What Happens When You Stop Exercising??

This has been a hot topic for me lately, mainly because I had caught spinal meningitis and was not able to exercise for 2 months and am just getting back into it.  So what does happen to your body when you miss workouts?  Quite a bit actually, and the longer you’re off the worse it becomes.  So without further babble here are some of the effects of taking time off.

Your Blood Pressure Rises: oh yea! Nope!

Your blood vessels start changing immediately upon stopping exercise and within a month you start to have stiffening of the arteries and veins. 

Your Blood Sugar Spikes!

After five days of not exercising your post meal blood sugar levels remain elevated instead of dropping.  Your muscles and other tissues do not process sugar as effectively according to the journal Medicine & Science in Sports and Exercise.

What about my Muscles?

Ten weeks of 3 weekly strength training session increase your total volume of fast twitch fibers by 22%, as well as the ratio of type IIa to type IIx.  But this starts to drop off as soon as five days of not exercising.  Your muscles also start to lose their fat burning potential and your metabolism slows down.  A study by the Journal of Strength and Condition found that in 5 weeks of not exercising collegiate swimmers’ fat mass increased by 12%.  I don’t know the other factors of this study but any increase is not good.

You don’t actually lose your muscle cells and they don’t convert over to fat, but they do shrink.  And your fat cells grow.  This equals change in appearance.  Perfect Party time – NOT!

So let us get to the meat of the endurance athlete changes from not exercising.  We all talk about this number all the time and its meaning…VO2. 

Here’s what research on detraining by Randy Wilber at the Olympic Training Center in Colorado Springs, Colorado tells us about the changes that happen after three weeks of no training [Wilber]: (This is pulled from Joel Friels Books The Triathlon Training Bible – a great read by the way.)

Effected Physiology


Heart stroke volume


Heart rate at submax effort


Plasma volume


Capillary density


Aerobic enzymes


Blood lactate


Lactate threshold


Time to fatigue





I even found information showing a 7-10% decline in VO2 after 12 days of sudden inactivity, 14-15% after 50 days and 16-18% after 80 days.  Research also showed maximal values for cardiac output, stroke volume, and the ability for mitochondria to extract oxygen each decline along the same lines while heart rate increase.

So bottom line, don’t stop exercising and stay as active as you can.  The good news is any decrease can be reversed with activity but you will have to be patient as you won’t be running your PR’s or getting your massive lifts right away.  300 minutes a week is recommended for any endurance athlete to gain benefits and keep your workloads around 70% of your current VO2.  For you math geniuses out there that’s 5 days a week of 60 minutes.  Have fun and stay active!

Interesting perspective on how devices have changed training over time.  Does this remind you of yourself or anyone else you know?  Remember whether training with a ton of devices or with just a watch, stay focused on what your goal is for that workout.  Have fun and train smart!

Coach Crow