Here’s a summary of a question from Chris D.: I overhear an accomplished triathlete (HI Ironman) giving advice to people who want to run a marathon to spend months running below a certain heart rate to “build a big engine”. “It’s all about aerobic capacity.” He states you will get faster and faster at that heart rate. Even if you are out in the heat (which as you know will elevate the heart rate), keep your heart rate low by walking if you have to. But keep it below the magical number. You can do speed work but only in the last 2-3 months before the marathon. He advocates no more than 40 miles per week but this is all directed at decently accomplished half-marathoners (sub-2:00). What exactly is the training effect of running at a low heart rate for several months doing say 30-40miles/week? Does it indeed build a better engine? I know it won’t help you run fast, but will it help you run a marathon or Ironman or similarly long distance event where you need to remain relatively deep in the comfort zone?
If I were to take the analogy of a big engine as posed – then 16-wheelers would be the fastest vehicles on the road. To take another angle, let’s say he is building a bigger “gas tank” with his advice. Again it fails because he may have a 15 gallon tank and I may have a 12 gallon tank but if he only gets 10 miles per gallon and I get 20 then he will get 150 miles on his tank and I will go 240. So, let’s ditch the faulty analogy.
Let’s start with some related research data on world-class marathoners:
The best correlation between finishing times and training was – average training workout pace.
That means that the runners with the fastest average overall workout paces ran the fastest marathons.
The fastest marathoners run up to 30% of their miles at about 10k pace or faster each week.
And for everyone who is not elite here is one tidbit: VO2max is a poorer predictor of actual performance (race times) than lactate threshold, vVO2max and even sprint times (50-300 meters depending on the research study) for distance runners!
Slow training at distances shorter than the marathon teach you to run slow for less than the marathon. Miles of training improve your ability to process oxygen (VO2max). However, VO2max is a poor predictor of performance. Heart rate is a worse predictor of performance – almost no correlation to running times. The critical training ingredients need to train you neuromuscularly (specific to distance and pace), improve lactate threshold and improve efficiency.
So, here is what needs to happen in your training. Teach your muscles to fire powerfully and economically (use less energy/oxygen); and improve your lactate threshold (LT) and vVO2max (good predictors of performance at most distances 800 meters and longer). The research is pretty good on the LT topic. You have to run faster than your LT to improve your LT, not at that pace or slower. vVO2max is a better predictive measure than VO2max (it includes efficiency elements). Improvement in power and race pace economy are attained through goal paced running (not slow jogging) and high powered paces (just a bit slower than 10k pace up through sprinting). Powerful muscles developed through high quality running and running specific plyometric type training which yields more muscle cells (not bulk). This means less cells are needed to maintain given paces. Strength gained at specific speeds is generally transferable to slower speeds but not vice versa.
To answer your specific questions: Running as an exercise (like cycling and swimming and aerobics) generally reduces resting heart rate and as you get in better condition your heart rate may end up lower for a given effort. There is no such thing as a magic heart rate number. Your marathon “comfort zone” will be improved through the process of conditioning. Yes, if you go from sedentary to moving, you will improve greatly at first just from running – easy OR fast. However, the more seasoned you become the less this is true and the key to improvement is in WHAT you do with the miles (increased percentage of quality miles) more than how many miles you run. Therefore, his advice is way off base for these sub-2:00 HM runners.
So let’s sum up how you get faster at the marathon (or half marathon):
1. Lactate threshold – a good predictor of performance – is improved through faster than LT pace.
2. vVO2max – a good predictor of performance – is improved through high quality training.
3. Efficiency is gained through progressively higher percentage of goal paced running (your actual target marathon pace).
4. Efficiency is gained through high quality running which flows down to all slower speeds.
5. Efficiency is gained through powerful muscles which is gained through fast running and plyometric type training.
6. Long runs improve your ability to run the distance.
1 + 2 + 3 + 4 + 5 + 6 = overall high quality training yields faster marathon times.
Those long runs only have to be done every 2-3 weeks NOT every week!