Cellular Memory Suggests Exercise Benefits Persist Even After Training Breaks

What's new

Recent scientific findings suggest that the body's cells maintain a persistent record of previous exercise, challenging the long-held belief that all benefits of physical activity are lost during periods of inactivity. This cellular memory appears to be stored in muscle and liver cells, potentially influencing how quickly individuals can regain fitness after a break and offering lasting advantages such as enhanced endurance and better blood sugar regulation [1]. The research, primarily conducted by the authors' team, indicates that this cellular memory can accelerate muscle growth upon retraining and improve the liver's efficiency in supplying fuel to muscles, even persisting through dietary challenges [1].

The science behind it

Researchers have employed an ON-OFF-ON exercise protocol in studies, often using mice, to observe how cells form, maintain, and recall exercise memories. This involves an initial training period, followed by a detraining phase, and then a second training bout. Studies have shown that skeletal muscle cells retain a memory that accelerates muscle growth during retraining. Compared to untrained subjects, those with a training history developed larger muscle fibers upon resuming exercise. This 'remembered' muscle was also more efficient at matching energy production to demand, a capability that endured even without continuous exercise [1].

The liver also plays a role in this cellular memory. Exercise training leads to the liver releasing higher levels of carboxylesterases, enzymes that break down circulating lipids into a form muscles can readily use for energy. This enhanced efficiency in fuel delivery to muscles persists even after a period of detraining, indicating a lasting cellular adaptation in the liver [1]. Furthermore, preliminary research suggests that these recorded cellular memories might even be passed down across generations. Studies in mice indicate that parental exercise can offer offspring protection against poor blood sugar control and excessive weight gain for up to a year after birth, hinting at epigenetic or other transgenerational effects [1]. This expanded understanding challenges the traditional view that only neurons and immune cells possess memory, suggesting that many cell types can retain records of past interactions and adapt accordingly [1].

What it means in practice

For individuals who experience unavoidable breaks from exercise due to injury, illness, or life circumstances, this research offers encouraging news. It suggests that the effort invested in previous workouts is not entirely wasted. While consistent exercise remains crucial for optimal health, the cellular memory means that returning to fitness after a hiatus may be a more efficient process than starting from scratch. This could translate to faster muscle regrowth, quicker improvements in endurance, and more efficient metabolic responses upon resuming training [1]. The findings also imply that even past periods of activity could confer some long-term health benefits, such as better blood sugar control, even if current activity levels are lower. This perspective could reduce the psychological barrier of feeling like one is 'starting over' after a break, encouraging a return to activity with the knowledge that the body has a head start [1].

Caveats

While promising, much of this research is still in its early stages, with many findings derived from animal models (mice) rather than human clinical trials. The exact mechanisms by which cells store and recall exercise memories are still being investigated, as is the duration for which these memories persist [1]. It is also important to note that these findings do not negate the importance of consistent exercise. The article explicitly states that "none of these findings are evidence for skipping the gym; nothing in our data suggests the effects of past training can substitute for present training" [1]. The benefits of immediate and ongoing physical activity, such as improved cardiovascular health, mental well-being, and disease prevention, remain paramount. This research primarily offers a more nuanced understanding of how the body adapts to and remembers exercise, rather than a justification for prolonged inactivity [1].

Source: https://theconversation.com/your-cells-keep-a-record-of-every-workout-youve-ever-done-and-those-gains-persist-even-after-a-break-from-exercise-291243