Monday, April 7, 2008

Analysis of Heart Rate vs Effort

So I decided to wear a heart rate monitor for Cherry Blossom to try and help determine/undestand what goes on inside the body during a race. The figure on left shows average heartrate during each mile of the race vs mile pace as the race progressed.
(1) The average hr for the first mile is low compared to the others since the heart jumps from 100 bpm to 175 bpm in the first mile

(2) Even though pace and effort were maintained throughout the first five miles, heartrate slowly increased. A quick Google searched revealed the increase in heartrate may be attributed to Cardiac Drift. During long and strenuous workouts, the heart has a tendency to beat slightly faster even though you do not feel as if you are working any harder—this is called cardiac drift, or cardiac creep. The heart rate increases even for the same effort expended because as you sweat, your blood volume decreases due to fluid loss and also your heart tries to do its part in regulating body temperature.
(3) At the 5 mile mark, a decision was made to pick up the pace just a bit to see where the heart rate would go. The graph shows an increase in the heart rate change right around the 5 mile mark (a slight upward bend in the slope)
(4) In the last mile of the race, heart rate peaked to 191! A slight downward bend for the last mile may reveal a tipping point, where heart rate begins to decrease (resulting in a slower pace) or levels out (also resulting in a slower pace). Using a heart rate tipping point of 187, taking cardiac drift into consideration, and assuming weather/course are very similar, a 5:41 pace should be maintainable for 13 miles (1:14:30 HM)


Peter said...

Mathias, that is really interesting. I think you may be an aspiring Jack Daniels. What kind of heart rate monitor do you use? I need to see if I can download that kind of data from my Polar F6.

P Murph said...

Speaking of HRMs, I have yours Matias. Wed. night is a good night for me to bring it to you if that works.

Melissa said...

Very interesting. Thanks for sharing.

Matias said...

Talks are brewing about a workout at Hains Point on Wednesday, the cyclists have a 1k marked off. If there's any interest, we're meeting on the corner near the tennis courts at 6pm for warm up, roll at 6:30. We can start later if it's more convenient. PM, I can swing by your place after the workout on Wednesday.

Peter, bought a Suunto HRM off