I have been wondering lately why I can run 400m easily in 1:10 or 800m in 3:00mins, but I can barely run a 10k in under 55 mins. I know there's a big difference between 400m and 10,000m, but I feel like I should be a little faster. After many weeks of research, I think I have finally found my problem. I have a very weak aerobic system.  When I look at McMillian running calculators predicted race paces after plugging in my 800m time this is what I get: 

These time are predict if I'm correctly trained. I have never been able to run any of these times for any of the races listed above. I think because I have always been a sprinter, I have the speed, but nothing to back it up with. 

In my research I discovered MAF Training. the basis of this training is to run at you 180 formula heart rate This formula was developed by Dr. Philip Maffetone. 

The 180 Formula

To find the maximum aerobic heart rate:

1.Subtract your age from 180 (180 – age).

2. Modify this number by selecting a category below that best matches your health profile:

1. If you have, or are recovering from, a major illness (heart disease, high blood pressure, any operation or hospital stay, etc.) or you are taking medication, subtract an additional 10.

2. If you have not exercised before or have been training inconsistently or injured, have not recently progressed in training or competition, or if you get more than two colds or bouts of flu per year, or have allergies, subtract an additional 5

3. If you’ve been exercising regularly (at least four times weekly) for up to two years without any of the problems listed in a or b, keep the number (180 – age) the same.

4. If you have been competing for more than two years duration without any of the problems listed above, and have improved in competition without injury, add 5.

For example, if you are 30 years old and fit into category b: 180 – 30 = 150, then 150 – 5 = 145.

So my MAF HR is 152. You are supposed to give yourself a 10bpm range, so my range is 142-152.

To start this training you do a MAF test, in which you warm up for 15mins then run at your MAF HR for you desired distance. You are never supposed to let your HR go above this number. You repeat this test on the same exact course every 3-4 weeks to see your improvement. 

I performed this test today, and let me tell you. I was served a hearty helping of humble pie. I honestly felt embarrassed with how slow I had to run jog. I think a lady with a walker blew past me. My test results were as follows:

Mile 1 - 11:53

Mile 2 - 11:17

Mile 3 - 12:12

Mile 4 - 13:08

Average pace 12:10/mi and average heart rate 151

As you can see I was keeping it really close to my MAF HR. According to Dr. Maffetone, it is normal for the mile paces to decrease every mile. During mile #1 I was running downhill, and the final mile was uphill. 

I have been running at a low HR for the past week and so far what I have noticed about this type of training is:

1. I sometimes have to walk uphills to keep the HR down
2. My legs get really tired during these runs.
3. It is going to take a lot of patience and discipline to keep up the slow pace

Regarding #2, it's weird that my legs are fatiguing. The only reason I can think of why this may be happening is because my slow-twitch muscles are not used to being activated.

I am putting a lot of faith in this training. I guess I technically have nothing to lose. I'm not an elite athlete that has to be ready for some big race. I am training for a half marathon in April, so I am kind of training backwards, but I will need the aerobic strength to complete the race. It will be my longest race to date. I hope to come in under 2 hours, but it is a soft goal.

Have any of you trained at a low HR?

What were your results?