Mid-40s man. Is heart rate hitting low 180s during cardio safe, or should this be concerning? (lemmy.world)

submitted 1 month ago by tomkatt@lemmy.world to c/fitness@lemmy.world

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I'm in my mid-40s and I do cardio 3x weekly, and during my sessions, it's basically HIIT training. I try to keep my HR above 150 during my sessions, but it peaks in the low 180s intermittently.

Is this okay? My doctor noted potential concerns with getting my HR up that high, but it could be fine, she wasn't sure. I don't get any dizziness or anything (generally that happens if I sustain a heart rate above 185 for a bit). I'm not staying at 180 bpm, that's just the peak, I'm targeting an average HR of around 150-155 for my workouts.

In a 60 minute workout, I'll probably spend 10-15 minutes with my HR between 166 and 182 range.

Not sure if I should scale it down a bit or take it easier, or if this is fine.

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[-] MalReynolds@slrpnk.net 3 points 1 month ago* (last edited 1 month ago)

You're fine with that resting. One thing to note is that if you're low carb or exercising fasted, the heart runs better on ketones (cleaner fuel) but has more work to do (fat->liver->ketones->muscles and direct fat->muscles instead of in-situ glycogen->muscles) so runs about +10BPM in cardio. Known phenomena and actually a good sign heart health wise.

[-] tomkatt@lemmy.world 4 points 1 month ago* (last edited 1 month ago)

Good to know. I'm not doing keto, but I have a relatively low carb diet because I'm a type 2 diabetic (well controlled, IIRC my last A1c was 5.7). I exercise in the afternoon/evenings, so never fasted.

[-] MalReynolds@slrpnk.net 2 points 1 month ago

If you want the nitty gritty (or feel the need to convince a doctor) check out "The Art and Science of Low Carbohydrate Performance" by Phinney and Volek. Pretty much the bible on the subject. Fair warning, technical, but a good reference.

Thanks for making me look, turns out there's a "The Art and Science of Low Carbohydrate Living" now that I'll be checking out, might be more accessible. Ignore the overheated blurb on the back, these guys are serious scientists, seems their publishers are not.

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