
Cardio Comes and Cardio Goes
Have you ever returned to the gym after a week off and noticed your cardio didn’t come back with you…and it’s only the warm-up?
How could this be possible? You put yourself through grueling workouts every day and have been for months. How could your endurance slip away after a mere business week off? As Scar says at the beginning of Lion King, “life’s not fair…is it?” Struggling in this way feels much like being that little mouse trapped under the claws of a lion voiced by Jeremy Irons.
There is science behind this phenomenon and it has to do with oxygen and blood. “Once cardiovascular training is stopped for two to four weeks, you may see reductions in your respiratory ability, VO2 max [the maximum amount of oxygen your body can take in and use in a minute], and your body will become fatigued more easily.” – Mark Barroso, C.P.T., a New Jersey-based trainer and Spartan SGX coach. “The benefits of cardiovascular training are more transient than those in strength training, meaning they occur quickly and go away quickly too.”
https://www.shape.com/syndication/shape-health-womens-half-marathon-2022
One study on Nutrition, Metabolism, and Cardiovascular Disease had a group of adults engage in regular cardio for four months, then take a month off. Ready for the bad news? They lost all their aerobic gains. Improvements in the good cholesterol and insulin sensitivity disappeared. Another expert noted that in two weeks there are significant changes in the body’s ability to utilize oxygen and glycogen.

https://www.nmcd-journal.com/article/S0939-4753%2814%2900042-8/fulltext
“The activity of oxygen-processing enzymes in the body’s muscles decreases and the muscles begin to hold less and less glycogen, your body’s stored form of carbohydrates. There’s a decrease in the number and concentration of blood capillaries in your muscles, which help deliver oxygen to your muscles and clear out waste products such as hydrogen ions.” – Chris Jordan, C.S.C.S., C.P.T., director of exercise physiology at the Johnson & Johnson Human Performance Institute.
The good news is that the benefits of strength training take much longer to wear off. Mark Barroso noted it could take six weeks to see a decrease in muscle, tendon, and the size and strength of the ligaments. It certainly doesn’t feel that way – but we’ll take it.
The bad news is that cardiovascular capability does wear off very quickly after a decrease in training, but it will come back!
The good news is that being healthy and fit is a lifestyle. We aren’t in here sweating just to look good on vacation. We train because we love to sweat, we love to get strong, and we love our CrossFit community. If our cardio progress disappears quicker than we’d like it to, then that’s just the way the cookie crumbles.
So if you just got back from vacation, or even an accidental week off when life just got busy, fear not. The body will readapt and you’ll be soaring through workouts in no time. But for now, stop stalling by the bike shop door and finish the hundred meter jog – we still have a whole workout to do!
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