Is 220-age accurate for MHR?

Short answer...no.

Longer answer...the best method to establish your training zones is a clinical AT/LT test but that costs a few $100 and you need to find someplace to do it.  The next best option is to go out and test your HR max for both running and biking and then dig through the multitude of sometimes conflicting information to figure out exactly how you should set your zone limits...or just read a few threads because I went through all this back in the winter

http://beginnertriathlete.com/discussion/forums/thread-view.asp?tid=18173

http://www.beginnertriathlete.com/discussion/forums/thread-view.asp?tid=12470

220-age is usually a reasonable guesstimate.  But individuals can vary widely from this formula. 

The test for yourself could be done on a treadmill or a hill.  Basically after warming up, you push yourself harder & harder 'til you can't go anymore.  See where your HR hit.

Sounds like fun, huh?  It is probably best to go with the formula to start if you don't have the base to try such a test.

Eventually you may want to try to estimate your lactate threshold HR which is a better metric to use to establish your traiing zones.  One way to do this is a time trial of 30-60 minutes (could use a 10k) and use your average HR as your LTHR (some say to take the average after the first 10 minutes).

+1

You can also determine your training zones using the triathlete training bible

Not so much injury unless yo push too hard too soon.  It's more a matter of being patient while your body builkds the ability to efficiently ustilize fatty acids for fuel, builds mitochondria, builds capilary density...all benefits of training in and below Z2.  Going above Z2 on a regular basis before you've built that base can sobotage your efforts.  I've got some articles around somewhere that explain the technical aspects but basically during early season base work it's very important to stay in the proper zone for best results.

You'd be better off actually testing your HR max on the bike also...same basic concept as the run test although finding a place to do it is a little more difficult unless you have a trainer...or a velodrome handy

Understandable...but be careful not to confuse my apparent conflicting lifestyle choices with a lack of knowledge on training and nutrition.  Yes, I enjoy a smoke from time to time and sure, it must have some negative impact on my health.  But I could walk away from smoking tomorrow if I wanted to.  Like I said in the other thread...it could easily be weeks since my last smoke and the thought wouldn't even cross my mind.  Fact is I enjoy a smoke just like some people enjoy a beer when they get home from work.  I personally drink very little...even when I'm out at a bar or party.  Everyone has those things that they take pleasure in for whatever reason and chances are that whatever it is could be bad for your health overall.  I tend to believe that most anything is fine in moderation (within limits of course).  So while I understand how my dirty little habit might make you question my advice, please look over my training log and my diet journal and decide for yourself if I know what I'm talking about.  I'm not claiming to be the best triathlete around or trying to brag about my abilities but I think you'll see that I am a serious triathlete that has taken the time to research and learn what I can about training and nutrition and I enjoy passing that info along to others if it can help them improve.

Back to HRM training, this is my first season ever using a HRM but I can tell you it certainly works as advertised.

Here is a quote from Dr. Maffetone regarding the 220-age formula:

"This old formula contains two errors.  It assumes that 220 minus your age is your maximum heart rate.  In reality, most athletes who obtain their maximum heart rate by pushing themselves to exhaustion will find it is probabaly not 220 minus their age.  About 1/3 find their max to be above, a third will be below, and only 1/3 may be close to 200-their age."

I won't go onto quote the other error he talks about as it is not relevent to the discussion at hand I don't think.

Does anyone know how to determine thier zones based on VO₂ max?  I got mine clinically tested as a freebie but have yet to figure out how to use it.

Isn't that test just a "blow a gasket" test?!  Man, I didn't think I ever pushed that hard before, not even a dead sprint at the end of a 5k...well ok...maybe then. 

That's great!  Now you can get your HR zones right on the money.  I'll ask my coach how he interpreted my data to determine my HR zones from my V02 max data and get back to you.

Let me know:

1. your V02max
2. what percentage of V02 max your LT was
3. what your HR was at your LT

you can just PM me the info if you like.