Wow, do you open up a can of worms when you tell people to train at high intensity. There are a few very basic and simple points to the intensity portion of this recipe.
- Intensity is relative: What is "heavy" to me and what is "heavy" to someone else may not be the same and what is "fast" likely isn't either. For this I generally give 2 analogies
- If you are lifting 100 pounds and your technique is no good, then it's probably a bad idea to try to lift 200 pounds. That seems like a no-brainer but you might be surprised at what your ego can get you to do if the person next to you is lifting 300 pounds.
- Nobody learns to drive a car 150/mph on the freeway. You need to go through the steps of getting comfortable operating your body just like a car. So start out doing laps around the parking lot, and then when you're ready you can venture out into the neighborhoods and main roads. Eventually you'll make it to the freeway. Maybe you'll even become a race car driver
- Intensity is why this works: Long ago "fight or flight" was hard-wired into our DNA. It helped keep your ancestors alive. For example, if you were being attacked by a wild animal would you wouldn't jog away it would be a full sprint. If you were being mauled you wouldn't kind of fight back, it would be with every bit of strength you could muster. Those kinds of stimuli are powerful, and if you're successful your body will make very quick adaptation to help ensure further survival should you face that again. The intensity element in CrossFit works much the same way. We want intense because it kicks adaptation response into high gear. We just want it relative to good technique and control like we talked about in point one.
- Intensity is the easiest way to measure progress: So much of CrossFit is measuring. We want to know what we're capable of so we track a few variables and compare as we progress.
- Work: Mass X Distance
- Power: Work / Time
So if we consider an example where a person walked a mile in 20 minutes, jogged a mile in 10 minutes, and sprinted a mile in 5 minutes; in all 3 examples the same amount of "work" is being done as the same mass is travelling the same distance. Because in each example the speed is cut in half, then the power is being doubled. By tracking how long it takes to perform a fixed task, and by tracking how much work you can perform in a fixed time, and by diligently tracking the weights you lift on your strength work you can see your progress in a very clear and tangible way. This gives a more meaningful way to see our bodies beyond the number on the scale.