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Cardio: One Size Does Not Fit All

I learned a lesson with one of my online personal training clients recently, and figured it would be a great blog post. She is training for a bikini competition, so as you can imagine, she is doing A LOT of cardio. And what this lesson taught me is that with Cardio: One size does not fit all.

I had mixed in high intensity interval training AND steady state cardio in her program, however it seemed she was gaining weight versus loosing it. At that point, I basically ‘phoned a friend’ as they say, and consulted with a nutrition expert. What we both found, after examining her background, is that her stressful lifestyle was not conducive to the high intensity of interval training I had her doing. Let’s quickly talk about the hormones that are secreted during exercise to give you the big picture.

When you perform cardiovascular exercise, your body is naturally stressed and secretes cortisol. Cortisol is what we call a catabolic hormone, aka it ‘breaks down’ protein in your body. The opposite of a ‘break down’ hormone, is the ‘build up’ hormone, which we call anabolic hormones. These hormones are involved in muscle tissue growth (yay!). When you exercise, both of these hormones are secreted in your body, and as long as a balanced ratio is present, ALL IS GOOD. However, when you have a significant amount more of the ‘break down’ hormones, Cortisol, that’s when things can go bad.

With high amounts of cortisol in the body, the hormone basically EATS your nice lean muscle mass. This is NOT good, because having more muscle mass gives you a higher metabolism, which equals more calories burned a day. But if your muscle is being broke down by that bad guy Cortisol, say BYE BYE to that higher metabolism AND say hello to increased fat storage.

  Again, cortisol is secreted any time you exercise, and is OK in small doses. But exercise is not the only thing that increases cortisol….I present to you: STRESS.

YES- in this day in age, not enough time in the day, playing several roles to different people, careers, children, spouses, etc wreaks havoc on our stress levels. Let’s face it: OUR LIVES CAN BE STRESSFUL. And generally speaking, some people can handle stress better than others. But when your stress levels are extremely high, guess who comes to visit: Good ol Cortisol.

So we established that exercise secretes cortisol, and stress does as well. So let’s add in one more factor: High Intensity Aerobic Training. This type of cardiovascular training increases cortisol much more than just steady state cardio. This is exactly what happened to my online personal training client. Her cortisol levels were becoming so high because of the high intensity interval training she was doing AND her stressful lifestyle. This was preventing that lean muscle mass from forming and probably also breaking it down, causing her metabolism to be low and her body storing fat. (geesh that was a lot). Because of this, she was gaining weight. I then switched her plan to only doing steady state cardio that was 65%-75% of her max heart rate, and she starting loosing weight. WINNING!

TAKE ACTION: Determine your current level of stress in your life. I like to use the 1-10 scale. On a scale from 1 to 10, 1 being very little stress and 10 being a TON of stress. How would you rank your current stress level? If it is in the 7,8,9 range, take out the high intensity workouts, and back down your cardio to 65%-75% of your max heart rate until you can get your stress levels under control.

You determine your max heart rate subtracting your age from 220. Then you would take this number and times it by .65 and .70. For example:
30 years old
Max Heart Rate=190
190 x .65= 123
190 x .70= 133
Heart rate should stay between 123-133 beats per minute.


{ 4 comments… add one }
  • Melissa June 23, 2015, 9:17 pm

    Hi Amanda! What is the recommended amount of time to do cardio if you are targeting this heart rate range?

    • Amanda July 1, 2015, 7:43 pm

      Melissa- I would recommend no longer than 30 to 35 minutes. Anymore than that will start breaking down that nice lean muscle mass you want to keep.

  • Fitnesstrainer August 1, 2015, 8:03 am

    Hiit training produces testosterone not cortisol. Steady state training is catabolic

    • Amanda August 2, 2015, 2:34 pm

      Fitnesstrainer: When you are performing HIIT, your body is mostly working with anaerobic glycolysis. When you approach 85 to 95% of VO2max (is with most HIIT) , growth hormone, testosterone, endorphins, epinephrine (adrenaline), norepinephrine (noradrenaline), cortisol, and aldosterone all increase.
      Also- HIGH VOLUME steady state cardio creates catabolic responses. Lower volume steady state does not.

      In addition, I did state cortisol is increased with ALL aerobic exercise, including steady state.

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