Ever gotten out of breath when you're lifting heavy weights? If you have, you're not alone, and that response is totally normal in your physiological effort to recover from that stress.

I used to train a National Team Bobsleigh athlete who wore a shirt to training that read:

..and she would exclaim during training that if she had >5 rep exercises in her program that the program was a "cardio day", ha!

Well why then, might you ask, does it seem like your out-of-breathness (scientific term) seems to improve when you consistently stick to weight training for a number of weeks or months?

With a new study that came out, and some social media icons that made a pretty misleading post about the study, I felt the need to do a deep dive for you, so I wrote a full blog about it all HERE if you want to read my heavy lifting on the topic.

The TLDR (too long didn't read) on "squats as cardio" is:

• While traditional weight training primarily uses the anaerobic ("fast") energy system, and not the aerobic ("cardio") systems to produce energy, there IS some aerobic involvement to squats, and if you're working really hard at a moderate number of reps, you CAN elicit a high oxygen consumption relative to your VO2max
• This is deceiving because you need a lot of volume of training at VO2max to elicit changes to your VO2max (which is a gold-standard measure of aerobic fitness/capacity)
• Since really hard sets of squats only bring you to VO2max for a short period of time, you would need to do something like 20 sets of 10 reps of heavy squats with 3 minutes rest between sets (a gargantuan 80 minute workout) to elicit a similar volume of VO2max training that a basic VO2max workout while running, cycling or rowing could give you. This is problematic secondarily because of the amount of soreness this would cause you - the workout is really not repeatable... something that matters a lot for long-term adaptations
• It's important to keep in mind that things that raise your heart rate don't necessarily equate to effective training stimuli - for example you could spike your heart rate right now just stressing about your in-laws coming to town this weekend - and that wouldn't count as conditioning because your tissues wouldn't be taking in any more oxygen than if you were relaxed and thinking about the beach

Reach out if you have any questions or comments & as always, I hope this was helpful. Forward it to someone if it was.

Yours in physiology,

Carla