HRM accuracy?

rachylouise87

i did 40 minutes of zumba and 25 mins of hip hop abs earlier. my hr was averaging at 152 which is 80% of my target zone. my HRM calculated calories burned at 950 for 65 minutes? does this sound right? im 5ft1 167lbs? i used an online calculator which used the average of 152 and got 630? but i was hitting 170-180 sometimes but still averaging 152.

MeanderingMammal

HR as a proxy for calorie expenditure depends on working in a consistent manner and within the aerobic zone.

About a 30% overestimation wouldn't be a surprise for what you describe.

An HRM is little more than a toy in those classes.

bwogilvie

^ What MeanderingMammal said. HRMs measure your heart rate, but they only estimate calories expended. The calorie estimate is based on a formula derived from lab studies of how many calories people burn when performing continuous aerobic exercise and how that burn is correlated to heart rate. The calorie estimate is not very reliable for other forms of activity, and even for continuous aerobic activity there's a lot of variance that it doesn't account for—for instance, as you become more aerobically fit, your heart rate will get lower at the same level of energy output, so your HRM will estimate fewer calories unless it includes an adjustment for fitness.

rachylouise87

hi thanks. how will i know what im burning if this is so hugely innacurate?

MeanderingMammal

As long as you're consistent about what you use to approximate, then you can adjust your treatment of the figures based on your experience.

If you put the figures in and you lose slower than you intend, then your deficit is lower than planned, so compensate. If you're losing faster then you're in a larger deficit. Just tweak your usage as your performance develops.

rachylouise87

thanks i calculated my target zone to be between 106 and 164 with 189 being my maximum hr and i was working at 80% which is 152. so on that i calculated it to be 622 calories. i dont think my watch was set up correctly. i have set the zones correctly now so it should auto calculate if not i will continue using the online calc as it seems more realistic. i had a feeling i was burning around 500 an hour which was not far off knowing i was dripping in sweat and feeling the burn

Chieflrg

rachylouise87 wrote: »

hi thanks. how will i know what im burning if this is so hugely innacurate?

By how much you lose or gain depending on your goals. 3500 calories equates to one pound lost/gained. If you are consistent, you will know real close to what you are actually doing.

rachylouise87

thanks my goal is 1-2 lbs per week but i have not lost for 2 weeks now and i think my calories and exercise are good.

MeanderingMammal

rachylouise87 wrote: »

have not lost for 2 weeks

You're not in deficit then. Either more rigour around your intake or reduce the volume of exercise calories you consume.

rachylouise87

thanks for that i feel i am in deficit but i was told i could be consuming too little with exercising. when i lost weight 2 years ago i was regularly working out and only consuming 1200 cals and this worked for me but this time round it doesnt seem to be working although my fitness level and body shape is changing. i guess i need to find what works for me

bwogilvie

MeanderingMammal wrote: »

rachylouise87 wrote: »

have not lost for 2 weeks

You're not in deficit then. Either more rigour around your intake or reduce the volume of exercise calories you consume.

Not necessarily. Weight loss isn't linear; since the typical person takes in more than 10 lb. of food, water, and air every day, it's possible to stall for 2 or 3 weeks due to water or solid waste retention. If you reach a couple months without losing, that is clear evidence that you've found your maintenance level.

rachylouise87

thank you. i do suffer with bad bloating and not going to the loo often enough even thought i have a good diet with plenty of fibre i do suffer with IBS. i tend to weigh myself first thing on a morning with no clothes and before i have eaten plus going to the toilet. i do feel like im working out hard 6 days a week and usually over 1 hour per day since my hrm is reading 152 and im sweating. sometimes when i dont feel im working hard enough i will push harder but i can feel my fitness level definately changing but not the weight which is disappointing. but i will keep at it and if im the same in a few weeks time i will try something new