Heart rates and exercise safety

August 31, 2006 5:44 PM

Heart rates and exercise safety

Bathsheba has recently started working out every day after work. Before, she walked here and there sometimes and was pretty active on weekends, but she was not doing any kind of daily sustained exercise. She's kinda fat and out of shape but has never had any cardiac problems (as far as she knows). Her blood pressure is excellent and her resting heart rate is usually around 55 or 60.

Since she is in her mid-twenties, target heart rate guides suggest her maximum heart rate during a workout should be around 160. Sometimes she exceeds this level slightly with seemingly no adverse effects. She has no problem sustaining activity for half an hour or longer at a heart rate around 160.

Is exceeding the target heart rate dangerous? Could the guides just be wrong?

posted by riotgrrl69 to health (14 comments total)

yeah i think this is silly worrying on her part but she really wanted me to post it.
posted by riotgrrl69 at 5:47 PM on August 31, 2006

When I work out, my heart rate is regularly in the mid-170s, and sometimes goes over 180 -- though if I try to keep it above 180 I start feeling sick.

I'm a late 20s woman with a resting heart-rate around 50 or 55. I have no medical knowledge whatsoever, but I've been doing this for about six months and I've been feeling the best I've ever felt in my life.
posted by croutonsupafreak at 5:51 PM on August 31, 2006

The guides are just guides, with considerable variation between people (I know a superfit marathoner who maxes out at 180 or 190). If she can sustain it for 30 minutes, she's likely working aerobically (ideally she should be able to hold a conversation while working out).

Of course, there's always the possibility that there's something wrong with her and a full medical exam would be needed to try to rule that out, but exceeding 160 bpm isn't definitive proof of a problem.
posted by cardboard at 5:53 PM on August 31, 2006

I wouldn't worry at all until at least 180. The targets for aerobic exercise are more about fat burning and cardiovascular training rather than safety - too high and you burn carbs rather than fat (and will tire too quickly); too low and you're wasting time.

Barring a medical condition, I think it's pretty hard to get in to a dangerous situation.
posted by 0xFCAF at 6:09 PM on August 31, 2006

To determine your correct max heart rate, you need to do some tests. Google for something like "how to find your maximum heart rate" and you'll see some examples.

Like has already been stated, everyone is different. A friend of mine who does triathalons has a max HR of, like, 175. I'm in my mid-twenties and my max HR is 203 (which means I try to keep my heart rate between about 155 and 180 when working out).

If you need more info, I can dig up the sites I used to determine my max HR and the like. Email's in my profile.
posted by bibbit at 6:25 PM on August 31, 2006

Those guidelines are not great science. Google the origin of the chart and prepare to roll your eyes.

Your actual max heart rate is exactly that-as fast as your heart will beat.

Let me give you some context. I am forty-seven and female. Today in spin class I stayed pretty much in the 160 heartrate range and was aerobic. When I have pushed it in the past to see how high I could go I could max around 184 (not that I recommend that. ) Just from exercising for awhile, I have a pretty good idea of what my heart rates should be depending on my goals for the workout.
posted by konolia at 6:29 PM on August 31, 2006

I kept an average of 168bpm over two hours of biking (18-22mph) this morning, and that's pretty usual for me on that route. My max was 190bpm. I spent over 50% of my time over 90% max, which is theoretically 185bpm for me. Now, the point here is that I know people in roughly the same physical shape as me that do the same rides at much, much lower, around 120-140 average. Even allowing them being in better condition, that's a large difference.

So.. it's pretty much just an individual thing, and if you're concerned, a doctor can give you great advice. My last EKG was a bit strange, but my PCP said she sees the specific weirdity "in athletes", and that it's no big deal. My pulse/HR and sweat are all very quick to increase and decrease in intensity, and I think that's a good thing - though perhaps a little gross. :) From what I've read, those who sweat more quickly and more intensly are typically better suited for physical activity, even though it sounds like the opposite at first glance. I bet the same could be said about heart rate, but again, no one can say if she's in danger or not but a qualified physician.
posted by kcm at 6:41 PM on August 31, 2006

The heart rate chart says I should max out around 180, but it's impossible for me to keep the heart rate that low and get any kind of decent workout.

Go at a pace that keeps you breathing heavy and gets your muscles working without leaving you breathless.
posted by schroedinger at 6:42 PM on August 31, 2006

This site discusses the rating of perceived exertion and the "talk-sing" test as other ways of measuring how hard you're working.
posted by mogget at 8:02 PM on August 31, 2006

Depends on what she's trying to accomplish. A longer workout at a lower heart rate is best for building endurance and burning fat, whereas a shorter, more intense workout is appropriate for building strength and speed.

The maximum heart rate for someone in their mid-twenties is actually somewhere around 195 (160 is definitely NOT a problem assuming that you're in reasonable health - I'm not a doctor, yada yada). The aerobic zone, which is best for burning fat is between 60% and 80% of that (140 - 168 bpm). Between 80% and 90% (168 - 182 bpm), you're depleting glycogen stores (ie. starving your muscles). You can go between 90% and 100% for short period of time and this will build speed (this is what you do in interval training).

I've never seen any information that says whether extended workouts at or near 100% are dangerous, but then again I've never been able to sustain 90% for more than a few minutes at a time -- my legs (I'm a runner) shut down long before I feel like my heart is going to stop/explode/whatever.

There are lots of good sites that can help you calculate your optimal heart rate for your goals - just google "Max Heart Rate".
posted by jknecht at 8:24 PM on August 31, 2006 [1 favorite]

Here's the one I use.
posted by cowbellemoo at 9:29 PM on August 31, 2006

Sounds like she's fine. Congratulate her on her decision to get more exercise, and be supportive! :)

If she starts feeling pain when her heart rate gets that high or is unable to breathe adequately, that could be a problem. But otherwise, she doesn't need to worry.

Does she have a doctor she can go to just for a physical?
posted by drstein at 9:44 PM on August 31, 2006

No chest pains? No dizziness? No shortness of breath? She's fine.
posted by nanojath at 11:11 PM on August 31, 2006

Is she basing her rate on the sensors on a machine in a health club? I don't think those are at all accurate.
posted by ClaudiaCenter at 11:17 PM on August 31, 2006