Agehacking: Can Regular Exercise Slow or Reverse Aging?
Updated: Jan 24
Does regular exercise in adulthood cause your body to age more slowly, or are older adults who exercise more active because they are naturally aging more slowly? Chicken or egg? Well, that’s what scientists these scientists have answered!
Let’s take this back a few decades: In 1966, the University of Texas Southwestern Medical School recruited five healthy 20-year-olds for the Dallas Bed Rest and Training Study. These seemingly lucky young men would get paid to spend three weeks doing nothing but staying in bed. By the end of the short trial, the three weeks of incapacitation had caused physiological characteristics more common in men twice their age: reduced muscle strength, higher body fat, but also worrying changes to the heart: higher resting heart rates and systolic blood pressure, lower maximum pumping capacity. The consequences of a sedentary lifestyle laid bare.
Then came the next phase in the study. The men were put on an intensive eight-week exercise regime. This program was successful in regaining the ground lost due to bed rest, and in some cases improved upon the baseline measurements of the men. The study showed that while bed rest and other sedentary behavior rapidly reduces your physiological health, this does not have to be permanent, and in fact can be reversed relatively quickly.
While compelling for it’s time, research on these five men didn’t stop here. Follow up studies were done 30- and 40-years on with all subjects agreeing to be reevaluated again at 50-years-old and 60-years-old. The 30-year interval showed the steady march of time on the body: the men had gained an average of 50-lbs each (over 25% of their original body weight) and average body fat doubled from 14% to 28%. But interestingly, while their cardiac function was below that of their 20s’ peak, it was still above that of their results following the three weeks of bed rest back in 1966. While they weren’t asked to be on bed rest again, nor have an intensive eight-week regime, they were put on a more age appropriate six-month program. Though only losing on average 10 of the 50-lbs gained over the 30 years, the six-month exercise program returned resting heart rate, systolic blood pressure, and maximum pumping capacity to that of their 20-year-old selves, reversing three decades of decline in 6-months! The take home of these results being that aerobic or endurance exercise is the best way to counteract the harmful impacts of sedentary behavior and the effects of aging on cardiovascular function. As concluded by the authors of the paper, The Dallas Bed Rest and Training Study: Revisited After 50 years, “Bed rest was found to be extremely harmful and endurance training beneficial across the spectrum of age. The original study not only demonstrated the extraordinary adaptive capacity of the cardiovascular system and the compelling adverse effects of sedentary behavior, but it also had immediate clinical impact, sustained to the present day, minimizing sedentary time in the management of acute and chronic medical conditions.”
But does lifelong exercise slow aging?!
More recently, in 2018, a more expansive study was published by researchers at University of Birmingham and King’s College London. The study assessed the overall health of 125 amateur cyclists aged 55 to 79 who had maintained a high level of physical activity (in this case, cycling) through much of their adult lives against 75 adults in the same age group who had not maintained physical activity in adulthood. In addition, the cyclist group was assessed against 55 young adults aged 20-36 who were not involved in regular exercise.
Lab tests were done on all participants and the study revealed that those who had exercised regularly throughout adulthood, as compared to those who had not:
Were not affected by loss of muscle mass
Were not affected by increased cholesterol
Were not affected by increased body fat
Were not affected by loss of testosterone (if male, thus avoiding “male menopause”)
However, the most surprising discovery of all was that those who exercised regularly had the same immune system strength as the young adults in the study, meaning that over adulthood their immune systems had not declined with age.
Quick background: Central to our immune health is an organ called the thymus. The thymus is unique in that it is largest in childhood, and after puberty begins to shrink and become replaced by fat. As the thymus shrinks, we produce less and less new T-cells (Killer T-cells are responsible for detecting and destroying infected cells), therefore reducing T-cell diversity over time. By the age of 75, the average thymus is reduced almost completely to fatty tissue. This compromises our immune system and is a major contributing factor in the increased susceptibility of the elderly to infection and disease. (Read more about using drugs to revive the thymus in our article Can Age Be Reversed?)
Despite the normal course of thymus degeneration, the study showed that the thymuses of the cyclists were producing as many T-cells as the young (20-35) participants! In a university release, Dr Niharika Arora Duggal, of the University of Birmingham, said: “We hope these findings prevent the danger that, as a society, we accept that old age and disease are normal bedfellows and that the third age of man is something to be endured and not enjoyed.”
Regular aerobic exercise can slow aging and help maintain the physiological characteristic of younger adults associated with good health and wellbeing.