Physical activity has been shown to have many benefits for health and longevity and has been referred to as one of the most powerful anti-aging interventions. While exercise can improve health during aging, its benefits inevitably decline over time. Despite this, the cellular mechanisms behind the relationship between exercise, fitness, and aging are still not well understood.
A recent study published in the Proceedings of the National Academy of Sciences sheds new light on this relationship. Researchers at Joslin Diabetes Center investigated the role of one cellular mechanism in improving physical fitness through exercise training and found one anti-aging intervention that could delay the declines that occur with aging. These findings could lead to new strategies for promoting muscle function during aging.
Understanding the Essential Mediator of Exercise Responsiveness
The essential mediator identified in the study is the cycle of fragmentation and repair of the mitochondria, which are the specialized structures inside cells responsible for producing energy. The researchers found that the disruption of mitochondrial dynamics, which is the cycle of repairing dysfunctional mitochondria, has been linked to the development and progression of chronic, age-related diseases such as heart disease and type 2 diabetes.
“As we perceive that our muscles undergo a pattern of fatigue and restoration after an exercise session, they are undergoing this mitochondrial dynamic cycle,” said T. Keith Blackwell, MD, PhD, a senior investigator at Joslin. “In this process, muscles manage the aftermath of the metabolic demand of exercise and restore their functional capability.”
Exercise and Aging in Model Organisms
The researchers studied the role of mitochondrial dynamics during exercise in the model organism C. elegans, a simple, well-studied microscopic worm species. They observed a typical age-related decline in physical fitness over the course of the worms’ 15 days of adulthood, and saw a significant and progressive shift towards fragmented and/or disorganized mitochondria in the aging worms.
In young worms, the researchers observed that a single bout of exercise induced fatigue after one hour, but that the performance and mitochondrial function were restored within 24 hours. In older worms, however, the performance did not return to baseline within 24 hours, and the network reorganization that occurred during the cycle of fragmentation and repair was reduced compared to that of the younger worms.
The Benefits of Long-Term Exercise and Anti-Aging Interventions
In a second set of experiments, the researchers found that a long-term training program of swimming for one hour per day for 10 consecutive days significantly improved the fitness of the middle-aged worms at day 10 and mitigated the impairment of mitochondrial dynamics typically seen during aging.
The researchers also tested known, lifespan-extending interventions for their ability to improve exercise capacity during aging. They found that worms with increased AMPK, a molecule that is a key regulator of energy during exercise and promotes remodeling of mitochondrial morphology and metabolism, exhibited improved physical fitness. Worms engineered to lack AMPK exhibited reduced physical fitness during aging, and did not receive the age-delaying benefits of exercise over the course of their lifespan.
“Our data point towards potentially fruitful intervention points for forestalling the decline in muscle function and exercise tolerance during aging,” said Blackwell. “It will be of great interest to determine how mitochondrial network plasticity influences physical fitness along with longevity and aging-associated diseases in humans.”
This study provides new insights into the link between exercise, fitness, and aging, and highlights the importance of the cycle of fragmentation and repair of the mitochondria in maintaining physical fitness during aging. Further research will be needed to fully understand the role of mitochondrial network.
Do keep in mind that Strength training was added to the 2010 Global Recommendations on Physical Activity for Health, so keep exercising to mitigate the aging effects.