And as time passes, you notice your gains disappear and your appetite suppress. After standing on the scales, your worst fears are confirmed: you've dropped weight and all those meals consisting of veggies and chicken have gone to waste.
But an amazing new piece of research performed on rodents has given us hope - according to a study published in Frontiers in Physiology, while you might lose muscle due to inactivity, those gains can quickly reappear when you return to exercise.
The findings suggest that the nuclei - the control centres that build and maintain muscle fibres - developed during exercise could retain their gains even when muscle cells shrunk due to deterioration over time or lack of use.
“Two independent studies – one in rodents and the other in insects – have demonstrated that nuclei are not lost from atrophying muscle fibres, and even remain after muscle death has been initiated,” writes the study.
“Muscle growth is accompanied by the addition of new nuclei from stem cells to help meet the enhanced synthetic demands of larger muscle cells," says Author of the journal Lawrence Schwartz from the University of Massachusetts.
“This led to the assumption that a given nucleus controls a defined volume of cytoplasm – so that when a muscle shrinks or ‘atrophies’ due to disuse or disease, the number of myonuclei (left over nuclei) decreases."
And it turns out that when you're back in the gym, your nuclei actually supports faster muscle growth.
“It is well documented in the field of exercise physiology that it is far easier to reacquire a certain level of muscle fitness through exercise than it was to achieve it the first place, even if there has been a long intervening period of detraining. In other word, the phrase “use it or lose it” is might be more accurately articulated as ‘use it or lose it, until you work at it again’,” adds Schwartz.
This research is not only important in comforting those spending time out of the gym, but also crucial to preventing fragility in your elderly years.