Back in the 70s and 80s, aerobics became incredibility popular. Remember the step aerobics craze? Jazzercise (still going strong)? Tae Bo? For years, exercise was synonymous with the term aerobics, yet that’s really only one small domain of physical function. Cardiorespiratory is three distinct systems that all function together: aerobic, anaerobic, and CP (creatine phosphate) systems. Longer distance activities, like walking, swimming, and running, use the aerobic component, things that are done repetitively for a long period of time.

Aerobic Exercise

Oftentimes people think they need to take up running to get exercise or to get in shape, but you really don’t. You absolutely do not have to “be a runner!” The truth is, if you don’t intend to run marathons or half marathons or even a 5k, you only need enough aerobic capacity to do whatever it is you like to do, right? Maybe that’s tennis, golfing, swimming, skiing, whatever. You need the aerobic capacity to do these activities and to remain healthy, but you don’t have to have the aerobic capacity of an Ironman triathlete! Keep that in mind when you think about aerobic endurance.

Anaerobic and Creatine Phosphate Exercise

The other two categories are equally important: anaerobic and creatine phosphate. It’s likely you’ve never heard about your creatine phosphate function, but you’ve probably heard of that joke “I don’t have to be able to outrun the bear, I only have to be able to outrun you.” That’s the creatine phosphate system. It’s our short-burst sprint energy system. If you have to run up a set of stairs really quickly, then you’re using your creatine phosphate system. If you have to run to your parked car in the pouring rain, you’ll use your short-burst energy system. Now most of us don’t train this aspect much. When was the last time you went on a 20-yard sprint? When was the last time you jumped up and down from the floor ten times? Short bursts are important; we need to train that system as well because you never quite know when you will need to do something very quickly.

The anaerobic system is somewhat in between. It’s your ability to do something fairly intensely for about 30-90 seconds. It might be running with a child up a short hill, chasing after an escaped pet, or climbing three or four flights of stairs fairly quickly. Anaerobic work is much more intense than going for a walk or for a run. In fact, it’s something that you can’t do for more than a minute or a minute and a half. But we have to be able to do these things so we are ready for anything, right? For example, think about going for an outdoor hike. Most of it is going to be in the aerobic zone, slow and steady. But what if we come to a steep, rocky section on the hike? All of a sudden, we have a pretty strenuous climb – while navigating rocks! It may only be a rough terrain for about 100 yards, but are you ready for it? When you get to the other side of that climb, can you recover quickly and continue? Or are you wiped out because you don’t have good anaerobic systems, and you just can’t continue. This is when you see and notice what differentiates people who can endure vigorous outdoor activity from people who can’t.

Some people don’t have the anaerobic capacity to take on hills or steep elements, and often they have to turn back. You don’t want this to be you, right? Hopefully, this explanation shows you that there is more to our cardiorespiratory system than just aerobics, and that we need to train differently to improve each aspect of our cardiorespiratory system.

Achieving a Good Cardio Mix

With a fitness coach that understands the six-domain approach to physical training, you will find that your training sessions include a variety of exercises and drills that improve your aerobic, anaerobic, and creatine phosphate systems. Don’t worry! They won’t yell that while you’re working out! Instead, at times you will think “Wow, that was really intense. We were working out our creatine phosphate system!” Or, maybe, “Whew. Those suicide sprints were exhausting… nice anaerobic exercise!”

As part of a workout, the coach might include one-minute, high-intensity exercises that are followed by a brief recovery period. This combination is important – intense, then recover- because it challenges your body, gives you a brief rest, and then the challenge starts again before your heart rate returns to its resting rate. Studies show that these short bursts of exercise activate your muscles so effectively that even after you’re done with your workout, the muscles are still functioning at a higher, more intense level.1 Of course, your workouts will, at times, also include aerobic activities. You might jump rope, do step ups, or even jog around the gym between exercises.

The key to an effective, overall workout is variety! We know how to vary and balance your workouts so that they target what you need over time. At the same time, we are making sure that you are working out all six domains. The biggest bonus? Doing different types of exercises during every workout makes it fun! You never know what’s coming next, but you’ll quickly find out that you can meet the challenge!

  1. Katherine Hobson, “Does 1-Minute Interval Training Work? We Ask The Guy Who Tested It,” NPR, February 7, 2017,