It didn’t seem that hard, I was going about 25 mph in a pack full of riders. However, when I looked down at my heart rate, I was surprised to see 168 looking back at me. I felt fine and my breathing was steady, so what gives? I glanced over at the guy next to me who also had a heart rate monitor on his bars – 132 … crap!
Under ‘normal’ circumstances, 168 would have me breathing hard. But here I was, cruising around feeling fine. After adjusting my chest strap to make sure it wasn’t faulty, I realized what the issue was – I was out of (aerobic) shape!
Performance-based metrics such as heart rate, power (cycling), cadence, etc… have limited value in isolation. The true value of these metrics occurs when they are correlated with other metrics. My rate of perceived exertion (RPE) on a scale from 1-10 in the example above was around a 4 or 5. When correlated with RPE, it makes no sense. I should have been at a 8 or 9 RPE. So what gives?
In this scenario, the problem was that I was aerobically out of shape and therefore I was more or less relying on my anaerobic capacity to get me through it. And the reason why it felt so easy, is because the absolute effort I was putting in wasn’t that high. As I got into better aerobic condition during the year, my heart rate dropped while going the same speed and riding at the same RPE.
YOU’RE ON BORROWED TIME
When your body is primarily reliant upon the anaerobic energy system, you’ve got about 90 minutes tops before the bottom falls out. Therefore, ‘faking’ it through workouts or races when your aerobic capacity sucks is only really possible during short races.
As noted below, you’re also limited on how fast or hard you can go. As your heart rate can only go so high, when you’re aerobically deconditioned and you pick up your intensity, your heart rate tends to elevate rapidly instead of gradually – as typically occurs with someone who is aerobically conditioned. Therefore, if you pick up the pace dramatically, the result is usually that you blow up. Additionally, since you’re not in good aerobic shape, it will take a long time for your heart rate to drop back to a level which will allow you to continue exercising at a sustainable effort level.
In my case, it probably would have been better to drop out of the race and cruise around on my own at a much lower heart rate. However, in my situation, I didn’t even get that far. As soon as the pace picked up dramatically, my heart rate did as well as I was dropped. I went from feeling great to horrible in a few seconds. This is another hallmark of being aerobically deconditioned.
Early season or anytime you are aerobically unfit, paying attention to your heart rate is helpful. One of the biggest mistakes athletes of all levels make is that they go too hard when they should be going easy. Why? It’s humbling. It’s not fun to ride your bike uphill at 8 mph getting passed by everyone because you’re trying to keep your heart rate at a manageable level. In order to do so, you must focus on the long term, not the short term.
NOT ALL OLD TRAINING METHODS SUCK
There is a lot of new data that states that early season base building is a waste of time and that it’s largely a myth that has been passed down from the pro ranks to us amateurs. While there is some truth to this, the reality is that if you are deconditioned, going easy to build up your aerobic threshold is never a bad idea.
Critics of this theory will point to the fact that the rest periods during intervals or hard efforts are aerobic in nature and therefore you get the best of both worlds. Again, this is true but depending on the level of one’s aerobic deconditioning, intervals might not be possible and even if they are, they still might not be the best course of action.
In closing, if your speed, RPE, heart rate, power and whatever other metrics you use to track your performance aren’t seeming to correlate accurately over a period of time, you’re either having a bad day and likely need rest, or perhaps your aerobic engine needs a bit of attention.
It should be noted that some individuals have naturally high heart rates. As such, the above information may not be applicable to them.
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