Quite a lot of research on exercise in the context of aging and age-related disease has been published in the past few months. More than usual, I think - not just a case of noticing because it is on my mind. Research moves in waves and cycles, just like all other human endeavors. Below you will find links to a selection of these items, those that caught my attention as they passed by.
Along with donating to the SENS Research Foundation and the practice of calorie restriction, regular moderate exercise is just about the best thing you can do for your long term health here and now. Both calorie restriction and exercise have been shown to slow aging to a modest degree in animal studies, and the human data is pretty compelling. It is fair to say that exercise produces greater benefits for a basically healthy individual than any presently available medical technology. It even produces better results than the available therapies for a number of age-related conditions. It is all a matter of degrees, however. That I can say this about exercise is less a glowing recommendation for working out and more a dismal review of medicine as it exists in clinical practice today. The research and development community can and will do better, and I don't think that exercise and calorie restriction will go unbeaten by therapies and enhancements for another decade at this point, but it is still frustrating to be in the midst of such a revolutionary period in life science research, yet to reap the harvest of that progress. We don't want medicine that just slows the inevitable a little, we want the inevitable defeated, removed, cured.
A sizable fraction of the aging research community is interested in mimicking the effects of calorie restriction on health and longevity, using drug discovery to find ways to tinker with the same switches in our biochemistry. The same is true of exercise, though researchers in that case are some years behind on the same path, with some catching up to do. While I'm definitely in favor of taking advantage of exercise, as it is here and it is free, and that is a cost-benefit equation hard to argue with, I'm much less enthusiastic about the panoply of approaches that aim to produce much the same outcome via drugs, some way to modestly slow the progression of degenerative aging by taking a pill or undergoing some form of enhancement such as gene therapy. I think the cost to achieve that goal though, for example, standard issue drug discovery and development is unfavorably high, given the very modest scope of the benefits expected to result. If that was all that could be done, then so be it, but it isn't. There are other alternatives, such as the SENS portfolio of research and development based on repair of the cell and tissue damage that causes aging, that have the potential to achieve rejuvenation rather than slowing of aging, and thus produce far greater benefits to health and longevity.
For many mammals, including humans, the speed of muscle repair slows as they grow older, and it was once thought that complete repair could not be achieved after a certain age. This report shows, however, that after only eight weeks of exercise, old mice experienced faster muscle repair and regained more muscle mass than those of the same age that had not exercised. This is important, as it further highlights exercise's therapeutic potential. To make this discovery, researchers used three groups of mice: old mice that were exercise trained, old mice that were not exercise trained, and young mice that were not exercised trained. In the first group, old mice were trained three days/week for eight weeks. The effect of exercise in aging muscle was measured by comparing the three groups of mice. "This is a clean demonstration that the physiological and metabolic benefits of exercise radiate to skeletal muscle satellite cells, the adult stem cells responsible for repair after injury, even in senescent animals. Strikingly, even as the contractile elements of muscle tissue wane with age, the capacity of the satellite cells to respond to exercise cues is maintained. This aging-resistant retentive property could be added to the list of features that define adult stem cells."
To conduct the study, the investigators identified 23 randomised trials of exercise that included at least 50 heart failure patients who were followed up for six months or longer. After asking the authors of all 23 studies for individual patient data, they received the information from 20 trials. The 20 trials included 4043 patients with heart failure. The investigators used the individual patient data to assess the impact of exercise on the time to all-cause mortality and first hospitalisation. The investigators found that exercise was associated with an 18% lower risk of all-cause mortality and an 11% reduced risk of hospitalisation compared with no exercise. "This analysis did in fact show that there is a mortality benefit from doing exercise. In other words, patients who exercised had a lower risk of death than those who didn't. Patients with heart failure should not be scared of exercise damaging them or killing them. The message for heart failure patients is clear. Exercise is good for you, it will make you feel better, and it could potentially make you live longer."
Exercise may decrease cancer incidence and slow the growth rate of tumors. That's the conclusion of a mouse-based study, reporting that training mice regularly on a wheel decreased the growth of multiple types of tumors, including skin, liver, and lung cancers. Furthermore, mice that exercised regularly had a smaller chance of developing cancer in the first place. The beneficial effects of running went beyond tumor formation and growth, extending to cancer-associated weight loss, a process termed cachexia that is seen in cancer patients. Mice that exercised regularly showed no signs of cancer-associated weight loss in the researchers' lung cancer mouse model.
The researchers say they identified several factors behind the anti-tumor effects of exercise. These anti-cancer effects are linked to the release of adrenaline (also called epinephrine), a hormone that is central to the "fight-or-flight" response. Adrenaline production is known to be stimulated by exercise. The researchers say that, the production of adrenaline results in a mobilization of immune cells, specifically one type of immune cell called a Natural Killer (NK) cell, to patrol the body. These NK cells are recruited to the site of the tumor by the protein IL-6, secreted by active muscles. The NK cells can then infiltrate the tumor, slowing or completely preventing its growth. Importantly, the researchers note that injecting the mice with either adrenaline or IL-6 without the exercise proved insufficient to inhibit cancer development, underlining the importance of the effects derived only from regular exercise in the mice.
In a prospective observational study consisting of 19,815 adults ages 45 to 50, (79 percent men, 90 percent Caucasian) researchers measured participants' heart and lung exercise capacity and categorized them as having either a high, middle or low level of fitness. The study found that those with the highest level of fitness had a 37 percent lower risk of stroke after age 65, compared to their counterparts with the lowest level of fitness. This inverse relationship between fitness and stroke risks existed even after researchers considered stroke risk factors: high blood pressure, type 2 diabetes and atrial fibrillation. The study reinforces the benefits of being physically fit throughout life. "Low fitness is generally ignored as an actual risk factor in clinical practice. Our research suggests that low fitness in midlife is an additional risk to target and help prevent stroke later in life."