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Garmin Forerunner 305 GPS Heart Rate Monitor has a Useless Calorie Counting Feature

eebee's picture

If you're in the market for a heart rate monitor and place great value on the calorie counter function, I would not recommend you buy a Garmin Forerunner 305.

Thinking it strange that the Garmin unit didn't seem to care what sport I was going to be doing if it wasn't cycling or running, I selected the 'other' sport during set up, along with my weight and date of birth. Imagine my amusement when an hour of slightly hilly skating with the Garmin 305 yielded a calorie count TWICE that of my old Polar monitor. I know this watch is huge, but it doesn't weigh THAT much! After hurriedly consulting the Garmin 305 flyer--I mean manual--I found no answers there as to how the thing calculates calories burned. Are all those 'rollerblading calorie charts' wrong? Do I really burn 1,500 cals an hour instead of 750? Wow! That's two whole bags of jalapeño potato chips.

Not that Polar, or anybody at all has it down to an exact science, but the Garmin 305 way of counting calories sadly isn't even in the ball park. Perhaps it'll take some preposterous lawsuit à la Trimspa/Anna Nicole ("Waaah! I'm still fat because of you!") to prompt Garmin to change this useless feature before they lose the hard-working, money-earning endurance athlete crowd.

Today I finally made the time to check the Garmin stuck-at-square-one website for an answer, but gave up and checked independent reviews instead. Not looking for concurrence, I found some who echo my findings. A good review by Kristin Kalning of MSNBC, posted about a year ago:

"We endurance athletes tend to be an obsessive lot."

Um, yes.

"...the Garmin Forerunner 305, a GPS-enabled trainer for runners, cyclists, hikers, walkers, inline skaters..."

Hey! She called us inline skaters! Thank you.

"...the calorie-count feature was the biggest disappointment of the Forerunner...tallied a whopping 700 calories burned during my bike ride, while my trusty Polar heart rate monitor tracked the same ride at just 550 total calories. Sure, I’d like to believe the Forerunner...but 150 calories is a big discrepancy."

She explains...

"Garmin uses speed traveled — not heart rate — to calculate calorie output on the Forerunner."

It does WHAT with it, Walt? Well no wonder! If the computer thinks I'm cross-country skiing it must think I'm exerting my butt off at 30mph instead of chilling down some steep hill, watching the ducks. Kalning then adds you can't use the calorie counting function indoors for the same reason, since it won't know how far you traveled.

"The company acknowledged that the calorie-counting aspect is the weak link of the device, but a free software download, available on their site, apparently improves the accuracy quite a bit."

Well I will try that and post about it later.

In other reviews or angry blog comments, others claim Garmin uses speed and/or elevation to calculate calories. One poor guy slogged his heart out on the tennis court for an hour, but only covered a short distance and therefore only burned 205 calories! What a swindle.

Aside from this major flaw in the Garmin Forerunner 305, I am enjoying its other features, such as the GPS, elevation, distance, average heart-rate at any given point in your skate/ride/run without having to call a new lap, automatic laps based on location--all displayable in multiples of 4. And how prettily they all come together in charts on my computer screen at the end of the day.

It's not that I'm not open to newer, possibly more accurate ways of nailing down calorie expenditure, but to base it on distance, speed or anything other than the hot bod itself exerting the energy seems like a bad idea, and a flippant decision by Garmin.


MikeB's picture

things that make you go "hmmmmm"

Thanks eebee. It never dawned on me to have this kind of data at my disposal. Time skated would be good to know, and/or lap times (hence the triathlon watch) but I can sure see how GPS, elevation, distance, heart rate, calorie count etc. would all come in very very handy. I'd like to hear from others to see what they use and the pros and cons. MikeB
roadskater's picture

You Mean I'm Not Burning 50% More Calories Doing the Same Thing?

Good stuff, eebee. It's a shame you're so shy about it all, or we'd know what you really think!

