A sizable body of work points to the ability of older individuals to continue to obtain benefits through regular physical activity, and particularly in the case of strength training. A perhaps surprisingly large fraction of what is commonly regarded as an inevitable decline in physical fitness and muscle quality with age is in fact the result of lifestyle choices - in particular the choice to exercise less, and the failure to work on maintenance of strength in muscles. We live in an age of comparative comfort, surrounded by low cost transportation machinery, calories, and tools to substitute for physical effort. The result is a growing number of people who are weak and overweight in comparison to their ancestors. Those ancestors still had a much worse time of it, of course, given the absence of modern medicine and sanitation, but we sabotage ourselves nonetheless.
Today I'll point out a few recent papers on activity and strength (or lack thereof), and the benefits realized (or lost). They may for interesting reading, but I think it is important to bear in mind that this is only of interest because exercise is essentially free, and is a reliable source of the benefits it provides. These benefits are not large in the grand scheme of things: 75% of the fittest people fail to reach 90 years of age. It is impossible to add decades to human life spans through exercise. When looking ahead to the future, the quality and length of our lives will become ever more determined by the state of progress in rejuvenation therapies, treatments capable of repairing the cell and tissue damage that causes aging, and ever less by modestly effective approaches to good general health, a few of which can slightly slow the progression of that damage. Large gains can only arrive through the right sorts of progress in medical science.
Autophagy is a major catabolic route in cells responsible for the clearance of proteins and organelles. Pathological levels of autophagy are associated with muscle wasting, but physiological levels are important for cellular recycling. In the present study, indicators of autophagy and unfolded protein response (UPR), which is another system for maintaining cellular homeostasis, were investigated from the muscle biopsies after a single bout of resistance exercise and after 21 weeks of resistance training in previously untrained young and older men.
Aging may blunt some of the positive effects of resistance training when it comes to improvement in muscle quality, but the researchers reported that UPR that is induced by the accumulation of misfolded proteins in endoplasmic reticulum (ER) was activated by a bout of unaccustomed resistance exercise regardless of age. Skeletal muscle appears to adapt to resistance exercise similarly in young and older people in many ways.
Becoming more physically active after a heart attack reduces the risk of death. A study that followed more than 22,000 patients found that those who became more physically active after a heart attack halved the risk of death within four years. Levels of physical activity were reported 6-10 weeks and 12 months after the heart attack. The difference between answers was considered a change in physical activity over the year following the heart attack.
On both occasions, patients were asked how many times they had exercised for 30 minutes or longer during the previous seven days. Patients were categorised as constantly inactive, reduced activity, increased activity, or constantly active. A total of 1,087 patients died during an average follow-up of 4.2 years. The researchers analysed the association between the four categories of physical activity and death, after adjusting for age, sex, smoking, and clinical factors. Compared to patients who were constantly inactive, the risk of death was 37%, 51%, and 59% lower in patients in the categories of reduced activity, increased activity, or constantly active, respectively. "Our study shows that this advice applies to all heart attack patients. Exercise reduced the risk of death in patients with large and small myocardial infarctions, and for smokers and non-smokers, for example."
Researchers recruited 35 people ages 45 to 75 and asked about their physical activity levels and the average number of hours per day they spent sitting over the previous week. Each person had a high-resolution MRI scan, which provides a detailed look at the medial temporal lobe, or MTL, a brain region involved in the formation of new memories. The researchers found that sedentary behavior is a significant predictor of thinning of the MTL and that physical activity, even at high levels, is insufficient to offset the harmful effects of sitting for extended periods.
This study does not prove that too much sitting causes thinner brain structures, but instead that more hours spent sitting are associated with thinner regions, researchers said. In addition, the researchers focused on the hours spent sitting, but did not ask participants if they took breaks during this time. The researchers next hope to follow a group of people for a longer duration to determine if sitting causes the thinning and what role gender, race, and weight might play in brain health related to sitting.
"Frailty progresses with aging, but older women who engage in a high level of daily physical activity can reverse certain characteristics related to aging, such as slow walking and decreased function. But for women over the age of 75, muscle strength and endurance declines. Starting resistance exercise when they are young and continuing it is important so that when they reach a very advanced age they have already built up their strength and endurance reserves."
The study looked at 46 women across two different age ranges, 60-74 and 75-90, to learn how physical activity affects frailty differently in the two groups. Researchers found that there was a larger difference between the two groups in terms of muscle strength and endurance among those who were very physically active. With mobility - as measured by the length of a person's step - and basic functional ability, there was a gap between the two age groups among women who engaged in minimal physical activity. However, that gap disappeared if they did a high level of physical activities. "Their main physical activities consisted of light gardening, light housework and stretching. Is this because they are still working and don't have time for exercise, or do they think they are healthy and don't need to? It appears that committing to regular exercise is not yet a standard part of older women's lifestyles and is instead a reactive behavior to, for example, falls or illness."