Friday, May 18, 2007

Bio-Med in the year 1979

Now that is a catchy title but only to someone who in 1979 bought one of those original baton shaped heart rate monitors with the very tiny red LED display which ate 9 volt batteries at the rate of one every 3 weeks (The price may have been about $300). Owning a number of different models since then and collecting a lot of data on different runners, what can be said about heart rate monitors for training?

1) During volume repetition workouts (aiming for 3 or more miles worth) the best results to prevent over training are achieved if the HR gets to a bit over 90% of maximum at the end of each repetition (and not go much higher during the any of the reps) and returns to a fixed level (say 120 or 130) before the next rep. If either of those two (the end of the rep HR or the rest level HR climb, that's when to end the work out whether it is 2 reps or 10). In other words what Arthur said about not running the intervals too intensely (which causes the repetition HR to stack) and quiting when you had enough (the HR does not return to a fixed 120-130 in the given time) still is the best advice (even without the HRM)

2) An elevated HR or a depressed HR on a distance run means you have not recovered fully from a previous workout. Sounds inconsistent, it's too low, it's too high and it means you're fatigued. I've seen it too many times in too many athletes to be a quirk. What I think is going on is the first type of fatigue is caused by calling in new muscle fibers which are not as efficient causing a greater demand on the heart and the other is when there are not enough fibers to call on which means the fibers don't fire and the demand on the heart stays low because nothing is creating a demand.

3) Picking a set heart rate for a distance workout can cause under training or over training. Under training is not bad but many athletes are fooled into over training by picking a level (75% Max HR) and running at that level. Running at 75% max HR can be over whelming to the muscle fibers if they have not been conditioned properly, yet if they are conditioned properly running at 85% max HR may not be a high enough load for improvement to the muscle fiber.

Training properly is more than picking a number (whether it is miles, a certain pace, a percent heart rate,etc) it is studying your reaction to that number . So for heart rate monitors noting when some heart rate is not expected is is a good use but as a device to set goals for your training they are of limited value.

Mike's HR test of yesterday was just a baseline test to see where he is as of the start of base training, in 4 weeks (when we repeat it) he should have a faster pace with the same HR if not maybe the pace of the workouts needs to be slowed down to allow the fibers to adapt more efficiently. Of course getting Mike to wear bunny ears during his running is easier than getting him to slow down.

5 comments:

Marc said...

Thank you very much for this most informative post!

D said...

Very interesting and enlightening post.

Love2Run said...

Very interesting. I've had the depressed hr when fatigued and thought it was kind of weird, but now it makes sense. Bunny ears would be cute.

Greg said...

I've been wearing a monitor for 18 months and your post encapsulates a lot of what I've learned from experience. The lower heart rates when I was tired was the most surprising, but I've seen it a number of times. When I'm a little tired, my heart rate is elevated for a given pace, but when I'm very tired, it's lower. The effect can be pretty dramatic. I've run a 10K at 176 bpm average when I was tired and then run an equivalent 10 mile time averaging 183 bpm when i was well rested.

I've also found getting enough recovery during intervals is necessary or I get the stack up you're talking about. The first indicator is that I can't get my heart rate down during the warmdown (it might be 15-20 bpm higher than the warmup at the same pace). If I overdo on intervals on Tuesday, I find it hard to do a tempo run on Thursday. Watching my heart rate is a good way to avoid that.

Your third point is a good one as well and I think is a common misperception by those who are "anti-HRM" (for lack of a better term). All those wearing HRMs aren't robots rigidly following a heart rate zone. I use it as another bio-feedback device (like noting your breathing). I know something is different when everything doesn't match up (like my pace doesn't match my usual heart rate, or my breathing is hard for the same heart rate, etc.). Often times having a number is a good way of confirming what you already know but don't want to admit to yourself.

Mehalia said...

People should read this.