I have loved having the Garmin Forerunner 305 and at under $200 it seemed like a bargain, and I think it still is. However, there are annoyances, especially for non-runner, non-bicyclists, and I occasionally wish I were wearing both the 305 and my Polar 720i (or whatever). So far I have not worn both, but one day I hope to do some laps with both and compare the output for the world here. I was hoping to get in better shape first, ha!

But the dream of just ONE device that does it all well still eludes me. We'll see what the future Forerunner/Edge series come up with, and who knows, maybe Polar will get a clue? (That's a prompt for a Skatey-Mark rant, optional of course.)

One annoyance is that I have to look at a skier, runner or cyclist to represent what mode I'm in. With all their work with icons, why not either find a generic icon or let us choose from a few? This is a minor thing, but they "specified me out," as so often happens to "fringe" sports...except when it suits Olympic coverage when USAmericans, especially outgoing and pretty ones, are thought to be in medal contention.

I can say that I knew but didn't really think enough about the altitude info before I bought the 305. With the Polar 720i (whatever 700 series unit), if I go do laps at Country Park and forget to count them, I can look at the altitude graphs later and easily count the laps even if I never pressed any buttons...and I can get an idea how long I sat on the bench and watched the ducks and geese. That's kind of cool. The elevation readings may be trending upward or downward because of the weather, but the shape of the altitude graphs is very similar from lap to lap. I can even insert lap markers in the software diary and such. It's a nice setup. But no speed or positional data for skaters wearing Polar 7xxi series.

There are a couple of major ways to determine altitude, and the Polar 720i uses a barometric altimeter. This means it measures the air pressure to calculate the altitude, which is fairly accurate if you start at a known altitude and if a weather front doesn't move through during your workout, or the temperature at the point of measurement doesn't change dramatically. When the ambient barometric pressure changes, this will affect your Polar's readings, but they'll drift upward or downward and if you're doing laps it will be easy to see. If doing a long course or hike, the readings can be affected dramatically by the weather, so it's good to reset the reference altitude on hikes, for example, where elevation signs are handy. Disregarding weather-based barometric changes, the lower you are in altitude, the greater the pressure pressing down on you from the column of air above, so this is why barometric pressure relates to altitude.

Also, for more accuracy, keep the device where the temperature is most likely to remain consistent. Sometimes, if you've been wearing the device all day, for example, this may be on your wrist. Sometimes it will mean wear it outside your jacket or clipped to your pack...if you care that much!

Instead of including a barometer in the Forerunner 305, Garmin apparently uses only the Global Positioning System measurement of elevation. GPS altitude (the Z-direction) has as much as 50% more error than the X-Y direction error (North-East-South-West, etc.). What does that mean? Well, if you have only 30 feet error in the X-Y direction, that's pretty good (though not the best you'll do, this will often be the best in valleys with tree cover). 10 yards is not far to travel, particularly on fairly flat land. But think about that 150% error in the Y direction and you'll realize that the up to 30 foot X-Y error means up to 45 feet of Z (elevation) error.

For me, skating up 45 feet is a million times harder (OK I exaggerate) than skating 30 feet across flat land. While GPS is frighteningly accurate, or thought to be, especially in terms of targeting rather large bombs, for peaceful human active transportation purposes, it's not always as good as we'd like, especially hiking Mt. Mitchell, biking up Pilot Mtn., or skating up Old Rosser Road and over Silver Hill.

The best idea is to do what the Garmin eTrex Vista does. It uses the barometric method of measurement but automatically self-corrects the readings and adjusts the reference altitude based on GPS data and internal map data built in to the eTrex. These more sophisticated handheld GPS handle atitude information very well (but they are bulkier, chew batteries like taffy, and don't read the heart rate info).

I wonder if the Garmin Edge series handles this issue any better than the Forerunner?

And why so much talk about altitude and speed when eebee was writing about calories? Well, it is amazing if true that Garmin would be so silly as to base calorie burning on speed measurements, even if including altitude, while ignoring heart rate. Heart rate seems to me to be the most reliable way of estimating calories, even if depending on the user to look up their activity in a chart like the Medion cheapies we bought at Aldi (which worked fine by the way and have often served as backups for our more expensive hardware; also the Performance Bike Axiom units have been great).

