During the holidays, many of us take some time off from our regimented workout schedules.  But exactly how long does it take for your body to start losing all of the progress you've made? While inactivity does leads to deconditioning, the good news is that with minimal effort, you can maintain the fitness levels that you previously had.

To answer this question, a number of factors have to be considered — age, length of training, type of exercise, etc.  Many of the items that will be discussed here — for example, VO2 Max — should be measured specifically for each individual.  So if you are truly interested in a specific answer to how fast YOU get out of shape, then you should go to a performance lab and have these numbers measured.  For now, I'll cover the general guidelines for everyone.

When talking about being in shape, one of the numbers professionals assess is the VO2 max. Without getting overly complicated, the VO2 max is the amount of oxygen that your body can consume.  Why does this matter?  Because the more oxygen you can consume, the more oxygen can be delivered to your muscles and the faster you will be able to run/row/perform.  Simply put, it measures your cardiovascular system's ability. Your heart is able to handle more blood when it is working out, when you stop, it is not able to handle as much blood and some of the capillaries that were carrying the blood will become diminished.  Once you begin working out again, though, these capillaries can refill.

Typically, within two weeks, we start to see a sharp decrease in VO2 max.  Some studies note that a sharp drop in oxygen intake can occur within 10 to 14 days. By four weeks, this number is notably decreased.  Fortunately, after several weeks (around 12-16 depending on which study you read) these losses begin to stabilize and you no longer lose much as time goes on.  Most studies say you will lose about 80 percent of your fitness levels after three months as it stabilizes.

Muscle strength is another factor is falling out of shape.  The bad news: It takes less time to lose muscle than it does to gain muscle.  The literature points to about four weeks before there begins to be a decline in muscle strength.  However, it does depend on how long you have been working out.  If you have been working out steady for a year, the time period seems to be slightly slower and you are able to hold onto muscle strength for a slightly longer period of time.  After one month, muscle fibers begin to diminish.  After eight weeks, the change becomes significant.

The good news is that you can maintain your previous strength and endurance levels by doing minimal exercise.  While you won't gain much from doing a minimal workout, you won't lose any of your cardio or your muscle strength either.  The video below shows a series of exercises that can be done at home.  It does not take very long but can be used to help you stay in shape over the holiday season.  You can do these exercises every day since they are body weight exercises and just meant to maintain what you already have.  If you feel any pain, you should stop and contact your healthcare provider.

No matter what you chose to do, you should make sure that during the busy holiday season you strive to maintain the strength and cardio endurance that you worked so hard to gain in the first place.

Read more Sports Doc for Sports Medicine and Fitness.