heart rate not increasing during exercise

kalincombs · August 2019

hello! i was hoping someone could give me advice about something. i typically weight train 5x a week (have been since about november) typically at the hypertrophy level and when i do i wear my fitbit to track my heart rate. i am studying for my personal trainer certification with ACE, and i learned recently from my textbook that your rate of perceived exertion can be determined on a 6-20 scale, with 6 corresponding to a heart rate of 60bpm and 20 corresponding to 200 bpm. lately my workouts have shown my heart rate average around just 105bpm, though i feel like i am exerting myself much more than that. on the RPE scale, 10-11 represents a “fairly light” level of exertion. i understand that this includes my heart rate during rest periods, but even my max recorded heart rate seems low. on my most recent leg day might highest HR was 125bpm. my resting HR is about 60 bpm usually. when i am doing LISS (for example, stairclimber on level 7 for 20 minutes) my heart rate gets up pretty high, up to 171 bpm on my last stairclimber session. but when i lift weights it just never seems to represent the level of difficulty i perceive. i’ve been weight training for about 9 months, with at least 6 where i knew what i was doing and followed a good routine. i’m female, 132-133 lbs, 5 7, and about 16.7% bf.
for reference, my most recent leg day:
3x 12 stiff leg deadlifts @ 70 lbs
3x 10 sumo squats @45 lbs with squat jump
3x 8 leg curls (machine) @80 lb (i think)
(superset) 3x (each leg) 10 lunges on the smith @80 lb + 3x 30 calf raises (same weight)
3x 12 hip thrusts on the smith @125 lbs
3x 12 half squats on the smith @90lb
3x 12 hip abductors @280 lbs (leaning forward)
if anyone could give me some kind of help with this i would really appreciate it! it’s very discouraging for my fitbit to show me that i’m not working very hard even though i feel like i am

thank you!

dewd2 · August 2019

OK - I would be questioning the certification if that is what it teaches...

There are so many variable to HR that it is not possible to make a blanket statement like that. Do you know your actual max and min HR? How accurate is a Fitbit at measuring (guessing it is wrist based).

Variables include things like temperature and humidity. How tired are you. Have you been over/under training. How long have you been training.

Seriously, I would question this.

Cherimoose · August 2019

It's normal for strength training to not spike your heart rate. RPE works best with cardio. That said, verify the accuracy of your Fitbit by checking your pulse manually.

AnnPT77 · August 2019

There are different types of exertion, simplistically speaking. The exertion you subjectively perceive during weight training is not primarily cardiovascular exertion, so there's no reason to expect your heart rate to correlate with that subjective sense of exertion in the same way as it does for cardiovascular exercise.

Heart rate is not the measure of anything other than heart rate. It correlates with oxygen uptake (VO2), which is relevant to the type of exertion that occurs during aerobic exercise. Heart rate increase during weight training is related to pressure or strain, not oxygen uptake.

sijomial · August 2019

Perceived exertion doesn't equate to certain heartrates, not on an individual level for different exercise let alone on a population level.

My tested max HR is 176 so does that mean I can't ever achieve high rate of exertion becuase it's a physical impossibility for me to hit 200bpm? Your HR of 171bpm during LISS is beyond what I will hit climbing a 20% gradient on my bike at maximum sustainable effort.

There really isn't any benefit to knowing your HR during strength training by the way - it's not cardio.

There's a list of professionally designed programs in the "Must Reads" sticky threads at the top of this forum.

yirara · August 2019

Ok, ask for your money back and look for a decent certificate. Next to what others have said, maximum heartrate is very individual and determined by genetics. About 50% of all people fall way out of the rubbish 220-age equation (Hey, I'm 45 and my max is at around 205). Also, there are so many other factors that influence HR, like temperature, being a bit sick, being on asthma or thyroid meds, time of day, time of month for women and lots of other things.

gottswald · August 2019

I'm on a beta blocker for migraines. My hr is artificially low and resists changing. What you're talking about is the Borg scale, which is perceived exertion, not any kind of mechanical valuation.

Jthanmyfitnesspal · August 2019

Try doing a cardio workout, such as walking up a hill or on a treadmill at >4% grade. It'll go up.

Azdak · August 2019

The correlation of the Borg RPE levels with a particular heart rate is an old correlation that dates from when the Borg scale was first developed. At the time, most exercise training was geared towards younger individuals—we were ALL younger back then :-(
So the relationship of the Borg readings with a specific heart rate (eg RPE 6 = 60 bpm) was part of basic training in exercise physiology, but that’s a long time ago. That part of the Borg scale was being dismissed when I was in school over 35 years ago.

The ACE certification is not a bad one. I wouldn’t consider it top tier, but it’s at the next level down and there are very good people involved in the organization. It just shows what you have to watch out for when education is based on a certification program rather than a grounding in the fundamental principles of exercise physiology.

And, to be honest, a lot of experienced lifters and exercise professionals make this same mistake—maybe even the majority.
Even in degree programs for EP, the nuances of heart rate response are not really addressed. A brief search on the Internet will find innumerable articles which claim that the HR increase during strength training “proves” that lifting weights can be the same as cardio—often written by people with lots of letters after their names and a “celebrity” status.

The takeaways here are: A: the Borg RPE scale is not relevant to resistance training; B: Heart rate response during weight training does not correspond to lifting effort; C: Heart rate increase during strength training is driven by a completely different physiologic mechanism than during cardio and so you cannot compare the two.

Start with those and then plan to learn exactly why that is and you will make yourself a better professional.

quemalosuerte · August 2019

Using your fitbit for accurate heart rate monitoring will drive you crazy. Exactly where it is located on your wrist can change the heart rate it measures drastically, especially during physical activity. Heck, i’ve even noticed mine change numbers based on which hand or pocket my phone is in, if i get a text, etc. If you want to accurately measure heart rate during exercise, you may want to look into a chest strap design, and/or consult a doctor for recommendations.

cwolfman13 · August 2019

Weight lifting isn't cardio...you have plenty of rest periods, so suffice it to say your average HR is going to be lower. 105-110 as an average during a lifting session sounds about right. Your HR during a lifting session does not correspond to effort.

heart rate not increasing during exercise

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