As for the calories, I can't recall the details, but several on occasions I was aware that the 305 was giving me generous calorie burns vis-a-vis the Polar and others. And those other units had that intensity setting that affected the calorie burn number too. I think once in the car I was still wearing the 305 and had not turned it off...I was burning mondo calories in my car even including stop lights...with no heart rate from the strap (might not have been on even)? As I say I can't recall the details but I had already begun to question those figures and eebee's comments seem correct.

Sad, especially considering the really cool feature that lets you add pack weight or any kind of "extra weight" into the calculations of the Garmin. Nice idea that gives a perhaps false sense of precision.

Of course, we should say that the Polar figures may not be correct, and we've sometimes thought even those to be generous. But based on all we can find, the Polar seems to have a much better calories burned estimation. 

Regarding that "Other" sport mode, with the little skier icon, I plan to switch over to using the bike mode at some point, I think, to see if I like the workouts there. This is all if I get around to doing it of course! But the bike and run modes have some preset workouts that seem pretty cool.

Overall, I really like the 305. I especially enjoy the various kinds of data you can get fairly easily and the programmable screens (though I wish there were at least one or two more screens I could set up to rotate among).

I like a lot of the automatic features and that they can be turned off. It's nice to have your dream speed (average speed while you were moving only) and get real speed (including while you were in a ditch crying or at a rest stop panting). I especially LOVE how it uses the GPS to count laps automagically based on your button press or start position or both, and that it can take more segment readings based on position as well.

It's a really nice product overall, and the GPS reception seems really good...better than the old handhelds I have around. The WAAS corrections seem to help with accuracy, too.

I think there is a lot to love in that little Garmin 305 (OK not so little, but after wearing it I'm used to it). But calories burned is questionable, I agree, at least until we can find out ways to tweak it perhaps, and oh yeah, check out that firmware download. (Please let us know if you find a link for that.)

I still miss some things about the Polar 720i, but then I don't miss being angry at the Wear-Link strap, which some days just doesn't want to take readings for a while. This may be "my fault" somehow, but as timv often mutters, even an inexpensive heart rate monitor should have a strap that works. And I won't miss the whole Polar scam of not having a replaceable battery in their best straps.

Too bad Polar wasn't quite listening soon enough to keep some loyalty from a bunch of us fairly patient and extremely loyal customers. We paid some high prices to get the features we wanted, and had they moved more quickly to user-replaceable batteries and GPS, they'd still have us. I think they are using foot pod technology for their speed info, which works for their main market, runners, but not for skaters, as far as I know. And their other main market, cyclists, have many ways to get good speed, cadence and distance data.

Would I still buy a Garmin Forerunner 305 for $200 tax included today? Yes. But I'd check into the 4xx series and take a look at what Polar is doing. I'd use it and live with the calorie info being inflated and try that firmware download. But where altitude data was extremely important, I'd probably bring along the Polar 720i too, or an eTrex Vista with some maps uploaded into it, if out in the woods.

One last thought is that some day the Forerunner may really save the day. I noticed a few weeks ago that on the way back along a route we were doing, it was mildly useful to see where the turns were. Even if not exercising, this alone might be worthwhile when visiting an unfamiliar place on skates or even in the car. 

Those are my thoughts as of today...revised, even.

MikeB's picture

Garmin 305 now worth the $$?

The cost of the 305 continues to come down making it more intriguing to purchase. Did the firmware download help with calorie count calculations? Hindsight being 20/20 - would you buy it again or upgrade to the 405? Maybe the 205 would be the best fit/value? Santa wants to know what I want this year. I've been pretty good. Probably good enough for the 305, not sure....debatable. There are a couple weeks left so perhaps the charms can come on strong and get me to the 405 level...(since I already have a football and a Red Ryder BB gun with a compass in the stock). Now there's a Garmin idea for us NC backroads skaters - a BB Gun with a GPS in the stock!....sure could use one when unleashed dogs are waiting on their porches for their next prey to come by.

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