In September I joined a gym. Big deal right (because who doesn’t belong to a gym nowadays?) but it’s significant for me. For the last 10 years I’ve worked as an exercise instructor, which means free memberships wherever I teach. I could only manage part-time, teaching at most four classes a week because I was also working 40 hours of “real” jobs. But just practicing for four classes was a workout in itself. So I’ve never needed to join a gym.

Now that my other jobs have demanded more time, I’ve sadly had to let some classes go. I wish teaching exercise class just meant showing up and jumping around. The easiest and quickest part is the teaching. But hours are spent beforehand searching, creating, testing, remembering, and rehearsing choreography. Some instructors do the same class weeks at a time, but I changed it up every week. I just couldn’t juggle the time to make everything fit.

So I’m a student again, taking others’ classes, and boy do I love it. It feels great to be able to put 100% physical and mental focus into the workout. I went a little crazy at first, taking two classes a day (also to make that ridiculously expensive monthly fee worth it)…barre, cycle, kickboxing, HIIT, Zumba, more Zumba, power yoga, hot yoga. And then I injured my hip. So I cut back to a few intense but safer workouts. This particular gym offers some classes at a pace that’s almost frenetic (yes, frenetic yoga exists) without the instructor watching people’s form, which is where I fell prey.

It got me thinking, what is a good level of exercise intensity to reach and when does it become not safe? We may self-regulate and slow down when a little discomfort sets in, such as heavier breathing or muscle or mental fatigue. If we slow down too much, this can cheat us of receiving full benefits of the exercise. The formats I’m still taking, cycle, muscle, and kickboxing, push for a higher intensity throughout most of class. There’s also a competitive spirit in classes where you want to keep up but most of all complete the whole workout. So I don’t usually slow down if at all possible. But when is enough enough, or occasionally too much?

The pics don’t show it, but my arms are SHAKING trying to maintain stability with these medicine ball planks!

Exercise experts suggest using the “talk test,” one measure of perceived exertion. If you can talk to a friend while exercising, you’re not reaching a high intensity level. Another is the Borg Rating of Perceived Exertion (RPE) Scale, an easy-to-use tool that fairly accurately estimates your actual heart rate during exercise. Below are my own intensity indicators but please note they’re not scientific in any way, just my experiences.

• Sweating steadily, I have to drink water and towel off every 15 minutes.
• I’m breathing quickly but at a steady rhythm.
• Nothing can distract me. I’m not able to think about anything or anyone else except willing my body to move as instructed.
• I start coaching myself: “push it, get through this, breathe.”
• I have to daydream scenarios to push through or increase my intensity: I’m riding the tour de France, I’m punching the daylights out of a terrorist.
• I feel like I can’t go on, but I do.

Compare these with indicators that suggest you may not be reaching your full intensity capacity:

• You’re checking the clock every 10 minutes.
• You’re chatting with a friend between sets.
• You admire that person’s shoes or outfit.
• You yawn.

Does that jive? You simply have the ability to be distracted, maybe because you’re bored or just don’t like the workout so you slow down or tune out. These indicators can also happen outside of class, for example if you’re on a treadmill or lifting weights.

The following are indicators that your intensity level may no longer be safe:

• You have difficulty catching your breath after a set is over and a few minutes have passed.
• You feel dizziness and lightheadedness that doesn’t resolve in a few seconds.
• You develop a sharp pain in a specific area of your body that nags you throughout the workout.
• You stumble on your feet; this may indicate excess fatigue so that you’re not alert.
• Your heart rate stays elevated after the class ends; this may be caused by dehydration or excess electrolyte loss from sweating.

In these cases, it would be a good idea to slow down the pace or even end the workout early. Keep in mind that each person’s capacity will be completely different, which is why a group fitness instructor should be watching their class at all times to catch people who are exercising beyond a safe level.

What is your experience with exercise and do you have a level of intensity that you aim for? How do you measure it?