Heartrates tend to be lower in races, even when going all out?

wrist heart rate monitors are inaccurate

Maybe youre in good shape but just need to build up your leg power more so you can race at higher intensities, your heart may be ready to handle those faster paces but your legs aren’t powerful enough to hit them. If this is the case, hit the hills, sprints and weights.

Update: just read the thread properly and saw that youre using a garmin so I’m no longer taking you seriously. Garmins don’t and cannot measure heart rate data accurately, why anybody uses those things to track HR I do not know. Throw the garmin out and check your pulse real time instead.

Correction- if it makes a difference, garmin 235.

I have also noticed this a couple times. To the posters who said wrist monitors aren't reliable, yes, I know they aren't as reliable as chest straps; However, they have improved a bunch in the last couple years and if worn correctly can track the HR close to the correct number. I had two races where my HR on the warm up and cool down was right where it always is, but my 3200 race had a high of 168, when my max is 200. I find it hard to believe that my watch worked perfectly all day and then happened to not register correctly just for the race.

Your stroke volume/plasma volume was higher, thus your heart rate was lower.

metoometoo wrote:

I had two races where my HR on the warm up and cool down was right where it always is, but my 3200 race had a high of 168, when my max is 200. I find it hard to believe that my watch worked perfectly all day and then happened to not register correctly just for the race.

There are a couple of differences between jogging and racing that might affect a wrist HRM. You're moving your arms through a wider range and the force of impact comes faster, which could be moving the watch a little away from your wrist and that affects the reading. If you tighten the watch more, it might restrict circulation, which could also affect the reading.

During a race, blood flow to the hands can be reduced as your circulatory system shunts more blood where it's needed most.

The bottom line is your wrist HRM isn't getting the job done during a race. If you want accurate HR readings, get a compatible HRM chest strap off eBay.

Interesting. This makes sense, but it hasn’t happened in fast workouts, such as 800’s at 3200 pace.

Could you explain why this would happen and what to do about it?

I know some watches are unreliable, but you might want to consider what your hear is actually doing when you run. There are several variables.

Fisky's right, it's easy to see why it won't being reading correctly for a race. I'll add that chest straps also suck, almost all of them. If not right away, they become unreliable after a few weeks of wear, especially the soft styles. The old school Polar rubber ones might be the exception. The sure thing is the stick-on electrodes that are used institutionally, but they are not mobile (have wires).

Anyone getting readings that seem odd or don't make sense should default to assuming that the watch or strap is glitching, rather than assuming their heart is doing odd things. It's just that much more common. Of course, if you're not in a race, you should verify odd readings with a finger to pulse count (a 6 second count x10 is accurate enough).

Faulty readings are one thing, but stroke volume is variable and it affects your heart rate for a given effort.

don't ask a cardiologist, he won't know, but.... wrote:

Your stroke volume/plasma volume was higher, thus your heart rate was lower.

What causes higher stroke/plasma volume?

Mine too. It’s because the Garmin 235 hr monitor is a piece of sh*t

You might as well pay a 5 year old to measure your heart rate and that will be more accurate

In 800 meter interval workouts you will top your heartrate at the second or third 800, the intervals will make it possible to have a higher rate than for steady running, especially if your race is a 1500 meter or more.

If the reading is at the highest when cooling down I guess the watch picks up your cadence and / or read both outgoing and ingoing bloodstream.

I use a cheststrap n the winter and if I want more precise readings, just be sure to moist the strap to avoid electrical disturbances, in the summer it is a hazzel and I am happy about my wristreading then, just need to be a bit more aware of possible misreadings, which are not a lot (it is a Garmin Fenix 3).

moreplease wrote:

don't ask a cardiologist, he won't know, but.... wrote:

Your stroke volume/plasma volume was higher, thus your heart rate was lower.

What causes higher stroke/plasma volume?

Two things:

1, Training more/ sweating more, so you store more water. Plasma is around 90% water. Plasma volume can vary a lot and you notice this when you run more and your resting and working heart rates go down over a period of a fews days or weeks. And conversely sweating less does the opposite. Advantages and disadvanatages of this is dependent on the climatic conditions and the length of your race.

2, Getting older. Young people have higher heart rates. Older people have lower heart rates. I think older people retain blood volume more but the subject is under researched.

At some point we are all going to lose cardiac output (heart rate x stroke volume) but this probably happens around the same time that we lose muscle and bone mass, which is why a runner on another thread can retain a very high VO2 peak at age 54... Partly training and good health, mostly genetics.