Thursday, January 17, 2008

The Heart of It

In the past week I have gotten three of the same questions from athletes about heart rate.

In each case, the athlete had been reading other blogs. And they read that some athletes are training at higher heart rates or have higher heart rate zones. So they started to wonder if something was wrong with their heart rate because it wasn’t as high or if it indicated they were not as fit.

The answer is no.

Heart rate is highly individual. Meaning that two individuals of roughly the same age, fitness level, even gender will not have the same heart rate. Maximum heart rate is determined mostly by genetics. Your heart rate on any given day can be influenced by dehydration, altitude, age, fatigue among other things. But max heart rate likely will not change.

Having a higher heart rate (or higher heart rate zones) does not indicate a higher level of fitness or speed. Let’s see how this works:

Two males, roughly the same age, both fit. One is my husband, the other is a friend I have coached for a few years:

Chris’ max HR on the run 192 bpm
Marcus’ max HR on the run is 154 bpm

If you look at warming up in the Zone 1 heart rate zone – Chris is still in Zone 1 at 160 bpm whereas Marcus is warmed up around 124 bpm.

What does all of this mean? Chris and Marcus are different people and therefore have different heart rates. The fact that Marcus has a lower heart rate has no impact on his speed as Chris and Marcus ran within 10 seconds of each other at the same 5K.

The variance in heart rate is amazing. How we can all be human but all be designed so differently. Here are some examples of how heart rate can differ:

Marcus (M30-34) = 154 bpm
TS (M60-64) = 155 bpm
The ELF (F30-34) = 184 bpm
Chris (M35-39) = 192 bpm
RK (F20-24)= 194 bpm

As you can see, there is quite a range that crosses the lines of age and gender. It is important to note that each of these individuals is very fit – and their heart rate is not an indicator of their fitness. And so, that is why comparing heart rates or heart rate zones doesn’t make much sense. We are all different.

Not only are we different in how we are built – but our efficiency and economy in each sport is different too. Meaning that I may be able to hold a faster pace in Zone 1 because I am more efficient – whereas another athlete may fatigue quicker because of form sending their heart rate into a different zone at the same pace. That is why you also cannot compare heart rate zones to another individual or even heart rate zones to pace.

It is important to also note that heart rate will vary by sport. Your heart rate in cycling may be 10 – 15 beats lower than running. Swimming may be 10 – 15 beats lower than cycling. This is not indicative of your fitness rather the work your body needs to do in each sport. Running is obviously the most strenuous, followed by cycling, and followed by swimming which requires no weight bearing at all (easier on the heart).

Keep in mind that heart rate will also fluctuate day to day. This is where those fancy little GPS watches can actually drive you nuts more than anything else. Yesterday I went for a run. There was a two-and-a-half minute variance in my pace in the same heart rate zone (Zone 1). Why? Well, there were hills, and wind, and it was cold, and I may have been tired, or……who knows. This is why it is difficult to use both pace and heart rate in the same training session. There is a time to obsess over pace – that is on the track, on a tempo run, on a long run, during time trial intervals. All other runs and rides – let it go. Go by heart rate, go by time – let go of distance and speed.

Other factors: Heart rate is also affected by hydration. If you find your heart rate goes up the longer the workout goes on – you are likely not hydrating enough. Heart rate is also affected by fatigue. If you cannot get your heart rate up, you are likely tired. Back off or call it a day. Heart rate is also affected by distance over time. If you are on hour number 5 of a 7 hour ride my guess is you are stuck somewhere in Zone 2. There is a limit as to how long you can work in Zones 3 and above.

In sum, it’s not that your heart rate will go higher as you get fit. Rather it is your ability to produce more work output at that same heart rate. As you become more fit, you can essentially go faster at any given heart rate. You teach your body to do this by training appropriately in your zones; this is why building aerobic capacity and efficiency in Zones 1 – 2 at this time of the year is so important.

As athletes, I know we have strong feelings about numbers. To some extent, how fast and far we go is a measure of our self-worth in sport. It’s important to us. But at times you just have to let it go, accept that it will change (day to day) and some days you’ll be fast and other days you’ll be…slow. Day to day numbers don’t matter. And the best athletes let the numbers go. They realize that it is patterns and consistency over time that count not numbers from each swim, bike, run.

Be cautious about comparing numbers across blogs. The nuts and bolts of another athlete’s training doesn’t really have much relevance to anyone else – except that athlete. Numbers really don’t mean much. What counts is what you do on race day. I have never shown up to a race and known that it would take a xx:xx 10K to win. Pace, numbers – don’t really count. What counts is how you respond to the race day – the conditions, the weather, the competition and yourself.

The next time you train – rather than worrying how fast how fast how fast how about worrying about how to climb that hill more efficiently or correct flaws in your form or smooth out your pedal stroke or have someone watch your swim stroke. Added up these are things that will make you fast in numbers. That is how you get to the heart of getting fast.

7 comments:

Benson said...

Great information. We're all little freaks of nature.

brandon said...

Thanks!

Conversely, can a person's resting heart rate be used as an indicator of fitness? Do you have the RHR for those individuals you listed?

~B

E.L.F. said...

Great question! Most fit endurance athletes find their RHR is b/w 40 - 60 bpm. It is also not unusual and not problematic to find it as low as in the 30's. Keep in mind RHR is highly variable and individualized meaning lower is NOT necessarily better or fitter. It's just the way your RHR is. RHR is influenced by genetics but day to day is influenced by both physical and psychological stress. Keep track ofchanges in your RHR over time. If you are usually in the 40's and wake up a few morning in the 60's you are likely sick, fatigued or even overtrained. A better indicator of fitness if your Recovery Heart Rate. In other words - how quickly does your heart rate fall in 60 seconds. Highly fit athletes may see a decrease of 50 beats in that one minute (of course assuming that this was a HIGH intensity effort they were recovering from). This indicates how quickly your heart rate can recover from a harder effort. Watching this number over time is an indicator of your fitness and how it changes (more fitness typically leads to quicker recovery).

~Robyn~ said...

HR is also affected by medication don't forget! I am on asthma medication constantly and it tends to make my HR a bit higher than "normal" people who are as fit as me. Just some input from teh peanut gallery over here in the exercise science dept :)

Bob Mitera said...

Liz - GREAT blog entry! I am getting my A$$ kicked all winter by people I beat easily in the spring, summer and fall.

RHR = 48
Recovery in 1 min after a run 54 bpm

IronMin said...

As always, you have a way of explaining these things in a way that makes total sense! Thanks for putting this out there. It clears up a lot of confusion.

Jason said...

The heart rate monitor is only tool. As with all tools, they only work well if you know how to use it properly. The numbers don't mean much if using them doesn't result it getting faster in the long run.

Good explanation.