There are many reasons why training with power is more effective than heart rate, first of all being the influences other factors have on your pulse. I currently take daily medication which gives me an elevated pulse, so if you were to measure my resting heart rate you would have to heart rate app do it in the evening right before I take the next daily dose of medication. This will already give an influenced result as, what most people will tell you, if you take your pulse in the evening you are taking into account a days' worth of work, exercise and so on. However, my pulse is even faster still in the morning, meaning another influenced result.
But if you don't take medication that elevates your pulse you'll be OK? Well even if you can measure your resting heart rate you may have other influences that occur when you exercise. So you measure your pulse to determine what zone you should train in. What about diet, amount of sleep, daily activity amount, stress, sickness, I could go on. If you work 9-5 Monday to Friday, in a high pressure job you may always get a reading higher than what would be considered normal for the time of day you check it. So if you use your pulse to test, or check, which zone is appropriate for you to train in you may never get a reading that suggests that you are capable of training in a high heart rate zone.
Even if you don't use your pulse to determine what zone to train in, the factors that influence your heart rate, as mentioned above, will have the same affect when you begin to exercise. If you are stressed, tired, haven't eaten enough, or eaten too much, have a lot on your mind, and so on your pulse will be higher, and rise higher faster with exercise. This will mean you will find it difficult to train in lower zones, and analysis of your training will suggest you trained in a higher zone than you would be if you were rested.
Moving onto why training with power is superior. Firstly, power is not affected by the factors mentioned above. You maximum power output as measured in the Advanced Wattbike Tests I conduct will either rise or drop depending on how well you train. For example, my Maximum Minute Power (MMP) was 422 watts when I was last tested. This means if I want to train in zone 5 I would need to be training above 359 watts.
For those of you who don't really know or understand what "Zones", in terms of a training plan, are they determine the level of your training session. To start with you find your maximum heart rate and/or maximum minute power rate. With this you then set the "Zones" as a set percentage of the maximum, based on basic training principles. You are then left with an amount which you aim to achieve or maintain throughout your session. For example, on a recovery day, you will only want to train in zone 1 or lower, so if you take my maximum minute power of 422 watts, during a recovery ride I will not exceed 190 watts. If I wanted to train hard using fast short intervals I would use higher zones, and this is the basic principle of training plan zones.
I'm not looking at my heart rate to set my training zone therefore none of the outside influences are affecting my ability to train. I simply jump on The Wattbike and conduct a series of intervals that are above 359 watts. Job done, and with time my MMP will increase due to the training I am doing, which moves me on nicely to my final point.
Measuring and Testing using heart rate is difficult. Not only are there the influences mentioned above to factor into performance testing, but your maximum heart rate should not get faster. If it gets faster you probably weren't going hard enough during your initial test. Maximum heart rates drop as you get older. So what you are looking for when testing using heart rate is a higher quality or faster time or distance covered at your maximum heart rate. Confused? Well it gets worse. As your heart rate will drop with age any performance tests you do to measure improvement at your maximum heart rate will be off due to the fact you can no longer reach your previous maximum heart rate. There must be a simpler way?
Measuring and Testing using power is easy. As I mentioned above my Maximum Minute Power when I last tested was 422 watts, but what was it when I was first tested? I first managed 402 watts, so in the time I have been training I have improved my MMP by 20 watts. This shows positive movement without having to mess around with maximum heart rates. What this means to me is I can change my training heart rate app zones to account for the improvement I have made, thus maximizing the effect of my training yet again. What this actually means on the road will be seen this year, but if my times on Strava are anything to go by it should be a good season for me.
I do use a heart rate monitor to check my effort. I have both an Ant+ and a Bluetooth monitor, and this will be the subject of next week's review. But I don't let it rule my training and it is just to see how hard my heart has pumped. It can also be useful if you can see your pulse on a unit, i.e. Garmin, in front of you so you know when you are likely to rack in a sustained effort like a time trial or long climb. But that's the extent of my usage of heart rates.