Use It or Lose It? How Long Does It Take to Lose Hard Won Fitness Gains?

March 9, 2020

We’ve all been sidelined at some point, an injury, a sudden change in your schedule, sickness, vacation, or just needing a break to rest and recover…sounds a lot like, well, life! Nevertheless, and understandably, you may wonder how long it could take to begin to lose those hard-earned fitness benefits. Turns out the answer isn’t so simple. Let’s examine what we know.


The principle of reversibility refers to the loss of function experienced when a training program is ceases. Put another way, the fitness gains achieved through a program of regular exercise will be reversed to pre-training levels if that program is ended. But perhaps this is best summed up as ‘use it or lose it’. When we stop exercising, we can expect to see a decline in our levels of cardiovascular fitness and muscular strength.


Cardiovascular Fitness

Aerobic capacity will decline more quickly than strength, and in fact, can start to happen in just a few days. Highly trained athletes experience a rapid decrease in the first 3 weeks, which then tapers off at that point. A significant level of fitness, however, is retained for about 12 weeks.


Conversely, those with low to moderate fitness levels experience little change in cardiovascular fitness in the first few weeks, but then rapidly decline to pre-training levels. Not surprisingly, beginners are more likely to lose their progress during periods of inactivity than more highly trained individuals. And some research suggests that older adults may lose fitness at a faster rate than their younger counterparts.


But there’s good news! Research looking into the effect of decreasing training, as opposed to stopping completely, has yielded encouraging and consistent findings. First, fitness levels can be maintained fairly well with one exercise session performed at your regular level of intensity. Also, shorter daily bouts can help retain some fitness. As for regaining cardiovascular fitness that has been lost, know that you’ll be able to reach peak fitness level more quickly than you did when you first began training, and the longer and more regularly you had been exercising, the quicker you’ll be able to return to your former fitness level.



1) If you must curtail your training, aim to maintain one weekly session at your usual intensity, a strategy proven to be extremely effective at forestalling the decline that results if you stop completely.


2) If time is a barrier, try high intensity interval training. Not only do you save time, but HIIT is extremely efficient.


3) Injured? Consider other options that will not exacerbate your injury. Long walks? Stretching? Swimming?


We know definitively that it takes only 8-12 week of a regular strength training program to achieve significant increases in muscle mass and strength, approximately 2-4 lb. and 40-60% respectively. Contrast these gains with the fact that non-exercisers could lose ½ lb. of muscle per year. Simply put, if you’re not training, you could lose three lbs. of muscle in 6 years. But, choose to train, and you could add three lbs. of muscle in only 12 weeks! This speaks to the critical role strength training plays in maintaining a high level of functioning as we age. But how long does it take to lose those muscle mass and strength gains?


Because muscle retains a memory of exercise for weeks, on a genetic level no less, strength gains will last longer than cardiovascular fitness. In fact, you can take about 3 weeks off before seeing a noticeable decline in your muscle strength. However, if you have been training most days of the week for at least a year, or 2-3 times/week for years, you can expect to lose less overall mass and strength compared to lesser trained individuals.


In general, strength is lost at about half the rate at which it was gained. Put another way, you will lose half the strength you’ve gained in the same amount of time it took to make those gains. Or, it will take twice the amount of time to lose gains as it did to make them! And a little more good news – similar to what we see with cardiovascular training, strength can be well-maintained with just one strength training session/week, performed at your usual level of intensity.



1)   Strength gains are pretty well maintained for about 3 weeks, especially in those who have been training regularly. Peace of mind if you’ve been sidelined by an injury.

2)  As is true of cardiovascular fitness, reducing the frequency of training to just once a week at your regular intensity significantly forestalls strength losses.

3)  Muscle weighs more than fat, but takes up less space. Consequently, body weight is not an accurate reflection of lean body weight. Whether you’re training, taking a break, or getting back to training, be mindful of how your clothes are fitting rather than the number on the scale.



Starting Over

If, however, you haven’t been training for about 4 months, you’ve likely lost enough cardiovascular fitness and strength to warrant starting as a beginner.


Cardiovascular Fitness

Begin by exercising for 20-30 minutes, 3-4/week, at a low to moderate intensity. You should feel like you are working slightly out of your comfort zone, yet able to maintain that intensity for the duration. Once you are able to complete 30 minutes without stopping or slowing down, increase the duration by about 5 minutes. Once that’s accomplished, then increase the intensity of your exercise slightly. Continue alternately increasing duration and intensity 5-10% until you’re back to your previous level of fitness.


Strength Training

Think about training movement as opposed to muscle. Base your training and exercises on the 5 basic human movement patterns:

Push: shoulder press; push-ups; chest press; triceps press

Pull: cable rows; lat pulldowns; one arm rows; pull ups; biceps curl

Bend and Lift: squats; leg press; plies; deadlifts

Single Leg movements: lunges (forward, side and reverse) & step-ups

Rotation: cross body rotations; trunk rotations



A certified Personal Trainer can help you develop a strength training plan tailored to your unique needs and goals.



1)  Aim for two sessions/week.

2)  Choose a resistance at which it is quite challenging to complete 15 repetitions.

3)  Complete 2 sets of each exercise, with a 30 second rest in between sets.

4)  Once you can comfortably complete 15 repetitions, increase the resistance ~ 10-20%.

5)  And as is good practice in life, exhale on the exertion.

The Author

Randi Kant, MS, MPH, CHES, CPT

Randi’s deeply held belief in the power of lifestyle related behaviors to maximize health and well-being has driven her in all she has done within her wellness career. A passion for fostering a proactive approach to health, a natural ability to create nurturing, yet empowering relationships, and a unique background that encompasses exercise science, health education, and health coaching enable Randi to affect positive change in individuals, organizations and communities. Says Randi, “I believe in meeting you exactly where you are, engaging you in the design of your experience and encompassing the complexity of variables you bring to life and living. Together we’ll create a pathway to achieve what it is you want for yourself, but ultimately, the unfolding of your development is in your hands, and the choices, work and outcomes all belong to you.”

Leave a Reply

Your email address will not be published. Required fields are marked *