I've noticed several times that by the end of a cardio (exercise bike) session my breathing is not elevated, in fact when I notice during a session it feels I'm barely breathing at all.

This is a reasonably strenuous workout by my standards (40-45min, 19mph, 150bpm, 350kCal) by no means a spin class but I'm sweating substantially and my legs are tired, and I'm neither young (40) nor a physically active person.

Logically it makes sense for an endurance exercise your body has to find a level it can sustain but having no knowledge of such things, is it typical to not be out of breath? Does it mean I'm not working enough?

1 Answer 1


There are three types of energy systems used for the body:

  1. Anaerobic Alactic (ATP-CP) Energy System (High Intensity – Short Duration/Bursts)
  2. Anaerobic Lactic (Glycolytic) Energy System (High to Medium Intensity – Uptempo)
  3. Aerobic Energy System (Low Intensity – Long Duration – Endurance)

It's best to think of a work ratio, #2 is a work/rest ratio of 1:2, such as working out a minute and resting one to two minutes, while #1 is about 1:5 -> 1:10, working out for 20 seconds and resting 3 minutes. Aerobic is the opposite, any ratio where the work is greater than the rest, typically with a 2:1 ratio.

The thing about the energy systems is that they are actually all used to some degree in each kind of endurance exercise, but one is heavily used more than the other. Breathing heavy after cardio is a result of your body using more oxygen to power through your workout. This can be reduced if you're in shape, don't have asthma or other respiratory conditions, doing higher intensity, or conditioned to your workout.

To answer your question, it's perfectly fine, if not even an achievement that you are not out of breath. These are some reasons why without knowing the smaller details:

  • You have been doing this workout for a while and are conditioned to it
  • The workout could be strenuous enough to reach into the other energy systems, although after 40-45 minutes this would naturally lead into aerobic, but the beginning of it could be using the others, and you could possibly be slowing down by the end of it, relying on aerobic energy. It is difficult to use a high intensity for a long time, as naturally your body will quit using that specific energy system and go down the ladder, until it ends with aerobic. Imagine sprinting as long as you can, you're going to slow down until you basically are jogging after a couple minutes as your aerobic energy is not strong enough to power your body into a sprint
  • If there are rests involved, you could be using more of other energy systems and relying on them(not sure if your program involves rest periods)
  • Even if this is a new workout, your body might just be in shape more than you think, and not running out of breathe
  • You are just good at controlling deep meaningful breathes instead of short huffs. You actually are breathing hard, but just in a relaxed, controlled manner that might not be as perceptible. If there are no rests involved, and are working more than you are resting (45 minutes 0 rest), than you definitely are using oxygen at an increased rate

Most people somewhat in shape won't be huffing and puffing after a workout, but it is normal to have increased breathing in and out. Just because you arent suffocating after a workout doesn't mean you are doing something wrong. In fact if you were out of breath, it might be an indicator you're out of shape.

  • Interesting stuff, thanks. I do quite a bit of singing and wonder if this might contribute to "good at controlling deep meaningful breathes" as you put it
    – Mr. Boy
    Mar 14, 2022 at 16:49

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