for heart disease, according to new research. Current evidence for resting heart rate and risk of death and risk of death from heart disease is inconsistent. To understand if resting heart rate is correlated with an increased risk of death, researchers assessed 46 studies involving 1,246,203 patients and 78,349 deaths from all causes, and 848,320 patients and 25,800 deaths from heart disease. "Results from this meta-analysis suggest the risk of all-cause and cardiovascular mortality increased by 9% and 8% for every 10 beats/min increment of resting heart rate. The risk of all-cause mortality increased significantly with increasing resting heart rate in a linear relation, but a significantly increased risk of cardiovascular mortality was observed at 90 beats/min ... consistent with the traditionally defined tachycardia threshold of 90 or 100 beats/min for prevention of cardiovascular disease."

The authors found that people with a resting heart rate of more than 80 beats/min had a 45% higher risk of death from any cause than those with a resting heart rate of 60-80 beats/min, who had a 21% increased risk. However, the absolute risk is still small. Findings were similar for people with cardiovascular risk factors.

Resting heart rate is correlated with fitness, and becoming fitter tends to reduce it. Given the relationship between fitness and mortality, this is probably enough to explain the results observed in the last study noted above.